JPH07100781A - Articulated robot - Google Patents

Abstract

PURPOSE:To efficiently carry out the power work in any direction of an anticulated robot by installing an angular displacement error position correcting means which position-corrects the angular displacement error of the redution gear for each articulation on the basis of the position correction quantity obtained by an angular displacement error position correction quantity calculating means. CONSTITUTION:The position correction quantity of each angular displacement error of the reduction gears 2b, 4b and 6b for each articulation which corresponds to each working force in the work carried out by a robot, on the basis of the displacement angle equation of the reduction gears 2b, 4b and 6b for each articulation for the force applied on the hand 8 of a robot is calculated by an angular displacement error position correction quantity calculating means. Then, the angular displacement error of the reduction gears 2b, 4b and 6b for each articulation is position-corrected by an angular displacement error position correcting means 9 on the basis of the position correction quantity obtained by the angular displacement error position correction quantity calculating means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an articulated robot, and more particularly, it can be applied to a position correction technique of an articulated robot arm, and particularly, it occurs when a force is applied to a reducer of each joint. The present invention relates to an articulated robot capable of efficiently performing a force operation in any direction by correcting a position so as to eliminate an angular displacement error due to elastic deformation of a speed reducer.

[0002]

2. Description of the Related Art Conventionally, an articulated robot generally uses a servo motor to drive a joint, and a reducer is attached to the motor shaft of the servo motor, and a plurality of rotatably supported arms are connected to each other. It is composed of multiple joints. The multi-joint robot has a structure in which each joint is positioned and controlled with the motor angular position of each joint as a target value to obtain multiple degrees of freedom. For this reason, this multi-joint robot can increase the rigidity in the normal direction orthogonal to the rotation direction of each joint, and thus it is possible to prevent a large displacement from occurring even if a force is applied to the arm. Have.

[0003]

As described above, since the conventional articulated robot has a structure in which each joint is positioned and controlled with the motor angular position of each joint as a target value to obtain multiple degrees of freedom, This has the advantage that the rigidity in the direction normal to the direction of rotation of each joint can be increased so that even if force is applied to the arm, a large displacement is unlikely to occur, but force is applied in the direction of rotation of each joint. If the speed reducer backlashes and elastically deforms, twisting occurs in the rotational direction, and if the motor angular position is accurately positioned, the arm supported by the speed reducer may have an error due to the angular displacement of the elastic deformation. Occurs, resulting in a position error in the arm tip coordinates. For example, in the case of a work requiring force, if the axial rigidity of the arm, that is, the rigidity of the reducer of the joint is high, the arm moves from point A to point B with the positioning accuracy of the robot, as shown in FIG. However, no matter how much reaction force is exerted on the arm, it is possible to surely perform the force work.

However, the rigidity of the speed reducer actually used is low, and as shown in FIG. 16 (b), it elastically deforms and twists the shaft. In this case, even if the movement operation from point A to point B is executed by arm control and the position pulse value of the encoder of the servo motor matches, the position of the arm is twisted and deformed by the joint axis. Position error occurs.
Since this error differs depending on the posture of the arm and the work force, it cannot be compensated by simple correction control. Therefore, in the articulated robot having the conventional structure, there is a problem that, in the case of a work requiring an assembling force such as press-fitting and assembling of components, screwing, the assembling can be performed only in the direction without the rotation direction of each joint.

Therefore, according to the present invention, position correction is performed so as to eliminate an angular displacement error due to elastic deformation of the reduction gear that occurs when a force is applied to the reduction gear of each joint, so that force work in any direction can be efficiently performed. The purpose is to provide an articulated robot that can be used.

[0006]

The invention according to claim 1 is
A servomotor that drives a plurality of joints, a speed reducer attached to the motor shaft of the servomotor, and an arm that is rotatably supported by the speed reducer at each joint. And a multi-joint robot that drives each joint with a motor angular position of each joint as a target value and obtains multiple degrees of freedom, the displacement angle expression of the reducer of each joint with respect to the force applied to the hand of the robot An angular displacement error position correction amount calculation means for calculating the position correction amount of the angular displacement error of the reduction gear of each joint according to each work force of the work performed by the robot, and the angular displacement error position correction amount calculation means And an angular displacement error position correcting means for correcting the angular displacement error of the speed reducer of each joint based on the position correction amount obtained in (4).

According to a second aspect of the present invention, there is provided a servomotor for driving a plurality of joints, a speed reducer attached to a motor shaft of the servomotor, and an arm rotatably supported by each speed reducer at each joint. In the articulated robot, which has multiple joints by connecting a plurality of the arms and drives each joint with the motor angular position of each joint as a target value, the robot's hand or the hand Substituting the pressure sensor provided in the turret and the pressure value signal of the pressure sensor into the displacement angle formula of the reducer of each joint with respect to the force applied to the hand of the robot, the angle of the reducer of each joint Based on the angular displacement error position correction amount calculation means for calculating the position correction amount of the displacement error and the position correction amount calculated by the angular displacement error position correction amount calculation means, the angular displacement error of the reducer of each joint is calculated. It is characterized in that it has a angular displacement error position correcting means for location correction.

