EVOLVING PHYSICAL PARAMETERS FOR A PASSIVE DYNAMIC WALKER .

1. EVOLVING PHYSICAL PARAMETERS FOR A PASSIVE DYNAMIC WALKER. Artificial Life Coursework Project MSc Evolutionary And Adaptive Systems Juan Pablo Calderon

2. PASSIVE DYNAMIC WALKING • Passive means no control nor actuator unit. The only source of energy is that of gravity (or internal springs). • Tad McGeer (1990) developed some models of passive dynamic walkers. • He also developed a methodology to obtain the correct physical parameters so as to observe stable periodic gait cycles in passive dynamic walkers.

3. Some of Tad McGeer Models Figures taken from Cornell’s Human Power, Biomechanics, and Robotics Laboratory.

4. Other People’s Work • Correct Physical parameters for stable PDW have been found using nonlinear dynamics theory, physical simulation and some analytical methods. • Physical models of PDW with knees have even been constructed. • A mass distribution criteria for efficient stable periodic gait has been formulated by the research team at Cornell.

5. My Work • I evolved the physical parameters of a 2D passive dynamic walker with knees. • Found parameters for (what seems) a stable periodic gait.

6. Genetic Algorithm • Simulation was done with ODE (Open Dynamic Engine) provided by Russell Smith. ( www.q12.org/ode ) • GA for 200 individuals with tournament selection, 30 % chance of multiple crossover, and 10 % mutation rate on every gene. • Fitness was rated on distance travelled and the hip having a constant average height.

7. One Step

8. Applications of PDW • Robotics • Prosthetic Medicine • Biology. (understanding biped walking.) • Understanding the roles of muscles and nerves.

9. What comes next? • A more realistic 3D simulation. • Check if the parameters obtained satisfy the mass distribution criteria formulated by Cornell. • Construct a Physical Model. • And much more…

10. Some Animations

11. More Animations