Object-oriented Dynamics Modeling for Legged Robot Trajectory Optimization and Control

This paper discusses the development and application of object-oriented modeling and implementation techniques to achieve a representation of the mechanical model amenable to the various requirements by legged robot applications. This leads to a uniform, modular, and flexible code generation while reaping the performance of efficient domain-specific articulated body algorithms. Trajectory optimization problems of bipedal and quadrupedal robots are investigated as applications. It is shown how a high-level specification of multibody dynamics models using component libraries serves as a basis for generation of a number of modules forming an “overall” computational dynamics model. The selected examples illustrate how one copes with the emerging complexity by integrating various modules for, i. e., equations of motion, non-linear boundary conditions, symmetry and transition conditions, for multiple phases during motion. Variations of the mechanical structure, e. g., contact conditions can be treated either by multiple models or by reconfiguration of one model. Numerical results are presented for timeand energy-optimal trajectories of full three-dimensional models of a humanoid robot and a Sony four-legged robot.