Simplified Modelling of Legs Dynamics on Quadruped Robots' Force Control Approach

摘要

In this work, a dynamical model simplification was implemented and analysed considering a small quadruped mobile robot, equipped with pantographic leg mechanisms. This specific leg design and characteristics were considered, as well the context of realistic possible physical realization (dimensions, masses, inertias) of a laboratory prototype. A simplification was proposed aiming the reduction of computational efforts for the evaluation of the matrices C(q,dq/dt) and G(q), corresponding respectively to the centrifugal and Coriolis forces, and to the gravitational dynamical contributions. The resulting advantages of the presented proposition were verified when comparing the numerical simulations of the leg mechanism motions taking the complete and simplified models. The obtained results of dynamical performance for both cases are very similar, i.e. the difference is around 1 degree on steady state, and a delay bellow 2 degrees on the transitory phase. On the other hand, the computation time reduction using the simplified model is quite expressive (around 9%). These two facts confirm the validity of using the proposed simplified model, it can be useful on experimental applications of locomotion control approaches based on the dynamical model of the walking robot. For instance, this time reduction can be advantageous for pre-computed torque and feedforward control approaches. Considering the critical requirements of the real-time control of a complex system as a legged mobile robot. The future works include the construction of the leg mechanism and robot prototypes, the application of the simplifications proposed here on this experimental legged robot, and the analysis of this system performance using diverse force control approaches.