Sprung worm gripper for a robotic device

Patent metadata

Field	Value
Publication number	US-10016901-B2
Application number	US-201615146692-A
Country	US
Kind code	B2
Filing date	May 4, 2016
Priority date	May 4, 2016
Publication date	Jul 10, 2018
Grant date	Jul 10, 2018

Abstract

A robotic gripping device is provided. The device includes a finger having a worm gear coupled to its base end. The device also includes an actuator having a motor and a shaft, wherein the shaft is configured to rotate a worm coupled to the worm gear, and the actuator is mounted on a carriage such that the actuator is configured to slide along an axis. The device also includes a spring having first and second ends, wherein the first end is coupled to the motor and the second end is fixed. Further, the actuator is configured to (i) rotate the shaft relative to the motor by a first amount to move the finger toward an object, and (ii) when the finger is in contact with the object and is prevented from further movement, further rotate the shaft relative to the motor to slide the actuator along the axis.

First claim

The invention claimed is:

1. A robotic gripping device comprising:
a finger having a worm gear coupled to a base end of the finger, wherein a shape of the worm gear is a partial circle;
an actuator having a motor and a shaft, wherein the shaft is configured to rotate a worm coupled to the worm gear, and wherein the actuator is mounted on a carriage such that the actuator is configured to slide along an axis; and
a spring having a first end and a second end, wherein the first end is coupled to the motor of the actuator and the second end is fixed, such that the actuator is held in a first position along the axis when the spring is at equilibrium;
wherein the actuator is configured to:
rotate the shaft relative to the motor by a first amount, thereby rotating the worm and the worm gear to move the finger toward an object;
when the finger is in contact with the object and the finger is prevented from further movement, further rotate the shaft relative to the motor to slide the actuator along the axis to a second position at which the spring is no longer at equilibrium; and
disengage the worm from the worm gear when a torque greater than a threshold torque is applied to the finger.

2. The robotic gripping device of claim 1 , wherein the finger is configured to move translationally.

3. The robotic gripping device of claim 1 , further comprising:
a linear encoder configured to determine a difference between the first and second positions of the actuator along the axis; and
a control system, wherein the control system is configured to determine an amount of torque applied to the finger based on the difference between the first and second positions of the actuator.

4. The robotic gripping device of claim 1 , wherein the spring is positioned around the actuator.

5. The robotic gripping device of claim 1 , wherein the finger comprises a first finger, and wherein the robotic gripping device further comprises a second finger having a respective worm gear and associated worm, actuator, and spring.

6. The robotic gripping device of claim 1 , wherein the finger is an underactuated finger.

7. The robotic gripping device of claim 1 , wherein the spring comprises two springs each positioned on opposite sides of the actuator.

8. A robotic device comprising:
a robotic gripping device, wherein the robotic gripping device comprises:
a finger having a worm gear coupled to a base end of the finger, wherein a shape of the worm gear is a partial circle;
an actuator having a motor and a shaft, wherein the shaft is configured to rotate a worm coupled to the worm gear, and wherein the actuator is mounted on a carriage such that the actuator is configured to slide along an axis; and
a spring having a first end and a second end, wherein the first end is coupled to the motor of the actuator and the second end is fixed, such that the actuator is held in a first position along the axis when the spring is at equilibrium, wherein the actuator is configured to disengage the worm from the worm gear when a torque greater than a threshold torque is applied to the finger; and

a control system configured to control the robotic gripping device, wherein the control system comprises:
one or more processors;
a non-transitory computer-readable memory; and
program instructions stored on the non-transitory computer-readable memory and executable by the one or more processors to:
cause the actuator to rotate the shaft relative to the motor by a first amount, thereby rotating the worm and the worm gear to move the finger toward an object; and
when the finger is in contact with the object and the finger is prevented from further movement, cause the actuator to further rotate the shaft relative to the motor to slide the actuator along the axis to a second position at which the spring is no longer at equilibrium.

9. The robotic device of claim 8 , wherein the finger is configured to move translationally.

10. The robotic device of claim 8 , the robotic gripping device further comprising a linear encoder configured to determine a difference between the first and second positions of the actuator along the axis, wherein the program instructions are further executable to determine an amount of torque applied to the finger based on the difference between the first and second positions of the actuator.

11. The robotic device of claim 8 , wherein the spring is positioned around the actuator.

12. The robotic device of claim 8 , wherein the finger comprises a first finger, and wherein the robotic gripping device further comprises a second finger having a respective worm gear and associated worm, actuator, and spring.

13. The robotic device of claim 8 , wherein the finger is an underactuated finger.

14. The robotic device of claim 8 , wherein the spring comprises two springs each positioned on opposite sides of the actuator.

15. A method comprising:
identifying an object for a robotic gripping device to grasp, wherein the robotic gripping device comprises a finger, an actuator, and a spring, wherein:
(i) the finger has a worm gear coupled to a base end of the finger, wherein a shape of the worm gear is a partial circle,
(ii) the actuator has a motor and a shaft, wherein the shaft rotates a worm coupled to the worm gear, and wherein the actuator is mounted on a carriage such that the actuator is configured to slide along an axis; and
(iii) the spring has a first end and a second end, where the first end is coupled to the motor of the actuator and the second end is fixed, such that the actuator is held in a first position along the axis when the spring is at equilibrium;

rotating the shaft relative to the motor by a first amount, thereby rotating the worm and the worm gear to move the finger toward an object;
when the finger is in contact with the object and the finger is prevented from further movement, further rotating the shaft relative to the motor to slide the actuator along the axis to a second position at which the spring is no longer at equilibrium; and
disengaging the worm from the worm gear when a torque greater than a threshold torque is applied to the finger.

16. The method of claim 15 , wherein the finger is configured to move translationally.

17. The method of claim 15 , wherein the robotic gripping device further comprises:
a linear encoder configured to determine a difference between the first and second positions of the actuator along the axis; and
a control system, wherein the method further comprises:
determining, by the control system, an amount of torque applied to the finger based on the difference between the first and second positions of the actuator.

18. The method of claim 15 , wherein the spring is positioned around the actuator.

19. The method of claim 15 , wherein the finger comprises a first finger having a respective first shaft, motor, actuator, spring, worm gear, and worm, and the robotic gripping device further comprises a second finger having a respective second shaft, motor, actuator, spring, worm gear, and worm, wherein the method further comprises:
for each of the first and second respective shafts, motors, actuators, springs, worm gears, and worms:
rotating the shafts relative to the motors by first amounts, thereby rotating the worms and the worm gears to move the fingers toward an object; and
when the fingers are in contact with the object and the fingers are prevented from further movement, further rotating the shafts relative to the motors to slide the actuators along respective axes to second positions at which the sp

Assignees

• X Dev Llc

Inventors

• Strauss Marc

Classifications

• B25J9/102

  Gears specially adapted therefor, e.g. reduction gears (gearings in general F16H) · CPC title

• B25J15/0213 Primary

  actuated by gears · CPC title

• B25J15/0009 Primary

  comprising multi-articulated fingers, e.g. resembling a human hand · CPC title

• B25J9/126

  Rotary actuators · CPC title

• B25J15/0028

  with movable, e.g. pivoting gripping jaw surfaces · CPC title