JP2016203897A - Steering control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steering control device capable of suitably detecting whether or not a driver places hands on a steering wheel.SOLUTION: An EPSECU controls the operation of an EPS actuator of a steering auxiliary mechanism of an electric power steering device. The EPSECU comprises: a periodic operation generation part 80 for calculating a pinion angle control quantity Tp for giving a change of a sin waveform to the downstream side from a torque sensor of a steering shaft by the EPS actuator; and a steering state determination part 60 for determining whether or not a driver places hands on a steering wheel on the basis of steering torque τ detected by the torque sensor when the change of the sin waveform is given.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a steering control device.

  Conventionally, a system for supporting driving of a vehicle is known. While such a driving support system is effective in reducing the driving load on the driver, the driver is in a state of letting go of the steering wheel because he is overconfident in the system. In this case, for example, in the case of a system that stops driving support in an emergency, it is not possible to respond by manual steering immediately after the stop. Therefore, in a system that supports driving, it is required to detect whether or not the driver is working on the steering wheel so that stopping driving can be considered in an emergency. As a method of detecting whether or not such a driver is putting a hand on the steering wheel, the method described in Patent Document 1 is known. Patent Document 1 discloses that an actual steering state, a steered state, and a hand-off state are detected according to a work amount obtained by integrating a product of a time differential value of a steering angle generated in a steering wheel and a steering torque generated in the steering wheel. Has been.

JP 2004-175122 A

  By the way, in the case of the method of Patent Document 1, whether or not the driver is placing a hand on the steering wheel when the vehicle is moving straight and the steering wheel does not move so much that the steering wheel does not generate much steering torque. It is difficult to detect. Therefore, there is room for improvement in terms of functional safety when assisting the driving of the driver.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a steering control device that can suitably detect whether or not the driver is placing a hand on the steering wheel. is there.

  A steering control device that solves the above problems includes a steering mechanism that includes a steering wheel, a steering mechanism that is connected to a steered wheel, and a steering mechanism and a part of the steering mechanism that are connected to the steering mechanism and the steering mechanism. A steering shaft that is provided on the steering shaft, detects a torque generated in the steering shaft, and a steering assist mechanism that applies an assist force to assist the steering operation of the driver to the steering mechanism or the steering mechanism. The operation of the steering assist mechanism of the steering device provided with is controlled. The steering control device includes a downstream control amount calculation unit that calculates a downstream control amount for periodically changing the state amount downstream of the torque detection unit of the steering shaft by the steering assist mechanism; And a steering state determination unit that determines a steering state as to whether or not the driver is placing a hand on the steering wheel based on the output of the torque detection unit when a change is given.

  According to the said structure, a periodic change can be intentionally generated downstream from the torque detection part of a steering shaft. Such a periodic change is detected through the torque detector. In this case, the driver is holding the steering wheel (the inertial force is applied by the driver upstream of the torque detection unit of the steering shaft) and the state where it is not (upstream of the torque detection unit of the steering shaft). The detection result of the torque detection unit appears differently from the state in which the driver's inertial force does not work. Thereby, it can be suitably detected whether or not the driver is placing a hand on the steering wheel.

In the steering control device, the periodic change is preferably a sin wave-like or cos wave-like change.
As described above, if only the point where the change is intentionally generated on the downstream side of the steering shaft is seen, it is possible to give a pulse-like change (including a rectangular shape) in addition to giving a sin wave-like change. . In that respect, as in the above configuration, a sin wave-like or cos wave-like change can be detected as an output of the torque detection unit rather than a pulse-like change because a continuous change and the width of the displacement can be relatively large. There is an advantage that it is easy to be done.

  In the steering apparatus, the downstream control amount calculation unit corrects the downstream control amount so that the downstream state amount of the steering shaft when the periodic change is given becomes a starting point of the periodic change. It is preferable.

  According to the above configuration, when a change is intentionally generated on the downstream side of the steering shaft, a sudden change with respect to the downstream state at that time can be suppressed. This makes it difficult for the driver to notice the intentional change given to the downstream side of the steering shaft. Therefore, when the driver is putting a hand on the steering wheel, the steering state can be determined without giving the driver a sense of incongruity.

  In the steering control device, the downstream control amount calculation unit calculates a target value of the downstream state quantity of the steering shaft, and performs feedback control for causing the downstream actual state quantity to follow the target value. It is preferable to calculate the downstream control amount by executing.

  In the steering shaft, while the steering wheel and the steered wheels are connected, there are resistance components such as friction related to the connection. Therefore, even if the target value of the downstream state quantity is calculated in order to intentionally generate a change on the downstream side of the steering shaft, the downstream state quantity target value is reflected as a downstream change as it is. Not necessarily. In that respect, as in the above-described configuration, by executing feedback control that causes the downstream actual state quantity to follow the target value of the downstream state quantity of the steering shaft, the change that is desired to be generated is This can be suitably reflected as a downstream change. Thereby, it can be suitably detected whether or not the driver is placing a hand on the steering wheel.

In the steering control device, the steering state determination unit preferably determines the steering state of the steering wheel based on a result obtained by integrating the outputs of the torque detection unit.
According to the above configuration, the accuracy of information for determining the steering state of the steering wheel can be increased by integrating the outputs of the torque detector. Accordingly, it is possible to improve the accuracy of detection as to whether or not the driver is placing a hand on the steering wheel.

  According to the present invention, it can be suitably detected whether or not the driver is placing a hand on the steering wheel.

The figure which shows the outline of an electric power steering apparatus. The block diagram which shows the control structure of the high-order ECU and EPSECU about an electric power steering apparatus. The block diagram which shows the control structure of the electric current command value calculating part about 1st Embodiment. The block diagram which similarly shows the control structure of the electric current command value calculating part about 1st Embodiment. The table which summarized the output result of each operation part about a current command value operation part. The block diagram which shows the control structure of the periodic operation generation part about an electric current command value calculating part. (A) is a figure which shows the waveform which the target pinion angle production | generation part produces | generates about a periodic motion generation part, (b) is a figure which shows the waveform of the steering torque extracted by the steering state determination part. The block diagram which shows the control structure of the steering state determination part about an electric current command value calculating part. The block diagram which shows the control structure of the electric current command value calculating part about 2nd Embodiment. The block diagram which similarly shows the control structure of the electric current command value calculating part about 2nd Embodiment. The figure which shows the outline of another model about an electric power steering apparatus. The figure which shows the outline of another model similarly about an electric power steering apparatus.

