JP2012068200A - Shaft torque control device of dynamometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow suppression of resonance due to spring rigidity of a coupling in an engine bench system having an intermediate shaft and to allow suppression of resonance due to spring rigidity of a clutch also.SOLUTION: A shaft torque detection value T23 is added to a dynamometer torque command value T23ref via a low pass filter (LPF) 21 to obtain a new dynamometer torque command value. A machine model 20 in the engine bench system having the intermediate shaft is replaced by a three-inertia system machine model. A shaft torque control device has a configuration where a dead time element (TD) is used instead of the low pass filter, a configuration where the shaft torque detection value of the dynamometer which has passed the low pass filter or the dead time element is caused to pass a high pass filter (HPF), and a shaft torque controller which performs feedback control of the dynamometer torque command value by the shaft torque detection value which has passed the low pass filter is combined.

Description

  The present invention relates to a shaft torque control device for a dynamometer, and particularly to resonance suppression by coupling and resonance suppression by a clutch of an engine bench system having an intermediate shaft.

  FIG. 14 shows a mechanical system configuration and a control system configuration of a general engine bench system. In the mechanical system, a clutch 2, a transmission (MT) 3, and a propeller shaft 4 are coupled to an engine 1 to be tested, and a dynamometer 6 is coupled to the propeller shaft 4 via an axial torque meter 5. An incremental encoder 7 as a rotational speed detecting means is coupled to the rotational shaft of the dynamometer 6. The control system includes an engine controller 8 that controls the engine 1 and a throttle actuator 9, and a dynamometer controller 10 that controls the dynamometer 6 and an inverter (power converter) 11.

  The dynamometer controller 10 is fed back with the rotational speed detected by the encoder 7 and the shaft torque detected by the shaft torque meter 5 to control the shaft torque and the rotational speed of the dynamometer. The output of the engine 1 is also controlled by the engine controller 8.

  FIG. 15 shows a mechanical model of the engine bench system shown in FIG. In a general engine bench system, the moment of inertia of the propeller shaft 4 is smaller than the moment of inertia of the dynamometer 6 and the engine 1, and the torsional rigidity of the propeller shaft 4 is much larger than the torsional rigidity of the clutch 2. Therefore, it can be regarded as a two-inertia system model (a model composed of two inertia moments and an elastic element connecting them) as shown in FIG.

  For example, Patent Document 1 proposes a dynamometer torque control method and apparatus for controlling shaft torque with a dynamometer 6 in the engine bench system having the mechanical system configuration of FIG. 14 that can be regarded as a two-inertia system. ing.

  FIG. 16 shows a mechanical configuration and a control system configuration of another form of engine bench system, and the control system configuration is the same as FIG. In the mechanical system of FIG. 16, the output shaft on the engine 1 side is extended by the intermediate shaft 12, and the tip of the intermediate shaft 12 is axially coupled to the dynamometer 6 side by the coupling 13.

  The reason for this mechanical configuration is that when the engine is placed in a special environment (low temperature, low pressure, etc.), only the engine is placed in the environmental chamber (intermediate shaft) or (coupling) to obtain a shaft extension. is there. In the engine bench system shown in FIG. 16, the moment of inertia of the intermediate shaft is not necessarily smaller than the moment of inertia of the engine or dynamometer, and the torsional rigidity of the coupling is sufficiently harder than the torsional rigidity of the clutch. It is not. Therefore, the machine model of the engine bench system shown in FIG. 16 must be considered as a three-inertia system model as shown in FIG.

  18 shows a Bode diagram of torque response characteristics (dynamometer torque command → shaft torque detection characteristics) of an engine bench system having an intermediate shaft, FIG. 19 shows a step response waveform, and a resonance point by coupling (in FIG. 19). A resonance point having two large resonance gains appears (about 100 Hz) and a resonance point by the clutch (about 10 Hz in FIG. 19).

JP 2008-70119 A

  As shown in FIG. 19, the step response of the detected shaft torque value to the dynamometer torque command of the engine bench system having the intermediate shaft is based on the engine characteristic by the resonance (100 Hz in FIG. 19) being superimposed on the detected shaft torque waveform. It becomes difficult to measure accurately.

