JPH106180A - Work machining device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove influence of gravity and inertia force, and measure accurate pressing force and the moment by arranging a detecting means to detect pressing force applied to a work by a work means, in a fixing means to support and fix the work. SOLUTION: A work 2 is supported by a work support means 10 composed of a six-axial tension sensor 8 as a detecting means and a base stand 9. In the six-axial tension sensor 8, an under surface is fixed to the base stand 9 by a screw or the like. At the time of machining, pressing force applied to the work 2 is measured by the six-axial tension sensor 8, and measuring information of this pressing force is converted into an electric signal, and is transmitted to a robot controller 7. When the measured pressing force does not fall within a range of preset pressing force, it is controlled so that pressing force of a grinder 6 falls within a preset range by the robot controller 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work supporting apparatus for use in machining a workpiece with a robot, and a method for controlling a pressing force of the robot.

[0002]

2. Description of the Related Art When performing machining such as grinding or cutting on a workpiece, a grinding tool or a cutting tool may be attached to the tip of a robot arm to perform machining. In this robot, a grinding tool or a cutting tool is brought into contact with a workpiece with a predetermined pressing force by driving an arm in a three-dimensional direction, thereby performing machining of the workpiece.

In the case of performing machining using such a robot, if the pressing force is larger than an appropriate value, the grinding tool, the cutting tool, or the work will be damaged, and conversely, the pressing force will be lower than the appropriate value. If it is small, the processing speed will be low and the processing efficiency will be poor. In order to make the processing efficiency appropriate, it is necessary to control the pressing force of the grinding tool or the cutting tool on the work to an appropriate value. Also, when performing machining by contacting the work with the tool not on the point but on the surface, such as in buffing, etc., measure the moment generated during the machining and set the value of this moment to an appropriate value. It is necessary to control, and if this moment is not controlled, the accuracy of finishing may be affected.

For this reason, conventionally, a sensor capable of measuring a pressing force and a moment is attached to a robot arm, and the pressing force and the moment are controlled based on a measurement signal from the sensor according to the pressing force and the moment. Feedback.

The same applies to a configuration in which a workpiece is held by a robot arm, and the arm is driven to press the workpiece against a grinding tool or a cutting tool provided outside the robot to perform machining. That is, this configuration is different from the above configuration in that the workpiece is replaced with a grinding tool or a cutting tool, but even in this case, since the sensor is attached to the arm holding the workpiece, The generated pressing force and moment can be measured by this sensor.

The above-mentioned robot may be used, for example, for assembling in addition to machining.
Especially when performing precise fitting and assembling, even a slight displacement between the workpiece gripped by the robot and the workpiece to be assembled can cause galling and biting. The interaction force generated with the target work is measured by a sensor attached to the arm in the same manner as above, and if this measurement controls the movement of the robot so as to avoid galling and biting, reliable assembly processing can be performed. It is possible to do.

[0007]

The sensor mounted on the robot as described above simultaneously measures the gravity and moment due to the weight of the tool and the work. In order to accurately measure the gravity and the moment, it is necessary to remove the influence of the gravity and the moment from the measured value by this measurement.

[0008] However, the moment due to the gravity and the own weight of the tool or the work changes with the posture of the robot. Therefore, in order to accurately grasp the influence of gravity and moment, it is necessary to predict the influence value at that time by calculation from the posture of the robot, and to correct the measurement value of the sensor using the calculated value. This calculation process requires many calculation steps, and a more expensive computer is required to perform such a calculation process at high speed.

In order to measure the gravitational force and moment by the tool or the work as described above, an error occurs in the calculated value unless the weight of the tool or the work and the position of the center of gravity are accurately grasped. , Gravity and moment could not be measured accurately. The data on the weight and center of gravity of the tool and the work must be changed every time a new tool or work is carried. For this purpose, it is necessary to measure the weight and the center of gravity of all the tools or the work in advance. , It was necessary to measure every time I switched.

When the robot arm is driven, not only the effect of the gravity due to the tool or the work and the moment due to its own weight, but also the acceleration of the tool or the work held by the arm is generated, and the tool or the work is applied to the object. Even if they are not in contact with each other, they are measured as inertial forces, and some detection signals are generated from the sensors. Compensating for the effects of this inertia is much more difficult than compensating for the effects of gravity and moment, and there is usually no other way to treat this effect as noise. For this reason, in the above-described force control, there is a problem that the response is deteriorated. Even in this case, effective countermeasures have been devised when all contact positions between the object and the tool or work can be grasped, but such conditions are not always satisfied, and the influence of inertia is corrected. It is difficult.

The present invention has been made based on the above-mentioned circumstances, and an object of the present invention is to provide an accurate pressing force and moment without measuring gravity and inertia when measuring the pressing force and moment. It is an object of the present invention to provide a work supporting / processing apparatus capable of measuring the pressure and a method for controlling a pressing force of a robot.

[0012]

According to another aspect of the present invention, there is provided a workpiece processing apparatus, comprising: a processing means for processing a work; a fixing means for supporting and fixing the work; Detecting means for detecting a pressing force applied to the work by the processing means, and control means for controlling the pressing force applied to the work by controlling the processing means based on a detection result from the detecting means. Features.

