Limiting trial and error: introducing a systematic approach to designing clutching

When designing new interfaces we are likely to be confronted with the problem of clutching---creating a way to switch between engaged and disengaged input modes. Using constraint analysis we propose a systematic approach for designing clutching. Based upon Buxton's three-state model, we introduce a design procedure for determining optimal clutching mechanisms. Using this procedure, designers of future interfaces can benefit from reduced time for trial-and-error in clutching design, since key candidates for clutching mechanisms can now be quickly identified. Through a case study of clutching for pen tilt input, we show how our method can be applied to a concrete design task.