Efficient, stable locomotion in legged robots
Abstract/Contents
- Abstract
- Legged animals have explored more of the Earth's surface than any human designed vehicle. The agility, adaptability, and efficiency found in nature continues to inspire robotics researchers to develop efficient leg designs robust, stable and adaptable control strategies that can rapid changes in the environment. Understanding the dynamics of ground collision and contact is critical to advancing the state of the art of legged robotics and allowing legged robotics to narrow the performance gap with legged animals. Unfortunately modeling the dynamics of collision requires attention not just to whole cycle measures like the coefficient of restitution but also to the transient measures of slip and initiation of chatter. This thesis contributes to the model-based design and control of legged robots by developing compliant contact models for systems where the deformation of the contact bodies is small and the contact forces can be considered to act through a single point. A novel visco-plastic contact model is developed to represent collision dynamics during legged locomotion. The relationship between the model's damping parameter and the coefficient of restitution is formulated using the energetic coefficient which permits energy consistent formulation for collisions that are non-collinear and include slip reversal. Given experimental data of the position and force of the foot, the model parameter estimation is performed with an offline genetic algorithm and an online unscented Kalman filter. The effectiveness of the methods are demonstrated on one-dimensional collisions of a single mass and a mass spring damper system. The methods presented allow for a physics-based study of the effect of leg and foot compliance on the energy efficiency of legged locomotion and of locomotion controllers. An actuated, non conservative, continuous contact SLIP model is developed for greater analysis of dynamics of running. Methodologies for finding passive (and active) gait controllers are of great interest to robotics but for non-conservative models, there are no passively stable fixed points around which to build such controllers. Minimal heuristic controllers are generated for bouncing gait generation which allow for stable hopping in the presence of actuator and ground contact energy losses. Together with the online inverse model parameter estimation, the approach advances robotics toward realizing adaptive optimal efficiency locomotion based on terrain measurements.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2012 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Jacobs, Daniel A |
|---|---|
| Associated with | Stanford University, Department of Mechanical Engineering |
| Primary advisor | Waldron, Kenneth J |
| Thesis advisor | Waldron, Kenneth J |
| Thesis advisor | Cutkosky, Mark R |
| Thesis advisor | Gerdes, J. Christian |
| Advisor | Cutkosky, Mark R |
| Advisor | Gerdes, J. Christian |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Daniel A. Jacobs. |
|---|---|
| Note | Submitted to the Department of Mechanical Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2012. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2012 by Daniel A Jacobs
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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