Quasi-linearization Approach for the Under-actuated Robots

A novel technique to reduce energy consumption for industrial robots by using redundancy and under-actuated configurations is introduced in this paper. The study concentrates on kinematics including a passive axis which causes a highly nonlinear coupling of the Coriolis and centrifugal forces and high inertia coupling. The challenge of meeting the requirements of position accuracy, precision, and repeatability combined with the requirements for the speed, acceleration, and torque is coped with by solving a sequence of linear two point boundary value problems for controlling the movement of the end effector between two points. The advantages of this method are the ability of reducing the computation time dramatically, computer storage, and linearizing the nonlinear model. Furthermore the optimal trajectories are identified with minimizing energy consumption and enabling high speed capability. Numerical simulations are conducted to validate the theoretical analysis.