JP3005671B2 - Robot arm drive control system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a robot arm drive control system for controlling the drive of a robot arm by connecting one end of each wire to each joint axis of the robot arm and controlling the tension of each wire. .

[0002]

2. Description of the Related Art A robot arm has a plurality of links from a link at a base end to a link at a tip end for performing work, and each of the links is connected to an adjacent link by a joint axis. Each joint axis is rotated by an actuator provided for each joint axis, and each link operates according to the rotation of the joint axis. However, since the actuator is heavy, attaching the actuator directly to the joint is disadvantageous in terms of the output weight ratio, particularly for the joint near the hand of the robot arm, and the tendency is conspicuous. The actuator is mounted at a position closer to the base end than the target joint. In that case,
It is necessary to transmit the driving force from the actuator to the target joint by some means. Therefore, a robot arm by a wire interference driving method in which the driving force is transmitted using a wire is disclosed in, for example, Japanese Patent Publication No. 7-1.
No. 2596. In this robot arm using the wire interference driving method, one end of each wire is fixed to a link member constituting the robot arm, and the other end is fixed to an output shaft of an actuator, controls the output of the actuator, and is connected to the actuator. By controlling the tension of the wire to a predetermined tension, each joint axis is rotated by a desired angle, respectively, and the robot arm performs a predetermined operation as a whole.

[0003]

However, the above-mentioned conventional robot arm using the wire interference drive method requires the same number of actuators as the number of wires, and uses a large number of expensive and heavy actuators. This was a major factor in increasing the weight. Also, while the weight and weight of the robot arm have been reduced, the ratio of the volume and weight of the actuator to the whole has tended to increase. Furthermore, the actuator is required to generate various magnitudes of output shaft torque at a wide range of rotation speeds from stop to high-speed rotation, but electric motors and the like that can be used as actuators are most efficient at constant rotation and constant torque. It is inherently unsuitable for the above-mentioned use form that can be used and requires a wide range of rotation speeds and various torques, necessitating the use of the actuator with low efficiency, and correspondingly energy consumption Wasted. The present invention has been made in view of the above circumstances, and has a robot arm drive control system capable of realizing low cost and light weight, and using an actuator with high efficiency and suppressing energy consumption low. The purpose is to provide.

[0004]

In order to achieve the above object, according to the present invention, one end of a wire is connected to each joint axis of a robot arm, and drive control of the robot arm is controlled by controlling the tension of each wire. In the robot arm drive control system to be performed, one actuator serving as a power source for driving the robot arm, a plurality of clutches provided corresponding to each of the wires, and a control signal output to the clutch are output. A clutch control device for controlling the shaft torque, connecting the output shaft of the actuator to the input shaft of each clutch with a belt, attaching the other end of a wire to the output shaft of each clutch, and driving the actuator. Then, the power is transmitted to the input shaft of each clutch via a belt, and the output shaft torque of each clutch at that time is transmitted to the clutch control device. By controlling in controls each wire to each of the target tension, and so as to perform a desired movement to the robot arm, it is characterized in that.

[0005]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram schematically showing a configuration of a robot arm driven by the robot arm drive control system of the present invention. In the figure, a robot arm 1 is of a type driven by a wire interference drive system, and includes link members L1 and L2 extending from a base member L0 on the drive system side to a distal end on the hand side.
And the link member L1 are rotatably coupled via a joint axis Z1 of the joint J1, and the link member L1 and the link member L2 are rotatably coupled via a joint axis Z2 of the joint J2.

[0006] Three pulleys a11, a12, and a13 are independently rotatably provided on the joint axis Z1 of the joint Jl, and two pulleys a21, 2 are provided on the joint axis Z2 of the joint J2. a22 are provided independently and rotatably.

The wires W1, W2, W3 are connected to pulleys a11, a12, a13, a
21 and a22, and is fixed to the link members L1 and L2. (Wire W1) From the wire W1 drive system to be described later, one round is wound around the pulley a11 and one round is wound around the pulley a21.
The link member L2 is fixed to the projecting member F2. (Wire W2) From the wire W2 drive system to be described later, one round is wound around the pulley a12, and one round is wound around the pulley a22.
The link member L2 is fixed to the projecting member F2. (Wire W3) The wire W3 is wound around the pulley a13 by a wire W3 drive system to be described later, and is fixed to the projecting member F1 of the link member L1.

