Parallel manipulators are often used in haptic applications since they usually offer higher stiffness and lower inertia than their serial counterparts. However, classical parallel haptic devices generally do not provide grasping capabilities since all their motors are located at the base. This article presents a new 7-DOF robotic architecture, which has the particularity of providing 1-DOF grasping in addition to 6-DOF manipulation while all actuators are located at the base. This is possible thanks to the use of a novel configurable platform that replaces the single rigid body normally used as end-effector in conventional parallel manipulators. The grasping capability of this haptic device is part of the mechanical architecture itself and can be fully controlled from base-located motors. In this article, the architecture, kinematic analysis, kinematic performance, design, and implementation of the novel 7-DOF parallel haptic device are described.

Parallel manipulators with two end-effectors (PM2Es) enable the design of gripping robots with high dynamic performance. The gripping action is enabled by internal, relative degrees of freedom (DoFs) between the two end-effectors. Many standard methods for the analysis and control of parallel manipulators rely on a Jacobian, where a complete Jacobian analysis includes constraint relations. These constraint relations have not been consistently included in previous analyses of PM2Es, while they are specifically relevant for PM2Es because constraints play an important role in the static force analysis of a PM2E. This is because wrenches applied by the actuators can be transferred to the end-effectors through internal constraints, an effect which is not captured by kinematic relations alone. This paper presents a systematic approach to perform the Jacobian analysis of PM2Es, which is based on screw theory, and that takes all constraint relations into account. The approach is applied to a PM2E with three legs and one internal closed-loop chain. An example mechanism was built to experimentally validate the resulting Jacobian analysis using a static force analysis.

This paper presents a novel constant force mechanism based on a 11- revolute joints spatial linkage using simple pin joints and two regular springs. Passive linear sliders with ball bearings are not suitable for certain applications such as in medical environment or for miniaturization. Using only revolute joints in the mechanism allows for replacing all ball bearings with PTFE pin joints, which can be made smaller than ball bearings and are bio-compatible. Pin joints however have the disadvantage of generating friction, which can affect the quality of the constant force at the output link. This paper introduces the new pin joints constant force mechanism and presents an analysis of the effect of the friction generated by the joints on the output force.