Toward Autonomous Free-Climbing Robots Tim Bretl Jean-Claude Latombe Stephen Rock Special thanks to Eric Baumgartner, Brett Kennedy, and Hrand Aghazarian at the Planetary Robotics Lab, NASA-JPL

Goal Develop integrated control, planning, and sensing capabilities to enable a wide class of multi-limbed robots to climb steep natural terrain. Free-climbing vs. aid-climbing Talk about applications

Generic vs. Specific Robot Free-climbing vs. aid-climbing Talk about applications LEMUR IIb, Planetary Robotics Lab, NASA-JPL Sitti and Fearing, UC Berkeley

Previous Multi-Limbed Climbing Robots Each exploits a specific surface property Free-climbing vs. aid-climbing Talk about applications Neubauer, 1994 NINJA II Hirose et al, 1991 Yim, PARC, 2002

Free Rock Climbing is about Natural Friction …

… and Non-Gaited Motion Spend some time here explaining your problem in a bit more technical detail. (Basically, take this from Section 3.1 of your ISRR paper, leading up to the description of the One-Step Climbing Problem, which you can state with the next slide.) Also, here is where you can mention the similarities to re-grasping in a multi-finger hand, and to motion-planning methods for track and legged robots.

it is a problem-solving activity Overall, rock climbing is about how to apply strength, not about strength itself it is a problem-solving activity

Example System Spend some time here explaining your problem in a bit more technical detail. (Basically, take this from Section 3.1 of your ISRR paper, leading up to the description of the One-Step Climbing Problem, which you can state with the next slide.) Also, here is where you can mention the similarities to re-grasping in a multi-finger hand, and to motion-planning methods for track and legged robots.

Equilibrium Constraint Free-climbing vs. aid-climbing Talk about applications Feasible positions of robot’s center of mass

Configuration Space For each combination of knee bends: Position (xP,yP) of pelvis Joint angles (q1,q2) of free limb

Feasible Space q2 q1 -p p Free-climbing vs. aid-climbing Talk about applications

Feasible Space Simple test for the feasibility of (xp,yp) where… Free-climbing vs. aid-climbing Talk about applications

Feasible Space Qf Simple test for the feasibility of (xp,yp) Feasible (1,2) varying with (xp,yp), in one half of f Qf Free-climbing vs. aid-climbing Talk about applications where…

Feasible Space Simple test for the feasibility of (xp,yp) Feasible (1,2), varying with (xp,yp), in one half of f Switching between halves of f Free-climbing vs. aid-climbing Talk about applications

Motion Planning Basic Approach (Probabilistic Roadmap) Sample 4D configuration space Check equilibrium condition Check (self-)collision Check torque limit Refined approach Sample 2D pelvis space, lift to full 4D paths Narrow passages are found in the 4D space Free-climbing vs. aid-climbing Talk about applications

Achieve q2=0 Move with q2=0 Switch between halves of Qf Move to goal

backstep highstep lieback

JPL’s LEMUR robot

Current Work Terrain sensing and hold detection Force control and slippage sensing Uncertainty (hold location, limb positioning) Motion optimization Extension of feasible space analysis

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