ROBOT SAFETY WEIGHT COMPENSATION SYSTEM AND METHOD CAPABLE OF COMPENSATING WEIGHT OF ROBOT

Abstract

A robot safety weight compensation system and method calculate a difference between an estimated torque calculated by a dynamics model and a detected torque to form a weight tolerance. When the weight tolerance exceeds a predetermined trigger condition, an error notification is output, and the robot is brought to a safe state. When the weight tolerance is within a predetermined trigger condition, a weight compensation information is sent to correctly compensate the weight held by a robot.

Claims

1. A robot safety weight compensation system comprising: a controller configured to receive detection signals of a current sensor and a position sensor of an actuator in each joint of a robot to control a movement of the robot; a control unit set in the controller and configured to receive weight compensation settings of the robot; a safety module coupled with the control unit through an electrical or communication interface to receive weight compensation information from the control unit; a safe state unit coupled to the safety module and configured to control the robot to enter a safe state; a check weight compensation module set in the safety module and configured to obtain position information of the joint via the position sensor, receive the weight compensation information of the safety module, use dynamics to calculate an estimated torque of the robot, and detect a detected torque of the robot; and a collision sensing module set in the safety module and configured to receive a weight compensation information from the check weight compensation module to detect a collision force of the robot; wherein the control unit receives the weight compensation settings of the robot, the safety module receives the weight compensation information from the control unit, the check weight compensation module calculates a difference between the estimated torque and the detected torque to form a weight tolerance, if the weight tolerance exceeds a predetermined trigger condition, output an error notification, does not send the weight compensation information to the collision sensing module, and the safety module controls the safe state unit to take the robot to the safe state.

2. The robot safety weight compensation system of claim 1 wherein if the weight tolerance is within the predetermined trigger condition, send the weight compensation information to the collision sensing module.

3. The robot safety weight compensation system of claim 1 wherein the control unit is electrically or communicatively coupled to a human-machine interface or via electrical signals or analog input commands for setting the weight compensation settings of the robot.

4. The robot safety weight compensation system of claim 1 wherein the safety module comprises at least one of the following types of safe state: a zeroth type of safe state is a power-off shutdown function: when entering the zeroth type of safe state, a power of the actuator is turned off; a first type of safe state is an advanced power-off shutdown function: when entering the first type of safe state, a deceleration command is issued to the controller, after the robot is decelerated, the power of the actuator is turned off; and a second type of safe state is a non-power-off shutdown function: when entering the second type of safe state, the deceleration command is issued to the controller, after the robot is decelerated a standstill monitoring function is turned on to continuously monitor the position sensor, when the robot makes a move turning off the power of the actuator.

5. The robot safety weight compensation system of claim 1 wherein the check weight compensation module uses the current sensor of the actuator to sense a current of the actuator to calculate the detected torque of the robot.

6. The robot safety weight compensation system of claim 1 wherein the estimated torque and the detected torque obtained by the check weight compensation module are of a torque of the joint of the robot.

7. A robot safety weight compensation method comprising: starting a weight compensation operation when a weight is changed; performing a dynamic calculation to calculate an estimated torque; detecting a detected torque; generating a weight tolerance by calculating a difference between the estimated torque and the detected torque; if the weight tolerance exceeds a predetermined trigger condition, determining that weight compensation information is false, reporting a mistake while not sending weight compensation information, and taking a robot to a safe state.

8. The robot safety weight compensation method of claim 7 further comprising if the weight tolerance is within the predetermined trigger condition, determining that the weight compensation information is correct, sending the weight compensation information, and performing the weight compensation operation for the robot.

9. The robot safety weight compensation method of claim 8 wherein performing the weight compensation operation for the robot comprises: using a dynamic calculation to calculate an estimated torque; detecting a detected torque; calculating a difference between the estimated torque and the detected torque as an additional torque; and if the additional torque exceeds a predetermined stop condition, taking the robot to the safe state.

10. The robot safety weight compensation method of claim 9 further comprising: if the additional torque is within the predetermined stop condition, performing the weight compensation operation for the robot.

11. The robot safety weight compensation method of claim 10 wherein the estimated torque and the detected torque are of a torque of a joint of the robot.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 is a schematic diagram of a robot safety weight compensation system of the present invention.

[0012] FIG. 2 is a functional block diagram of the robot safety weight compensation system in FIG. 1.

[0013] FIG. 3 is a flowchart of a robot safety weight compensation method of the present invention.

[0014] FIG. 4 is a flowchart of another robot safety weight compensation method of the present invention.