(First embodiment)
Hereinafter, a first embodiment of a steering control device mounted on a steering device will be described. The steering device according to the present embodiment is a column-type electric power steering device that assists a driver's steering operation with a motor. The assistance includes an automatic steering state that does not involve a driver's steering operation.

  As shown in FIG. 1, the electric power steering device 1 is a steering mechanism 7 that steers the steered wheels 12 based on the steering operation of the driver, the steering mechanism 6, and steering that applies assist force to the steering mechanism 7. An EPS actuator 20 as an auxiliary mechanism and an EPS ECU 30 as a steering control device for controlling the operation of the EPS actuator 20 are provided.

  The steering mechanism 7 includes a steering wheel 2 operated by a driver and a column shaft 8 that rotates integrally with the steering wheel 2. The steering shaft 3 is constituted by the column shaft 8 connected to the center of the steering wheel 2, the intermediate shaft 9 connected to the lower end portion of the column shaft 8, and the pinion shaft 10 connected to the lower end portion of the intermediate shaft 9. Is done. The pinion teeth formed at the lower end of the pinion shaft 10 are meshed with the rack shaft 5 (more precisely, the portion 4 on which the rack teeth are formed) extending in the direction intersecting with the pinion shaft 10. Therefore, the rotational motion of the steering shaft 3 is converted into the reciprocating linear motion of the rack shaft 5 by the steering mechanism 6 including the pinion shaft 10 and the rack shaft 5. Such reciprocating linear motion is transmitted to the left and right steered wheels 12 via tie rods 11 respectively connected to both ends of the rack shaft 5, whereby the steered angles of these steered wheels 12 are changed.

  The EPS actuator 20 includes a motor 21 and a speed reduction mechanism 22. A brushless motor or the like is employed as the motor 21 that is a source of assist force. The motor 21 is connected to the column shaft 8 via the speed reduction mechanism 22. The reduction mechanism 22 reduces the rotation of the motor 21 and transmits the reduced rotational force to the column shaft 8. Then, the steering operation of the driver is assisted by applying the torque of the motor 21 to the steering shaft 3 as an assisting force.

  The electric power steering device 1 performs rotation of the column shaft 8 in the steering mechanism 7 by performing motor rotation angle control of the motor 21 coupled to the steering mechanism 7 based on an automatic steering control amount Tg and an assist control amount Ta described later. The angle, that is, the steering angle of each steered wheel 12 is controlled (steering angle control is performed). The electric power steering apparatus 1 includes a host ECU 40 that is a host controller that transmits an automatic steering control amount Tg as a control amount for automatic steering to the EPS ECU 30 at predetermined intervals via the in-vehicle network 29 (CAN). The EPS ECU 30 generates the assist control amount Ta at every predetermined period.

  The EPS ECU 30 and the host ECU 40 acquire detection results of various sensors provided in the vehicle as information indicating a driver's request or driving state, and perform the motor rotation angle control according to the acquired various information. The EPS ECU 30 is connected to a rotation angle sensor 23 and a torque sensor 24 as a torque detection unit. A steering sensor 25, a vehicle speed sensor 26, and a GPS 27 such as a car navigation system are connected to the host ECU 40.

  The rotation angle sensor 23 is provided in the motor 21 and detects the motor rotation angle θm of the motor 21. The torque sensor 24 is provided on the column shaft 8 and detects the steering torque τ. The steering sensor 25 is provided on the upstream side (steering wheel 2 side) of the column shaft 8 with respect to the torque sensor 24 and detects the steering angle θs. The vehicle speed sensor 26 detects a vehicle speed (vehicle traveling speed) SP. The GPS 27 detects the upper position information θcon of the vehicle.

  A torsion bar 8 a constituting a part of the torque sensor 24 is inserted into the column shaft 8. In the torque sensor 24, the steering torque τ is calculated based on the relative rotational displacement generated between the upstream side (steering wheel 2 side) and the downstream side (steered wheel 12 side) of the torsion bar 8a. A rotation angle sensor 23 is provided on the downstream side of the torque sensor 24 (torsion bar 8a). That is, the rotation angle sensor 23 can be converted into a rotation angle (pinion angle θp, downstream state quantity) of the pinion shaft 10 in the steering mechanism 6 connected to the downstream side of the torque sensor 24 of the steering shaft 3. The motor rotation angle θm is detected as a quantity and functions as a downstream state quantity detection unit.

  The EPS ECU 30 is connected to a mode changeover switch 28 operated by the driver. By operating the mode switch 28 by the driver, a mode permission condition M, which will be described later, of the control mode of the electric power steering apparatus 1 is switched. The control mode of the present embodiment is a so-called automatic steering mode in which a steering force is applied from the motor 21 to the steering shaft 3 without depending on the driver's steering operation, and the steering angle θs is automatically changed according to the traveling state. Has a mode. The control mode includes a so-called assist control mode in which an assist force is applied as a steering force from the motor 21 to the steering shaft 3 in accordance with the driver's steering operation to assist the driver's steering operation.

  The mode changeover switch 28 designates a mode permission condition M for permitting an automatic steering mode and an assist control mode, respectively. When “0” is selected (designated) as the mode permission condition M by the mode changeover switch 28, the assist control mode is permitted only while the driver is working on the steering wheel 2, and the automatic steering is performed otherwise. Specifies that the mode is allowed. When “1” is selected (designated) as the mode permission condition M by the mode changeover switch 28, the automatic steering mode is permitted only while the driver is holding the steering wheel 2, and assistance is performed otherwise. Specifies that the mode of control is allowed. The mode changeover switch 28 has a function of detecting the driver's selection (intention display) and reflecting the driver's selection to the control of the vehicle.

  In the present embodiment, the steering state related to the steering operation of the driver is divided into an actual steering state, a steered state, and a released state, and the actual steered state and the steered state are “hands on the steering wheel”. State.

