Parallel kinematic machines (PKMs) are commonly used for tasks that require high precision and stiffness. In this sense, the\nrigidity of the drive system of the robot, which is composed of actuators and transmissions, plays a fundamental role. In this\npaper, ball-screw drive actuators are considered and a 6-degree of freedom (DoF) parallel robot with prismatic actuated joints is\nused as application case. A mathematical model of the ball-screw drive is proposed considering the most influencing sources of\nnonlinearity: sliding-dependent flexibility, backlash, and friction.Using this model, the most critical poses of the robot with respect\nto the kinematic mapping of the error from the joint- to the task-space are systematically investigated to obtain the workspace\npositional and rotational resolution, apart from control issues. Finally, a nonlinear adaptive-robust control algorithm for trajectory\ntracking, based on the minimization of the tracking error, is described and simulated.
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