According to a third aspect of the present invention, there is provided a servomotor for driving a plurality of joints, a speed reducer attached to a motor shaft of the servomotor, and an arm rotatably supported by each speed reducer at each joint. Then, in a multi-joint type robot in which a plurality of arms are connected to each other to form a multi-joint, and each joint is driven with a motor angular position of each joint as a target value to obtain multiple degrees of freedom, the robot performs manual work. A pressure sensor provided on a jig on which a workbench or an assembly part is mounted, and a pressure value signal of the sensor are substituted into a displacement angle formula of a reducer for each joint with respect to a force applied to the hand of the robot, and An angular displacement error position correction amount calculation means for calculating a position correction amount of the angular displacement error of the reduction gear, and an angular displacement of the reduction gear of each joint based on the position correction amount obtained by the angular displacement error position correction amount calculation means. Mistake It is characterized in that it has a angular displacement error position correcting means located corrected.

According to a fourth aspect of the present invention, there is provided a servomotor for driving a plurality of joints, a speed reducer attached to a motor shaft of the servomotor, and an arm rotatably supported by each speed reducer at each joint. In the multi-joint type robot, in which a plurality of joints are formed by connecting the arms, and each joint is driven with the motor angular position of each joint as a target value to obtain multiple degrees of freedom, the output shaft of the servo motor is The provided torque sensor and the torque signal of the torque sensor are substituted into the displacement angle expression of the reduction gear of each joint with respect to the force applied to the hand of the robot, and the position correction amount of the angular displacement error of the reduction gear of each joint is calculated. Angle displacement error position correction amount calculation means, and the angular displacement error position for correcting the angular displacement error of the reducer of each joint based on the position correction amount calculated by the angle displacement error position correction amount calculation means. It is characterized in that it has a correction unit.

According to a fifth aspect of the present invention, there is provided a servomotor for driving a plurality of joints, a speed reducer attached to a motor shaft of the servomotor, and an arm rotatably supported by each speed reducer at each joint. In the multi-joint type robot, in which a plurality of arms are connected to form a multi-joint, and each joint is driven with a motor angle position of each joint as a target value to obtain multiple degrees of freedom, the servo motor is provided. A joint displacement angle measuring encoder for measuring the joint displacement angle provided in the link part of each joint separately from the encoder, an encoder position pulse measuring means for measuring the position pulse of the joint displacement angle measuring encoder, and a predetermined number The amount of movement of the joint displacement angle measuring encoder calculated by calculating the difference between the target value of the motor angular position of the joint and the value measured by the encoder position pulse measuring means. An angular displacement error position correction amount calculation means for obtaining the position correction amount of the angular displacement error of the reduction gear of each joint based on the movement amount, and a position correction amount calculated by the angular displacement error position correction amount calculation means And angular displacement error position correcting means for correcting the angular displacement error of the reduction gear of each joint.

According to a sixth aspect of the present invention, there is provided a servomotor for driving a plurality of joints, a speed reducer attached to the motor shaft of the servomotor, and an arm rotatably supported by each speed reducer at each joint. In the multi-joint type robot, in which a plurality of arms are connected to form a multi-joint, and each joint is driven with a motor angle position of each joint as a target value to obtain multiple degrees of freedom, the servo motor is provided. Separately from the encoder, a rotary encoder in which a roller is attached to the shaft of the encoder is provided on the speed reducer input side of each joint, a rail provided on the speed reducer output side so that the roller can be rolled without slipping, and the rotary encoder Of the rotary encoder position pulse measuring means for measuring the position pulse of, the target value of the motor angular position of each joint determined in advance and the value measured by the rotary encoder position pulse measuring means. Is calculated to obtain the amount of movement of the rotary encoder, and based on the amount of movement, the angular displacement error position correction amount calculation means for obtaining the position correction amount of the angular displacement error of the reducer of each joint, and the angular displacement. And an angular displacement error position correcting means for correcting the angular displacement error of each joint based on the position correction amount obtained by the error position correction amount calculating means.

According to a seventh aspect of the present invention, there is provided a servomotor for driving a plurality of joints, a speed reducer attached to a motor shaft of the servomotor, and an arm rotatably supported by each speed reducer at each joint. In the articulated robot, in which a plurality of arms are connected to each other to form a multi-joint, and each joint is driven with a motor angle position of each joint as a target value to obtain multiple degrees of freedom, A wire cable for measuring a joint displacement angle, a wire cable moving amount measuring means for measuring a moving amount of the wire cable, a predetermined target value of a motor angle position of each joint and the wire cable moving amount measuring means. And a value calculated by the angular displacement error position correction amount calculation means for calculating the position correction amount of the angular displacement error of the reduction gear of each joint by calculating the difference from the calculated value. Based on the correction amount, it is characterized in that it has a angular displacement error position correcting means for the angular displacement error to position correction of the speed reducer of each joint.

[0013]

According to the invention described in claim 1, based on the displacement angle formula of the reducer of each joint with respect to the force applied to the hand of the robot, the reducer of each joint corresponding to each working force of the work performed by the robot A position correction amount of the angular displacement error is calculated by the angular displacement error position correction amount calculation means, and the angular displacement error of the reduction gear of each joint is calculated based on the position correction amount obtained by the angular displacement error position correction amount calculation means. The displacement error position correcting means is configured to correct the position.

Therefore, the position correction amount of the angular displacement error of the reducer of each joint is determined according to each working force of the work performed by the robot, which is obtained by the displacement angle formula of the reducer of each joint with respect to the force applied to the hand of the robot. Based on this, it is possible to correct the position of the angular displacement error of the reduction gear of each joint. That is, when repeatedly performing a predetermined assembly operation by the robot,
The work force of each work in which force work is generated is measured in advance, the result of each work force of this work measured in advance is set in the work program, and the speed reducer of each joint according to the set value is automatically set. After calculating the position correction amount of the angular displacement error based on the displacement angle formula of the reducer of each joint with respect to the force applied to the robot hand, the angular displacement error of the reducer of each joint is position corrected based on this position correction amount. Therefore, it is possible to prevent an angular displacement error due to elastic deformation of the reduction gear, and it is possible to efficiently perform a force operation in any direction of the articulated robot.

