TWI674179B - Method for releasing the brake of a robot arm - Google Patents

Abstract

A method for a robotic arm to release the brake, obtain the gravity angle of the drive module, and detect the rotation angle of the drive module by the encoder of the motor, compare the gravity angle and the rotation angle, and determine the load direction of the braking device from the comparison result. , The control motor outputs a preset torque in the opposite load direction, and controls the solenoid valve of the drive module to retract the blocking pin to release the brake.

Description

How to release the brake of the robot arm (2)

The present invention relates to a robot arm, and more particularly to a method for releasing the brake and allowing the robot arm to move while the robot arm stops rotating from the brake.

Factory automation uses robotic arms to automatically grab workpieces and move them back and forth for assembly and manufacturing to improve production efficiency. The robot arm moving back and forth, in addition to the drive module to provide power, also needs to rely on stable and reliable brakes in order to stop the robot arm at a predetermined position for accurate operations.

Please refer to FIG. 1, which is a driving module 10 of a robot arm of a prior art US patent US8410732. The driving module 10 of the prior art uses the motor 11 to drive the rotating shaft 12 to rotate, and after decelerating through the speed reduction device 13, the output power moves the robot arm. A brake device is provided in the driving module 10. The brake device fixes the ratchet wheel 14 on the rotating shaft 12, and a solenoid valve 15 is provided around the ratchet wheel 14. The solenoid valve 15 engages and disengages the ratchet wheel 14 by a telescopic blocking pin 16 to block or release the ratchet wheel 14 from rotating. . The drive module 10 also fixes an encoder 17 on one end of the rotating shaft 12 and detects the rotation angle of the motor 11 as a feedback signal for monitoring and controlling the rotation of the motor 11.

When the robot arm needs to move, the control solenoid valve 15 retracts the blocking pin 16 to release the ratchet wheel 14 and then controls the motor 11 to drive the rotation shaft 12 to rotate, and the encoder 17 monitors whether the motor 11 rotates according to the signal required angle. When the robot arm needs to stop, the drive module 10 brakes During operation, the solenoid valve 15 is extended to block the ratchet wheel 14 to prevent the ratchet wheel 14 from rotating, generating braking torque, and resisting the inertia force of the robot arm and the load formed by the workpiece to stop the rotation of the rotating shaft 12 fixed by the ratchet wheel 14, thereby preventing the robot arm from moving. The encoder 17 then monitors whether the motor 11 stops at the required angle in accordance with the signal.

However, after the stop pin 16 of the solenoid valve 15 stops the robot arm from rotating, the load of the robot arm will act on the elongated stop pin 16 of the solenoid valve 15 via the ratchet wheel 14. If the workpiece is excessively loaded, the load will cause the ratchet wheel 14 to stop A large frictional force is formed between the pins 16. When the robot arm needs to move again, the force of the control solenoid valve 15 to retract the stopper pin 16 is not enough to overcome the friction between the ratchet wheel 14 and the stopper pin 16, the stopper pin 16 is blocked by the ratchet wheel 14, and the solenoid valve 15 will fail. Retracting the blocking pin 16 releases the ratchet 14, so that the driving module 10 cannot release the brake. If the brake cannot be released, once the drive module 10 uses a larger force or a rotation angle to drive the motor 11 to rotate, the blocking pin 16 or the ratchet wheel 14 will be deformed, which not only affects the accuracy of the positioning of the robot arm, but also damages the robot arm. . Therefore, the robot arm still has problems to be solved in the method of releasing the brakes.

The purpose of the present invention is to provide a method for releasing the brake of a robotic arm. The gravity direction of the robotic arm is used to obtain the direction of gravity, and the rotation direction of the driving module is used to obtain the direction of the load. Release the brakes.

In order to achieve the purpose of the foregoing invention, the method for releasing the brake of the robot arm of the present invention obtains the gravity angle of the drive module, and the rotation angle of the drive module is detected by the encoder of the motor. As a result, the load direction of the brake device is determined, the control motor outputs a preset torque in the opposite load direction, and the solenoid valve of the drive module is controlled to retract the stopper pin to release the brake.

In the present invention, a gravity sensor provided on a control circuit board of a driving module detects a direction of gravity, and then the driving module determines a gravity angle of the direction of gravity relative to the driving module according to a rotation reference. Subtract the rotation angle from the gravity angle, and compare the positive and negative results of the gravity angle and the rotation angle. The comparison result is positive, it is judged that the load of the robot arm is acting on the brake device in a clockwise direction, and the comparison result is negative, it is judged that the load of the robot arm is acting on the brake device in a counterclockwise direction.

20‧‧‧ robot arm

21‧‧‧First Drive Module

22‧‧‧first support arm

23‧‧‧Second Drive Module

24‧‧‧Second support arm

25‧‧‧ terminal

26‧‧‧Jaw

27‧‧‧Workpiece

30‧‧‧Drive Module

31‧‧‧Motor

32‧‧‧ shaft

33‧‧‧ Reducer

34‧‧‧Control circuit board

35‧‧‧ gravity sensor

36‧‧‧Brake device

37‧‧‧ Ratchet

38‧‧‧ Solenoid Valve

39‧‧‧ stop pin

40‧‧‧Spring

41‧‧‧Encoder

FIG. 1 is a side sectional view of a driving module of a prior art robot arm.

