Co-presentation of force cues for skill transfer via shared-control systems

During training and rehabilitation with haptic devices, it is often necessary to simultaneously present force cues arising from different haptic models (such as guidance cues and environmental forces). Multiple force cues are typically summed to produce a single output force, which conveys only relative information about the original force cues and may not be useful to trainees. Two force co-presentation paradigms are proposed as potential solutions to this problem: temporal separation of force cues, where one type of force is overlaid with the other in staggered pulses, and spatial separation, where the forces are presented via multiple haptic devices. A generalized model for separating task and guidance forces in a virtual environment is also proposed. In a pilot study where sixteen participants were trained in a dynamic target-hitting task using these co-presentation paradigms, simple summation was in fact most effective at eliciting skill transfer in most respects. Spatial separation imposed the lowest overall workload on participants, however, and might thus be more appropriate than summation in tasks with other significant physical or mental demands. Temporal separation was relatively inferior at eliciting skill transfer, but it is hypothesized that this paradigm would have performed considerably better in a non-rhythmic task, and the need for further research is indicated.