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1. WO2020194233 - DÉTECTION DE COLLISION

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

[ EN ]

Claims

1. A method of monitoring movement of a robotic arm, the robotic arm being arranged to be moved by an actuator, the method comprising:

determining an expected robotic arm condition based on a known robotic condition and a torque applied to the robotic arm by the actuator;

measuring an actual robotic arm condition during movement of the arm caused by the applied torque; and

determining whether a collision has occurred by comparing the actual robotic arm condition with the expected robotic arm condition and generating a collision signal if a difference between the actual robotic arm condition and the expected robotic arm condition exceeds a threshold.

2. The method of claim 1, wherein the comparing is carried out by a hardware module.

3. The method of claim 1 or 2, further comprising stopping motion of the robotic arm based on the collision signal.

4. The method of claim 3, wherein the stopping comprises activating a brake.

5. The method of any preceding claim, wherein the robotic arm condition comprises at least one of:

a position of the robotic arm,

a velocity of the robotic arm, and

an acceleration of the robotic arm.

6. The method of claim 5, wherein the position, velocity and/or acceleration are angular position, angular velocity and/or angular acceleration respectively.

7. The method of claim 6, wherein the measuring is performed by an encoder assembly on the robotic arm.

8. The method of claim 7, wherein the encoder assembly comprises two encoders arranged to output data to an encoder comparator and wherein the encoder comparator is arranged to determine a difference between the outputs of the encoders.

9. The method of any preceding claim, further comprising:

picking up a load with the robotic arm;

wherein the threshold is based at least partially on the mass of the load.

10. The method of claim 9, further comprising:

modifying the threshold subsequently to the picking up of the load.

11. The method of any preceding claim, further comprising estimating the torque based on an electrical current input to the actuator.

12. The method of any preceding claim, wherein the estimated torque is less than 80% of the maximum torque of the actuator.

13. The method of any preceding claim, further comprising calculating a Fourier transform of the applied torque before the movement of the robotic arm and selecting the applied torque based on the Fourier transform.

14. The method of any preceding claim, wherein a rate of change of the applied torque is within the bandwidth of the actuator.

15. The method of any preceding claim, wherein a highest frequency component of the applied torque has a lower frequency than the lowest resonant frequency of the robotic arm.

16. The method of any preceding claim, wherein the robotic arm comprises a plurality of joints, each joint having at least one actuator, and wherein the measuring comprises measuring a relative position, a relative velocity and/or a relative acceleration for each joint.

17. The method of any preceding claim, wherein the determining the expected robotic arm condition is based at least partially on estimated robotic arm kinetic parameters, and

wherein the method further comprises estimating the robotic arm kinetic parameters based on an actual robotic arm condition measured during movement of the robotic arm by the actuator.

18. A robotic arm comprising:

a first member,

a second member moveably coupled to the first member,

an actuator arranged to move the first member relative to the second member, a measuring device for determining a condition of the first and/or second member, and a controller coupled to the actuator and measuring device arranged to carry out the method of any preceding claim.

19. The robotic arm of claim 18, wherein the controller comprises:

a motion controller arranged to determine the expected robotic arm condition; and a separate comparison module arranged to compare the expected robotic arm condition to the measured robotic arm condition.

20. The robotic arm of claim 19, further comprising a brake arranged to prevent movement of the first and/or second member selectively, wherein the comparison module is arranged to drive the brake directly.