  20 and 21 show control characteristics when the shaft torque controller of the engine bench system having the intermediate shaft is configured by the control method of Patent Document 1. FIG. 20 is a Bode diagram of the detected shaft torque value with respect to the shaft torque command value, and FIG. 21 is a step response of the detected shaft torque value with respect to the shaft torque command value. In the Bode diagram of FIG. 20, control can be performed so that the command value is maintained up to around 10 Hz which is the resonance point of the clutch. However, when FIG. 21 is seen, the resonance point of the 100 Hz coupling becomes unstable and gradually diverges. You can see that Therefore, the control method of Patent Document 1 cannot be applied to an engine bench system having an intermediate shaft.

  An object of the present invention is to provide a shaft torque control device for a dynamometer that can suppress resonance caused by the spring stiffness of a coupling in an engine bench system having an intermediate shaft, and can further suppress resonance caused by the spring stiffness of a clutch. There is.

  In order to solve the above problems, the present invention adds a shaft torque detection value to a dynamometer torque command value through a low-pass filter (LPF) as a dynamometer torque command value in an engine bench system having an intermediate shaft. A configuration that provides a new dynamometer torque command value, a configuration that adds a shaft torque detection value to a dynamometer torque command value through a dead time element (TD), and a new dynamometer torque command value, and a low-pass filter (LPF) Alternatively, a configuration in which the shaft torque detection value of the dynamometer that has passed the dead time element (TD) is added to the dynamometer torque command value through a high-pass filter (HPF) to obtain a new dynamometer torque command value, and also the dynamometer A shaft torque controller that feedback-controls the torque command value with a shaft torque detection value that has passed through a first low-pass filter (LPF), and a second low-pass filter (LPF) or the dead time element (TD) is added to the control output of the shaft torque controller at a predetermined ratio to obtain a new dynamometer torque command value. It is characterized by the configuration of

(1) A mechanical system configuration in which an intermediate shaft provided on the output shaft of the engine is coupled to a dynamometer through a coupling, the engine performs output control according to an engine control command, and the dynamometer performs shaft torque control according to a shaft torque command value. In the engine bench system with a control system configuration,
A dynamometer shaft torque detection value is added to a dynamometer torque command value through a low-pass filter to obtain a new dynamometer torque command value. The low-pass filter has a phase at a resonance frequency generated by the spring stiffness of the coupling. It features a configuration in which the delay is close to the set value.

(2) An intermediate shaft provided on the output shaft of the engine is coupled to a dynamometer through a coupling. The engine performs output control according to an engine control command, and the dynamometer performs shaft torque control according to a shaft torque command value. In the engine bench system with a control system configuration,
The detected value of the shaft torque of the dynamometer is added to the dynamometer torque command value through the dead time element (TD) to obtain a new dynamometer torque command value, and the dead time element is a phase lag at the resonance frequency due to the spring stiffness of the coupling. It is characterized by a configuration in which the dead time length becomes close to the set value.

(3) A mechanical system configuration in which an intermediate shaft provided on the output shaft of the engine is coupled to a dynamometer through a coupling, the engine performs output control according to an engine control command, and the dynamometer performs shaft torque control according to a shaft torque command value. In the engine bench system with a control system configuration,
The new dynamometer torque command value is obtained by adding the shaft torque detection value of the dynamometer that has passed through the low-pass filter (LPF) or dead time element (TD) to the dynamometer torque command value through the high-pass filter (HPF). age,
The low-pass filter makes the phase lag at the resonance frequency generated by the spring stiffness of the coupling close to a set value,
The dead time element is a dead time length in which the phase delay is close to a set value at the resonance frequency due to the spring stiffness of the coupling,
The characteristic frequency of the high-pass filter is characterized in that it is in a range lower than the resonance frequency due to the spring stiffness of the coupling.