The processing means is a robot and a processing tool provided on the robot. (Claim 2) A work processing apparatus according to claim 3 is provided in a holding / moving means for holding and moving a work, a fixing means for holding and fixing a processing tool, and a fixing means. Detecting means for detecting the pressing force applied to the working tool by the held work, and control means for controlling the holding / moving means based on the detection result from the detecting means to control the pressing force applied to the working tool. It is characterized by having.

According to the first and second aspects of the present invention, the fixing means is provided separately from the robot and the detecting means is provided. Therefore, when machining is performed by the robot, the gravity of the working tool due to its own weight, and this own weight. Pressure can be detected accurately without being affected by the inertia of the workpiece.Furthermore, by controlling the robot based on the pressing force obtained by the detecting means, the pressing force of the machining tool on the workpiece can be set within an appropriate range. Can be kept.

According to the third aspect of the present invention, the work is held by the robot, and the processing tool is held by the fixing means having the detection means provided separately from the robot. Accurate pressing force can be detected without being affected by gravity due to its own weight and inertia due to its own weight.Furthermore, by controlling the robot based on the pressing force obtained by the detecting means, it The pressing force (= the pressing force of the working tool against the work) can be kept within an appropriate range.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a work processing apparatus according to the present invention will be described below with reference to FIGS. As shown in FIG. 1, the robot 1 performs mechanical processing such as grinding and cutting on a work 2. The configuration of the robot 1 is a configuration in which an arm 4 is attached to a base 3. The arm 4 includes a first arm member 4 a, a second arm member 4 b, a third arm member 4 c, and a fourth arm member 4 in that order from the base 3 side. The arm member 4d is connected by a plurality of movable nodes 5a to 5c, and has a structure that can be driven in a three-dimensional direction. In the present embodiment, a grinder 6 as a tool for performing a grinding process is attached to the distal end portion 4e of the fourth arm member 4d.

A drive means (not shown) is provided inside the base 3 so as to rotate the first arm member 4a in the θ direction in FIG. In addition, movable joints 5a to 5
A motor as a driving means for driving the second to fourth arm members 4b to 4d is built in c, respectively, so that the respective arm members 4b to 4d can be rotationally driven.

The grinder 6 is also provided with a drive source (not shown), and the drive source rotates the grindstone 6a. The structure of the arm is not limited to such a configuration. For example, the arm members 4a to
A configuration may be adopted in which driving means for driving 4d is built in, and each of the arm members 4a to 4d is driven using transmission means such as a wire.

The arm 4 and the grinder 6 of the robot 1
Is driven and controlled by a robot controller 7 connected to the base 3. That is, control means (not shown) is provided inside the robot controller 7, and the control means controls the driving of the motors of the movable nodes 5 a to 5 c and the drive source of the grinder 6.

On the other hand, the work 2 is supported by a work supporting means 10 comprising a six-axis force sensor 8 as a detecting means and a base 9. The lower surface of the six-axis force sensor 8 is fixed to the base 9 with screws or the like, so that accurate measurement can be performed. In addition, a locking means for holding the work 2 so as not to move is provided on the upper surface, so that the work 2 does not fluctuate even in contact with a tool or machining.

The six-axis force sensor 8 is electrically connected to the robot controller 7 and, when detecting a pressing force or a rotating moment, converts measurement information corresponding to the pressing force or the rotating moment into an electric signal. To the robot controller 7. The robot controller 7 that has received the electric signal generates a control signal based on the measurement information, and the control unit controls a motor as a driving unit of the movable nodes 5a to 5c and a driving source of the grinder 6.

Such a six-axis force sensor 8 is composed of X, Y, Z
Is a sensor capable of measuring the force in the three axial directions and the force in the rotational direction about each axis. The operation of the work processing apparatus having the above configuration will be described below.

The 6-axis force sensor 8 holds the work 2 by the locking means. Then, the arm 4 is
The grindstone 6a of the grinder 6 attached to the tip of the work is moved to the work 2 by the movement of the arm 4, and the work 2
The grindstone 6a is pressed with a suitable pressing force to the workpiece 2 and the grindstone 6a is rotationally driven by a driving source to perform the grinding of the work 2.

At the time of this machining, the pressing force received by the work 2 is measured by the six-axis force sensor 8, and the measurement information of the pressing force is converted into an electric signal and transmitted to the robot controller 7. If the measured pressing force is not within the range of the preset pressing force, the robot controller 7 controls the pressing force of the grinder 6 to be within the set range.

FIG. 2 is a diagram showing a state of generation of a pressing force and a moment of the work processing apparatus. Hereinafter, capital letters (F0, Fs, T0, Ts, P) have not only a size but also a direction. As a vector, a description will be given of a force and a moment generated in the work 2 when grinding is performed on the work 2 using the grinder 6.