DETAILED DESCRIPTION

[0015] In order to achieve the above-mentioned objects, the technical means and effects adopted by the present invention are described below with embodiments and drawings.

[0016] Please refer to FIGS. 1 to 2 at the same time. FIG. 1 is a schematic diagram of a robot safety weight compensation system 10 of the present invention. FIG. 2 is a functional block diagram of the robot safety weight compensation system 10 in FIG. 1. In FIG. 1, the robot safety compensation weight system 10 comprises a robot 11, a controller 12, a human-machine interface 13, a workpiece 14, etc. The robot 11 comprises a plurality of joints 15, a base 16 at one end, and a moveable end 17 at the other end. The moveable end 17 is connected to a tool 18 such as a gripper. The robot 11 is coupled to the controller 12. The controller 12 comprises a control unit 19 and a safety module 20. Through the control unit 19, the controller 12 uses a current sensor 22 and a position sensor 23 of an actuator 21 in each joint 15 to detect signals, controls the moveable end 17 of the robot 11 to drive the tool 18 to pick and place the workpiece 14. The controller 12 is also coupled to the human-machine interface 13 for editing programs of the robot 11 or operating and controlling the robot 11.

[0017] In FIG. 2, the current sensor 22, the position sensor 23, and a torque sensor 24 in the robot safety compensation weight system are coupled to the controller 12 through an electrical or communication interface to transmit detection signals to the controller 12. The control unit 19 of the controller 12 uses the received detection signal to control the operation regardless of safe functions including function setting, motion control, and program control of the robot 11. The human-machine interface 13 electrically, communicatively, wired-connection, or wirelessly coupled to the controller 12 can program the weight compensation settings of the robot 11, use electrical signal, or input communication commands such as sensing vision, force, or human body motion for setting the weight compensation settings into the control unit 19. The controller 12 further comprises a safety module 20. The safety module 20 communicates with the control unit 19 through an electrical or communication interface. The safety module 20 can receive the weight compensation information from the control unit 19. The weight compensation information can be used to compensate the center of mass or the moment of inertia of a load.

[0018] The safety module 20 is connected to the safe state unit 25. The safe state unit 25 can control the robot 11 to enter the three types of safe state. The zeroth type of safe state is the power-off shutdown function: when the safety module 20 determines that the robot 11 should enter a safe state, it directly turns off the power of the actuator 21. The first type of safe state is the advanced power-off shutdown function: when the safety module 20 determines that the robot 11 should enter the safe state, a deceleration command is issued to the controller 12, after a fixed period of time or after the robot 11 is decelerated, the power of the actuator 21 is turned off. The second type of safe state is the non-power-off shutdown function: when the safety module 20 determines that the robot 11 should enter the safe state, a deceleration command is issued to the controller 12, after a fixed period of time or after the robot 11 is decelerated, a standstill monitoring function is turned on to continuously monitor the position sensor 23 when the robot 11 makes a move, turn off the power of the actuator 21. The robot 11 can enter a safe state with either one of the above types or can trigger any of the above types by different conditions.

[0019] The safety module 20 includes a check weight compensation module 26 and a collision sensing module 27. The check weight compensation module 26 has a kinematics model which uses the position sensor 23 installed on the joint 15 to learn the position information of the joint 15 of the robot 11, including speed information and acceleration information. The check weight compensation module 26 obtains the weight compensation information of the robot 11 from the control unit 19 and uses a dynamic calculation of the robot 11 to obtain the estimated torque of the joint 15. The check weight compensation module 26 further uses the current sensor 22 of the actuator 21 of the joint 15 of the robot 11 to measure the current of the actuator 21 to calculate the detected torque of the joint 15. Using the aforementioned kinematics model established by the robot 11 to obtain the estimated torque of the joint 15 and calculating the detected torque of the joint 15 from the current of the actuator 21 are of the prior art and can be referenced to Chinese patent number CN105643639A.

[0020] Next, the difference between the estimated torque of the joint 15 and the detected torque of the joint 15 can be calculated and recorded as the weight tolerance. If the weight tolerance exceeds the predetermined trigger condition, the weight compensation information are obviously erred, an error notification is issued, the check weight compensation module 26 would determine that the weight compensation information are incorrect and not send the weight compensation information to the collision sensing module 27, and the safety module 20 would control the safe state unit 25 to take the robot 11 to a safe state. If the weight tolerance is within the predetermined trigger condition, the check weight compensation module 26 would determine that the weight compensation information are correct and send the weight compensation information to the collision sensing module 27.

