Energy-efficient inverse dynamic model of a Hexapod robot

A hexapod robotic system is a complex multi-body system that exhibits complex motion characteristics due to the effect of forces and torques (both internal and external). In the present study, inverse dynamics model using Newton-Euler approach was developed for the hexapod robotic system. It is assumed that the prescribed motion of the model is fully known and consistent with the kinematic constraints of the realistic model. The kinematic motion parameters (displacement, velocity and accelerations) obtained from the inverse kinematic analysis of the robotic system with specified path and gait planning for straight forward motion in varying terrain are substituted in the inverse dynamic model which is a set of algebraic equations. The equations are solved for to determine the joint torques and resulting reaction forces for the foot in contact with the ground that are responsible to generate the prescribed motion trajectories. The solution is not unique due to the redundant set of forces/ moments and/or constraints used. Therefore, the solution of the problem has been obtained by minimizing the total instantaneous power consumption of the system, considered as the objective function with respect to linear equality and inequality constraints. The simulated results of foot-ground contact and variation of instantaneous power consumption for the dynamical system are discussed thereafter.