(4) A mechanical system configuration in which an intermediate shaft provided on an output shaft through an engine clutch is coupled to a dynamometer through a coupling, the engine performs output control according to an engine control command, and the dynamometer according to a shaft torque command value In an engine bench system with a control system configuration that controls shaft torque,
A shaft torque controller that calculates a torque control output by performing PID calculation on a deviation from a shaft torque detection value that has passed through a first low-pass filter (LPF) with respect to a dynamometer torque command value;
The shaft torque detection value that has passed through the second low-pass filter (LPF) or dead time element (TD) is added to the control output of the shaft torque controller at a predetermined ratio to obtain a new dynamometer torque command value,
The shaft torque controller obtains the torque control output T3A by the PID calculation of the following equation,
T3A = (Ki / s) * (T23ref−T23det) − (Kp + s * Kd) / (a2 * s * s + a1 * s + 1) * T23det
Where T23ref: shaft torque command, T23det: first low-pass filter (LPF) output of shaft torque detection value, Ki: integral coefficient, Kp: proportional coefficient, Kd: differential coefficient, a1, a2: proportional / differential element The filter coefficient of the second low-pass filter is such that the phase lag at the resonance frequency generated by the spring stiffness of the coupling is close to a set value, and the dead time element has a phase lag at the resonance frequency due to the spring stiffness of the coupling. It is characterized by a configuration with a dead time length that is close to the set value.

  As described above, according to the present invention, the shaft torque detection value is added to the dynamometer torque command value through the low-pass filter (LPF) or the dead time element (TD) to obtain a new dynamometer torque command value. Thus, resonance caused by the spring stiffness of the coupling can be suppressed.

  Furthermore, a new dynamometer torque command is obtained by adding the shaft torque detection value of the dynamometer that has passed through the low-pass filter (LPF) or the dead time element (TD) to the dynamometer torque command value through the high-pass filter (HPF). By setting the value and the characteristic frequency of the high-pass filter in a range lower than the resonance frequency due to the spring stiffness of the coupling, the engine can be started without assistance from the dynamometer side.

  Furthermore, a shaft torque controller that performs feedback control with a shaft torque detection value that has passed through the first low-pass filter (LPF) with respect to the dynamometer torque command value, and a second low-pass filter (LPF) or wasteful In addition to resonance suppression by coupling by adding the shaft torque detection value through the time element (TD) to the control output of the shaft torque controller at a predetermined ratio to obtain a new dynamometer torque command value, The resonance can be suppressed by the clutch.

The block diagram of the control system by embodiment (1) of this invention. 3-inertia machine model. The board diagram by the structure of embodiment (1). Step response according to the configuration of the embodiment (1). The block diagram of the control system by Embodiment (2) of this invention. The board diagram by the structure of embodiment (2). Step response according to the configuration of the embodiment (2). The block diagram of the control system by embodiment (3) of this invention. Engine speed response according to the configuration of the embodiment (1) or the embodiment (2). Engine speed response according to the configuration of the embodiment (3). The block diagram of the control system by embodiment (4) of this invention. The Bode diagram according to the configuration of the embodiment (4). Step response according to the configuration of the embodiment (4). Mechanical system configuration and control system configuration of a general engine bench system. The machine model of FIG. Mechanical system configuration and control system configuration of an engine bench system with an intermediate shaft. The machine model of FIG. Torque response characteristics of an engine bench system with an intermediate shaft (conventional). Step response characteristics of an engine bench system with an intermediate shaft (conventional). A Bode diagram of detected shaft torque of an engine bench system with an intermediate shaft. Step response of shaft torque detection value of engine bench system with intermediate shaft.

Embodiment (1)
FIG. 1 shows the configuration of a control system according to this embodiment. In this configuration, an adder is added to the torque control of the dynamometer 6 in the three-inertia engine bench system having the intermediate shaft shown in FIG. 16 through the low-pass filter (LPF) 21 having a certain characteristic for detecting the shaft torque (T23). (Sum) 22 is fed back and added to the dynamometer torque command (T3ref) to obtain a new dynamometer torque command. With this configuration, in an engine bench system having an intermediate shaft, the dynamometer 6 is stably controlled by suppressing resonance by the coupling 13 that couples the dynamometer 6 and the intermediate shaft 12.

  In FIG. 1, 20 (MIM3J) is a mechanical model of the engine bench system having the intermediate shaft shown in FIG. 16, and in this embodiment, the simulation can be performed by replacing it with the three-inertia mechanical model shown in the block configuration in FIG. However, an actual system is configured to have the mechanical system and control system shown in FIG. Constants in the engine 1, the intermediate shaft 12, and the dynamometer 6 in each block in FIG. 2 are as follows, as shown in FIG. Note that s is a Laplace operator.