According to a second aspect of the present invention, the pressure sensor provided on the robot hand or the turret part to which the hand is attached, and the deceleration of each joint with respect to the force applied to the robot hand by the pressure value signal of the pressure sensor. The position correction amount of the angular displacement error of the speed reducer of each joint is calculated by the angular displacement error position correction calculating means, and the position correction amount is obtained by the angular displacement error position correction amount calculating means. Based on the above, the angular displacement error of the reduction gear of each joint can be corrected by the angular displacement error position correcting means.

Therefore, based on the position correction amount of the angular displacement error of the reducer of each joint obtained by substituting the pressure value signal of the pressure sensor into the displacement angle formula, the angular displacement error of the reducer of each joint is adjusted. Since the correction can be performed, an angular displacement error due to elastic deformation of the reducer can be prevented from occurring, and the robot can efficiently perform the force work in any direction, and the force work in advance according to claim 1 occurs. It is possible to eliminate the trouble of measuring the work force of each work, and to correct the angular displacement error of the speed reducer in every work in real time. In addition, it is possible to accurately perform work such as pressure and screw tightening, which cause large variations in manual work during assembly work.

According to the third aspect of the invention, the pressure value signal of the pressure sensor provided on the workbench on which the robot performs the manual work or the jig on which the assembly parts are mounted is decelerated by each joint with respect to the force applied to the hand of the robot. The position correction amount of the angular displacement error of the reduction gear of each joint is calculated by the angular displacement error position correction amount calculation means, and the position correction calculated by the angular displacement error position correction amount calculation means Based on the amount, the angular displacement error of the reduction gear of each joint can be corrected by the angular displacement error position correcting means.

Therefore, similar to the second aspect of the invention, each joint is based on the position correction amount of the angular displacement error of the reducer of each joint obtained by substituting the pressure value signal of the pressure sensor into the displacement angle expression. Since the angular displacement error of the speed reducer can be position-corrected, the angular displacement error due to the elastic deformation of the speed reducer can be prevented, and the force work in any direction of the robot can be efficiently performed, and the workbench can be efficiently used. Alternatively, since the sensor is provided in the jig, wiring in the robot arm can be made easier than in the case where the pressure sensor is provided in the robot hand or the turret according to claim 2.
Maintenance for disconnection can be facilitated. In addition, if a dedicated pressure sensor suitable for the shape of the assembly parts and the work force is installed on the assembly jig, highly accurate position correction control can be performed.

According to the fourth aspect of the invention, the torque signal of the torque sensor provided on the output shaft of the servomotor is substituted into the displacement angle formula of the reducer of each joint with respect to the force applied to the robot hand, and the deceleration of each joint is reduced. The position correction amount of the angular displacement error of the machine is calculated by the angular displacement error position correction amount calculation means,
The angular displacement error position correcting unit is configured to correct the angular displacement error of the reducer of each joint based on the position correction amount obtained by the angular displacement error position correction amount calculating unit.

Therefore, the angular displacement error of the reducer of each joint is corrected based on the position correction amount of the angular displacement error of the reducer of each joint obtained by substituting the torque signal of the torque sensor into the displacement angle formula. Therefore, the force work in any direction of the robot can be efficiently performed without causing an angular displacement error, and the torque of the servo motor directly applied to the speed reducer is measured. Since the reliability can be made higher than that of the pressure sensor of the invention of claim 3 and the calculation error such as the error of arm length can be reduced, the accuracy is higher than that of the invention of claims 1 to 3. Position correction control can be performed.

According to a fifth aspect of the present invention, a joint displacement angle measuring encoder for measuring the joint displacement angle provided in the link portion of each joint separately from the encoder provided in the servomotor, and the joint displacement angle measuring encoder. Encoder position pulse measuring means, and the joint displacement angle measuring encoder calculates the difference between the predetermined target value of the motor angle position of each joint and the value measured by the encoder position pulse measuring means. The amount of movement that has been moved is calculated, the position correction amount of the angular displacement error of the reduction gear of each joint is calculated by the angular displacement error position correction amount calculation means, and the angular displacement error position correction amount calculation means is calculated based on the calculated movement amount. The angular displacement error of the reduction gear of each joint can be corrected by the angular displacement error position correcting means based on the position correction amount.

Therefore, based on the position correction amount of the angular displacement error of the speed reducer, which is obtained by calculating the difference between the target value of the motor angular position of each joint and the value measured by the encoder position pulse measuring means, Since the angular displacement error of the joint reducer can be corrected, the angular displacement error can be prevented and the force work in any direction of the robot can be performed efficiently, and the joint built-in encoder directly Since the displacement angle can be measured,
Since the difference between the motor angle position target value and the joint movement angle can be accurately obtained, the most accurate position correction control can be performed.