Next, the electrical configuration of the electric power steering apparatus 1 will be described in detail.
As shown in FIG. 2, the host ECU 40 receives the steering angle θs, the host position information θcon, and the vehicle speed SP as inputs. The host ECU 40 includes a host microcomputer 41 composed of a microprocessing unit or the like. The upper microcomputer 41 generates an optimum automatic steering control amount Tg based on the steering angle θs, the upper position information θcon, and the vehicle speed SP. The host microcomputer 41 transmits the automatic steering control amount Tg to the EPS ECU 30 at predetermined intervals based on the various inputs via the in-vehicle network 29 (CAN).

Next, each function of EPSECU 30 will be described in detail.
As shown in FIG. 2, the EPS ECU 30 receives the automatic steering control amount Tg, the steering torque τ, the mode permission condition M, and the motor rotation angle θm as inputs. The EPS ECU 30 includes an EPS microcomputer 31 including a microprocessing unit. The EPS microcomputer 31 outputs a motor control signal Sm such as a PWM signal. The EPS ECU 30 includes a drive circuit 32 such as an inverter circuit that drives the motor 21 to supply drive power based on the motor control signal Sm.

  The EPS ECU 30 is connected to a current sensor 33 for detecting a current value Im applied to the motor 21. The EPS microcomputer 31 of the EPS ECU 30 outputs a motor control signal Sm output to the drive circuit 32 based on the current value Im of the motor 21, the automatic steering control amount Tg, the steering torque τ, the mode permission condition M, and the motor rotation angle θm. Is calculated.

  The microcomputer 31 for EPS uses a current command value calculation unit 34 that calculates a current command value I * as a control target value for assist force applied to the steering mechanism 7 and a motor control signal Sm for controlling the operation of the drive circuit 32. And a control signal generation unit 35 for generation.

  The current command value calculation unit 34 calculates a current command value I * based on the automatic steering control amount Tg, the steering torque τ, the mode permission condition M, and the motor rotation angle θm. The current command value I * is a command value indicating a current to be supplied to the motor 21. Precisely, the current command value I * includes a q-axis current command value (Iq *) and a d-axis current command value (Id *) in the d / q coordinate system. In this embodiment, the d-axis current command value is set to zero. The d / q coordinate system is a rotation coordinate according to the motor rotation angle θm of the motor 21. The control signal generation unit 35 converts the three-phase current value Im of the motor 21 into a two-phase vector component, that is, a d-axis current value and a q-axis current value in the d / q coordinate system, using the motor rotation angle θm. . Then, the control signal generator 35 obtains the deviation between the d-axis current value and the d-axis current command value and the deviation between the q-axis current value and the q-axis current command value, respectively, and current feedback so as to eliminate these deviations. (F / B) Control is executed. In addition, the control signal generation unit 35 generates a q-axis voltage command value (Vq *) and a d-axis voltage command value (Vd *) by executing current feedback (F / B) control. By mapping to the phase coordinate system, each voltage command value (Vu *, Vv *, Vw *) in the three-phase coordinate system is calculated, and a motor control signal Sm is generated based on each voltage command value.

Here, the current command value calculation unit 34 will be described in more detail.
As shown in FIGS. 3 and 4, the current command value calculation unit 34 includes an assist control amount calculation unit 50 for use in calculation of the current command value I *, a steering state determination unit 60, a mode selection unit 70, and a periodic operation. The generator 80 and the assist calculator 90 are included.

  The assist control amount calculation unit 50 inputs the pinion angular velocity ωp and the steering torque τ. The pinion angular velocity ωp is the rotational angular velocity of the pinion shaft 10 and is obtained by further multiplying the motor angular velocity ωm obtained by differentiating the motor rotational angle θm that can be converted into the pinion angle θp with a predetermined conversion coefficient. It is the bar lower angular velocity. When the pinion angular velocity ωp and the steering torque τ are input, the assist control amount calculation unit 50 calculates an assist control amount Ta composed of various components of the assist force generated in the assist control mode, and calculates the assist control amount Ta as an assist calculation. Output to the unit 90. The various components of the assist force include a basic assist component that is the basis of the assist force, a steering return component that becomes a load when the steering wheel 2 is returned, a damping component that reduces minute vibrations transmitted to the steering wheel 2, and the like.

  The steering state determination unit 60 inputs the steering torque τ. When the steering torque τ is input, the steering state determination unit 60 is in a state where the driver is placing a hand on the steering wheel 2 based on the steering torque τ (hereinafter referred to as “hands-on”), or the driver The steering state is determined to detect whether the hand 2 is not released (hereinafter referred to as “hands off”). The steering state determination unit 60 outputs “1” to the mode selection unit 70 as a steering state determination value Hs indicating that in the case of hands-on. The steering state determination value Hs serves as an index as to whether or not to output the assist control amount Ta and the automatic steering control amount Tg as a result of a logical operation or the like in subsequent processing. In addition, the steering state determination unit 60 outputs “0 (zero)” to the mode selection unit 70 as the steering state determination value Hs indicating the fact in the case of hands-off. Details of the steering state determination unit 60 will be described later in detail.

  The mode selection unit 70 inputs the steering state determination value Hs (“0” or “1”) input from the steering state determination unit 60 and the mode permission condition M (“0” or “1”). The mode selection unit 70 selects a control mode according to the mode permission condition M based on the steering state determination value Hs, and includes a logical operation unit (hereinafter referred to as “XOR”) 71 that calculates an exclusive OR. , And a logical operation unit (hereinafter referred to as “NOT”) 72 for calculating negation. The XOR 71 inputs the steering state determination value Hs as one of the inputs, and inputs the mode permission condition M as the other input. The XOR 71 derives “0” or “1” as a logical operation result based on each input, and outputs the result to the NOT 72 and the assist operation unit 90. The NOT 72 inputs the logical operation result of the XOR 71 and outputs the result obtained by inverting it to “0” or “1” to the assist operation unit 90. That is, the mode selection unit 70 outputs “0” and “1” to the assist calculation unit 90 through the outputs of the XOR 71 and the NOT 72, respectively. Depending on the combination of the outputs of these XOR 71 and NOT 72, the type of mode at that time appears.

