JP3383614B2 - Impedance control device for horizontal articulated robot arm - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal articulated robot arm impedance control device suitable for handling work and the like.

[0002]

2. Description of the Related Art Conventionally, when performing impedance control on a robot arm, as shown in the block diagram of the conventional impedance control device for a horizontal articulated robot arm shown in FIG. A force sensor 102 attached to the hand of arm 101 measures an external force such as a force or a moment acting on the hand, and calculates a relief amount at the hand position from a set virtual impedance 107, or a torque shown in FIG. As shown in the block diagram of the impedance control device for the horizontal articulated robot arm using the sensor, the torque applied to each joint is measured from the torque sensor 103 of, for example, a magnetostrictive type attached to the base of each joint axis, and the Based on the joint torque information, there is a method to calculate the escape amount of each joint from the set virtual impedance and perform avoidance operation. That.

[0003]

However, in the above-mentioned conventional example, as shown in FIG. 4, when impedance control is performed by using an external force measured by a force sensor attached to the arm tip, the arm is not the tip. When the robot contacts the environment, there is a problem that the avoidance operation cannot be performed because the external force cannot be measured. In addition, as shown in FIG. 5, when impedance control is performed using an external torque measured by a torque sensor attached to the base of each joint axis of the arm, a small amount of force is applied particularly to the vertical direction of the arm due to loss of friction of the drive unit. There is a problem that it is difficult to measure the force, and when the arm is operating, the influence of the inertial force of the arm itself is large, and it is difficult to perform an appropriate avoidance operation. Therefore, it is an object of the present invention to provide an impedance control device for a horizontal articulated robot arm that can perform an appropriate avoidance operation regardless of where the robot arm contacts the environment.

[0004]

In order to achieve the above object, the invention according to claim 1 provides a horizontal articulated robot arm for performing various handling operations, and an external force for measuring an external force acting on the arm and an external torque. In an impedance control device for a horizontal articulated robot arm, in which a plurality of types of measurement sensors are attached and force control is performed on each joint based on the sensor information, the information measured by the external force measurement sensor is applied to each joint and the external force applied to the hand. A joint displacement calculation unit that separates the applied external torque and calculates the arm clearance from the external torque applied to each joint and the set virtual impedance of the joint, and the arm from the external force applied to the hand and the virtual impedance of the set hand And a hand end displacement calculation unit that calculates the escape amount. According to this impedance control device for the horizontal articulated robot arm, the escape amount of the arm is calculated from each joint torque of the arm that combines the joint torque in the horizontal direction and the acting force in the vertical direction, and the escape amount of the arm, and The external force applied to the arm and the escape distance of the arm calculated from the virtual impedance of the hand part are added and given to the servo controller as an angle command to drive the arm, so that the part touches the environment during horizontal or vertical movement. Even then, an appropriate avoidance operation can be realized. Further, the invention according to claim 2 is a joint displacement calculation for converting all the information measured from the external force measuring sensor into a torque applied to each joint, and calculating an escape amount of the arm from the set joint virtual impedance. Have a section. According to the impedance control device for the horizontal articulated robot arm, the external force applied to the hand is converted into torque, and each joint torque obtained by combining the horizontal joint torque with the vertical acting force of the arm is added to this. Since the arm joint clearance is calculated from the joint virtual impedance and the servo controller is driven, the clearance of the joint (angle command value regardless of where the arm contacts the environment during horizontal or vertical movement) ), An appropriate avoidance operation can be realized. Further, in the invention according to claim 3, the hand displacement calculation for converting all the information measured by the external force measuring sensor into a force applied to the hand portion and calculating the escape amount of the arm from the set hand portion virtual impedance. Have a section. According to the impedance control device for the horizontal articulated robot arm, the force applied to the hand portion and the acting force obtained by converting each joint torque including the vertical direction into the hand acting force are added,
The amount of escape of the arm tip is calculated from the virtual impedance of the arm, and the servo controller is driven as an angle command for each joint, so the edge of the arm escapes even when the arm is in horizontal or vertical motion and in any part of the environment. An appropriate avoidance operation can be realized by the amount (position command value).