According to a sixth aspect of the present invention, in addition to the encoder provided in the servomotor, a rotary encoder in which a roller is attached to the shaft of the encoder is provided on the input side of the speed reducer of each joint, and the output side of the speed reducer is provided with the rotary encoder. A roller provided so that the roller can roll without slipping, the position pulse of the rotary encoder is measured by the encoder position pulse measuring means, and the target value of the motor angular position of each joint determined in advance and the rotary encoder position pulse measurement The difference from the value measured by the means is calculated, and based on this value, the position correction amount of the angular displacement error of the reduction gear of each joint is calculated by the angular displacement error position correction calculation means, and this position correction is performed. Based on the amount, the angular displacement error of each joint can be corrected by the angular displacement error position correcting means.

Therefore, the position correction amount of the angular displacement error of the reduction gear obtained by calculating the difference between the predetermined target value of the motor angular position of each joint and the value measured by the rotary encoder position pulse measuring means. Based on, it is possible to correct the angular displacement error of the reducer of each joint, so that it is possible to efficiently perform the force work in any direction of the robot without causing the angular displacement error.
By reducing the diameter of the roller, a high-resolution encoder pulse can be obtained with respect to the joint displacement angle, and by using a general-purpose rotary encoder, a low-cost system can be configured.

In the invention according to claim 7, the joint displacement angle provided at the link portion of each joint is measured by the wire cable, and the movement amount of the wire cable is measured by the wire cable movement amount measuring means, and each joint is determined in advance. By calculating the difference between the target value of the motor angular position and the value measured by the wire cable movement amount measuring means, the position correction amount of the angular displacement error of the reducer of each joint is calculated by the angular displacement error position correction amount calculating means. The angular displacement error position correcting means calculates the angular displacement error of the reducer of each joint based on the position correction amount calculated by the angular displacement error position correction amount calculating means.

Therefore, the position of the angular displacement error of the reducer of each joint is calculated by calculating the difference between the predetermined target value of the motor angular position of each joint and the value measured by the wire cable movement amount measuring means. Since the angular displacement error of the reducer of each joint can be position-corrected based on the correction amount,
It is possible to perform a force work in any direction of the robot without causing an angular displacement error, and in particular, by providing a measuring mechanism in the linear portion of the arm, a complicated mechanism as claimed in claims 5 and 6 is provided. Can be realized even if it is not provided in the vicinity of the joint speed reducer, and the system can be constructed by lowering the moment of inertia of the robot arm as compared with the case of the invention of claims 5 and 6.

[0027]

EXAMPLES Examples of the present invention will be described below in comparison with conventional examples. First, a conventional articulated robot will be described.
FIG. 1 is a diagram showing the configuration of a typical conventional articulated robot, and FIG. 2 is a diagram showing the direction of a conventional joint axis. A conventional articulated robot has a first shaft 2 on an upper part of a body portion 1, and the first shaft 2 is composed of a first servomotor 2a for driving a joint and a first speed reducer 2b. Next, the first speed reducer 2b rotatably supports the first arm 3, and a tip end of the first arm 3 is provided with a second shaft 4 that rotates in the same normal direction as the first shaft 2. . Like the first shaft 2, the second shaft 4 is also composed of a second servo motor 4a and a second speed reducer 4b, and the second speed reducer 4b rotatably supports the second arm 5. Then, at the tip of the second arm 5, a third arm that rotates in the same normal direction as the first shaft 2 and the second shaft 4 is attached.
A shaft 6 is provided, and the third shaft 6 is also composed of a third servo motor 6a and a third speed reducer 6b like the first shaft 2 and the second shaft 4. A hand 8 is provided at the tip of the third shaft 6 via a turret 7.

The articulated robot shown in FIG. 1 is generally called a SCARA type robot, and has a degree of freedom in which the tip of the arm can freely move in a two-dimensional plane, so that the rigidity in the vertical direction is high and the articulated robot is in a horizontal plane. It has the characteristics of low rigidity and compliance characteristics. Therefore, the operation on the two-dimensional plane can be easily realized, and the structure is easy to assemble in the vertical direction.

However, as described above, in this conventional articulated robot, since the rigidity in the vertical direction is high,
Although it is suitable for vertical assembly, it has a disadvantage that it cannot perform horizontal assembly work, especially work requiring force, because of its low rigidity in the horizontal plane. The problem that this lateral assembling work (work requiring particularly force) cannot be performed is that even if the servo rigidity of the motor is increased, the speed reducers 2b and 4b of the first shaft 2 and the second shaft 4 are This is because elastic deformation causes a large displacement of the arm tip. Therefore, this scalar-type articulated robot cannot perform lateral assembly work.

Next, FIG. 3 is a diagram showing the rigidity of a speed reducer used in a conventional general articulated robot. here,
The spring constant of elastic deformation of the reduction gear is K, the backlash is B, and the load torque corresponding to the backlash B is T.
_Set to ₀ . The angular displacement Δθ ₀ of the speed reducer when the load torque T is applied to this speed reducer can be expressed by the following equation (1).

[0031]

[Equation 1]

Next, as shown in FIG. 4, the posture angle in the Y-axis direction is set to θ, and the arm tip having the length L is laterally (X direction).
The angular displacement Δθ of the reducer when the acting force from F to F is applied is
It can be shown by the following equation (2).