  The periodic motion generation unit 80 as the downstream control amount calculation unit inputs the pinion angle θp. The pinion angle θp is a torsion bar lower angle obtained by multiplying the motor rotation angle θm by a predetermined conversion coefficient. The periodic motion generator 80 performs pinion angle feedback control based on the pinion angle θp so that the steering state determination unit 60 periodically changes a specific frequency component to the steering torque τ, which is an element for determining the steering state. Do. The periodic motion generation unit 80 calculates a pinion angle control amount Tp as a downstream control amount based on the pinion angle θp, and outputs the pinion angle control amount Tp to the assist calculation unit 90. The details of the periodic motion generator 80 will be described later in detail.

  The assist calculation unit 90 includes an assist control amount Ta from the assist control amount calculation unit 50, “0” or “1” from the mode selection unit 70, and an automatic steering control amount Tg from the host microcomputer 41 (upper ECU 40). And the pinion angle control amount Tp from the periodic motion generator 80 are input. The assist calculation unit 90 includes various calculators 91 to 93 that calculate the current command value I * using a control amount corresponding to the control mode selected by the mode selection unit 70.

  The arithmetic unit 91 having a multiplication function inputs the assist control amount Ta as one input, and inputs the output from the NOT 72 of the mode selection unit 70 as the other input. The arithmetic unit 92 having a multiplication function inputs the output from the XOR 71 of the mode selection unit 70 as one input and inputs the automatic steering control amount Tg as the other input.

  The calculator 91 outputs “0 (zero)” (no control) to the calculator 93 as the assist control amount Ta when the input from the NOT 72 is “0” as the calculation result based on each input. In this case, this is an automatic steering mode. In addition, when the input from the NOT 72 is “1” as a calculation result based on each input, the calculator 91 outputs the assist control amount Ta (with control) calculated by the assist control amount calculation unit 50 to the calculator 93. To do. In this case, the mode is an assist control mode.

  The arithmetic unit 92 having a multiplication function inputs the output from the XOR 71 of the mode selection unit 70 as one input and inputs the automatic steering control amount Tg as the other input. When the input from the XOR 71 is “1” as a calculation result based on each input, the calculator 92 outputs the automatic steering control amount Tg (with control) calculated by the host microcomputer 41 to the calculator 93. In this case, this is an automatic steering mode. Further, when the input from the XOR 71 is “0” as the calculation result based on each input, the calculator 92 is “0 (zero)” (no control) as the automatic steering control amount Tg calculated by the host microcomputer 41. Is output to the calculator 93. In this case, the mode is an assist control mode.

  The arithmetic unit 93 having an addition function inputs the outputs of the arithmetic units 91 and 92, that is, the assist control amount Ta or the automatic steering control amount Tg, to two of the inputs, and the pinion angle control amount Tp to the other inputs. Enter. The calculator 93 outputs the result obtained by adding the pinion angle control amount Tp to the control amount corresponding to the control mode at that time to the control signal generation unit 35 as the current command value I *.

Specifically, the flow in which the current command value I * for each mode permission condition M is calculated will be described together with the output relationship of each unit.
As shown in FIGS. 3 and 5, when the mode permission condition M is “0”, that is, when the assist control mode is permitted only during hands-on, “0” is input to the input on the mode permission condition M side of the XOR 71. The When the steering state determination value Hs of the steering state determination unit 60 is “1”, that is, when the hands are on, “1” is input to the input on the steering state determination value Hs side of the XOR 71. In this case, the output of the XOR 71 is “0” and the output of the NOT 72 is “1”. Thereby, the mode selection unit 70 selects the assist control mode because the mode permission condition M is “0” and the hands-on. In this case, the assist calculation unit 90 calculates the current command value I * based on a control amount (Ta + Tp) obtained by adding the pinion angle control amount Tp to the assist control amount Ta calculated by the assist control amount calculation unit 50.

  On the other hand, when the steering state determination value Hs of the steering state determination unit 60 is “0”, that is, when the hands are off, as shown in FIG. “0” is input to the input on the value Hs side. In this case, the output of the XOR 71 is “1”, and the output of the NOT 72 is “0”. Accordingly, the mode selection unit 70 selects the automatic steering mode because the mode permission condition M is “0” and the hands are off. In this case, the assist calculation unit 90 calculates the current command value I * based on a control amount (Tg + Tp) obtained by adding the pinion angle control amount Tp to the automatic steering control amount Tg calculated by the host microcomputer 41.

  As shown in FIGS. 4 and 5, when the mode permission condition M is “1”, that is, when the automatic steering mode is permitted only during hands-on, “1” is input to the input on the mode permission condition M side of the XOR 71. The When the steering state determination value Hs of the steering state determination unit 60 is “1”, that is, when the hands are on, “1” is input to the input on the steering state determination value Hs side of the XOR 71. In this case, the output of the XOR 71 is “1”, and the output of the NOT 72 is “0”. Accordingly, the mode selection unit 70 selects the automatic steering mode because the mode permission condition M is “1” and the hands are on. In this case, the assist calculation unit 90 calculates the current command value I * based on a control amount (Tg + Tp) obtained by adding the pinion angle control amount Tp to the automatic steering control amount Tg calculated by the host microcomputer 41.

  On the other hand, when the steering state determination value Hs of the steering state determination unit 60 is “0”, that is, when the hands are off, as shown in FIG. “0” is input to the input on the value Hs side. In this case, the output of the XOR 71 is “0” and the output of the NOT 72 is “1”. Accordingly, the mode selection unit 70 selects the assist control mode because the mode permission condition M is “1” and the hands are off. In this case, the assist calculation unit 90 calculates the current command value I * based on a control amount (Ta + Tp) obtained by adding the pinion angle control amount Tp to the assist control amount Ta calculated by the assist control amount calculation unit 50.

Next, the periodic motion generator 80 will be described in detail.
As illustrated in FIG. 6, the periodic motion generation unit 80 includes various arithmetic units 81 and 82 that are used to calculate the pinion angle control amount Tp, a target pinion angle generation unit 83, a pinion angle correction unit 84, and a feedback control unit 85. And have.

