Gecko Inspired Adhesives for Robotic Space Applications

Transcription

1 Gecko Inspired Adhesives for Robotic Space Applications ARUL SURESH IN-SPACE INSPECTION WORKSHOP JOHNSON SPACE CENTER, 2 FEB 2017

2 Manipulation Tasks Assistive free-flyers on the ISS Perching for inspection/monitoring Tool retrieval, return Unpacking cargo Alternative to specialized docking adapter Complex in-space manipulation and proximity operations tasks On-orbit servicing, assembly Debris removal EVA assistance Restore-L Servicer Nozzle Capture [1] SPHERES Astrobee AERCam Sprint [1] A. Griffith, Sr. et al., NASA JSC 13 2

3 Current State of the Art Traditional spacecraft docking and robotic manipulators Requires complex, time-consuming procedures for maneuvering, alignment, docking Often need specialized docking or grasping features Difficult to capture moving, spinning objects Can have large or poorly controlled forces when engaging/disengaging ISS Canadarm during resupply NASA Docking System Capturing the Wester 6 satellite 3

4 Natural Gecko Adhesives Directional Strong adhesion with minimal preload Detaches quickly and easily Sticks to wide variety of surfaces Self cleaning Does not self adhere Not sticky by default K. Autumn, Biological Adhesives,

5 Synthetic Gecko-Inspired Adhesives Use microstructure to create large true area of contact; wedges use geometry to achieve low attach/detach forces 5

6 Adhesive Grippers Grasping with adhesives is fundamentally different from grasping with internal forces and friction It is no longer necessary to partially enclose objects. It is possible to attach and detach without imparting momentum. Motion planning is simplified; gripping capabilities are extended. Adhesives have been made that: Use space-qualified polymers Tested in vacuum, over wide temperature range Tested for over 30,000 cycles Remained engaged for over a year 6

7 Adhesive Grippers Macro-micro fabrication process [1] Curved gripper with momentapplying ability [3] Flat gripper [2] [1] Suresh et al., ASME JMR 15 [2] Jiang et al., ICRA 15 [3] Estrada et al., ICRA 16 7

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9 Video 1: 9

10 ISS Experiments 10

11 ISS Experiments Video 2 Jeff Williams 11

12 Electrostatic/Gecko Adhesives Plain wedges work well on smooth surfaces, but have difficulty developing adhesion on rough surfaces 12

13 Electrostatic/Gecko Adhesives Set of conductive electrodes Polarizes substrate to generate adhesive force Functions on wide range of materials and surfaces Polarization Relative Permittivity F = PE = εe 2 Electrostatic Force Electric Field Strength * Monkman, G.J. An analysis of astrictive prehension. International Journal of Robotics Research, Vol. 16 No 1. 13

14 Electrostatic/Gecko Adhesives Electrostatic-only adhesive on left, hybrid adhesive on right. 14

15 Experimental Results On smooth substrates, Flat adhesives > gecko-like adhesives Electroadhesion helps On rougher substrates, Gekco-like > flat Electroadhesion helps 15

16 Experimental Results Hybrid adhesives more evident on rough surfaces. Hybrid can be greater than the sum of its parts 16

17 Experimental Results Electrostatic element provides substantial benefit on all flexible substrates 17

18 Engineered Adhesives Prior synthetic adhesives use lithographic techniques, must be highly uniform, and have tight constraints on achievable geometries 18

19 Engineered Adhesives The gecko, on the other hand, has a highly nonuniform arrangement of adhesive features K. Autumn, et al., Phil. Trans. R. Soc. A,

20 Engineered Adhesives Sculpting process allows for wide range of shapes, and enables nonuniform distribution of adhesive features S.A. Suresh, et al., ASME JMR,

21 Engineered Adhesives Sculpting process allows for wide range of shapes, and enables nonuniform distribution of adhesive features S.A. Suresh, et al., ASME JMR,

22 Engineered Adhesives Highly anisotropic shear adhesive achieves 200:1 ratio of shear performance in preferred/antipreferred directions. 22

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