[0033]

[Equation 2]

Next, as shown in FIG. 5, when the acting force (work reaction force) of F is generated from the lateral direction (X direction) in the scalar type articulated robot, the length of the first arm is set to L ₁ , The length of the second arm is L ₂ , the spring constant of elastic deformation of the first shaft reducer is K ₁ , the backlash is B _1, and the load torque corresponding to the backlash B ₁ is T _1. Second
It is assumed that the elastic constant of the elastic deformation of the shaft reducer is K ₂ , the backlash is B _2, and the load torque corresponding to the backlash B ₂ is T ₂ . The posture of the scalar-type articulated robot at this time is shown in FIG. 4, where the first arm has an angle of θ ₁ and the second arm has an angle of θ ₂ with respect to the Y axis. In this case, the angular displacements Δθ ₁ and Δθ ₂ of the first and second axis speed reducers are respectively expressed by the following equation (3),
It can be expressed by equation (4).

[0035]

[Equation 3]

[0036]

[Equation 4]

The articulated robot of each embodiment of the present invention will be specifically described below. (Example 1) In the articulated robot of this example,
As shown in FIG. 7, the general system of FIG. 6 for positioning and controlling the motor angular position of each joint, as shown in FIG. 7, is the displacement of the reducer of each joint with respect to the force applied to the robot hand of the above formulas (3) and (4). An angle displacement error correction unit 9 for providing an expression for calculating an angle, setting each work force of the work performed by the robot in a work program in advance, and performing position correction control of the angular displacement error of the reducer of each joint according to the set value A multi-joint type robot is constructed by adding to the conventional system.

Therefore, based on the position correction amount of the angular displacement error of the reducer of each joint corresponding to each work of the robot, which is obtained from the displacement angle of the transmission of each joint with respect to the force applied to the hand of the robot. The position of the angular displacement error of the reducer of each joint can be corrected, that is, when the robot repeatedly executes a predetermined assembly work, the work force of each work in which the manual work is generated is measured in advance. , The result of each work force of this work measured in advance is set in the work program, and the position correction amount of the angular displacement error of the reducer of each joint corresponding to the set value is automatically set to the force applied to the robot hand. After calculating based on the displacement angle formula of the reducer of each joint, the angular displacement error of the reducer of each joint can be position-corrected based on this position correction amount. To, any force working of the articulated robot can also be performed.

In the first embodiment, the working force of each working point of the robot is stored in a predetermined memory map, and the numerical value on the memory map is called during working to determine the angular position error of each joint angle. Formula (3), Formula (4)
A joint articulated robot is constructed by adding an angular displacement error correction unit that performs position correction control of angular position error to the conventional system by calculating from the displacement angle formula of the reducer of each joint with respect to the force applied to the robot's hand. Alternatively, it is calculated from the work force of each work point of the robot, and is calculated by the formulas (3) and (4) from the displacement angle formula of the reducer of each joint with respect to the force applied to the robot hand. The angular position error is stored on a predetermined memory map, the numerical values on the memory map are called during work, and the angular displacement error correction unit that controls the position correction of the angular position error of each joint is added to the conventional system to provide multiple joints. A die robot may be configured, and in these cases, the same effect as that of the first embodiment can be obtained. (Embodiment 2) In the articulated robot of this embodiment, as shown in FIG. 8, the hand 8 of the general articulated robot of FIG.
The pressure sensor 9 is provided in the, and the electric signal of the pressure value of the pressure sensor 10 is converted into a digital signal by the A / D converter 11,
The position of the angular displacement error of the reducer at each joint is corrected by importing it into the controller that controls the robot and substituting it in the displacement angle formula of the reducer at each joint for the forces in the above formulas (3) and (4) in the controller. An articulated robot configured to calculate the amount and perform position correction control according to the work force of the robot in real time is configured.

Therefore, based on the position correction amount of the angular displacement error of the reducer of each joint, which is obtained by substituting the pressure value signal of the pressure sensor into the displacement angle formula, the angular displacement error of the reducer of each joint is determined. Since the correction can be performed, an angular displacement error can be prevented, and the force work in any direction of the robot can be efficiently performed, and the work force of each work in which the force work is generated in advance in the first embodiment. It is possible to eliminate the trouble of measuring, and to correct the angular displacement error of the speed reducer in every work in real time. In addition, it is possible to accurately perform work such as pressure and screw tightening, which cause large variations in manual work during assembly work. (Third Embodiment) In the second embodiment, the angular displacement error correction unit 9 is provided in the hand 8 of the articulated robot of FIG. 6, but in the articulated robot of the present embodiment, as shown in FIG. A pressure sensor 12 is provided in the turret portion 7 to which the hand 8 of the articulated robot is attached, and an electric signal of the pressure value of the pressure sensor 12 is converted into a digital signal by the A / D converter 11 to control the robot. The position correction amount of the angular displacement error of the reducer of each joint is calculated by taking in the controller and substituting it in the formula of the displacement angle of the reducer of each joint with respect to the force of the above formulas (3) and (4) in the controller. Then, the articulated robot is configured to perform the position correction control according to the work force of the robot in real time. Therefore, this embodiment can also obtain the same effect as that of the second embodiment. (Embodiment 4) In the articulated robot of this embodiment, as shown in FIG.
6, the articulated robot of FIG. 6 is provided with a pressure sensor 14 on a workbench 13 for performing manual work, and an electric signal of the pressure value of the pressure sensor 14 is converted into a digital signal by an A / D converter 11, Similar to Embodiments 2 and 3, the articulated robot is configured to calculate the position correction amount of the angular displacement error of the reducer of each joint and perform the position correction control according to the work force of the robot in real time. .