  The target pinion angle generator 83 generates a target pinion angle θpbase when the steering state determination by the steering state determination unit 60 is necessary. In the present embodiment, a situation where the determination of the steering state is required is made to come periodically, for example, every 10 control cycles. The target pinion angle generation unit 83 generates a target pinion angle θpbase so that the pinion angle θp exhibits a sin wave-like periodic change having a predetermined peak value, and outputs the target pinion angle θpbase to the calculator 81. When the determination of the steering state is necessary, the target pinion angle generation unit 83 generates the target pinion angle θpbase so that, for example, one cycle (0.2 [sec]) of a sin wave-like change of 5 [Hz] appears. . For example, when the control cycle of the periodic motion generator 80 (EPS microcomputer 31) in the present embodiment is 2 [msec], it is necessary to determine the steering state every 10 control cycles, that is, every 0.2 [sec]. It becomes. In this case, the target pinion angle generation unit 83 repeatedly generates the target pinion angle θpbase indicating a sin wave-like change of 0.2 [sec]. This 5 [Hz] is an example of a frequency that is empirically derived as a sinusoidal periodic change is easily detected by the torque sensor 24.

  The pinion angle correction unit 84 holds (holds) the correction angle θpoff and outputs the correction angle θpoff to the calculator 81. When a situation that requires the determination of the steering state arrives, the pinion angle correction unit 84 acquires the pinion angle θp at that time, and holds (holds) it as the correction angle θpoff. That is, the pinion angle correction unit 84 acquires the pinion angle θp and updates the held correction angle θpoff every time a situation that requires determination of the steering state comes.

  The computing unit 81 having an addition function adds the correction angle θpoff to the target pinion angle θpbase. That is, as shown by the solid line in FIG. 7A, when a sin wave-like change appears due to the target pinion angle θpbase without correction of the correction angle θpoff, the correction angle as shown by the broken line in FIG. The sin wave shape itself is corrected in the amplitude direction so that θpoff (the pinion angle θp at the arrival of the situation that requires the determination of the steering state) becomes the starting point of the sin wave shape change. Then, the calculator 81 corrects (offsets) the correction angle θpoff to be the sin wave-shaped start point of the target pinion angle θp0, and sets the corrected target pinion angle θp0 to the addition side of the calculator 82 having a subtraction function. Output.

  The pinion angle θp is input to the subtraction side of the calculator 82. The calculator 82 calculates a deviation between the target pinion angle θp0 and the pinion angle θp, and the pinion angle deviation Δθp, and outputs the calculated deviation to the feedback control unit 85. The feedback control unit 85 calculates the pinion angle control amount Tp and outputs it to the assist calculation unit 90 in order to perform feedback control for causing the actual pinion angle θp to follow the target pinion angle θp0. Thereby, the periodic motion generating unit 80 gives a sin wave-like change to the downstream side of the torque sensor 24 of the steering shaft 3, that is, to the pinion shaft 10.

Next, the steering state determination unit 60 will be described in detail.
As shown in FIG. 8, the steering state determination unit 60 includes a bandpass filter (hereinafter referred to as “BPF”) 61 used for detection of the steering state, an integration unit 62, and a determination value calculation unit 63.

  The BPF 61 inputs the steering torque τ. The BPF 61 is configured to pass a sin wave-like change frequency (here, 5 [Hz]) given by the periodic motion generation unit 80 as a specific frequency and attenuate other frequencies. That is, the BPF 61 extracts the steering torque τs (torque value) based on the sin wave-like change given by the periodic motion generator 80 and outputs it to the integrator 62. The steering torque τs thus extracted is, for example, whether or not the driver is placing a hand on the steering wheel 2, as indicated by the solid line and the alternate long and short dash line in FIG. 7B, that is, hands-on (solid line in the figure). It appears differently depending on whether it is a hands-off or a one-dot chain line in the figure.

  The integrating unit 62 outputs an integrated value add obtained by integrating the steering torque τs (torque value) extracted by the BPF 61 to the determination value calculating unit 63. The accumulating unit 62 accumulates a predetermined number of samplings (in this embodiment, one sin wave-like change given by the periodic motion generating unit 80) necessary for determining the steering state. As a method for such integration, a value obtained by calculating the mean square of the integrated values add for a predetermined number of samplings may be used, or a value obtained by integrating the effective values as they are may be used. In the present embodiment, since the sin wave-like change is repeatedly given, the integrated value add is continuously calculated.

  Determination value calculation unit 63, when integrated value add is input from integration unit 62, is an evaluation value for determining steering state determination value Hs (an index indicating whether or not to output a control amount) based on a steering state determination value map. And the steering state determination value Hs (“0” or “1”) corresponding to the result of the evaluation value is output to the mode selection unit 70. The steering state determination value map indicates the relationship between the integrated value add and the evaluation value. When the steering state determination value map is equal to or greater than the predetermined integrated value addth, the evaluation value is set to increase based on the increase of the integrated value add. Is done. The predetermined integrated value addth is set as a value that is empirically derived as being appropriate for the possibility that the hands-on is higher than the hands-off. When the evaluation value is less than “0.5”, the determination value calculation unit 63 outputs “0”, that is, a hands-off result as the steering state determination value Hs. In addition, the determination value calculation unit 63 outputs “1”, that is, a hands-on result as the steering state determination value Hs when the evaluation value is “0.5” or more. Thus, the steering state determination unit 60 is based on the output of the torque sensor 24 (steering torque τ) when the sinusoidal change is applied to the downstream side of the torque sensor 24 of the steering shaft 3, that is, the pinion shaft 10. 2 is determined.

According to the steering control apparatus described above, the following operations and effects (1) to (6) can be obtained.
(1) When determining the steering state of the steering wheel 2, by applying a sin wave-like change to the pinion shaft 10 (pinion angle θp), a periodic change is intended downstream of the torque sensor 24 of the steering shaft 3 Can be generated automatically. Such a periodic change is detected through the steering torque τ of the torque sensor 24. In this case, the state where the hands are turned on (the inertial force by the driver works upstream of the torque sensor 24 of the steering shaft 3) and the state where it is not (the inertial force of the driver upstream of the torque sensor 24 of the steering shaft 3). And the steering torque τ detected by the torque sensor 24 appears differently.

  Specifically, the inertia on the upstream side (steering wheel 2 side) of the torque sensor 24 (torsion bar 8a) of the steering shaft 3 is higher than the hands-off in the case of hands-on. In this case, if a sin wave-like change is applied to the downstream side of the torque sensor 24 (torsion bar 8a) of the steering shaft 3, the sin wave shape given by the upstream side of the steering shaft 3 is higher in the hands-on than the hands-off. It is difficult to follow the changes. On the other hand, when a sin wave-like change is applied to the downstream side of the torque sensor 24 (torsion bar 8a) of the steering shaft 3, the upstream side of the torque sensor 24 of the steering shaft 3 is increased by the amount of inertia lower than that of the hands-on. It is easy to follow the applied sin wave-like change.