J1 = engine moment of inertia, J2 = intermediate shaft inertia moment, J3 = dynamometer moment of inertia, K12 = clutch spring stiffness, K23 = coupling spring stiffness, T1 = engine torque, T3 = dynamometer torque, T23 = shaft torque (cup) Ring), T12 = shaft torque (clutch), ω1 = engine angular speed, ω2 = intermediate shaft angular speed, ω3 = dynamometer angular speed Note that the characteristics of the low-pass filter (LPF) 21 are phase delayed at the resonance frequency due to the coupling 13 Is close to the set value, for example, about 45 degrees. For example, when the resonance frequency due to the spring rigidity of the coupling 13 is 100 Hz as shown in FIG. 18, the characteristic of the low-pass filter (LPF) 21 is a primary low-pass filter of 100 Hz, A 200 Hz secondary low-pass filter.

  FIG. 3 shows the transfer function of the shaft torque (T23) with respect to the dynamometer torque command (T3ref) measured and data-processed by the digital processor 50 by executing a simulation of the dynamometer shaft torque control in the configuration shown in FIG. A Bode diagram is shown and the step response is shown in FIG. As is clear from these figures, the resonance gain due to coupling near 100 Hz, which was about 35 dB in FIG. 18, is reduced to about 5 dB as shown in FIG. Therefore, in FIG. 19, the vibration of 100 Hz is superimposed, but in FIG. 4, the vibration of 100 Hz is almost suppressed, and only the vibration by the clutch (about 7 Hz) appears.

Embodiment (2)
FIG. 5 shows a control system configuration of the present embodiment. 1 is different from that shown in FIG. 1 in that the torque value of the dynamometer 6 in the three-inertia engine bench system having the intermediate shaft shown in FIG. In the adder (Sum) 24, a new dynamometer torque command is added to the dynamometer torque command (T3ref). With this configuration, in an engine bench system having an intermediate shaft, resonance caused by the spring rigidity of the coupling 13 that couples the dynamometer 6 and the intermediate shaft 12 is suppressed and the dynamometer 6 is stably controlled.

  The dead time length of the dead time element (TD) 23 is set so that the phase delay is close to a set value, for example, about 45 degrees at the resonance frequency due to coupling. For example, when the resonance frequency by the coupling 13 is 100 Hz as shown in FIG. 18, the delay of the dead time element (TD) is set to about 1.25 ms. When this configuration is configured by a digital control system having a sampling time of 1 ms, a sample delay element (1 / z) may be used. In the case of a digital control system with a sample time of 100 μs, a 12-sample delay element (1 / z ^ 12) may be used.

  FIG. 6 shows a Bode diagram of the transfer function of the shaft torque (T23) with respect to the dynamometer torque command (T3ref) measured and processed by the digital processor 50 in the configuration shown in FIG. 5, and the step response is shown in FIG. Show. As is clear from these figures, the vibration suppressing effect equivalent to that of the embodiment (1) is obtained.

Embodiment (3)
FIG. 8 shows a control system configuration of this embodiment. 1 differs from FIG. 1 and FIG. 5 in that the torque value of the dynamometer 6 in the three-inertia engine bench system having the intermediate shaft shown in FIG. 25 and an adder (Sum) 27 through a high-pass filter (HPF) 26 and added to the dynamometer torque command (T3ref) to obtain a new dynamometer torque command.

  The delay element (G) 25 is the low-pass filter (LPF) 21 of the embodiment (1) or the dead time element (TD) 23 of the embodiment (2). Further, the characteristic frequency of the high-pass filter (HPF) 26 is appropriately determined so that the control becomes stable in a range lower than the resonance frequency caused by the spring stiffness of the coupling.

  With this configuration, in an engine bench system having an intermediate shaft, resonance by the coupling 13 that couples the dynamometer 6 and the intermediate shaft 12 is suppressed by the intervention of the delay element (G) 25, and a high-pass filter (HPF) 26 is provided. By suppressing the low-frequency feedback of the detected value of the shaft torque (T23), the engine can be started even when the dynamometer torque command is T3ref = 0.

  First, FIG. 9 is obtained by measuring and data processing the step response of the engine speed with respect to the engine torque in the embodiment (1) and the embodiment (2) by the digital processing device 50. As shown in FIG. 9, in the embodiment (1) and the embodiment (2), the engine speed does not increase despite the engine generating torque, and there is no assistance from the dynamometer side (T3ref = 0). ) Cannot start the engine. This is because the direct current component of the detected shaft torque value (T23) is also fed back in the embodiment (1) and the embodiment (2).

