Virtual Reality (VR) is gaining more importance in our society. For many years, VR has been limited to the entertainment applications. Today, practical applications such as training and prototyping find a promising future in VR. Therefore there is an increasing demand for low-cost, lightweight haptic devices in virtual reality (VR) environment. Electroactive polymers seem to be a potential actuation technology that could satisfy these requirements. Dielectric polymers developed the past few years have shown large displacements (more than 300%). This feature makes them quite interesting for integration in haptic devices due to their muscle-like behaviour. Polymer actuators are flexible and lightweight as compared to traditional actuators. Using stacks with several layers of elatomeric film increase the force without limiting the output displacement. The paper discusses some design methods for a linear dielectric polymer actuator for VR devices. Experimental results of the actuator performance is presented.
In this paper precise specifications are given for a microgripper based on a polyarticulated micromechanism. This polysilicon gripper actuated by Scratch Drive Actuators (SDA) has dimensions of 1.2mm.x 1.6mm and a thickness of 0.0045mm. The stroke of its jaws is about 0.275mm each, with a stroke ratio of 5. These specifications can be useful to compare such compliant micromechanisms. In particular, we propose an alternative to the polyarticulated mechanism based on a compliant structure. A new conceptual design method, based on compliant building blocks, is introduced. The proposed method, using a genetic algorithm, quickly leads to several compliant solutions. A compromise between these solutions has performances close to the polyarticulated microgripper (about 20% less).
The paper introduces a new design method for the synthesis of compliant mechanisms. This method is based on the optimization of the distribution of compliant building blocks within a given design domain. Building blocks are modeled by elementary frame ground structures. The topology, dimensions, material, contacts, fixed frame and actuators of the optimal compliant mechanism are generated automatically using a multi objective genetic algorithm such that the force/motion ratio is maximized. The set of optimal solutions is explored by using the notion of Pareto optimality. An application of this design method is tested on an actuated compliant mechanism with two output degrees of freedom.