Prof. Sam K Zachariah


Autonomous Control for Bipedal Locomotion 

Prof. Sam K Zachariah
Adjunct Professor,
Indian Institute of Space Science and Technology,

Keynote Talk Abstract:

The talk presents the details on the development of a novel autonomous control framework, called Hybrid-state Driven Autonomous Control (HyDAC) for bipedal locomotion, with special emphesis on the control aspects in sagittal plane. Autonomous control of bipedal locomotion is identified as a challenging problem by the control community due to its multiphase hybrid nature and the unilateral characteristics of ground contact forces. The underactuation during heel and toe centred rolling motions and the intermittent ground impacts introduce additional complexity. In HyDAC, the control synthesis is formulated as a two-level hierarchical control with a hybrid-state based supervisory control in outer level and a coordinated set of constrained motion control primitives, called task level control, in inner level. The supervisory level is designed based on a human inspired heuristic approach whereas the task level control is formulated as a quadratic optimization problem with linear constraints. The explicit analytic solution obtained for joint acceleration and ground contact force is used in turn to generate the joint torque command based on inverse dynamics model of the biped. Unlike many other bipedal control schemes, HyDAC does not require any preplanned trajectory or orbit in terms of joint variables for locomotion control. Moreover, it is built upon a set of basic motion control primitives similar to those in human walk which provides a transparent and easily adaptable structure for the controller. The talk provides illustration of HyDAC to planar bipedal walking over nonuniform stair case having arbitrary parameter distribution, justifying it as a potential solution for oudoor walking control.

Autonomous walking control, Motion Control Promitives, Supervisory Level Control, Task level control

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