JPH085034Y2 - Manipulator-joint torque detection mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a manipulator joint torque detection mechanism for detecting torque acting on a joint such as a manipulator.

B. Outline of the Invention The present invention uses a belt for power transmission to a joint shaft in a manipulator, and a tension pulley is pressed against the belt to detect a reaction force received by the tension pulley with a force sensor to measure the tension of the belt. By doing so, the torque acting on the joint shaft is detected.

C. Conventional technology and its problems For example, in the master-slave manipulator,
The torque in the slave side arm is detected, and a torque is applied to the master side arm in accordance with this torque to give a feeling of operation to a person who operates the arm. A strain gauge is usually used as a means for detecting torque in such a manipulator. Since this strain gauge is used by pasting it with an adhesive or the like, in a manipulator or the like to which a small servo motor is applied, the adhesive erodes the strain gauge sticking part and the sticking part deteriorates over a long period of time. Becomes This deterioration of the attached portion of the strain gauge may lead to peeling of the strain gauge and the like, and it may not be possible to perform good torque detection. Therefore, in order to suppress this deterioration, a means such as sealing with a bellows is adopted, but this leads to an increase in size.

On the other hand, the drive torque can be obtained from the current of the motor or the like used as the drive device. However, in this case, the reduction of the mechanical efficiency of the reduction gear device is large, so that the torque of the output shaft cannot be accurately obtained.

In view of the above problems, an object of the present invention is to provide a manipulator joint torque detection mechanism having a simple structure and good detection accuracy.

D. Means for Solving the Problems The constitution of the present invention which achieves the above object is characterized in that a belt is used for power transmission, and the torque is detected by measuring the tension of the belt.

E. Action By using a belt for power transmission, high-sensitivity transmission can be achieved without loss of power transmission, and since the weight is light and the inertia is small, response is quick and control is easy. Further, the tension pulley is pressed against the belt so that the initial tension of the belt can be easily adjusted and the change in the tension of the belt is measured to detect the torque.

F. Embodiment Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.

This embodiment shows an example in which the present invention is applied to the hand of the master arm of the manipulator shown in FIG. The master arm is composed of an upper arm 1, a forearm 2, a wrist frame 3 and a grip 4, and a person grips the grip 4 to perform an operation. Here, the upper arm 1 is capable of vertical swing A of the shoulder and horizontal swing B of the shoulder, the forearm 2 is capable of bending C of the elbow with respect to the upper arm 1, and the hand portion is 4 free. Have a degree. In other words, the wrist frame 3 is capable of vertical bending D of the wrist and lateral bending E of the wrist,
The grip 4 can rotate the wrist F and has a gripping switch.

In such a master arm, in order to transmit the reaction received by the slave arm to the operator, the torque received by each joint of the slave arm is measured, and a mechanism for applying a torque corresponding to the torque to each joint of the master arm is incorporated. Has been. In this embodiment, an example in which the joint torque detecting mechanism of the present invention is applied to a mechanism that gives a reaction to the rotation F of the wrist is shown.

As shown in FIGS. 1 and 2, the wrist frame 3 swings along a groove (not shown) formed in the forearm arm 2 (longitudinal bending D of wrist) and rotates (lateral bending E of wrist). A grip 4 is rotatably provided on the wrist frame 3 via a bearing 11. Further, the grip 4 is provided with a switch 5 for causing the slave arm to perform a grasping operation. A large pulley 13 is fixed to the joint shaft 12 fixed to the grip 4, and the large pulley 13 is connected to a small pulley 16 provided on a drive shaft 15 of a motor 14 by a timing belt 17. That is, the grip 4 is given a reaction force when it is rotated by the motor 14. A tension pulley 18 is pressed against the timing belt 17. The tension pulley 17 is rotatably supported around a shaft 21 by a frame 20 which is rotatably supported by a pin 19, and when the timing belt 17 is driven, the tension pulley 18 moves around the shaft 21. By rotating and rotating the frame 20 around the pin 19, the timing belt 17 can be moved in the thickness direction. As a pressure contact means for pressing the tension pulley 18 against the timing belt 17, the pressing screw 22 is a frame.
20 is provided on the opposite side of the timing belt 17. The pressing screw 22 is screwed into the sensor cover 23, and the tip of the pressing screw 22 presses the frame 20 via the sensor receiver 24 and the force sensor 25. This force sensor 25
Is in pressure contact with the opposing portion of the frame 25, and the pressure contact force (torque) by the frame 25 can be detected. That is, when the pressing screw 22 is screwed in, the sensor receiver 24 slidably supported on the wrist frame 3 moves in the screwing direction, and the force sensor 25 fixed to the surface of the sensor receiver 24 fixes the frame 20 to the frame 20. It is pressed so that the tension pulley 18 is pressed against the timing belt 17. Therefore, the force sensor 25 can detect the reaction force from the timing belt 17, and the change in the tension of the timing belt 17, that is, the torque acting on the joint shaft 12 is detected by measuring the change in the reaction force. be able to. Further, the initial tension applied to the timing belt 17 can be adjusted by such a pressure contact mechanism.

