Type Synthesis of a Family of 4-, 5- and 6-DOF Sea Lion Ball Mechanisms With Three Limbs

In this paper, a family of novel mechanisms with three limbs is proposed. The novel family of mechanisms looks like a sea lion playing a ball therefore we called it the sea lion ball mechanism (SLBM). Its characteristics are described in detail below. The SLBM is composed of an upper part and a lower part connected together by three limbs in series. One of the most important advantages of SLBMs is that the translational and rotational motions are partially decoupled: the end-effector position is only determined by the inputs of the lower part, while the rotational angles are mainly determined by the inputs of the upper part. Then, the procedures for the type synthesis of SLBMs with three limbs are proposed based on the G_F sets theory and the concept of virtual chain. Furthermore, according to the proposed procedure, 4-, 5- and 6-DOF SLBMs are investigated in terms of type synthesis based on a concept of upper-lower combination. The synthesis method of the upper limbs and lower limbs are presented. The P_R and Pa joints are introduced to realize the functions of R and P joints to achieve more mechanisms. The six types kinematic limbs with 3T3R, 3T2R, 2T3R, 3T1R, 2T2R and 1T3R motion patterns of SLBMs are designed. Lastly, several novel 4-, 5- and 6-DOF SLBMs are proposed and sketched. The concept of the upper-lower combination may provide a new idea for type synthesis of decoupled parallel mechanism.