For this reason, as in the second and third embodiments, based on the position correction amount of the angular displacement error of the reducer of each joint obtained by substituting the pressure value signal of the pressure sensor into the displacement angle equation, Since the angular displacement error of the reducer can be position-corrected, it is possible to perform the force work in any direction of the robot efficiently without generating the angular displacement error, and to implement the sensor on the workbench. Wiring in the robot arm can be made easier than when the pressure sensor is provided in the robot hand or turret in Examples 2 and 3, and maintenance for disconnection can be made easier. (Fifth Embodiment) In the fourth embodiment, the pressure sensor 14 is provided on the work table 13 in which the articulated robot of FIG. 6 performs the manual work, but in the articulated robot of the present embodiment, as shown in FIG. Work table 13 in which the articulated robot of FIG.
The pressure sensors 16a and 16b are provided on the jigs 15a and 15b to which the assembly parts of FIG.
The electric signals of the pressure values of a and 16b are converted into digital signals by the A / D converter 11, and the position correction amount of the angular displacement error of the reducer of each joint is calculated in the same manner as in the second and third embodiments. An articulated robot is configured to perform position correction control in real time according to the work force of the robot. Therefore, this embodiment can also obtain the same effect as that of the fourth embodiment. (Sixth Embodiment) In the articulated robot of this embodiment, as shown in FIG.
6, torque sensors 18a, 18b, 18c are provided on the output shafts of the servomotors 17a, 17b, 17c used for the joints of the articulated robot of FIG. 6, and the electric signals of the torque values are converted by the A / D converter 11. It is converted into a digital signal, taken into the controller that controls the robot, and substituted into the displacement angle equation of the reducer for the axial torque of each joint in the above formula (1) in the controller, and the position of the angular displacement error of the reducer of each joint A multi-joint robot is configured to calculate a correction amount and perform position correction control according to the work force of the robot in real time.

Therefore, the angular displacement error of the reducer of each joint is corrected based on the position correction amount of the angular displacement error of the reducer of each joint obtained by substituting the torque signal of the torque sensor into the displacement angle formula. Therefore, it is possible to efficiently perform the force work in any direction of the robot without causing the angular displacement error, and to measure the torque of the servo motor directly applied to the speed reducer.
The reliability can be made higher than in the case of the pressure sensor of the inventions of ˜5. Moreover, since the calculation error such as the error of the arm length can be reduced, the position correction control can be performed with higher accuracy than the case of the invention of claims 1 to 3. (Embodiment 7) In the articulated robot of this embodiment, as shown in FIG.
As shown in (a) to (c), an encoder 20 provided on the servo motor 19 at each joint of the articulated robot of FIG.
Separately from the above, an encoder 21 for measuring the joint displacement angle is provided at the link portion of each joint, and the position pulse of this encoder 21 is counted to calculate the difference between the target value of the motor angular position of each joint and the actually moved angle. Then, the articulated robot is configured so that the displacement angle of the reduction gear is directly obtained and position correction control of the angular displacement error of the reduction gear is performed in real time.
The encoder 21 here includes an encoder detection unit 22 and a reflection plate 23 for an encoder which are composed of a light emitting element 22a and a light receiving element 22b, an encoder detection unit 24 using an optical fiber and a reflection plate 25 for a fiber, and a magnetic MR element 26. It is composed of a magnetic tape 27 which is pulse-magnetized.

Therefore, the position of the angular displacement error of the reduction gear calculated by calculating the difference between the predetermined target value of the motor angular position of each joint and the position pulse of the actually measured joint displacement angle encoder. Since the angular displacement error of the reducer of each joint can be position-corrected based on the correction amount, it is possible to efficiently perform the force work in any direction of the robot without causing the angular displacement error. Since the joint displacement angle can be directly measured by the encoder incorporated in the joint, the difference between the motor angle position target value and the joint movement angle can be accurately obtained, and the most accurate position correction control can be performed. (Embodiment 8) FIG. 14 shows the articulated robot of this embodiment.
As shown in FIG. 6, a universal rotary encoder 28 and a roller 29 mounted on the shaft of the encoder 28 are installed on the reducer input side of each joint of the articulated robot of FIG. By providing a dedicated rail 30 for rolling without slipping and counting the position pulse of the encoder 28, the displacement angle of the speed reducer is directly obtained by calculating the difference between the target value of the motor angular position of each joint and the angle actually moved, The articulated robot is configured to perform position correction control of angular displacement error of the reducer in real time.

Therefore, the position correction amount of the angular displacement error of the reduction gear calculated by calculating the difference between the predetermined target value of the motor angular position of each joint and the actually measured position pulse of the rotary encoder is used. Since the angular displacement error of the reducer of each joint can be corrected based on this, the angular displacement error can be prevented from occurring, and the force work in any direction of the robot can be efficiently performed. By reducing the diameter of the, a high-resolution encoder pulse can be obtained with respect to the joint displacement angle, and by using a general-purpose rotary encoder, a low-cost system can be configured. (Embodiment 9) In the articulated robot of this embodiment, as shown in FIG.
As shown in FIG. 6, in the articulated robot of FIG. 6, a wire cable 32 is provided from a wire cable stop 31 at the link part of the reducer output side arm of each joint, and the wire cable 32 is provided via the pulley 33 provided at the reducer input side arm. And the take-up pulley 3 provided on the shaft of the potentiometer or encoder 34
The wire cable 32 is wound by 5 and the winding spring mechanism 36. And a potentiometer or encoder 3
4, the amount of movement of the wire cable 32 is measured, the target angle value of the motor angular position of each joint is calculated, and the angular difference actually moved is calculated to directly obtain the displacement angle of the reducer, and the position displacement of the angular displacement error of the reducer is corrected. An articulated robot is configured to control in real time.

