Ph.D Thesis

Ph.D StudentShapiro Amir
SubjectDesign and Control of an Autonomous Spider-Like Robot for
Motion in 2D Tunnels Environments
DepartmentDepartment of Mechanical Engineering
Supervisor PROF. Elon Rimon


In conventional motion planning a wheeled mobile robot navigates toward a goal configuration while avoiding collision with obstacles. However, many motion-planning problems are more suited for legged robots that interact with the environment in order to achieve stable locomotion. For example, surveillance of collapsed structures for survivors, inspection and testing of complex pipe systems, and maintenance of hazardous structures such as nuclear reactors, all require motion in congested, unstructured, and complex environments.

In this work, second generation of a 3-limbed planar spider-like robot for motion in tunnel environments has been developed. The spider-robot moves quasi-statically by bracing with two limbs against the frictional tunnel environment while moving it's free limb to a new foothold position.  A decentralized control method for the spider-robot is introduced. The control method is based on new and original results in the fields of grasp theory and control of asymmetric second-order linear systems. The control method ensures that when a spider-like mechanism bracing against the environment at equilibrium posture the naturally occurring compliance at the contacts stabilizes the mechanism as a single rigid body.  

An algorithm, named PCG, for selecting sequence of foothold positions along the tunnel has been developed.  The PCG algorithm generates a 3-2-3 gait sequence that moves the robot from start to target using minimum number of foothold exchanges.

Finally, experimental results demonstrating motion of the spider-robot along the tunnel environment are presented. The experiments verify the theoretical results of this work and show their applicability.