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This paper presents the design of a new user-cooperative rope robot. This robot serves as a large-scale haptic interface in a multi-modal Cave environment used for sport simulation. In contrast to current rope robots, the configuration of the presented robot is adaptable to different simulation tasks what makes the robot more versatile. However, this adaptability and the high dynamics in sports lead to challenging requirements and specific design criteria of the hardware components. We present the requirements on the single robot components as well as the design of the entire setup optimized in terms of user-cooperativity and versatility. The setup includes sensors to measure the relevant parameters for user-cooperative control, i.e. position with a high resolution and the rope forces. Furthermore, an algorithm is introduced, which calculates the distance between the single ropes and the user in order to avoid collisions between the ropes and the user. Single points on the user's body are, therefore, tracked with a motion tracking system; the user's single body parts are then represented by geometrical objects whose distances to the ropes are calculated. The algorithm is programmed in such way that the collision detection runs in real-time. Both, the hardware and the algorithm, were evaluated experimentally in two applications, a rowing simulator and a tennis application. The hardware concept combined with the distance calculation allows the use of new kinematic concepts and expands the spectrum of realizable movement tasks that can be implemented into the Cave environment.

Efficient rowing requires both physical and technical abilities of the human. Teaching and learning of the technical abilities is thereby mainly restricted to on-water training. The aim of this project was to develop a rowing simulator. This simulator should serve as a high-level indoor training tool that can be used by rowing novices and professionals. The users should perceive acoustic, visual, and haptic cues about their current performance and their environment in real time.The newly-developed rowing simulator consists of a rowing boat hull equipped with multiple position sensors attached to the oar and seat. The boat hull was mounted on a podium placed inside a Cave setup. The Cave comprises projection screens, a loudspeaker system, and actuated winches for visual, acoustic, and haptic feedback, respectively. A mathematical real-time rowing model was developed, which computes the boat velocity and the oar force as a function of the movement of the oar and the user. All relevant boat, oar, and user parameters can be arbitrarily set, thus allowing the simulation of different boat types.The rowing model was validated by comparing results of the simulation with data from on-water measurements. Both the boat velocity and the oar force predicted by the model correlated highly with the experimentally-obtained data. Furthermore, the rowing simulator was successfully tested with professional rowers who rated the level of realism and the applicability of the simulator for indoor training as high. Based on the feedback of the rowers, various hardware and software extensions are planned for the simulator, including an increase of the number of actuated degrees of freedom of the boat and the oar, in order to improve the haptic feedback. r

The objective of this study was to quantify the reduction of friction forces by obstetric gels aimed to facilitate human childbirth. Lubricants, two obstetric gels with different viscosities and distilled water, were applied to a porcine model under mechanical conditions comparable to human childbirth. In tests with higher movement speeds of the skin relative to the birth canal, both obstetric gels significantly reduced dynamic friction forces by 30-40% in comparison to distilled water. At the lowest movement speed, only the more viscous gel reduced dynamic friction force significantly. In tests modifying the dwell time before a movement was initiated, static friction forces of trials with highly viscous gel were generally lower than those with distilled water. The performed biomechanical tests support the recommendation of using obstetric gels during human childbirth. Using the presented test apparatus may reduce the amount of clinical testing required to optimize gel formulation.

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