  For example, as shown by a solid line in FIG. 7B, when a change in the steering torque τs in the hands-on with respect to the given sin wave-like change appears, as shown by a one-dot chain line in FIG. The amplitude of the change in the steering torque τs at the hands-off with respect to the change appears smaller than the hands-on. Thereby, it can be suitably detected whether or not the driver is placing a hand on the steering wheel 2.

  (2) As described above, if only the point that the change is intentionally generated downstream of the torque sensor 24 of the steering shaft 3 is seen, a pulse shape (including a rectangular shape) is provided in addition to giving a sin wave change. It is also possible to give changes. In that respect, as in the above-described embodiment, since the sin wave-like change can show the continuous change and the width of the displacement relatively large, the steering torque detected by the torque sensor 24 rather than the pulse-like change. There is an advantage in that it is easily extracted from τ.

  (3) As shown by the broken line in FIG. 7 (a), when a sin wave-like change is applied to the pinion shaft 10 (pinion angle θp), the pinion angle θp at that time becomes the start point of the sin wave wave of the target pinion angle θp0. I am trying to correct it. Therefore, when the change is intentionally generated on the downstream side of the torque sensor 24 of the steering shaft 3, a sudden change with respect to the downstream pinion shaft 10 can be suppressed. This makes it difficult for the driver to notice the intentional change given to the downstream side of the torque sensor 24 of the steering shaft 3. Therefore, in the case of hands-on, the steering state can be determined without causing the driver to feel uncomfortable.

  (4) In the steering shaft 3, while the steering wheel 2 and the steered wheel 12 are connected, there are resistance components such as friction related to the connection. Therefore, even if the target pinion angle θp0 is calculated in order to intentionally generate a change downstream of the torque sensor 24 of the steering shaft 3, the target pinion angle θp0 is directly reflected as a change on the downstream side. Not exclusively. In that respect, as in the above-described embodiment, by executing feedback control that causes the actual pinion angle θp to follow the target pinion angle θp0, a change that is intentionally generated is downstream of the torque sensor 24 of the steering shaft 3. This can be suitably reflected as a change in. Thereby, it can be suitably detected whether or not the driver is placing a hand on the steering wheel 2.

  (5) In order to cause the motor 21 to generate torque, how the assist control amount Ta or the automatic steering control amount Tg is reflected can be customized according to the steering state of the steering wheel 2 of the driver. In the above-described embodiment, customization is performed which includes a case where the assist control mode is permitted only during hands-on and a case where the automatic steering mode is permitted only during hands-on. In addition, as described above, it can be suitably detected whether or not the driver is holding the steering wheel 2, which is also effective from the viewpoint of functional safety.

  (6) The steering state determination unit 60 determines the steering state of the steering wheel 2 based on the integrated value add obtained by integrating the steering torque τs of the torque sensor 24. Therefore, by accumulating the steering torque τs of the torque sensor 24, the accuracy of deriving the evaluation value, which is information for determining the steering state of the steering wheel 2, can be increased. Thereby, the accuracy of detection of whether or not the driver is holding the steering wheel 2 can be improved.

(Second Embodiment)
Next, a second embodiment of the steering control device will be described. Note that the same configurations and the same control contents as those in the embodiment already described are denoted by the same reference numerals, and redundant description thereof is omitted. In the present embodiment, the main differences from the first embodiment are the configuration of the control mode and the configuration of the mode selection unit 70 among the current command value calculation unit 34.

  The control mode of the present embodiment includes an automatic steering mode and an assist control mode, as well as an assist force that changes the steering force θ according to the driver's steering operation while automatically changing the steering angle θs according to the driving state. It has an automatic steering mode with control.

  When [0] is selected as the mode permission condition M by the mode changeover switch 28, the automatic steering mode with assist control is permitted only during hands-on, and the automatic steering mode and the assist control mode are otherwise set. Specifies that neither is allowed. That is, the mode permission condition M [0] is used in a situation where only hands-on steering is assumed, such as when a relatively heavy vehicle is parked. When [1] is selected as the mode permission condition M by the mode changeover switch 28, the assist control mode is permitted only during hands-on, and the switching condition for permitting the automatic steering mode is specified otherwise.

Next, the mode selection unit 70 will be described in detail.
As shown in FIGS. 9 and 10, the mode selection unit 70 includes a computing unit 73 having a subtraction function and a conditional computing unit (hereinafter referred to as “UNSIGN”) 74 having a function of adding a condition excluding a sign to an input value. And have. The computing unit 73 inputs the steering state determination value Hs as one of the inputs, and inputs the mode permission condition M as the other input. The computing unit 73 derives “0” or “1” as the computation result based on each input, and outputs the result to the UNSIGNE 74. Note that the steering state determination value Hs input to the calculator 73 is also input to the calculator 91 of the assist calculator 90. The UNSIGN 74 receives the calculation result of the calculator 73 and also outputs the result of removing the sign (if it is “0” or “1”, it is “1” if it is “−1”). Output to.

  When the input from the steering state determination unit 60 is “0”, the calculator 91 of the assist calculation unit 90 calculates the assist control amount Ta (with control) calculated by the assist control amount calculation unit 50 as the calculation result based on each input. ) Is output to the calculator 93. In addition, when the input from the steering state determination unit 60 is “0”, the calculator 91 outputs “0” (no control) as the assist control amount Ta to the calculator 93.

  The computing unit 92 of the assist computing unit 90 computes the automatic steering control amount Tg (with control) computed by the host microcomputer 41 when the input from the UNSIGN 74 is “1” as a computation result based on each input. Output to the device 93. Further, when the input from UNSIGN 74 is “0”, the calculator 92 outputs “0” (no control) to the calculator 93 as the automatic steering control amount Tg.

