Tendon-based parallel manipulators with n d.o.f. use at least m = n + 1 tendons to guide the endeffector along a given trajectory. Since tendons can only transmit limited and tractive forces, it is essential to apply a valid tendon force distribution. Due to safety and precision requirements, a combined position and force control is needed where the force calculation delivers the desired tendon force distributions. The high dynamic potential of the robot demands for realtime capable algorithms. To avoid steps in the motor torques the calculated tension force distributions also have to be continuous along the trajectory. In this paper, a new algorithm for tendon force distribution calculations capable for usage on a realtime system is proposed and its continuity is proven.

This paper presents an algorithm to determine feasible force distributions for parallel wire robots in closed-form. The force distributions are continuous along trajectories and differentiable at most of the points. The computational efforts are strictly bounded and small even for large numbers of wires. The algorithm is compared to other approaches for calculation of force distribution in terms of the numerical effort and their applicability for control purposes.

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Intralogistics systems are a rapidly growing market. Today, high racks and automated storage retrieval machines are widely used to store and handle industrial goods. Conventional storage retrieval machines show a major drawback: While the containers or goods to be moved are often very lightweight, the storage retrieval machine itself may weight up to two tons which limits the energy efficiency and the motion capabilities. This limitation is a problem since the reduction of cycle times is crucial in logistics applications. Therefore, faster motions are desired. At the same time, a main focus in intralogistics development is on energy-saving solutions as part of the ongoing climate change debate. Together with the rising energy costs, this paves the way for radical new concepts which go beyond the lightweight construction of conventional storage retrieval machines. Recently, a huge research project started to realize an alternative approach for a storage retrieval machine system. This approach uses a parallel wire robot system to move the goods to be stored to the desired position. The system is extremely lightweight and therefore, fast motions are possible while the required energy is comparably low. Therefore, cycle times for the transport of the goods can be drastically reduced which is crucial in this application. The paper presented here describes both design concepts which were already presented, as well as optimized geometries which are superior in terms of workspace coverage and stiffness. First simulation results are shown and discussed with a focus on the potential of the system for precise loading and unloading of containers. Besides that, the overall mechatronic system design is introduced.

Redundancy resolution of redundantly actuated cable-driven parallel robots (CDPRs) requires the computation of feasible and continuous cable tension distributions along a trajectory. This paper focuses on n-DOF CDPRs driven by n+2 cables since, for n = 6, these redundantly actuated CDPRs are relevant in many applications. The set of feasible cable tensions of n-DOF n+2-cable CDPRs is a two-dimensional convex polygon. An algorithm that determines the vertices of this polygon in a clockwise or counterclockwise order is first introduced. This algorithm is efficient and can deal with infeasibility. It is then pointed out that straightforward modifications of this algorithm allow the determination of various (optimal) cable tension distributions. A self-contained and versatile tension distribution algorithm is thereby obtained. Moreover, the worst-case maximum number of iterations of this algorithm is established. Based on this result, its computational cost is analyzed in detail, showing that the algorithm is efficient and real-time compatible even in the worst case. Finally, experiments on two 6-DOF 8-cable CDPR prototypes are reported.