Kinematic analysis and optimal design of a novel 3-PRR spherical parallel manipulator

Abstract

<jats:p> This paper introduces a novel three degree-of-freedom spherical parallel manipulator with 3-PRR topology, where P and R denote a curved prismatic joint and a revolute joint, respectively. The first revolute joint of each PRR leg is actuated via a double Rzeppa-type driveshaft, and hence underlined. The manipulator has at most eight working modes and eight assembly modes. However, only one working mode and one assembly mode of the manipulator are acceptable during its motion which can be easily identified. Singularity and kinematic dexterity analyses reveal that the proposed 3-PRR spherical parallel manipulator has no forward kinematic singularity for a wide range of rotation of the moving platform around its central axis. An optimal design of the manipulator is also presented having a workspace with good kinematic dexterity. </jats:p>

Task-based torque minimization of a 3-PṞR spherical parallel manipulator

“…Several three-degree-of-freedom (3-DOF) spherical parallel manipulators (SPMs) have been proposed and their mechanical properties have been studied before; see for instance [1,8,9,10,11,12,13,14,15,16,17,18,19,20]. But, in the case of torque minimization of 3-DOF SPMs, the literature is so limited.…”

“…A novel 3-PRR SPM was recently introduced by the author [1], and its kinematics and workspace were analyzed in detail. A 3D CAD model of the 3-PRR SPM is shown in Fig.…”

“…Distal links of the PRR legs are connected to the proximal links via revolute joints. Each of these revolute joints is actuated by an actuating system having an electromotor fixed to the base, a gearbox and a double Rzeppa-type driveshaft [1]. The driveshaft is composed of an input shaft, an output shaft and two intermediate shafts (a cylinder and a piston) connected to each other through two Rzeppa joints and a prismatic joint.…”

Self-excited vibration of a 3-PRR planar parallel robot

“…8 classified the singularity of a reconfigurable eight-bar parallel mechanism into three types, including constraint singularity, redundant singularity and constraint-redundant singularity. Many other algebraic 9 and geometric 10 methods are also utilized for singularity analysis. In the practical application, it is also needed to detect how far the end-effector stays away from the singular configurations.…”

“…As mentioned above, the research on singularity mainly focuses on theoretical analysis, such as singularity classification 6–10 and singularity avoidance. 13–20 However, few studies have investigated the dynamic characteristics of parallel robots at singularities.…”