  As shown in FIG. 9, when the mode permission condition M is “0”, that is, when the automatic steering mode with assist control is permitted only during hands-on, the input of the calculator 73 on the mode permission condition M side is “0”. Is entered. When the steering state determination value Hs of the steering state determination unit 60 is “1”, that is, when the hands are on, “1” is input to the input on the steering state determination value Hs side of the calculator 73 and the mode of the calculator 91 is set. “1” is input to the input on the selection unit 70 side. In this case, the output of the computing unit 73 is “1” and the output of UNSIGN 74 is “1”. Thereby, since the mode permission condition M is “0” and hands-on, the mode selection unit 70 selects the automatic steering mode with assist control. In this case, the assist calculation unit 90 adds the pinion angle control amount Tp to the assist control amount Ta calculated by the assist control amount calculation unit 50 and the automatic steering control amount Tg calculated by the host microcomputer 41 (Ta + Tg + Tp). ) To calculate the current command value I *.

  On the other hand, as shown in FIG. 9 (refer to the values shown in parentheses in the figure), when the steering state determination value Hs of the steering state determination unit 60 is “1”, that is, when the hands are off, the steering state determination value of the computing unit 73. “0” is input to the input on the Hs side, and “0” is input to the mode selection unit 70 side of the calculator 91. In this case, the output of the computing unit 73 is “0”, and the output of UNSIGN 74 is “0”. Thereby, since the mode permission condition M is “0” and the hands are off, the mode selection unit 70 selects a mode in which neither the automatic steering mode nor the assist control mode is permitted. In this case, the assist calculation unit 90 calculates the current command value I * based only on the pinion angle control amount Tp.

  As shown in FIG. 10, when the mode permission condition M is “1”, that is, when the assist control mode is permitted only during hands-on, “1” is input to the input on the mode permission condition M side of the calculator 73. . When the steering state determination value Hs of the steering state determination unit 60 is “1”, that is, when the hands are on, “1” is input to the input on the steering state determination value Hs side of the calculator 73 and the mode of the calculator 91 is set. “1” is input to the selection unit 70 side. In this case, the output of the computing unit 73 is “0”, and the output of UNSIGN 74 is “0”. As a result, the mode selection unit 70 selects the assist control mode because the mode permission condition M is “1” and the hands are on. In this case, the assist calculation unit 90 calculates the current command value I * based on a control amount (Ta + Tp) obtained by adding the pinion angle control amount Tp to the assist control amount Ta calculated by the assist control amount calculation unit 50.

  On the other hand, as shown in FIG. 10, when the steering state determination value Hs of the steering state determination unit 60 is “0”, that is, when the hands are off, “0” is input to the input on the steering state determination value Hs side of the calculator 73. At the same time, “0” is input to the mode selection unit 70 side of the calculator 91. In this case, the output of the computing unit 73 is “−1”, and the output of UNSIGN 74 is “1” excluding the sign. Accordingly, the mode selection unit 70 selects the automatic steering mode because the mode permission condition M is “1” and the hands are off. In this case, the assist calculation unit 90 calculates the current command value I * based on a control amount (Tg + Tp) obtained by adding the pinion angle control amount Tp to the automatic steering control amount Tg calculated by the host microcomputer 41.

According to the steering control device described above, in addition to the operations and effects according to (1) to (6) of the first embodiment, the following operations (7) and (8) are exhibited.
(7) As shown in FIGS. 9 and 10, the mode selection unit 70 is realized by using a simple arithmetic unit having a subtraction function and a function excluding a sign, not a logical arithmetic unit. Therefore, the configuration of the mode selection unit 70 can be realized particularly simply and inexpensively. Further, with such a simple configuration, it is possible to flexibly cope with customization of the control mode thereafter.

  (8) As a control mode, an automatic steering mode with assist control is provided. When the vehicle is parked, a relatively large assist force is required because the vehicle speed is relatively low, and an accurate steering operation (steering) for placing the vehicle in a limited parking space is required. Meeting these requirements becomes more difficult as the vehicle weight (vehicle body) increases. In that respect, in the above-described embodiment, it is possible to favorably assist the driver's steering operation even when a vehicle having a relatively heavy weight (vehicle body) is parked.

  On the other hand, when the automatic steering mode with assist control is assumed to be when the vehicle is parked, there is a possibility that an unfavorable situation may occur if the mode is switched to the automatic steering mode by hands-off during parking. In that respect, in the above embodiment, in the case of the mode permission condition M “0” that can be switched to the automatic steering mode with assist control, neither the automatic steering mode nor the assist control mode is permitted if it is a hands-off. Yes. Therefore, it is possible to reduce as much as possible the possibility of falling into an unfavorable situation when switching to the automatic steering mode by hands-off during parking.

Each embodiment may be changed as follows.
The steering state determination unit 60 may change the method of integrating the steering torque τs (torque value) based on the sin wave-like change. For example, the steering torque τs for two cycles of sin wave change may be integrated. Further, the steering state determination unit 60 may determine the steering state based on the maximum value of the steering torque τs (torque value) based on the sin wave-like change, instead of integrating the steering torque τs. In this case, the integration unit 62 may be omitted.

-The electric power steering device 1 of each said embodiment should just have at least the mode of assist control.
-The situation where the determination of the steering state is not necessary may not occur continuously. For example, a time margin may be set between the determination of the steering state. In addition, the periodic motion generation unit 80 may give a sin wave-like change when the automatic steering control amount Tg calculated by the host microcomputer 41 is input as a situation where the determination of the steering state is necessary. As a result, the situation in which the steering shaft 3 is intentionally changed can be reduced, and the situation in which the driver can feel uncomfortable can be minimized.

  The periodic motion generator 80 may be configured not to perform feedback control. In this case, a configuration that applies a sin wave-like change to the pinion angle θp is more effective than a pulse-like change.

  The pinion angle θp may be converted from the angle by providing a rotation angle sensor on the downstream side of the torque sensor 24 (torsion bar 8a). Further, the pinion angle θp may be converted from the displacement (movement amount) of the rack shaft 5. In addition, the pinion angle θp may be directly detected by providing a rotation angle sensor on the pinion shaft 10.

  The pinion angle correction unit 84 of the periodic motion generation unit 80 may correct (offset) the periodic phase of the sin wave-like change so that the sin wave start point of the target pinion angle θp0 becomes the correction angle θpoff. .

  The periodic motion generation unit 80 may not include the pinion angle correction unit 84. In this case, when the situation that requires the determination of the steering state arrives, the periodic motion generation unit 80 may give a predetermined sin wave-like change regardless of the pinion angle θp at that time.

