УДК 621.01 © J. Kotlarski, B. Heimann, T. Ortmaier INFLUENCE OF KINEMATIC REDUNDANCY ON TYPE-II SINGULARITY LOCI OF PARALLEL KINEMATIC MACHINES In this paper the effect of kinematic redundancy in order to reduce the type-II singularity loci and to increase the operational, i.e. singularity-free, workspace is demonstrated. <...> The proposed approach consists of one additional prismatic actuator allowing one base joint to move linearly. <...> Exemplarily, kinematically redundant schemes for the planar 3RRR and the spherical 6UPS are considered. <...> The relationship between the redundancy and the operational workspace is studied and several analysis examples demonstrate the effectiveness of the proposed concept. <...> Keywords: parallel robots, kinematic redundancy, singularity avoidance, operational workspace I. INTRODUCTION A parallel mechanism is a complex mechatronic system consisting of a closed-loop kinematic structure. <...> It is shown that the singularities of the direct kinematics (type-II singularities) are most relevant since they occur right within the workspace. <...> Due to these singularity loci, the workspace is divided in different regions [2]. <...> To cope with the mentioned drawbacks, redundancy can be applied, such that the number of actuated joints exceeds the number of degrees of freedom (DOF) of the moving platform [3]. <...> Two redundancy approaches are established for parallel mechanisms, actuation redundancy and kinematic redundancy [4, 5]. <...> Actuation redundancy can be realized whether by adding a kinematic chain to the mechanism or by actuating a passive joint. <...> Furthermore, an additional kinematic chain mostly reduces the overall workspace. <...> Therefore, in this paper the authors focus exclusively on kinematic redundancy, realized by adding at least one actuated joint to one kinematic chain [5, 7, 8]. <...> The paper presents a study on the efficiency of kinematic redundancy to increase the operational, i.e. the singularity-free, workspace of parallel mechanisms. <...> As examples, intuitive redundant schemes for the classical planar 3RRR and the spherical 6UPS mechanisms are proposed. <...> In each case, an additional prismatic actuator is added to an arbitrary base joint. <...> The introduced mechanisms are denoted as 3(P)RRR and 6(P)UPS. <...> After a general introduction to singularity analysis and to the idea of redundancy (section II) the exemplarily considered redundant parallel robots as well as fundamental definitions related to their Jacobian analysis are presented (section III, IV <...>