In general, concurrent augmented feedback has been shown to effectively enhance learning in complex motor tasks. However, to optimize technical systems that are intended to reinforce motor learning, a systematic evaluation of different augmented feedback designs is required. Until now, mainly visual augmented feedback has been applied to enhance learning of complex motor tasks. Since most complex motor tasks are mastered in response to information visually perceived, providing augmented concurrent feedback in a visual manner may overload the capacities of visual perception and cognitive processing. Thus, the aim of this work was to evaluate the practicability of auditory feedback designs supporting a three-dimensional rowing-type movement in comparison with visual feedback designs. We term a feedback design practical if the provided information can easily be perceived and interpreted, and immediately be used to support the movement. In a first experiment, it became evident that participants could interpret three-dimensional auditory feedback designs based on stereo balance, pitch, timbre, and/or volume. Eleven of 12 participants were able to follow the different target movements using auditory feedback designs as accurately as with a very abstract visual feedback design. Visual designs based on superposition of actual and target oar orientation led to the most accurate performance. Considering the first experimental results, the feedback designs were further developed and again evaluated. It became evident that a permanent visual display of the target trajectories could further enhance movement accuracy. Moreover, results indicated that the practicability of the auditory designs depends on the polarity of the mapping functions. In general, both visual and auditory concurrent feedback designs were practical to immediately support multidimensional movement. In a next step, the effectiveness to enhance motor learning will be systematically evaluated.

Highly immersive environments for sports simulation can help elucidate if and how athletes perform under high pressure situations. We used a rowing simulator with a CAVE setup to test the influence of virtual competitors on 10 experienced rowers. All participants were using the simulator for the first time. The objective was to assess the degree of presence by quantifying how the actions of the virtual competitors triggered behavioral changes in the experienced rowers. The participants completed a virtual 2000 m race with two competing boats, one being behind and one ahead of the participant. For two trials, each boat would come closer to the participant without overtaking, resulting in four experimental conditions. The behavior of the participants was assessed with biomechanical variables, questionnaires, and an interview after the race. Behavioral changes were detected with statistically significant differences in the extracted variables of oar angles, timing variables, velocities, and work. The results for biomechanical variables indicate individual response patterns depending on perception of competitors and self-confidence. Self-reporting indicated a high degree of presence for most participants. Overall, the experimental paradigm worked but was compromised by perceptive and subjective factors. In future, the setup will be used to investigate rowing performance further with a focus on motor learning and training of pressure situations.

This paper describes evaluation experiments for visual and auditory feedback in a virtual obstacle walking scenario. Two studies with healthy subjects were carried out using the actuated gait orthosis L okomat . Controlled factors for the visual feedback experiment were three different perspectives and 2D/3D vision. In the auditory feedback experiment, controlled factors were rhythmic distance feedback and gradual foot clearance feedback. For the visual and auditory feedback experiments, outcome was assessed with task-specific performance parameters and questionnaires. Results for visual feedback indicate that the chosen side perspective is superior to behind and ego perspectives. It is also shown that 3D vision does not reduce the number of obstacle hits compared to 2D vision. Furthermore, it is demonstrated that adding continuous auditory feedback made subjects walk faster compared to the exclusive use of visual feedback. Subjects rated auditory distance feedback as more helpful than auditory foot clearance feedback. Therefore, we suggest using side perspective and auditory feedback on obstacle distance.

In specific fields, medical education at many universities is rather theoretical and the amount of practical training is limited. A significant improvement can be achieved using virtual reality training stations with lifelike visual, acoustic, tactile, and kinesthetic feedback. Particularly, when simulating procedures that require direct contact with the patient body, a realistic haptic simulation addressing tactile and kinesthetic senses can be essential for the acceptance of virtual simulation stations. A purely passive phantom may provide realistic haptic feedback, but its properties cannot be changed over time. This paper presents the haptic display of the Munich Knee Joint Simulator, which was developed to improve training and education of physical knee joint examinations. The haptic interface comprises a combination of passive phantom segments providing realistic tactile sensations, and strong actuators generating highly dynamic kinesthetic force feedback. A 3 degree of freedom (DOF) manipulator was developed in this study to drive the thigh prosthesis and one 6 DOF industrial robot was used to actuate the shank prosthesis. Both manipulators are driven by hybrid admittance-impedance controllers capable of simulating the complex dynamics of the thigh and the shank. Both actuators are equipped with a 6 DOF force torque sensor and they are virtually coupled by an analytical knee joint model. The proposed setup is capable of simulating a mechanical stiffness as high as 80 kN/m in the translatory DOF and simultaneously allows free motion in the rotatory DOF. Experimental tests of the simulator with orthopedic physicians proved the usability of the proposed concept.