Dynamics Modeling and Simulation of a Hexapod Robot with a Focus on Trajectory Prediction

Dynamics simulation is an important technique for hexapod robots. However, the realistic locomotion of a robot is comprehensive due to kinematics error, mechanism deformation, sinkage, slippage, and dragging of the feet on the ground. To investigate this phenomenon, this paper presents a kinematics and dynamics model of a hexapod robot to include this effect in dynamics simulation. The compliance of both the robot and terrain are taken into consideration. The total compliance matrix and compatibility equation are established with the consideration of the compliance of the legs, body, and terrain. The body of the robot is modeled to have a coupled compliance to consider the effect of all six legs. The theory of terramechanics is introduced to describe the constraint between the feet of the robot and terrain. The complete dynamics model of hexapodal walking is built on the foundation of the compliant kinematics model and foot-terrain interaction mechanics model. Numerical simulation and experiments are performed based on a bio-inspired hexapod robot. The simulation and experimental results indicate that the model can provide a reliable accuracy with only analytical and a priori data as inputs.