The kinematic effects of simplifications in the analysis of linear translational parallel robots

Universal joints are required to achieve linear motion in the design of linear-translational-parallel-robots (LTPR). A usual practice among researchers is to assume that the angular velocity of a link attached to a universal joint is perpendicular to it. Although this assumption is intuitive, this research proves analytically and experimentally the existence of a component of the angular velocity in the direction of the link. Thus, proving that the angular velocity of a link attached to a U-joint is not perpendicular to it. Then, a new methodology is proposed to compute the exact value of the angular velocity and acceleration of links attached to universal joints, obtaining a reliable tool to analyze LTPR or robots with universal joints.