Optimal control of a half-circular compliant legged monopod

Abstract

, 119 pages Legged robots have complex architecture because of their nonlinear dynamics and unpredictable ground contact characteristics. They can be also dynamically stable and exhibit dynamically dexterous behaviors like running, jumping, flipping which require complex plant models that may sometimes be difficult to build. In this thesis, we focused on half circular compliant legged monopod that can be considered as a reduced-order dynamical model for the hexapod robot, called RHex. The main objective of this thesis is the development of an algorithm based on optimal control theory that allows a half circular compliant legged monopod to run with a desired forward velocity or height starting from rest. The algorithm optimizes the foot attack angle and parameters of the PD controller while minimizing the error between desired and actual velocity. The effectiveness of the developed control strategy is verified by a variety of computer simulations. After obtaining a wide range of constant velocity running, we designed another energy-efficient controller which can effectively perform one of the dynamic behaviors, jumping motion. The jumping motion increases the maneuverability of the robot on the variety of rough terrain in a qualitatively satisfying manner. We analyze the performance of the our jumping control with a different jumping task, called triple jumping motivated by the exceptional performance of triple jumper athletes.

A Bio-Inspired Adjustable Posture Quadruped Robot with Laterally Undulating Spine for Terradynamically Challenging Environments

“…3) Legs: C-shaped legs have become a mainstay in RHex-type robots, showcasing exceptional performance on various terrains [35], [41]- [45]. The C-shaped legs provide a fair trade-off between the enhanced mobility of legged robots and the sturdy stability of wheels.…”

Students’ Perception of Different Learning Options and Use of Authentic Research Papers in a First Year Engineering Course

“…Three quite new and authentic research papers were presented at the first day of the semester as a kind of 'appetizer' regarding what kind of engineering problems makes use of the dynamics treated in the course. The first paper discusses the optimal control of a half-circular compliant legged monopod [35] and the second studies the effect of toe stiffness on ankle kinetics in a robotic prosthesis [36]. They were both chosen because of a clear IMRD-structure and because they aligned nicely with most of the students building a robot with a specified task in the semester project.…”