JPS5943322A - Torque detecting method - Google Patents

Abstract

PURPOSE:To make it possible to obtain sufficient sensitivity, by adhering a stress gauge to the chain connecting element of a working arm mechanism including a chain in the power transmission mechanism thereof to convert the resistance change amount thereof to an electric amount. CONSTITUTION:The chain sproket attached to a motor output shaft 21, the chain sprocket 22 attached to a robor arm 23 and a chain 24 for transmitting power to the sprocket 22 from the sprocket 21 are provided. When the initial tension of the chain 24 is Fo/2 and the changes of tension are DELTAF1, DELTAF2, the torque T around the joint shaft 25 of the robot arm 23 is shown by the formula T= (DELTAF1-DELTAF2)XD/2 wherein D is the pitch circle diameter of the sprocket 22. As mentioned above, the joint torque can be obtained by detecting the tension of the chain. In this case, the chain tension is detected by adhering stress gauges 26, 27 being crossed gauges to the link elements 24a, 24b of the chain 24.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for detecting joint torque in an arm mechanism of a robot or manipulator whose force transmission mechanism includes a chain. [Prior art] Robot or manipulator Conventionally, attempts have been made to detect the total torque acting on each joint of the working arm in order to improve the detection or control performance of the work operation force. As an example of this method, the most common method is to attach strain gauge metal to the working arm member, but it is difficult to obtain sufficient sensitivity and there are problems in terms of maintainability. Another example is detecting the motor current sound for driving joints and converting it into torque, but the accuracy is poor because it is directly affected by the friction torque of the reducer. There are various other examples of special total torque detection, but problems remain in terms of cost, reliability, etc.

[Purpose of the invention]

An object of the present invention is to provide a torque sensor for a working arm that is simple and has sufficient sensitivity.

[Summary of the invention J The invention uses chain noise in the power transmission mechanism.

In the working arm mechanism, a strain gauge is attached to the chain link element or the chain connecting element, and its output is used to detect the total torque of the working arm joint (lζ
This method achieves a torque detection method that does not require any special mechanism, is simple and has sufficient sensitivity, and is not affected by the M vibration force of the reducer.

[Embodiments of the invention]

1 and 2 do not show an example of the working arm structure of a robot that can be applied to the torque detection method of the present invention.

FIG. 1 shows its external appearance. The working arm of this robot is the upper arm. Consists of 22 forearms, 3 wrists, L1 upper armpits, 1 base, and 4 bases.
1-1, one end of which is pivotally connected by the shoulder joint 5.
At the same time, the other end is the rhombus joint (5, r-9 and forearm 2
is pivotally connected to one end of the 7 and 8 are wrist joints, and the wrist 3 is pivotally connected to the forearm 2 through the wrist joints 7 and 8.

9 is a motor for driving the upper arm, 10 (not shown) is a motor for driving the forearm, and 12 is a motor for driving the wrist.

FIG. 2 is a schematic diagram of the power transmission mechanism of the working arm mechanism of the robot shown in FIG.

The upper arm drive motor 9 is attached to the base 4, and its output is transmitted to the shoulder joint 5 through the entire chain 13.

A forearm drive motor 10 is also attached to the base 4, and its output is transmitted through the chain 14 (7) to the shoulder joint 5''Ii, and further transmitted to the elbow joint 6 through the chain 15.

The wrist bending drive motor 11 is attached to the upper arm 1. The output is transmitted through 16 chains to the -l''-diamond joint 6, and then transmitted through a chain 17 to the bending joint 7 of the wrist 11. 6. Wrist swing drive motor 12
is also attached to the upper arm 1, and its output is connected to the chain 17.
It is once transmitted to the elbow joint 6 through the chain 18.
It is transmitted to the wrist bending joint via the The direction of rotation is changed by a bevel gear set 19 provided on the wrist bending joint 7, and the rotation is transmitted through the wrist swinging joint 8.

In this way, if the entire chain is used for the power transmission mechanism of the robot work arm, it can be installed near the motor (actuator) base, making the arm mechanism more compact. By detecting the tension in the joint, the entire torque of the joint can be known.

The principle is shown in Figure 3.

In Fig. 3, 20 is a motor output shaft 2111 (with 16 chains attached), 22f-j robot arm 2
A chain sprocket 3 is attached to the chain sprocket 3, and a chain 24 is a chain that transmits motion from the sprocket 20 to the sprocket 22. Assuming that the initial tension in the chain is kF (1/2) and the change in tension is ΔF++ΔF2, the torque T for the joint axis 251 of the robot arm is T-i (ΔF1-ΔF2)...
...(1). Here, it is the pitch circle diameter of the DH sprocket 22.

FIG. 4 shows an example in which 27 strain gauges 26 are attached to the link elements 24a and 24bv of the chain 24 as an example for detecting the entire chain tension.

Strain gauge'; 26 and 27 are orthogonal gauges;
As shown in Fig. 5, 26A and 27A are attached so that the sensitivity is in the tension direction (if et al.). 26D and 2
71) It is a bow dummy gauge and is pasted at right angles to the tension direction.

26.27 wiring example shown in Figure 6, 26A and 27A
7 Connect the wires so that it is on the side next to the Wheatstone bridge, and connect the Tli pressure F from the power supply 28 to the diagonal corner of the Wheatstone bridge.
J′ (il-mark) Jnl, the remaining diagonal +lT,
l13. e is e=4(ΔF1−Δl'2)...
......(2), where Kl is a proportionality constant. Therefore e? If amplified, T = K2- e ・・・・・・ ・・・
...(3), joint torque? Can be detected.

FIG. 7 shows an example in which a strain gauge (VtCI) is attached to coupling elements 29a and 29b for tension detection without being attached to the strain gauge. In this way, the torque detection sensitivity can be increased by adjusting the dimensions of the coupling element 29 to an appropriate value.

Figure 8 shows an example in which the chain's first) υ1 tension adjustment turnbuckle: 30a, 30bK strain gauge 1 is attached. - A strain gauge is pasted on the connecting element of the chain for driving the working arm of the Saitake Manbulator.
li is simple, has high sensitivity, and has a high sensitivity of 1.41 degrees.

4.Figure iA! Is the current situation in Figure 1 the actual torque detection method? APPLICATIONS - ROBOSO 1 - External view showing an example of the working arm, 2nd figure is a schematic diagram showing its power transmission mechanism, Principle diagram, Fig. 4, Fig. 7L9] and Fig. 8←j
1. A diagram showing an embodiment of the present invention, FIG. 5 is a diagram showing an example of how to attach a strain gauge to a link element, rJj', and FIG. 6 is an example of how to connect a strain gauge. FIG.

20.22... Chain sprocket, 24... Chain, 26.27... Strain gauge.

・¥’! + +/r (Small, ) Figure 11 Figure 7

Claims (1)

[Claims] A torque detection method that detects the entire torque of the chain sprocket drive shaft by attaching a strain gauge to the connecting element of the chain in the working arm mechanism where the power transmission mechanism includes a chain and converting the resistance change into an electrical quantity. .