  FIG. 10 shows a step response of the engine speed with respect to the engine torque in the present embodiment (3). In this embodiment (3), the DC component of the detected shaft torque value is not fed back by passing through the high-pass filter (HPF) 26. Therefore, as shown in FIG. 10, in this embodiment (3), the engine speed increases, that is, the engine can be started.

Embodiment (4)
FIG. 11 shows a control system configuration of this embodiment. 1 is different from that shown in FIG. 1 in the torque control of the dynamometer 6, the detected value of the shaft torque (T 23) is used as a feedback signal to the shaft torque controller (ATR) 29 through the low pass filter (TMLPF) 28. The torque control output T3A of the torque controller 29 is set as a torque command KT3A through the ratio adjustment amplifier (gain K) 30. Further, the detected value of the shaft torque (T23) is added to the torque command KT3A in the adder (Sum) 33 through the delay element (G) 31 and the ratio adjustment amplifier (gain P) 32 to obtain a new torque command value. The delay element (G) 31 is the low-pass filter (LPF) 21 of the embodiment (1) or the dead time element (TD) 23 of the embodiment (2).

  The shaft torque controller (ATR) 29 has the same configuration as the shaft torque controller described in Patent Document 1. In Patent Document 1, information on the two-inertia machine model shown in FIG. 15 (engine inertia J1, dynamometer inertia J2, clutch spring stiffness K12, engine angular velocity ω1, dynamometer angular velocity ω2) is used to determine the shaft torque command T12r and the shaft. A shaft torque controller that performs PID control with a deviation from the detected torque value T12. The calculation of the dynamometer torque control signal T2 at this time is determined by the following integral elements and proportional / differential elements.

T2 = (Ki / s) * (T12r−T12) − (Kp + s * Kd) / (a2 * s * s + a1 * s + 1) * T12 (Expression 1)
However, Ki: integral coefficient, T12r: shaft torque command value, T12: shaft torque detected value, Kp: proportional coefficient, Kd: differential coefficient, a1, a2: filter coefficient of proportional / differential element Here, the shaft torque command T12r is When T23ref in FIG. 11 is replaced, the detected shaft torque value T12 is replaced with T23det in FIG. 11, and the dynamometer torque control signal T2 is replaced with the torque control output T3A in FIG. 11, (Equation 1) becomes Become.

T3A = (Ki / s) * (T23ref−T23det) − (Kp + s * Kd) / (a2 * s * s + a1 * s + 1) * T23det (Expression 2)
Further, in Patent Document 1, since the coupling shaft of the engine and the dynamometer has nonlinear spring characteristics, the integral and proportionality of the PID control of the shaft torque controller can be compensated for so that the resonance frequency can be compensated for by the magnitude of the shaft torque. The coefficients (integral coefficient Ki, proportional coefficient Kp, differential coefficient Kd, filter coefficients a1 and a2) of each element of differentiation can be automatically adjusted based on the detected shaft torque value T12.

  The shaft torque controller 29 of FIG. 11 in this embodiment is PID control similar to the shaft torque controller of Patent Document 1. However, since the shaft torque controller 29 is applied to the three-inertia machine model, the combination of the engine, the clutch, and the intermediate shaft in FIG. 17 is regarded as the engine in FIG.

  Specifically, the gains P and K of the ratio adjustment amplifiers 30 and 32 and the gain of the shaft torque controller (ATR) 29 in FIG. 11 are determined as follows.

The gain P of the ratio adjustment amplifier 32 is a gain that determines the strength of resonance suppression at the resonance point by coupling, and is set to a value of about 0.5 to 1. At this time, the ratio adjustment amplifier 30 gain K is
K = ((1-P) * (J1 + J2) + J3) / (J1 + J2 + J3)
And Further, the gain of the shaft torque controller (ATR) 29 determines the dynamometer torque control signal T3A (T2) according to the arithmetic expression of Patent Document 1 described above. However, the moment of inertia J1m2, the dynamometer moment of inertia J2m2, and the spring stiffness K12m2 of the coupling in FIG.
Jlm2 = JI + J2
J2m2 = J3
K12m2 = ((J1 + J2) * J3) / (J1 * (J1 + J2 + J3)) * ((J1 + J2) * (1-P) + J3) / (J2 * (1-P) + J3) * K12
Decide as.

