Event-based haptic interface of mobile robot with uncertain delay time via Internet

The haptic interface enables an operator to feel remote environment via Internet. However there is uncertain delay time via Internet and the speed of the sampling and calculation in the interface device is faster than the speed of the information feedback from the remote robot, which may lead to two problems. The first problem is the stability of the control and the second problem is that the feedback information can't be gotten by the haptic interface in time. So it is difficult for an operator to feel the force according with his commands quickly and correctly and the feeling of the force is not vivid. In this paper, a framework of the Internet-based operation system is proposed. The event-based control strategy is implemented which makes this system stability. The TCP protocol is used in order to implement the increasing command number. The feeling of force from haptic is calculated through the model of the DC motor. Because the model is not accuracy and varying, An ARMA model of the car-like robot is identified by the slave computer. The parameter of the ARMA model, which is not affected by the random delay time, is used as feedback event. The calculation model in the haptic computer is updated according to the feedback events, and the feedback force is calculated through the new model. The simulation and experiment results are given to show the effectiveness of the proposed method.