Therefore, the angular displacement error of the reducer of each joint is calculated by calculating the difference between the predetermined target value of the motor angular position of each joint and the actually measured movement amount of the wire cable. Since the angular displacement error of the reducer of each joint can be position-corrected based on the position correction amount, it is possible to perform the force work in any direction of the articulated robot without causing the angular displacement error. In particular, by providing the measurement mechanism on the arm straight portion, it is possible to realize even without providing the complicated mechanism around the joint speed reducer as in Examples 7 and 8, and in the cases of Examples 7 and 8. It is possible to configure the system by lowering the moment of inertia of the robot arm.

In each of the above embodiments, the SCARA type robot, which is often used as an industrial robot for assembling work, has been described as an example, but the present invention is not limited to this and other It is needless to say that the same effect can be obtained for the multi-joint robot, if the arithmetic expression is obtained from the structure of the multi-joint robot and similarly executed.

[0047]

According to the present invention, position correction is performed so as to eliminate an angular displacement error due to elastic deformation of the reducer generated when a force is applied to the reducer of each joint, and force work in any direction of the articulated robot. The effect is that it can also be performed.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a conventional articulated robot.

FIG. 2 is a diagram showing a direction of a joint axis in a conventional example.

FIG. 3 is a diagram showing the rigidity of a speed reducer used in a conventional articulated robot.

FIG. 4 is a diagram showing a state in which an acting force of F acts laterally on the tip of an arm having a length L, where θ is an attitude angle in the Y-axis direction.

FIG. 5 shows a length L _{1 of} a first arm, a length L _{2 of} a second arm, and a length L 1 of a first arm with respect to the Y axis when a force F is generated from a lateral direction in a scalar type articulated robot. It is a figure which shows the angle (theta) ₁ and the angle (theta) ₂ of the 2nd arm with respect to a Y-axis.

FIG. 6 is a diagram showing a system configuration for positioning control of a motor angular position of each joint in a conventional articulated robot.

FIG. 7 is a diagram showing a system configuration for performing position correction control of an angular displacement error of the reducer of each joint in the articulated robot according to the first embodiment of the present invention.

FIG. 8 is a diagram showing a system configuration for performing position correction control of angular displacement error of a reducer at each joint when a pressure sensor is provided in a hand of an articulated robot according to a second embodiment of the present invention.

FIG. 9 is a diagram showing a system configuration for performing position correction control of angular displacement error of a reducer of each joint when a pressure sensor is provided in a turret part in an articulated robot according to a third embodiment of the present invention.

FIG. 10 is a diagram showing a system configuration for performing position correction control of angular displacement error of a reducer at each joint when a pressure sensor is provided on a workbench in an articulated robot according to a fourth embodiment of the present invention.

FIG. 11 is a diagram showing a system configuration for performing position correction control of angular displacement error of a reducer of each joint when a jig and a pressure tool are provided in a multi-joint robot according to a fifth embodiment of the present invention.

FIG. 12 is a diagram showing a system configuration for performing position correction control of angular displacement error of a reducer of each joint when a torque sensor is provided on an output shaft of a servo motor in an articulated robot according to a sixth embodiment of the present invention. Is.

FIG. 13 is a diagram showing a configuration of an articulated robot according to a seventh embodiment of the present invention.

FIG. 14 is a diagram showing a configuration of an articulated robot according to an eighth embodiment of the present invention.

FIG. 15 is a diagram showing a configuration of an articulated robot according to a ninth embodiment of the present invention.

FIG. 16 is a diagram showing a problem of a conventional example.

[Explanation of symbols]

 1 Body part 2 1st axis 2a 1st servomotor 2b 1st reducer 3 1st arm 4 2nd axis 4a 2nd servomotor 4b 2nd reducer 5 2nd arm 6 3rd axis 6a 3rd servomotor 6b 1st 3 Reducer 7 Turret part 8 Hand 9 Angular displacement error correction part 10, 12, 14, 16a, 16b Pressure sensor 11 A / D converter 13 Workbench 15a, 15b Jig tool 17a, 17b, 17c, 19 Servo motor 18a, 18b, 18c Torque sensor 20, 21 Encoder 22, 24 Encoder detector 22a Light emitting element 22b Light receiving element 23 Reflecting plate for encoder 25 Reflecting plate for fiber 26 Magnetic MR element 27 Magnetic tape 28 Rotating encoder 29 Roller 30 Exclusive rail 31 Wire cable Stop 32 Wire cable 33 Pulley 34 Potency Meter or encoder 35 take-up pulley 36 take-up spring mechanism

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeru Yamada 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (7)