FIG. 2 is a schematic diagram of a load on a robot arm according to the present invention.

FIG. 3 is a side sectional view of a driving module of a robot arm according to the present invention.

FIG. 4 is a schematic diagram of a clockwise load of a robot arm according to the present invention.

FIG. 5 is a schematic diagram of a load action of a robot arm according to the present invention in a counterclockwise direction.

FIG. 6 is a flowchart of a method for releasing a brake of a robot arm according to the present invention.

Regarding the technical means adopted by the present invention to achieve the above-mentioned objectives, and their effects, preferred embodiments are described below with reference to the drawings.

Please refer to FIG. 2, FIG. 3, FIG. 4 and FIG. 5 at the same time. FIG. 2 is a schematic view of the load bearing of the robot arm of the present invention, FIG. 3 is a side sectional view of a driving module of the robot arm of the present invention, and FIG. 4 is a robot arm of the present invention. A schematic view of the load action in the clockwise direction. FIG. 5 is a schematic view of the load action of the robot arm in the counterclockwise direction of the present invention. The present invention is a robot arm 20 including at least one axis. In FIG. 2, this embodiment uses a multi-axis robot arm 20 as an example. The robot arm 20 uses the first driving module 21 to drive one end of the first support arm 22 to rotate at an angle α, and the other end of the first support arm 22 is fixed. The second driving module 23 uses the first support arm 22 as a rotation reference to drive one end of the second support arm 24 to rotate at an angle θ 1. The end portion 25 of the other end of the second support arm 24 is used to drive the clamping jaw 26 to grip the workpiece 27.

The first driving module 21 and the second driving module 23 of the present invention use the same driving module 30. In FIG. 3, the driving module 30 uses the motor 31 to drive the rotating shaft 32 to rotate, and after decelerating through the reduction device 33, the output power moves the robot arm 20. The driving module 30 is further provided with a gravity sensor 35 on the control circuit board 34 to detect the direction of gravity at the position where the driving module 30 is located. The driving module 30 is also provided with a braking device 36 which fixes the ratchet wheel 37 on the rotating shaft 32. In FIG. 3, the ratchet wheel 37 projects radially from the circumference of the rotation shaft 32, and a solenoid valve 38 is provided around the ratchet wheel 37. In the state (OFF), the spring 40 pushes out the blocking pin 39 and enters the rotation path of the ratchet wheel 37. When the state is ON, the spring 40 is pressed, and the blocking pin 39 is retracted to leave the rotation path of the ratchet wheel 37. The drive module 30 also fixes the encoder 41 on one end of the rotating shaft 32 to detect and record the rotation angle of the motor 31.

When the robotic arm 20 brakes, the solenoid valve 38 is controlled to be OFF, and the stopper pin 39 is pushed out by the spring 40, so that the stopper pin 39 enters the rotation path of the ratchet wheel 37 to prevent the ratchet wheel 37 from moving, generating a braking torque and resisting the load of the robot arm 20 The generated inertial force stops the rotating shaft 32 fixed by the ratchet wheel 37 from rotating, thereby preventing the robot arm 20 from moving. After the braking device 36 stops the robot arm 20 from rotating, the load of the robot arm 20 acts on the elongated stop pin 39 of the solenoid valve 38 via the ratchet wheel 37. Before the robot arm needs to move, the brake must be released to overcome the friction of the blocking pin 39 of the ratchet 37, control the solenoid valve 38 to be ON, and retract the blocking pin 39 so that the blocking pin 39 is separated from the rotation path of the ratchet 37. In order to prevent the ratchet wheel 37 from being blocked, the driving module 30 can be controlled to freely rotate the rotating shaft 32 to output power.

Taking the second drive module 23 as an example, since the robot arm 20 passes each horse, The encoder 41 records the rotation angle of the first driving module 21 and the second driving module 23, and the relative positional relationship between the parts of the robot arm 20 is known. Therefore, in FIG. 2, the present invention uses the rotation angle of each motor recorded by the robot arm 20 during braking, that is, the rotation angle α of one end of the first support arm 22 driven by the first drive module 21 and the second drive module 23 drives the first The rotation angle θ 1 of the two support arms 24. Since the second driving module 23 has been subjected to the rotation angle α of the first support arm 22, the relationship with the direction of gravity V cannot be judged only by the rotation angle θ 1. Therefore, the second driving module 23 needs to detect the gravity direction V of the second driving module 23 by means of a gravity sensor 35 provided on its control circuit board 34, and according to the first rotation reference of the second driving module 23, The support arm 22 determines a gravitational direction V relative to a gravitational angle θ of the second driving module 23.