In the robot arm 1, the link members L1 and L2 rotate around the joint axes Z1 and Z2 according to the tension of the wires W1, W2 and W3. Therefore, by controlling the tension of the wires W1, W2, and W3, the robot arm 1 can perform a predetermined motion. Next, control of the wire tension will be described.

FIG. 2 is a diagram showing the overall configuration of the robot arm drive control system of the present invention. In the figure, a robot arm drive control system 2 includes one actuator A serving as a power source for driving the robot arm 1 and clutches C1, C2, and C3 provided corresponding to the wires W1, W2, and W3, respectively. And a clutch control device PC that outputs a control signal to the clutches C1, C2, and C3 to control the output shaft torque.

A pulley pa is integrally provided on an output shaft Oa of the actuator A. Also, clutches C1 and C
Pulley p1 is connected to input shafts I1, I2 and I3 of C2 and C3.
1, p21 and p31 are provided integrally. Further, pulleys p12, p22 and p32 are integrally provided on the output shafts O1, O2 and O3 of the clutches C1, C2 and C3. The pulley pa of the actuator A and the pulleys p11, p21, p31 on the clutch input side are connected by one belt b. Pulley p on each clutch output side
The other ends of the wires W1, W2, and W3 are fixed around 12, p22, and p32 after several turns. One end of each of the wires W1, W2, and W3 is connected to each part of the robot arm 1 as described above. Clutch C1,
A clutch control device PC is connected to C2 and C3 via signal lines s1, s2 and s3.

In the robot arm drive control system 2 having the above configuration, when one actuator A is driven,
The power is transmitted to each clutch Ci (i = 1 to
3) is transmitted to the input shaft Ii (i = 1 to 3). Then, by controlling the output shaft torque of each clutch Ci at that time by the clutch control device PC, each wire Wi is controlled.
(I = 1 to 3) can be controlled to the respective target tensions, and this tension control allows the robot arm 1 to perform a desired operation.

Next, a method for determining the output shaft torque of the actuator A and a procedure for controlling each wire Wi to the target tension will be described.

The relationship between the tension fi of the wires W1, W2, and W3, the radius ri2 of the pulleys p12, p22, and p32 on the output side, and the output shaft torque toi of the clutches C1, C2, and C3 is represented by the following equation (1). The subscript i is
It represents one of 1, 2, and 3.

(Equation 1) Where fi: tension of the wire Wi (fi ≧ 0) toi: output shaft torque of the clutch Ci ri2: radius of the pulley pi2 on the output side

The radius ra of the pulley Pa of the actuator A, the radius ri1 of the pulley Pi1 on the clutch input side,
The relationship between the output shaft torque ta of the actuator A and the input shaft torque tIi of the clutch Ci is represented by the following Expression 2.

(Equation 2) Where ta: output shaft torque of actuator A tIi: input shaft torque of clutch Ci ri1: radius of pulley pi1 ra: radius of pulley pa

The output shaft torque toi of the clutch Ci is
And the control signal tti from the clutch control device PC is as shown in the following Expression 3.

(Equation 3) Here, toi: the output shaft torque of the clutch Ci tti: a control signal from the clutch control device PC to the clutch Ci As the clutch for which Expression 3 holds, the ER fluid (Electr
orheological fluid (ER clutch)
Control of Mechatronics Devices Using ER Fluid ”,“ Measurement and Control ”, Vol. 34, no. 9) can be used.

The output shaft torque ta of the actuator A is determined as follows. (1) The maximum target tension fmaxi (i = 1 to 3) of each wire Wi for realizing a predetermined motion on the robot arm 1 is determined. In determining the maximum target tension fmaxi,
For example, the method disclosed in Japanese Patent Publication No. 7-12596 may be used. (2) The output shaft torque toi of the clutch Ci is calculated from the above equation (1). (3) Since the relationship of tIi ≧ toi is established between the input shaft torque tIi and the output shaft torque toi of the clutch Ci, the above equation 2 is calculated as tIi = toi, and the output shaft torque ta of the actuator A is calculated. Ask for. However, there is a simple method in which ta is set to a sufficiently large positive value. (4) The actuator A is controlled so as to generate the output shaft torque ta. At this time, the output shaft torque ta of the actuator A is transmitted to the input shaft Ii of the clutch Ci via the belt b, thereby ensuring the maximum target tension fmaxi of each wire Wi.