[Claims] 1. A servo motor for driving a plurality of joints, a speed reducer attached to a motor shaft of the servo motor, and an arm rotatably supported by the speed reducer at each joint. In a multi-joint type robot which is connected to form a multi-joint and which has multiple degrees of freedom by driving each joint with a motor angular position of each joint as a target value, a reducer for each joint with respect to a force applied to a hand of the robot Angle displacement error position correction amount calculation means for calculating the position correction amount of the angular displacement error of the reducer of each joint according to each work force of the work performed by the robot, and the angular displacement error. Based on the position correction amount calculated by the position correction amount calculation means,
An articulated robot comprising: an angular displacement error position correcting means for correcting the angular displacement error of the reducer of each joint. 2. A servo motor for driving a plurality of joints, a speed reducer attached to a motor shaft of the servo motor, and an arm rotatably supported by the speed reducer at each joint. In a multi-joint type robot which is connected to form a multi-joint and which has multiple degrees of freedom by driving each joint with a motor angular position of each joint as a target value, a hand of the robot or a turret part to which the hand is attached And the pressure value signal of the pressure sensor are substituted into the displacement angle formula of the reduction gear of each joint with respect to the force applied to the hand of the robot, and the position correction amount of the angular displacement error of the reduction gear of each joint is substituted. And an angular displacement error position correction amount calculation means for calculating the angular displacement error position correction amount calculation means for correcting the angular displacement error of the reducer of each joint based on the position correction amount calculated by the angular displacement error position correction amount calculation means. Articulated robot, characterized in that it comprises a position correcting unit. 3. A servo motor for driving a plurality of joints, a speed reducer attached to a motor shaft of the servo motor, and an arm rotatably supported by the speed reducer at each joint. In an articulated robot that is connected to each other to form a multi-joint and that has multiple degrees of freedom by driving each joint with a motor angular position of each joint as a target value, a workbench or an assembly part on which the robot performs manual work is The pressure sensor provided in the mounted jig and tool, and the pressure value signal of the sensor are substituted into the displacement angle formula of the reducer of each joint with respect to the force applied to the hand of the robot to obtain the angular displacement error of the reducer of each joint. Angle displacement error position correction amount calculation means for calculating the position correction amount of the joint, and an angle for correcting the angular displacement error of the reducer of each joint based on the position correction amount calculated by the angular displacement error position correction amount calculation means. Strange Articulated robot, characterized in that it comprises and an error position correcting means. 4. A servo motor for driving a plurality of joints, a speed reducer attached to a motor shaft of the servo motor, and an arm rotatably supported by the speed reducer at each joint. In a multi-joint type robot that is connected to form a multi-joint, and drives each joint with a motor angular position of each joint as a target value to obtain multiple degrees of freedom, a torque sensor provided on the output shaft of the servo motor, Angular displacement error position correction in which the torque signal of the torque sensor is substituted into the displacement angle expression of the speed reducer of each joint with respect to the force applied to the hand of the robot to calculate the position correction amount of the angular displacement error of the speed reducer of each joint. And an angular displacement error position correction means for correcting the angular displacement error of the reduction gear of each joint based on the position correction amount obtained by the angular displacement error position correction amount calculation means. Articulated robot according to claim. 5. A servo motor for driving a plurality of joints, a speed reducer attached to a motor shaft of the servo motor, and an arm rotatably supported by the speed reducer at each joint. In an articulated robot which is connected to each other to form a multi-joint and which has multiple degrees of freedom by driving each joint with a motor angular position of each joint as a target value, each joint is provided separately from an encoder provided in the servo motor. A joint displacement angle measuring encoder for measuring a joint displacement angle provided in the link portion, and an encoder position pulse measuring means for measuring a position pulse of the joint displacement angle measuring encoder;
The difference between the predetermined target value of the motor angular position of each joint and the value measured by the encoder position pulse measuring means is calculated to obtain the amount of movement of the joint displacement angle measuring encoder, and based on the amount of movement. Angle displacement error position correction amount calculation means for calculating the position correction amount of the angular displacement error of the reduction gear of each joint, and the reduction gear for each joint based on the position correction amount calculated by the angle displacement error position correction amount calculation means. And an angular displacement error position correcting means for correcting the angular displacement error of the above. 6. A servo motor for driving a plurality of joints, a speed reducer attached to a motor shaft of the servo motor, and an arm rotatably supported by the speed reducer at each joint. In an articulated robot which is connected to each other to form a multi-joint and which has multiple degrees of freedom by driving each joint with a motor angular position of each joint as a target value, each joint is provided separately from an encoder provided in the servo motor. A rotary encoder having a roller attached to the shaft of the encoder on the input side of the speed reducer, a rail provided on the output side of the speed reducer so that the roller can roll without slipping, and a position pulse of the rotary encoder is measured. The rotary encoder position pulse measuring means calculates the difference between the predetermined target value of the motor angular position of each joint and the value measured by the rotary encoder position pulse measuring means, and calculates the rotary type encoder position pulse measuring means. An angular displacement error position correction amount calculation means for obtaining a movement amount moved by the coder, and a position correction amount for an angular displacement error of the reduction gear of each joint based on the movement amount, and an angular displacement error position correction amount calculation means. An articulated robot comprising: an angular displacement error position correcting means for correcting the angular displacement error of each joint based on the calculated position correction amount. 7. A servo motor for driving a plurality of joints, a speed reducer attached to a motor shaft of the servo motor, and an arm rotatably supported by the speed reducer at each joint. In a multi-joint type robot that is connected to each other and has multiple degrees of freedom by driving each joint with the motor angular position of each joint as a target value, measure the joint displacement angle provided at the link of each joint A wire cable, a wire cable movement amount measuring means for measuring the movement amount of the wire cable, and a difference between a predetermined target value of the motor angular position of each joint and a value measured by the wire cable movement amount measuring means. Based on the angular displacement error position correction amount calculation means for calculating the position correction amount of the angular displacement error of the reduction gear of each joint and the position correction amount calculated by the angular displacement error position correction amount calculation means, Articulated robot, characterized in that it comprises a angular displacement error position correcting means for position correction of the angular displacement error of the speed reducer section.