The rotation angle θ 1 of the second supporting arm 24 and the gravity angle θ of the gravity direction V are compared with the foregoing second driving module 23 to compare the gravity angle θ minus the rotation angle θ 1. The rotation angle θ 1 is not greater than the gravity angle θ, so θ-θ 1 ≧ 0, and the comparison result is positive, it can be judged that the second support arm 24 is located at one side of the rotation angle of the gravity direction V extension. As shown in FIG. 4, the load L of the robot arm 20 acts on the blocking pin 39 in a clockwise direction by the ratchet wheel 37. Therefore, the second driving module 23 needs to use the preset torque T to drive the motor 31 to rotate the ratchet wheel 37 in the direction of the opposite load L, so as to offset the force of the load L on the blocking pin 39 and cause the ratchet wheel 37 to oppose the blocking pin 39. The friction force is reduced or disappeared, the solenoid valve 38 can retract the stop pin 39 smoothly, and the brake is successfully released.

Similarly, under the condition that the second driving module 23 is rotated by the first support arm 22 by the rotation angle α, when the second driving module 23 drives the second support arm 24 by the rotation angle θ 2, as shown by the dashed line in FIG. 2 The second support arm 24 '. The gravity sensor 35 of the second driving module 23 detects the gravity direction V relative to the gravity angle θ of the second driving module 23. The result of comparing the angle of gravity θ minus the angle of rotation θ 2, since the angle of rotation θ 1 of the second support arm 24 is greater than the angle of gravity θ, so θ-θ 1 <0. If the result is negative, it can be judged that the second support arm 24 'is positioned on one side of the contraction and rotation angle of the gravity direction V. As shown in FIG. 5, the load L of the robot arm 20 acts on the stopper pin 39 in a counterclockwise direction by the ratchet wheel 37. As long as the second driving module 23 uses the preset torque T to drive the motor 31 to rotate the ratchet wheel 37 in the opposite direction to the load L, the load L acting on the blocking pin 39 can also be offset, and the friction of the ratchet wheel 37 to the blocking pin 39 can be eliminated. The force decreases or disappears, and the solenoid valve 38 can also smoothly retract the stop pin 39 to release the brake. Although the foregoing description of the present invention uses the second driving module 23 as an example to release the brake, the second driving module 23 is included and is not limited to the same. The driving load direction can also be inferred at each driving module to release the brake.

As shown in FIG. 6, it is a flowchart of a method for releasing a brake of a robot arm according to the present invention. The detailed steps of the method for releasing the brake of the robot arm according to the present invention are described as follows: Step S1, starting to release the brake; in step S2, the gravity direction is obtained by the gravity sensor to determine the gravity angle of the gravity direction relative to the driving module; step S3, obtain The rotation angle of the driving module; step S4, comparing the gravity angle and the rotation angle, that is, subtracting the rotation angle from the gravity angle to obtain a positive and negative comparison result; step S5, judging the load direction of the braking device from the comparison result; step S6, The control motor outputs a preset torque in the opposite load direction; step S6 performs brake release, that is, controls the solenoid valve to retract the stopper smoothly; finally, it proceeds to step S8 to end the brake release operation.

Therefore, according to the method for releasing the brake of the robot arm of the present invention, the gravity direction of the robot arm can be obtained by the gravity sensor of the robot arm, and the gravity angle of the gravity direction relative to the driving module can be determined. The result of the comparison of the gravity angle minus the rotation angle, determine the load direction of the brake device, and then rotate the motor with a preset torque in the opposite direction to offset the load of the blocking pin, allowing the solenoid valve to retract the blocking pin smoothly, and successfully release the brake. the goal of.

The above are only for the convenience of describing the preferred embodiments of the present invention, and the scope of the present invention is not limited to these preferred embodiments, and any changes made according to the present invention will not depart from In the spirit of the present invention, they all belong to the scope of patent application of the present invention.

Claims (7)

A method for releasing the brake of a robotic arm, the steps include: obtaining the gravity angle of the driving module; obtaining the rotation angle of the driving module; comparing the gravity angle and the rotation angle, subtracting the rotation angle from the gravity angle; and subtracting the positive and negative values from the comparison. As a result, the load direction of the brake device is determined; the control motor outputs a preset torque in the opposite load direction; and the brake is released. The method for releasing the brake of the robot arm according to item 1 of the scope of patent application, wherein the driving module determines the gravity angle of the direction of gravity relative to the driving module according to the rotation reference. The method for releasing the brake of the robot arm according to item 2 of the scope of the patent application, wherein the direction of gravity is detected by a gravity sensor provided on a control circuit board of the driving module. The method for releasing the brake of the robotic arm as described in the first item of the patent application scope, wherein the rotation angle of the driving module is detected by an encoder of the motor. The method for releasing the brake of the robot arm according to item 1 of the scope of patent application, wherein the release of the brake is to control the solenoid valve of the drive module to retract the stopper pin. The method for releasing the brake of the robot arm as described in the first item of the scope of the patent application, wherein the comparison result is positive, and it is judged that the load of the robot arm acts on the brake device in a clockwise direction. The method for releasing the brake of the robot arm as described in the first item of the scope of the patent application, wherein the comparison result is negative, and it is judged that the load of the robot arm acts on the brake device in a counterclockwise direction.