Using haptic feedback as an aid in the design of passive mechanisms

This paper presents a novel investigation of the effectiveness of haptic feedback for designing a class of interconnected multi-body systems such as passive mechanisms. The traditional application of haptic feedback in the design process has been in applications such as parts assembly or mold design. The design of the mechanism discussed in this paper is for applications where the user needs to manipulate the mechanism in order to interact with an environment. The objective of the design is to have the link ratios so that it can allow the user better movement control of the mechanism and thus give a better force amplification when there is a sudden change in the contact reaction force with the application environment. A haptic device is used as a design interface between the designer of such mechanisms and the virtual mechanism model. For this preliminary investigation, we used a four-bar mechanism. In our case study, we choose, as an example, to use the net distance travel of a tool when penetrating inside a model of a deformable surface as the design objective to minimize. The effects on the variation of this distance travelled can then be studied by adjusting some of the key design parameters used in the mechanism. To evaluate our proposed haptic-aided design environment, an informal preliminary user study was conducted, where each subject explored a sampled design space of the mechanism. The results of the user study suggest that the usage of a haptic device in the design of this class of mechanism can expedite the design process.