As shown in FIG. 2, when the grinder 6 applies a pressing force F0 to the work 2, a translational force Fs, which is a force equal to the pressing force F0, is applied to the work 2 by a six-axis force sensor 8.
It will be measured by. That is, if the translational force Fs is measured by the six-axis force sensor 8, it means that the pressing force F0 having the same force as the measured translational force Fs has been measured. In addition to the translational force Fs, the rotational moment Ts of the six-axis force sensor 8 about the determined sensor origin O1 is also measured. Here, arm 4
An origin O2 of the grinder 6 is determined at an arbitrary position near the tip portion 4e to which the grinder 6 is attached, and an arbitrary position vector of the origin O2 of the grinder 6 is represented by P. In this case, the moment T0 of the grinder 6 around the origin O2 is obtained by the following equation.

T 0 = Ts−Fs × P (1) In the above equation (1), x represents the outer product of the vectors. In this way, the pressing force F0 and the rotational moment T0 generated by the grinder 6 are obtained.
Is measured after removing the influence of the weight of the grinder 6 and the inertia. That is, the six-axis force sensor 8 measures the pressing force and the rotational moment received by the work 2, and the measured values are F0 and T0, respectively.

Since the measured value does not include the influence of the own weight or inertia of the grinder 6 as described above, the robot controller 7 to which the measurement information based on the measured value has been transmitted is added to the work 2. It is possible to more precisely control the pressing force and the rotational moment to the set values.

According to the work supporting and processing apparatus and the robot pressing force control method, the six-axis force sensor 8 for fixing and measuring the work 2 is provided separately from the movable part such as the arm 4 of the robot 1. Due to the configuration provided, when the robot 1 is operated to perform machining on the work 2 by the grinder 6 or the like, the gravity of the grinder 6 does not add to the work 2 due to its own weight, so that the pressing force can be measured. Accurate calculation can be performed without performing complicated calculation processing.

Since the six-axis force sensor 8 is not attached to the tip 4e of the arm 4, the measurement of the inertial force generated by the movement of the arm 4 is also eliminated. For this reason, it is also possible to remove the noise caused by the inertial force, which has been difficult to remove so far, and thus it is possible to more appropriately measure the pressing force by the six-axis force sensor 8.

Further, since the work supporting and processing apparatus is provided with the robot controller 7, the influence of the self-weight of the grinder 6 and the influence of the inertia force are removed, and the measurement signal based on the pressing force is converted into the above-described signal. Robot 1
And control can be performed.

Although the embodiment of the present invention has been described above, the present invention can be variously modified. This is described below. In the above embodiment, the grinder 6 is provided at the tip 4 e of the arm 4.
Alternatively, the work 2 may be held. In this case, a tool such as a grinder 6 is provided on an external 6-axis force sensor 8 separate from the robot 1 to measure the pressing force generated in the grinder 6. In this case, too, Since it is possible to generate an appropriate pressing force between the workpiece 2 and the grinder 6 while eliminating the influence of its own weight and the effect of inertia, it is possible to measure the pressing force as well as in the above embodiment. Becomes possible.

Further, in the above-described embodiment, the configuration using the grinder 6 is shown as an example of the tool. However, the tool is not limited to the grinder 6 and performs a cutting process such as a lathe or a milling machine. A tool may be attached.

In the above embodiment, the six-axis force sensor 8 is used as the measuring means. However, it is not always necessary to measure all six axes. A configuration may be adopted in which another measuring means is used without using the axial force sensor 8.

[0035]

As described above, according to the first and second aspects of the present invention, the fixing means is provided separately from the robot and the detecting means is provided. It is possible to accurately detect the pressing force without being affected by gravity due to its own weight and inertia due to this own weight, and further, by controlling the robot based on the pressing force obtained by the detecting means, the processing tool for the workpiece can be detected. Can be kept within an appropriate range.

According to the third aspect of the present invention, the work is held by the robot, and the working tool is held by the fixing means having the detecting means provided separately from the robot. Accurate pressing force can be detected without being affected by gravity due to its own weight and inertia due to its own weight.Furthermore, by controlling the robot based on the pressing force obtained by the detecting means, it The pressing force (= the pressing force of the working tool against the work) can be kept within an appropriate range.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a work supporting and processing apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a state in which a pressing force and a moment are generated using the work supporting / processing apparatus according to the embodiment;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Robot 2 ... Work 3 ... Base 4 ... Arm 5 ... Movable joint 6 ... Grinder 7 ... Robot controller 8 ... 6-axis force sensor

Claims (3)

[Claims] A processing means for processing the work; a fixing means for supporting and fixing the work; a detection means provided on the fixing means for detecting a pressing force applied to the work by the processing means; Control means for controlling the processing means based on the detection result from the control means to control the pressing force applied to the work. 2. The apparatus according to claim 1, wherein the processing means is a robot and a processing tool provided on the robot.
The work processing device as described. 3. A holding and moving means for holding and moving a work, a fixing means for holding and fixing a processing tool, and a processing tool provided on the fixing means and being held by the holding and moving means. Detecting means for detecting the pressing force applied to the machining tool, and control means for controlling the pressing force applied to the working tool by controlling the holding / moving means based on the detection result from the detecting means. Work processing equipment.