A Novel Three-loop Parallel Robot with Full Mobility: Kinematics, Singularity, Workspace and Dexterity Analysis Wei Li ∗ PhD candidate Department of Mechanical Engineering and Centre for Intelligent Machines McGill University Montreal, QC, H3A 0C3 Canada Email: livey@cim.mcgill.ca Jorge Angeles Professor, Fellow of ASME Department of Mechanical Engineering and Centre for Intelligent Machines McGill University Montreal, QC, H3A 0C3 Canada Email: angeles@cim.mcgill.ca ABSTRACT A novel parallel robot, dubbed the SDelta, is the subject of this paper. SDelta is a simpler alternative to both the well-known Stewart-Gough platform (SGP) and current three-limb, full-mobility parallel robots, as it contains fewer components and all its motors are located on the base. This reduces the inertial load on the system, making it a good candidate for high-speed operations. SDelta features a symmetric structure; its forward-displacement analysis leads to a system of three quadratic equations in three unknowns, which admits up to eight solutions, or half the number of those admitted by the SGP. The kinematic analysis, undertaken with a geometrical method based on screw theory, leads to two Jacobian matrices, whose singularity conditions are investigated. Instead of using the determinant of a 6 × 6 matrix, we derive one simple expression that characterizes the singularity condition. This approach is also applicable to a large number of parallel robots whose six actuation wrench axes intersect pairwise, such as the SGP and three-limb parallel robots whose limbs include, each, a passive spherical joint. The workspace is analyzed via a geometric method, while the dexterity analysis is conducted via discretization. Both show that the given robot has the potential to offer both large workspace and good dexterity with a proper choice of design variables. Keywords: three-limb parallel robots, hybrid robots, full mobility, cylindrical actuators, singularity, workspace, dexter- ity, parallel-kinematics machine (PKM) 1 Introduction A parallel robot, a.k.a. a parallel-kinematics machine (PKM), is defined as a multi-degree-of-freedom (multi-dof) artic- ulated mechanical system composed of one moving platform (MP) and one base platform (BP), connected by at least two serial limbs [1]. Compared with their serial counterparts, PKMs offer many attractive features, as per the pertinent litera- ture [1–3]. On the other hand, PKMs suffer of limited workspace, multiple singularities and coupled motion 1 , which makes their control especially challenging. These issues have motivated extensive research on PKMs. ∗ Corresponding author. 1 This means that pure rotation or pure translation cannot be produced by a subset of the actuators. JMR-16-1286, Li, 1