Several test rigs have been set up at the ISW for the experimental investigation of rope robots. The basic components of one of the rope robots available at the institute consist of ropes as force-transmitting elements, winches for winding and unwinding the ropes, the frame for attaching the winches, an industrial controller for real-time control of the rope winches and the movable platform as an assembly device for an end effector. The redundant tensioning of the platform with the cables results in the following advantages for cable robots: High rigidity comparable to industrial robots, large and flexible workspaces and high achievable speeds and accelerations.

With conventional cable robots, the platform's ability to rotate is limited to a maximum of plus/minus 45 degrees around the respective spatial axes and also depends on the position approached in the workspace. These characteristics limit the areas of application for conventional cable robots. In order to increase the rotational capability, cable robots can be supplemented with additional actuators, but the extended rotational capability must be purchased at the cost of additional weight and a media feed at the expense of the workspace. This also reduces the payload and the maximum achievable dynamics of the cable robot.

To avoid these disadvantages, the "Endless Z" research project is investigating a new concept that avoids additional actuators by using additional cables. One possible design is to replace the robot platform with a crankshaft geometry. Here, the additional degrees of freedom due to the added rotational joints must be taken into account in the kinematic description. In addition to the crankshaft geometry, other concepts are also the subject of research. For the investigations, existing algorithms for calculating workspaces as well as rope-rope and rope-platform collisions are being further developed for these special cases in the field of rope robotics. This is intended to open up further areas of application for cable robots where high rotational capability is required.

T. Reichenbach, A. Verl/as