Robotic gripper for autonomous rendezvous and capture of satellites

Patent metadata

Field	Value
Publication number	US-10414053-B2
Application number	US-201715454536-A
Country	US
Kind code	B2
Filing date	Mar 9, 2017
Priority date	Mar 9, 2017
Publication date	Sep 17, 2019
Grant date	Sep 17, 2019

Abstract

A robotic gripper for rigidly grasping a section of a Marman ring of a satellite, the robotic gripper having an outboard jaw which interfaces to an outer diameter side of the Marman ring, a inboard jaw which interfaces to an inner diameter side of the Marman ring, and a palm which interfaces to a separation surface of the Marman ring. The jaws, when grasping the section of the Marman ring, execute a two-stage motion comprising a first movement toward the opposing jaw in a direction parallel to the palm, and a second movement of drawing the Marman ring down against the palm or other suitable surface in order to fully rigidize the grasp.

First claim

We claim:

1. A robotic gripper for rigidly grasping a section of a Marman ring, the robotic gripper comprising:
an outboard jaw which interfaces to an outer diameter side of the Marman ring having an outer diameter;
an inboard jaw which interfaces to an inner diameter side of the Marman ring having an inner diameter; and
a palm which interfaces to a separation surface of the Marman ring, wherein the outboard jaw and the inboard jaw, when grasping the section of the Marman ring, execute a two-stage motion comprising a first movement toward an opposing jaw in a direction parallel to the palm, execute a clamp of the Marman ring across the outer diameter and the inner diameter, and wherein once a threshold clamp preload has been established, a second motion of the outboard jaw and the inboard jaw transitions to a downward motion, normal to the palm, which draws the Marman ring against the palm or other suitable feature in order to rigidize the grasp.

2. The robotic gripper of claim 1 , wherein both the inboard, aw and the outboard jaw are configured to actively drive toward each other during a clamping phase of grasping, and wherein both the outboard jaw and the inboard jaw execute a draw-down motion during a draw-down phase.

3. The robotic gripper of claim 1 , wherein the inboard jaw is mounted to a gripper chassis in such a way as to constrain five degrees of freedom of motion of the inboard jaw, permitting only linear motion of the inboard jaw in a direction normal to the palm to allow the inboard jaw to follow the outboard jaw during a draw-down phase of gripping, but causing the inboard jaw to remain fixed relative to the gripper chassis during a clamping phase.

4. The robotic gripper of claim 1 , wherein the inboard jaw comprises geometric features which work together to correct an orientation of the Marman ring during grasping, the geometric features comprising: a face of the inboard jaw that contacts the inner diameter of the Marman ring and comprises a small draft angle which encourages the inner diameter of the Marman ring to slide down, toward the palm, when the outboard jaw and the inboard jaw are driven together.

5. The robotic gripper of claim 4 , wherein the inboard jaw further comprises a ramped tooth which extends slightly proud from the palm and encourages the inner diameter of the Marman ring to lift away from the palm, against an inboard jaw contact surface.

6. The robotic gripper of claim 5 , wherein a draft and a tooth of the inboard jaw approximate a V-guide into which the inner diameter of the Marman ring is coaxed during clamp phase of grasping.

7. The robotic gripper of claim 6 , wherein at a top of the inboard jaw is a small lip which wraps around an upper surface of an inner diameter flange of the Marman ring, and which is disposed at an angle relative to the inboard jaw contact surface to urge the Marman ring down into a capture zone of the outboard jaw and inboard jaw during clamp-up.

8. The robotic gripper of claim 1 , wherein the outboard jaw comprises geometric features which work together to correct an orientation of the Marman ring during grasping, the geometric features comprising a face of the outboard jaw which contacts the outer diameter of the Marman ring, the face comprising a compound revolute geometry including a concave surface disposed between two convex surfaces in order to establish two points of contact on the outer diameter.

9. The robotic gripper of claim 8 , wherein the outboard jaw further comprises upper and lower lead-in surfaces possessing a cam profile that guides an outer diameter flange of the Marman ring into a female receiver area and clamping surface of the outboard jaw.

10. The robotic gripper of claim 9 , wherein an upper lead-in of the outboard jaw comprises a 15° surface that matches a profile of a clamp band interface surface on an outer flange of the Marman ring.

11. The robotic gripper of claim 1 , wherein an inboard jaw and an outboard jaw are mounted in rotatable fashion on respective jaw carriers, the respective jaw carriers each being configured to translate linearly in a fashion that drives them together, thereby imparting, via rotary jaws, simultaneous clamping and draw-down motion through a single underactuated mechanism.

12. The robotic gripper of claim 11 , wherein the inboard jaw further comprises a ramped tooth which extends slightly proud from the palm and encourages the inner diameter of the Marman ring to lift away from the palm, against an inboard jaw contact surface, and wherein the ramped tooth articulates relative to the inboard jaw and palm in order to correctly match variable profiles of a variety of Marman rings which the robotic gripper may be called upon to grasp.

13. The robotic gripper of claim 11 , wherein a location of a damping surface and a rotation axis of the inboard jaw and the outboard jaw are selected such that a clamping force applied on the clamping surface induces a moment about a respective rotary jaw pivot axis which tends to roll the inboard jaw or the outboard jaw down, drawing an upper lead-in features toward a palm plane and into contact with upper surfaces of an outer diameter flange and an inner diameter flange of the Marman ring.

14. The robotic gripper of claim 11 , wherein a draw-down forces induced on the Marman ring by the outboard jaw and the inboard jaw arise solely from motion of the outboard jaw and the inboard jaw induced by clamping forces and are applied simultaneously with the clamping forces.

15. The robotic gripper of claim 1 , wherein the robotic gripper is configured to grasp interfaces associated with any of the following spacecraft separation ring geometries:
a. Atlas V Type A/Delta IV Type 937-4/5 (37.215″ ring)
b. Atlas V Type B & B1/Delta IV Type 1194-4/5 (47.835″ ring)
c. Atlas V Type D/Delta IV Type 1666-4/5 (65.594″ ring).

16. The robotic gripper of claim 15 , wherein the robotic gripper constrains all six degrees of freedom when coupled to any of a set of interfaces.

17. The robotic gripper of claim 1 , wherein the robotic gripper corrects, through mechanical action only or through a combination of mechanical action and robotic compliance control, an orientation of a Marman ring that is misaligned in three translational directions and in roll, pitch and yaw, simultaneously.

18. The robotic gripper of claim 1 , further comprising an underactuated draw-down mechanism which transitions a motion of the outboard jaw from a horizontal configuration parallel to the palm to a vertical configuration normal to the palm.

19. The robotic gripper of claim 1 , in which a design of the outboard jaw and the inboard jaw approximates three flanged cylinders affecting a three-point contact against the Marman ring during a clamp phase.

Assignees

• Nasa

Inventors

• Ashmore Matthew S

Classifications

• B64G2004/005

  Robotic manipulator systems for use in space · CPC title

• B64G4/00 Primary

  Tools specially adapted for use in space · CPC title

• B25J15/0028 Primary

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

• B25J15/0052

  multiple gripper units or multiple end effectors · CPC title

• B64G1/1078

  Maintenance satellites (refuelling in space B64G1/4024) · CPC title