Modeling and motion control of the 6-3-PUS-Type Hexapod parallel mechanism

Abstract

This chapter reports the kinematics and dynamics models of the parallel mechanism known as Hexapod, which has a structure of the type known as 6-3- PUS. For computing the dynamics model, we start considering a non-minimal set of generalized coordinates and employ the Euler-Lagrange formulation; after that, we apply the so-called projection method to get a minimal model. It is worth noticing that the modeling approach presented here can be used for similar robotic structures, and the resulting models are suitable for automatic control applications. The computed analytical kinematics and dynamics models are validated by comparing their results with numerical simulations carried out using the SolidWorks Motion platform. In addition, this chapter describes the implementation of two motion tracking controllers in a real Hexapod robot. The tested controllers are one with a two-loop structure (a kinematic controller in the outer loop and a PI velocity controller in the inner loop) and other with an inverse dynamics structure. The experimental results of both controllers show a good performance.