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an impedance control device for a horizontal articulated robot arm according to a first embodiment of the present invention. In FIG.
Reference numeral 101 is an arm, 102 is a force sensor that measures an external force that acts on the arm tip, and 103 is a torque sensor that measures the torque that acts on each joint axis. Reference numeral 104 denotes a plurality of surface pressure-sensitive sensors that measure an external force acting in the vertical direction of the arm,
105 is a motor for driving the arm 101 (installed for each joint as shown in the figure), 106 is a rotation angle detector for detecting the rotation angle of each motor 105, 107 is a hand position of the arm 101 for other information such as hand acting force. Hand displacement calculator that converts to displacement,
Reference numeral 108 denotes an adding device, 109 denotes a horizontal and vertical (vertical) direction force combining device, 110 denotes a joint displacement calculation unit that converts horizontal joint torque information and vertical acting force information into a joint angular displacement of the arm 101, 111 Is a horizontal torque correction unit that corrects horizontal joint torque information measured by the torque sensor 103, 112 is an adder, 113 is a hand balance position setting unit that sets the hand position of the arm 101 when there is no load,
Reference numeral 114 is an inverse kinematics calculation unit that calculates a joint angle from the hand position of the arm 101, 115 is an adder, and 116 is a servo controller that controls the motor 105 based on an angle command.

Next, the operation will be described. The horizontal articulated robot arm used here allows caregivers in hospitals, medical welfare facilities, and other nursing care / medical service institutions to release the caregivers from the transportation of meals during meal times, serving, and lower-ranking work.
This is an example of being used in a meal transport robot introduced for the purpose of concentrating on important face-to-face care. Therefore, in the following explanation of the operation, an example of the case where the meal transport robot performs the work of setting and lowering the meal tray, etc., is carried out when the horizontal articulated robot arm is in danger of contacting the environment. I will explain how to realize. In addition, the horizontal articulated arm itself is a robot type that has been conventionally called a scalar type and is often used for assembly work and handling work in an automated assembly line. It has two joints corresponding to the two joints of the human shoulder and elbow extending in the direction, and the rotary shaft, the hand, etc. are arranged at the tip as the wrist part, and each joint is rotationally driven by each servomotor. Each of the arms is freely movable in the horizontal direction, and the entire arm can be moved up and down along the column by a Z-axis motor (not shown). In the present embodiment, the food tray and the like are gripped by the hand at the end of the arm, and the arm is moved in the horizontal direction and the vertical (vertical) direction to perform work such as serving and lower serving from the shelf. The operation of avoiding contact of the arm with the environment during this work will be described in detail. First, the horizontal torque correction unit 111 calculates the value of the joint torque generated by the horizontal motion of the arm itself from the angle / angular velocity / angular acceleration of the angular joint of the arm 101, and the joint torque generated by the hand acting force from the hand acting force information in the horizontal direction. calculate. This torque is added and corrected by the adder 108 with the horizontal joint torque measured by the torque sensor 103 attached to each joint. This joint torque and the vertical acting force measured by the pressure-sensitive sensor 104 that measures the external force that acts when the arm 101 is moved in the vertical direction by the z-axis motor are combined by the combining device 109 to make joint displacement. The value (Jj, dj, k) of the joint virtual impedance that is input to the calculation unit 110 and set is set.
The amount of displacement of each joint is calculated from j). Further, the hand acting force measured by the external force measuring sensor (force sensor) 102 attached to the hand is input to the hand displacement calculator 107, and the set hand end virtual impedance value (Je,
de, ke) is used to convert to the displacement amount of the hand. The hand tip displacement amount is added to the hand tip balance position of the hand tip balance position setting unit 113 (the hand tip balance position of the arm 101 when there is no load before contact) by the addition device 112, and the hand tip position command value is calculated. Then, the calculated hand position command is converted into an angle command for each joint in the inverse kinematics calculation unit 114. The joint command value is added to the displacement amount of each joint by the adder 115 and input to the servo controller 116. The servo controller 116 controls the motor 105 by comparing the difference between the input angle command and the angle information detected by the rotation angle detector 105. in this way,
According to the present embodiment, the information from each sensor is separated into the torque applied to each joint and the force applied to the hand, and the arm escape amount is calculated from the virtual impedances set for each, so that the arm can move horizontally. In addition, it is possible to realize an appropriate avoidance action with a low impact, no matter which part comes into contact with the environment during vertical movement.

Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a block diagram of an impedance control device for a horizontal articulated robot arm according to a second embodiment of the present invention. In FIG. 2, 201 is a force-to-torque conversion unit that converts the hand acting force Fe measured by the force sensor 102 attached to the hand unit into each joint torque τe, 202 is an addition device thereof, 203 is a joint balance angle setting unit, Reference numeral 204 is an adder. In addition, the same components as those in FIG. 1 are denoted by the same reference numerals, and overlapping description will be omitted. Next, the operation will be described. First, the horizontal torque correction unit 111 determines the joint torque value generated by the horizontal motion of the arm itself from the angle, angular velocity, and angular acceleration of each joint of the arm 101, and the joint torque generated by the hand acting force from the hand acting force information in the horizontal direction. Is calculated and added to the horizontal joint torque measured by the torque sensor 103 attached to each joint to be corrected. Then, the vertical acting force measured by the surface pressure-sensitive sensor 104 that measures the external force acting in the vertical direction of the arm and the synthesizing device 1
09, the joint torque τj is obtained. on the other hand,
The hand acting force measured by the external force measuring force sensor 102 attached to the hand is input to the force → torque converting unit 201, and converted into the torque τe applied to each joint by performing the calculation by the following formula (1). . τe = J ^T Fe (1) Here, Fe represents the hand acting force, J ^T represents the transposed Jacobian of the arm, and τe represents the torque applied to each joint. This joint torque τe is added to the previous joint torque τj in the addition device 202, and the joint displacement calculation unit 110
Entered in. The joint displacement calculator 110 calculates the amount of displacement of each joint from the values (Jj, dj, kj) of the set virtual impedance of the joint. The amount of displacement of each joint is added to the balance angle of the joint balance angle setting unit 203 by the adder 204 to calculate the angle command value of each joint.
The joint angle command calculated in this way is input to the servo controller 116, and the servo controller 116 controls the motor 105 by comparing the difference between the angle command and the angle information detected by the rotation angle detector 106. in this way,
According to the second embodiment, all of the sensor information is converted into the joint torque, and the hand acting force Fe is also calculated by the displacement amount calculation method using only the torque-corresponding joint virtual impedance values (Jj, dj, kj). After the joint torque τe is once converted, the joint action amount (angle command) corresponding to the torque is calculated by adding the joint torque τj in which the vertical acting force is also combined. Even if the part comes into contact with the environment, it is possible to perform an appropriate avoidance operation with a low impact, and at the same time, it is possible to achieve simplification and cost reduction.

Next, a third embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a block diagram of an impedance control device for a horizontal articulated robot arm according to a third embodiment of the present invention. In FIG. 3, reference numeral 301 is a torque-to-force conversion unit that converts the joint torque τj, which is a combination of horizontal torque and vertical acting force, into a hand acting force Fj that acts on the hand portion, and 302 is an adding device. In addition,
The other configurations that are the same as those in FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted. Next, the operation will be described. The horizontal torque correction unit 111 calculates the value of the joint torque generated by the horizontal motion of the arm itself from the angle / angular velocity / angular acceleration of each joint of the arm 101, and the joint torque generated by the hand acting force from the horizontal hand acting force information. To do. This torque is added by the adding device 108 to the horizontal joint torque measured by the torque sensor 103 attached to each joint and corrected. In addition, the vertical acting force measured by the surface pressure-sensitive sensor 104 that measures the external force acting in the vertical direction of the arm is combined with the combining device 109 to form the joint torque τj. The joint torque τj is input to the torque → force conversion unit 301, and is converted into the hand acting force Fj by performing the calculation according to the following equation (2). Fj = J ^−T τj (2) where τj is the torque applied to each joint, J ^−T is the transposed inverse Jacobian of the arm, and Fj is the hand acting force. The converted hand acting force Fj is added to the hand acting force Fe measured by the force sensor 102 attached to the hand by the adding device 302 and input to the hand displacement calculating unit 107 to set the hand end virtual impedance. Value (J
From e, de, ke), the displacement amount of the hand position is calculated.
This hand end position displacement amount is added to the balance position of the hand end balance position setting unit 113 by the addition device 112 to calculate the hand end position command value. This hand position command is converted into an angle command for each joint by the inverse kinematics calculation unit 114,
Inputting to the servo controller 116, the servo controller 116 controls the motor 105 by comparing the difference between the angle command and the angle information detected by the rotation angle detector 106. As described above, according to the third embodiment, all the sensor information is converted into the hand action force, and the displacement amount calculation method using only the value (Je, de, ke) of the hand part virtual impedance corresponding to the hand action force is used. As a result, the joint torque τj is also temporarily affected by the acting force Fj.
After being converted to, the force command Fe is added to calculate the position command value corresponding to the hand part force, and the angle command of each joint is converted. Even when it comes into contact with the environment, it is possible to perform an appropriate avoidance operation with low impact, and at the same time, it is possible to achieve simplification and cost reduction.

