Band brake for backdrivability control

Patent metadata

Field	Value
Publication number	US-11022191-B1
Application number	US-201916680061-A
Country	US
Kind code	B1
Filing date	Nov 11, 2019
Priority date	Nov 11, 2019
Publication date	Jun 1, 2021
Grant date	Jun 1, 2021

Abstract

A system for backdrivability control of end effectors in robotic systems is described. In one example, a brake assembly for backdrivability control includes a frame having a clearance area. The brake assembly is positioned so that the rotor of the motor extends through the clearance area. The brake assembly includes a brake band secured at one distal end along the clearance area, extending around a periphery of the clearance area, and secured at a second distal end at a flexure arm of the frame. The brake assembly also includes a brake actuator including a permanent magnet at the distal end of the flexure arm and an electromagnet secured to the fame. The brake actuator can be energized to tighten the brake band around the rotor of the motor, arresting or dampening motion of the end effector for certain movements.

First claim

Therefore, the following is claimed:

1. A system for backdrivability control, comprising:
a backing mount;
a motor, the motor comprising a rotor, and a stator secured to the backing mount;
a linkage secured to the rotor of the motor to translate movement of the rotor; and
a brake assembly for backdrivability control of the motor, the brake assembly comprising:
a frame secured to the backing mount, the frame comprising a flexure arm, a constriction channel, a brake actuator mount, and a circular clearance area that extends around the rotor of the motor;
a brake band comprising a first distal end secured along the circular clearance area, extending around a periphery of the circular clearance area, extending through the constriction channel, and comprising a second distal end secured at a distal end of the flexure arm; and
a brake actuator, the brake actuator comprising a permanent magnet seated at the distal end of the flexure arm and an electromagnet seated in the brake actuator mount.

2. The system according to claim 1 , wherein, when the electromagnet is energized, the flexure arm pulls on the second distal end of the brake band through the constriction channel, to tighten the brake band around the rotor of the motor.

3. The system according to claim 1 , wherein the brake actuator further comprises at least one permanent magnet seated in the frame to provide a bi-stable permanent magnet arrangement.

4. The system according to claim 1 , wherein:
the brake band extends around the rotor in a first direction; and
the system further comprises a second brake assembly comprising a second brake band that extends around the rotor in a second direction.

5. A brake assembly for a motor, comprising:
a frame comprising a flexure arm and a clearance area to extend around the motor;
a brake band comprising a first distal end secured along the clearance area, extending around a periphery of the clearance area, and comprising a second distal end secured at a distal end of the flexure arm; and
a brake actuator configured to pull on the distal end of the flexure arm and tighten the brake band around the motor based on an electric control signal, the brake actuator comprising a permanent magnet seated at the distal end of the flexure arm.

6. The brake assembly of claim 5 , wherein the clearance area extends around a rotor of the motor.

7. The brake assembly of claim 5 , wherein the brake actuator comprises a magnetic bi-stable mechanism.

8. The brake assembly of claim 5 , wherein:
the brake actuator further comprises an electromagnet seated in the frame; and
a permanent magnetic field of the permanent magnet is aligned to interact with an energized magnetic field generated by the electromagnet based on the electric control signal.

9. The brake assembly of claim 8 , wherein the electric control signal comprises an energizing current supplied by a controller for the brake assembly.

10. The brake assembly of claim 8 , wherein the brake actuator comprises a second permanent magnet seated at the distal end of the flexure arm and a third permanent magnet seated in the frame.

11. The brake assembly of claim 10 , wherein a second magnetic field of the second permanent magnet opposes a third magnetic field of the third permanent magnet to push on the distal end of the flexure arm and release the brake band from around the motor.

12. The brake assembly of claim 5 , wherein:
the motor comprises a direct drive motor in a robotic system; and
a controller provides the electric control signal to provide backdrivability control of the motor in the robotic system.

13. The brake assembly of claim 5 , wherein:
a stator of the motor is mounted to a backing mount;
the frame of the brake assembly is mounted to the backing mount; and
a rotor of the motor extends through the clearance area of the brake assembly.

14. The brake assembly of claim 5 , wherein the clearance area comprises a circular clearance area.

15. The brake assembly of claim 5 , further comprising:
a second frame comprising a second clearance area to extend around the motor;
a second brake band extending around a periphery of the second clearance area; and
a second brake actuator configured to tighten the second brake band around the motor.

16. A method for backdrivability control in a robotic system, comprising:
directing the robotic system to a first position for a pick operation;
engaging an end effector to conduct the pick operation;
constraining motion of the end effector using a brake assembly; and
directing the robotic system to a second position while constraining motion of the end effector, wherein the brake assembly comprises:
a frame comprising a flexure arm and a clearance area to extend around a motor of the robotic system;
a brake band comprising a first distal end secured along the clearance area, extending around a periphery of the clearance area, and comprising a second distal end secured at a distal end of the flexure arm.

17. The method according to claim 16 , wherein constraining motion of the end effector comprises at least one of arresting motion of the end effector or dampening motion of the end effector.

18. The method according to claim 17 , wherein constraining motion of the end effector comprises dampening motion of the end effector during a first period of time and arresting motion of the end effector during a second period of time.

19. The method according to claim 16 , wherein the brake actuator assembly further comprises a magnetic bi-stable mechanism.

Assignees

• Amazon Tech Inc

Inventors

• Marcus Beth A
• Romanishin John William

Classifications

• F16D2121/20

  using electromagnets · CPC title

• F16D63/002

  Brakes with direct electrical or electro-magnetic actuation · CPC title

• F16D49/08 Primary

  shaped as an encircling band extending over approximately 360 degrees · CPC title

• B25J9/1641

  compensation for backlash, friction, compliance, elasticity in the joints · CPC title

• F16D65/16

  arranged in or on the brake · CPC title