  The change given by the periodic motion generator 80 may be a cos wave-like change. That is, such a change is a periodic change but may not be a pulse-like change. Further, the change given by the periodic motion generation unit 80 may be a change that appears by combining a sine wave and a cosine wave, such as a distorted (dull) wave shape with respect to a smooth sine wave or a cosine wave. May be.

  The mode permission condition M may be a configuration instructed by the host ECU 40 (host microcomputer 41). Further, the host ECU 40 (host microcomputer 41) may be connected to the mode changeover switch 28 or may be able to input the steering state determination value Hs of the steering state determination unit 60. That is, the control mode may be switched mainly by the host microcomputer 41.

The content of the mode permission condition M may be changed, for example, the association between “0” and “1” can be reversed.
The mode switch 28 may be a means for switching (selecting) between the automatic steering mode and the assist control mode. In this case, the automatic steering mode may be permitted only during hands-on while the automatic steering mode is selected by the mode changeover switch 28, and the assist control mode may be permitted otherwise.

The mode selection unit 70 can be a logic arithmetic unit, a simple arithmetic unit, a microcomputer, or the like.
The steering state determination unit 60 may output the evaluation values “0” to “1” as the steering state determination value Hs. The steering state of the driver's steering wheel 2 can be determined in more detail. In this case, the mode selection unit 70 may be configured so that a control mode corresponding to the result of the detailed determination can be selected.

  In each of the above embodiments, the two microcomputers, the EPS microcomputer 31 and the host microcomputer 41, are used. However, the present invention may be realized using a single microcomputer having these functions.

  In each of the above embodiments, the electric power steering device 1 is embodied as the column assist EPS, but may be applied to a pinion assist EPS or a rack assist EPS as shown in FIGS. 11 and 12.

  Specifically, as shown in FIG. 11, the EPS actuator 100 of the pinion assist EPS includes a motor 21 and a worm reduction mechanism 101. The worm speed reduction mechanism 101 includes a worm shaft 102 connected to the output shaft of the motor 21. The worm shaft 102 is connected to the pinion shaft 104 via the worm wheel 103. The pinion teeth formed at the lower end portion of the pinion shaft 104 are meshed with the rack shaft 5 (more precisely, the portion 105 where the rack teeth are formed) extending in the direction intersecting the pinion shaft 104. Therefore, the rotation of the motor 21 is transmitted to the rack shaft 5 via the worm reduction mechanism 101 (worm shaft 102, worm wheel 103, and pinion shaft 104), whereby the torque of the motor 21 is applied as an assist force. In this case, the periodic motion generation unit 80 gives a sinusoidal change to the pinion shaft 10 through the rack shaft 5 and the pinion shaft 104.

  12, the EPS actuator 110 of the rack assist EPS includes a motor 21, a transmission mechanism 111, and a ball screw mechanism 112. The transmission mechanism 111 includes pulleys provided on the output shaft of the motor 21 and the ball screw mechanism 112, and a belt connecting the pulleys. A part of the rack shaft 5 constitutes a ball screw shaft of the ball screw mechanism 112. Accordingly, the rotation of the motor 21 is transmitted to the ball screw mechanism 112 through the transmission mechanism 111 and is transmitted to the rack shaft 5 through the ball screw mechanism 112, whereby the torque of the motor 21 is applied as an assist force. In this case, the periodic motion generator 80 gives a sin-wave change to the pinion shaft 10 through the rack shaft 5, the transmission mechanism 111, the ball screw mechanism 112, and the rack shaft 5.

  -As the motor 21 which is a drive source of the EPS actuator 20, it is employable regardless of the kind, such as an induction motor or a stepping motor.

  add: integrated value, Hs: steering state determination value, I *: current command value, Ta: assist control amount (control amount), Tg: automatic steering control amount, Tp: pinion angle control amount (downstream control amount), θm ... Motor rotation angle, .theta.p... Pinion angle (downstream state quantity), .theta.pbase, .theta.p0... Target pinion angle (downstream state quantity target value), .tau., .Tau.s. Shaft, 6 ... steering mechanism, 7 ... steering mechanism, 8 ... column shaft, 8a ... torsion bar, 9 ... intermediate shaft, 10 ... pinion shaft, 12 ... steering wheel, 20 (100, 110) ... EPS actuator (steering) Auxiliary mechanism), 24 ... torque sensor (torque detection unit), 30 ... EPSECU (steering control device), 34 ... current command value calculation unit, 50 ... assist control Calculation unit (control amount calculation unit), 60 ... steering state determination unit, 61 ... band pass filter, 62 ... integration unit, 63 ... determination value calculation unit, 80 ... periodic motion generation unit (downstream control amount calculation unit), 83 ... target pinion angle generation unit, 84 ... pinion angle correction unit, 85 ... feedback control unit, 90 ... assist calculation unit.

Claims (5)

A steering mechanism including a steering wheel; a steering mechanism connected to a steered wheel; a steering shaft that forms part of the steering mechanism and the steering mechanism and connects the steering mechanism and the steering mechanism; A torque detector provided on the steering shaft for detecting torque generated in the steering shaft; and a steering assist mechanism for applying an assist force to assist the steering operation of the driver to the steering mechanism or the steering mechanism. In the steering control device for controlling the operation of the steering assist mechanism of the steering device,
A downstream control amount calculation unit that calculates a downstream control amount for periodically changing a state quantity downstream of the torque detection unit of the steering shaft by the steering assist mechanism;
A steering state determination unit that determines a steering state as to whether or not a driver is placing a hand on the steering wheel based on an output of the torque detection unit when the periodic change is given;
A steering control device comprising: The periodic change is a sin wave-like or cos wave-like change.
The steering control device according to claim 1.   The downstream control amount calculation unit corrects the downstream control amount so that the downstream state amount when the periodic change is given becomes a start point of the periodic change. The steering control device according to claim 2.   The downstream control amount calculation unit calculates a target value of the downstream state quantity and executes feedback control for causing the actual state quantity on the downstream side to follow the target value, thereby executing the downstream control quantity. The steering control device according to any one of claims 1 to 3, wherein the steering control device is calculated.   The steering according to any one of claims 1 to 4, wherein the steering state determination unit determines a steering state of the steering wheel based on a result obtained by integrating the outputs of the torque detection unit. Control device.