  12 shows a Bode diagram of the transfer function of (T23) with respect to the dynamometer torque command (T23ref) measured and data-processed by the digital processing device 50 in the configuration shown in FIG. 11, and the step response is shown in FIG. As described above, when the shaft torque control method of Patent Document 1 is directly applied to an engine bench system having an intermediate shaft, the resonance point due to coupling becomes unstable and control is impossible as shown in FIGS. However, according to the present embodiment (4), as shown in FIGS. 12 and 13, both the resonance by the clutch and the resonance by the coupling are suppressed and controllable.

20 Three-inertia mechanical model of engine bench system 21 Low-pass filter (LPF)
22, 24, 27, 33 Adder (Sum)
23 Waste time element (TD)
25, 31 Delay element (G)
26 High-pass filter (HPF)
28 Low-pass filter (TMLPF)
29 Axis torque controller (ATR)
30, 32 Ratio adjustment amplifier 50 Digital processing device

Claims (4)

A control system configuration in which an intermediate shaft provided on the output shaft of the engine is coupled to a dynamometer via a coupling, the engine controls output according to the engine control command, and the dynamometer controls shaft torque according to the shaft torque command value In the engine bench system
A dynamometer shaft torque detection value is added to a dynamometer torque command value through a low-pass filter to obtain a new dynamometer torque command value. The low-pass filter has a phase at a resonance frequency generated by the spring stiffness of the coupling. A shaft torque control device for a dynamometer, characterized in that the delay is close to a set value. A control system configuration in which an intermediate shaft provided on the output shaft of the engine is coupled to a dynamometer via a coupling, the engine controls output according to the engine control command, and the dynamometer controls shaft torque according to the shaft torque command value In the engine bench system
The detected value of the shaft torque of the dynamometer is added to the dynamometer torque command value through the dead time element (TD) to obtain a new dynamometer torque command value, and the dead time element is a phase lag at the resonance frequency due to the spring stiffness of the coupling. A shaft torque control device for a dynamometer, characterized in that the dead time length becomes close to the set value. A control system configuration in which an intermediate shaft provided on the output shaft of the engine is coupled to a dynamometer via a coupling, the engine controls output according to the engine control command, and the dynamometer controls shaft torque according to the shaft torque command value In the engine bench system
The new dynamometer torque command value is obtained by adding the shaft torque detection value of the dynamometer that has passed through the low-pass filter (LPF) or dead time element (TD) to the dynamometer torque command value through the high-pass filter (HPF). age,
The low-pass filter makes the phase lag at the resonance frequency generated by the spring stiffness of the coupling close to a set value,
The dead time element is a dead time length in which the phase delay is close to a set value at the resonance frequency due to the spring stiffness of the coupling,
A shaft torque control device for a dynamometer, characterized in that a characteristic frequency of the high-pass filter is in a range lower than a resonance frequency caused by a spring stiffness of the coupling. An intermediate shaft provided on the output shaft through the engine clutch is coupled to a dynamometer through a coupling. The engine controls output according to the engine control command, and the dynamometer controls shaft torque according to the shaft torque command value. In the engine bench system with the control system configuration
A shaft torque controller that calculates a torque control output by performing PID calculation on a deviation from a shaft torque detection value that has passed through a first low-pass filter (LPF) with respect to a dynamometer torque command value;
The shaft torque detection value that has passed through the second low-pass filter (LPF) or dead time element (TD) is added to the control output of the shaft torque controller at a predetermined ratio to obtain a new dynamometer torque command value,
The shaft torque controller obtains the torque control output T3A by the PID calculation of the following equation,
T3A = (Ki / s) * (T23ref−T23det) − (Kp + s * Kd) / (a2 * s * s + a1 * s + 1) * T23det
Where T23ref: shaft torque command, T23det: first low-pass filter (LPF) output of shaft torque detection value, Ki: integral coefficient, Kp: proportional coefficient, Kd: differential coefficient, a1, a2: proportional / differential element The filter coefficient of the second low-pass filter is such that the phase lag at the resonance frequency generated by the spring stiffness of the coupling is close to a set value, and the dead time element has a phase lag at the resonance frequency due to the spring stiffness of the coupling. A shaft torque control device for a dynamometer characterized in that the dead time length is close to a set value.

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