Study On The Motion And Force Cuing Subsystems For The Interactive Bicycle Simulator

The interactive bicycle simulator integrates motion generating subsystem, force cuing subsystem, visual and acoustic subsystems. These subsystems respond to the rider's actions and provide the rider sensations of motion, force, vision and noise to realistically simulate bicycle riding. In virtue of these subsystems, the bicycle simulator sufficiently exhibits the characteristics of interaction, immersion and imagination, and thus it's a typical man-in-the-loop virtual reality system. Study and implementation of bicycle simulator and its subsystems can be helpful in exploring interactive measures between human and virtual environment and become a perfect tool in studying virtual reality technology.Aiming at constructing motion generating subsystem and force cuing subsystem for the interactive bicycle simulator, this paper begins with modeling the stable dynamics of the rider-bicycle system which puts forward requirements for the construction of subsystems, and finally comes to the integration technology of the whole simulator system.Based on the analysis of functions of this bicycle simulator, assumptions are forwarded for modeling the rider-bicycle system easily. Motion analysis is given to the rider-bicycle system, front wheel and handlebar, and an over-all dynamic model is constructed by using Newton-Euler formulation. This model takes into consideration of wind drag, road friction resistance, ground gradient and rider's controls which include pedaling, steering, braking and tilting. This dynamic model founds to be a system of 21 variables and 15 independent equations, and its calculability comes from current status collected by sensors. In addition, this model can be helpful in stability analysis and design for bicycles. Final simulation is given to validate this model.Newton-Euler formulation is adopted in modeling the motion platform. In this process, motion analysis is first carried out on the kinematical legs, and then on the upper platform. Legs and the upper platform are then related by constraints to give the recursive dynamic model. Further analysis is given to this recursive model, and explicit relationship is constructed between force and acceleration to form the task space and joint space close-loop dynamic model. Several trajectories are selected to validate these models.To enhance the dynamical performance of the motion platform, an optimal design method is presented based on the platform's motion formula. Since actuator forces are chosen as the optimization variables, this method avoids the shortness of kinematical index in expressing dynamical performance and gives an overall consideration of every dynamical factor, and it can be referred when pursuing optimization design method for parallel manipulators.To simulate variety of resistance forces during riding, based on the running characteristics of bicycle, this paper elaborates on the design of pedal and handlebar resistance devices and their control. Both force cuing devices are actuated by a single DC motor and armature current is chosen as controlled target in both cases. Software and hardware solutions are put forward to deal with possible problems in these devices. Study and development of force cuing subsystems may provide a clue in finding new force cuing method in virtual reality systems.To integrate all the subsystems to be a whole simulator, this paper finally discussed on the integration technology, which includes control system design, task assignment, communication among subsystems and compensation for translation delay. Integration is a key factor in determining the fidelity and performance of the bicycle simulator. We choose distributed control model to tackle this multi-task and real-time system. Tasks are assigned to four sub-controllers. Communication manners and data among sub-controllers are determined.The motion and force cuing subsystems are successfully integrated into the bicycle simulator and received test from a lot of riders.