[0021] The collision sensing module 27 in the safety module 20 has the kinematics model of the robot 11, uses the position sensor 23 installed on the joint 15 to learn the position information of the joint 15 of the robot 11, including speed information and acceleration information, obtains the weight compensation information of the robot 11 from the check weight compensation module 26, and uses the dynamic calculation to obtain the estimated torque of the joint 15. The collision sensing module 27 further uses the current sensor 22 of the actuator 21 of the joint 15 of the robot 11 to sense the current of the actuator 21 to calculate the detected torque of the joint 15 and calculates the difference between the estimated torque of the joint 15 and the detected torque of the joint 15, which is recorded as the additional torque of the joint 15. If the additional torque of the joint 15 exceeds the predetermined stop condition, the safety module 20 controls the safe state unit 25 to bring the robot 11 to a safe state. If the additional torque of the joint 15 is within the predetermined stop condition, the normal operation of the robot 11 is maintained.

[0022] The aforementioned predetermined trigger condition for the weight tolerance and the predetermined stop condition for the additional torque can be built-in values for the robot 11, set by the user via the human-machine interface 13, or set through electrical signals, analog input communication commands, and various sensors. In addition, although the detected torque of the joint 15 in this embodiment is calculated by detecting the current of the actuator 21, a torque sensor 24 can be installed on the joint 15 to directly sense the detected torque of the joint 15. In addition, although this embodiment uses joint torque as an example, the present invention includes but is not limited to this embodiment. The present invention can calculate the end torque from each joint torque. Further, the present invention can use a dynamics model to convert the end space and estimate torque generated by the load at the end 17. The torque sensor 24 can be disposed to the end 17 of the robot 11 to obtain the detected torque of the end 17. The difference between the estimated torque of the end 17 and the detected torque of the end 17 can be used to check if the weight compensation settings of the end 17 are correct, or can be used to infer load information, etc.

[0023] FIG. 3 is a flowchart of a robot safety weight compensation method according to an embodiment of the present invention. The detailed steps of the robot safety weight compensation method of the present invention are described as follows: Step S1, start the weight compensation operation when the weight is changed by, for example, one workpiece held by the robot 11; Step S2, use the dynamic calculation to generate the estimated torque; Step S3, detect the detected torque; Step S4, calculate the weight tolerance by calculating the difference between the estimated torque and the detected torque; Step S5, check if the weight tolerance exceeds the predetermined trigger condition? If the weight tolerance is within the predetermined trigger condition, go to step S6 to determine that the weight compensation information is correct, send the weight compensation information (relating to the workpiece held by the robot 11), and then go to step S7 to perform the weight compensation for the robot 11. In step S5, if the weight tolerance exceeds the predetermined trigger condition, go to step S8 to determine that the weight compensation information is false, and output an error notification, go to step S9 so as not to send the weight compensation information and go to step S10 to take the robot 11 to a safe state.

[0024] FIG. 4 is a flowchart of a robot safety weight compensation method according to another embodiment of the present invention. The robot safety weight compensation method in this embodiment is to continue step S7 of the previous embodiment and continue to perform the weight compensation operation on the robot 11. The detailed steps of the robot safety weight compensation method in this embodiment are described as follows: Step T1, start the weight compensation operation; Step T2, use the dynamic calculation to generate the estimated torque; Step T3, detect the detected torque; Step T4, calculate the difference between the estimated torque and the detected torque as the additional torque; Step T5, check if the additional torque exceeds the predetermined stop condition? If the additional torque is within the predetermined stop condition, go to step T6 to allow the robot 11 to perform the weight compensation normally. If the additional torque exceeds the predetermined stop condition, go to step T7 to take the robot 11 to a safe state.

[0025] In summary, the robot safety weight compensation system and method of the present invention can calculate the difference between the estimated torque obtained by the dynamic calculation of the robot and the detected torque obtained by the detection as the weight tolerance. If the weight tolerance is within the predetermined trigger condition, the weight compensation information is sent to perform the weight compensation. If the weight tolerance exceeds the predetermined trigger condition, an error notification is output and the robot is brought to a safe state. The invention calculates the difference between the estimated torque and the detected torque as the additional torque when performing the weight compensation. If the additional torque exceeds the predetermined stop condition, stop the weight compensation and bring the robot to a safe state. If the additional torque is within the predetermined stop condition, the normal weight compensation operation is performed to ensure correct the weight compensation and safe collaboration.

[0026] Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.