In such a mechanism, first, the tension pulley
The belt 18 is pressed against the timing belt 17 to give an initial tension. Here, when torque is applied to the grip 4, that is, the large pulley 13 by the motor 14, when the large pulley 13 is rotated clockwise in order to rotate the small pulley clockwise in FIG. The tension pulley 18 side of the belt 17 loosens, and the frame 20 rotates counterclockwise around the pin 20 via the tension pulley 18. Then, the pressure contact force of the frame 20 against the force sensor 25 weakens, and the reaction force received by the force sensor 25 decreases. On the other hand, when the pulley 13 is rotated counterclockwise in order to rotate the small pulley counterclockwise in FIG. 1, the tension pulley 18 side of the timing belt is stretched to the force sensor 25 by the frame 20. The pressure contact force of is increased, and the reaction force received by the force sensor 25 is increased.

That is, in the present embodiment, the torque when the large pulley 13 is rotated clockwise (in FIG. 1) is
The smaller the reaction force (detection value) received by the force sensor 25, the larger it becomes, and the torque when the large pulley 13 tries to rotate counterclockwise (in FIG. 1) is the reaction force (force) detected by the force sensor 25. The larger the detected value), the larger the value.
In the present embodiment, the torque acting on the large pulley 13, that is, the joint shaft 12, can be measured by obtaining the calibration curve of the reaction force received by the force sensor 25 and the actual torque value in advance. .

In this embodiment, the torque received by the slave arm side is separately measured, and a torque equivalent to this torque value is applied to the grip 4 by driving the motor 14. At this time, the torque on the slave arm side is increased. An appropriate torque can be applied to the grip 4 by comparing the value with the torque value obtained from the reaction force received by the force sensor 25 and feeding back the torque value to the motor 14.

The mechanism of the hand of the master arm shown in the present embodiment has a joint configuration similar to that of a human joint and uses the belt for power transmission, so that a human being who operates does not feel uncomfortable and a torque close to the actual one is transmitted quickly. Therefore, stable operation is possible.

Further, in the present embodiment, since the timing belt is used as the belt, the positional accuracy is higher and slip is completely eliminated, so that the power transmission can be surely performed.

In the above embodiment, the present invention is applied to the mechanism that applies torque to the joint shaft in the master arm, but of course it can be applied to the case where the torque actually received by the joint shaft is measured in the slave arm.

G. Effect of the Invention As described above in detail with the embodiments, the manipulator joint torque detection mechanism according to the present invention uses a belt for power transmission and measures the torque acting on the joint shaft from the tension of the belt. Therefore, the structure is simple, the detection accuracy is high, and the response is quick and easy to control. Therefore, as shown in the embodiment, when applied to a mechanism for exerting a torque on the joint axis in the master arm, a response is fast and an operational feeling close to the actual one can be surely obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a manipulator joint torque detecting mechanism according to an embodiment of the present invention, FIG. 2 is a partial sectional view showing a hand structure of a master arm of a manipulator using the manipulator, and FIG. 3 is its master arm. It is explanatory drawing which shows notionally. In the drawing, 3 is a wrist frame, 4 is a grip, 12 is a joint shaft, 13 is a large pulley, 14 is a motor, 16 is a small pulley, 17 is a timing belt, 18 is a tension pulley, 20 is a frame, 22 is a pressing screw, 24 is a sensor receiver and 25 is a force sensor.

Claims (1)

[Scope of utility model registration request] 1. A manipulator in which a first arm and a second arm are rotatably connected via a joint shaft, and a belt for transmitting power from a drive source to the joint shaft is provided and rotatably supported. A tension pulley is provided so as to be movable in the thickness direction of the belt, and is provided with a pressing means for pressing the tension pulley against the belt, and a force sensor for detecting a reaction force received by the tension pulley from the belt. And manipulator joint torque detection mechanism.