Next, a method of determining and controlling each clutch output shaft torque toi when the actuator A is operated so as to generate the output shaft torque ta as described above will be described. (1) A target tension fi (i = 1 to 3) of each wire Wi for realizing a predetermined motion in the robot arm 1 is determined. Note that the determination of the target tension fi is performed in the same manner as the determination of the maximum target tension fmaxi, for example, as described in Japanese Patent Publication No. 7-1.
The method disclosed in Japanese Patent No. 2596 may be used. (2) Formula 1 is calculated to determine the output shaft torque toi of each clutch Ci. (3) Using Equation 3, the control signal t to each clutch Ci
ti is calculated, and the control signal tti is output from the clutch control device PC to each clutch Ci. Thereby, each wire Wi is controlled to the target tension fi, and the robot arm 1
Performs a predetermined exercise.

As described above, in this embodiment, 1
Each of the clutches Ci is driven using the actuator A as a power source, and the output shaft torque to
i is controlled by the clutch control device PC to control the tension of each wire Wi, thereby causing the robot arm 1 to perform a predetermined motion. Therefore, only one actuator is required, and cost and weight are reduced. Both were significantly reduced. Further, since it is sufficient to drive the actuator A at a constant speed and a constant output, efficient operation becomes possible, and the energy consumption can be reduced.
An energy-saving robot arm drive control system could be constructed. By operating the actuator A at a constant speed and a constant output, not only an electric motor but also an engine or the like can be adopted as the actuator, so that the number of options can be increased and an optimal actuator can be selected. Furthermore, since the actuator was replaced with a clutch that was smaller in size and weight than the actuator, the weight and volume of the entire system could be reduced, and a lightweight and compact robot arm drive control system could be obtained. .

[0019]

As described above, according to the robot arm drive control system of the present invention, each clutch is driven using one actuator as a power source, and the output shaft torque of each clutch is controlled by the clutch control device. Then, the tension control of each wire is performed, thereby causing the robot arm to perform a predetermined motion. Therefore, only one actuator is required, and both cost and weight can be significantly reduced.

Further, since the actuator only needs to be driven at a constant speed and a constant output, efficient operation is possible, energy consumption can be suppressed low, and an energy-saving type robot arm drive control system can be constructed. .

By operating the actuator at a constant speed and a constant output, not only an electric motor but also an engine or the like can be used as the actuator, so that the number of options can be increased and an optimum actuator can be selected.

Further, since a clutch having a smaller size and weight than the actuator is used in place of the actuator, the weight and volume of the entire system can be reduced, and a lightweight and compact robot arm drive control system can be obtained. Can be.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration of a robot arm driven by a robot arm drive control system of the present invention.

FIG. 2 is a diagram showing an overall configuration of a robot arm drive control system according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Robot arm a11, a12, a13, a21, a22 Pulley of each joint axis of robot arm L0 Base member L1, L2 Link member JI, J2 Joint Z1, Z2 Joint axis W1, W2, W3 Wire 2 Robot arm drive control system A Actuator Oa Actuator output shaft pa Actuator output shaft pulley b Belt C1, C2, C3 Clutch I1, I2, I3 Clutch input shaft O1, O2, O3 Clutch output shaft p11, p21, p31 Clutch input side pulley p12, p22, p32 Clutch output side pulley PC Clutch controller s1, s2, s3 Signal line

Claims (1)

(57) [Claims] 1. A robot arm drive control system for controlling the drive of a robot arm by connecting one end of a wire to each joint axis of the robot arm and controlling the tension of each wire. A single actuator, a plurality of clutches provided for each of the wires connected to each joint axis of the robot arm, and a clutch control for outputting a control signal to the clutch and controlling the output shaft torque. And a device, wherein the output shaft of the actuator and the input shaft of each clutch are connected by a belt, and the other end of a wire is attached to the output shaft of each clutch, and the power is transmitted to the belt by driving the actuator. To the input shaft of each clutch, and the output shaft torque of each clutch at that time is controlled by the clutch control device. Ri, controls each wire to each of the target tension, and so as to perform a desired movement to the robot arm, the robot arm driving control system, characterized in that.