In the present invention, the horizontal articulated robot arm of the food conveying robot in a hospital or medical welfare facility has been described as an example up to this point. It can be applied to all places such as lunch, student cafeteria, restaurants, wedding receptions, and dinner places such as hotels, where large numbers of people are serving and preparing dishes. Also, not only the food conveyance robot, but also an industrial assembly robot (scalar robot) that uses a horizontal articulated robot arm in various automated assembly lines. The usage range can be expanded to SCARA robots that perform product loading / unloading and handling operations in / from the stocker in warehouses, workshops, and other workplaces.

[0010]

As described above, according to the present invention,
A horizontal articulated robot arm that performs various handling operations is equipped with multiple types of external force measurement sensors that measure the external force and external torque acting on the arm, and the horizontal multi-joint robot that controls the force of each joint based on the information from each external force measurement sensor. In an impedance control device for an articulated robot arm, the information from each sensor is separated into the torque applied to each joint and the force applied to the hand, and the arm escape amount is calculated from the virtual impedance set for each joint. There is an effect that an appropriate avoidance action can be realized regardless of which part comes into contact with the environment. In addition, by converting all sensor information for external force measurement into torque applied to each joint, or hand force applied to the fingertip, and calculating the escape amount from each set virtual impedance, the arm can be used in any part of the environment. There is an effect that an appropriate avoidance action can be performed even when the user touches, and the circuit configuration and control can be simplified and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram of an impedance control device for a horizontal articulated robot arm according to a first embodiment of the present invention.

FIG. 2 is a block diagram of an impedance control device for a horizontal articulated robot arm according to a second embodiment of the present invention.

FIG. 3 is a block diagram of an impedance control device for a horizontal articulated robot arm according to a third embodiment of the present invention.

FIG. 4 is a block diagram of a conventional impedance control device for a horizontal articulated robot arm.

FIG. 5 is a block diagram of an impedance control device for a horizontal articulated robot arm using a conventional torque sensor.

[Explanation of symbols]

101 Arm 102 Force Sensor 103 Torque Sensor 104 Surface Pressure Sensor 105 Motor 106 Rotation Angle Detector 107 Hand Displacement Calculator 108, 112, 115, 202, 204, 302 Adder 109 Synthesizer 110 Joint Displacement Calculator 111 Horizontal Torque Correction Unit 113 Hand balance position setting unit 114 Inverse kinematics calculating unit 116 Servo controller 201 Force → torque converting unit 203 Joint balance angle setting unit 301 Torque → Force converting unit

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-10-329071 (JP, A) JP-A-8-243958 (JP, A) JP-A-4-306710 (JP, A) JP-A-64- 44510 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B25J 19/06 B25J 13/08 B25J 9/10 G05D 3/00

Claims (3)

(57) [Claims] 1. A horizontal multi-joint type robot arm for performing various handling operations is provided with a plurality of types of external force measuring sensors for measuring an external force and an external torque acting on the arm, and a horizontal force for controlling each joint based on the sensor information. In an impedance control device for an articulated robot arm, the information measured from the external force measurement sensor is separated into external force applied to the hand and external torque applied to each joint, and the external torque applied to each joint and the set virtual joint A horizontal displacement calculation unit for calculating the amount of escape of the arm from the impedance; and a hand displacement calculation unit for calculating the amount of escape of the arm from the external impedance applied to the hand portion and the virtual impedance of the hand portion set. Impedance control device for articulated robot arm. 2. A joint displacement calculating section for converting all information measured by the external force measuring sensor into torque applied to each joint and calculating the escape amount of the arm from the set joint virtual impedance. The impedance control device for a horizontal articulated robot arm according to claim 1. 3. A hand tip displacement calculating section for converting all the information measured by the external force measuring sensor into a force applied to the hand tip section and calculating an escape amount of the arm from the set hand tip virtual impedance. The impedance control device for a horizontal articulated robot arm according to claim 1.