A Compliant Multi-module Robot for Climbing Big Step-like Obstacles

S. Avinash1    A. Srivastava1    A. Purohit1    S. V. Shah1    K. Madhava Krishna1   

1 IIIT Hyderabad, India   

A novel compliant robot is proposed for traversing on unstructured terrains. The robot has a set of modules where each module contains a trunk or link and an active wheel-pair, and it is connected to the adjacent module using a passive joint. This type of robots are inherently lightweight and provide high durability due to the absence of actuators at the link joints. However, they have limited climbing ability due to tendency of tipping over while climbing big obstacles. In order to overcome this disadvantage, the use of compliant joints is proposed in this work. Spring stiffness of each compliant joint is estimated by formulating an optimization problem using the static equilibrium equations of the robot. This is one of the key novelties of the proposed work. A design methodology is also proposed for developing an n-module compliant robot for climbing given height on a surface with prescribed coefficient of friction. The efficacy of the proposed formulation is illustrated for climbing big obstacles and traversing uneven terrains using simulation of 3- and 5-module robots. The robot is successfully able to climb maximum heights of 17 cm and 36 cm using 3 and 5 modules, respectively. Mechanical and electrical design of the robot is conceived, and a working prototype of the robot is developed. Simulation results are validated using the prototype.