Application of Inverse Simulation to a wheeled mobile robot

Abstract

This paper presents the application of Inverse Simulation to the control of a mobile robot. The implementation of this technique for motion control has been found to provide highly accurate trajectory tracking. Since the input to the Inverse Simulation is a time history of the desired response, then greater control over the position and orientation of the mobile robot can be achieved. There are many situations where the desired path of a mobile robot is known e.g. planetary rover navigation, factory or warehouse floor, bomb disposal. Typically the robot is either controlled remotely or runs an online controller to navigate the desired path. For a given path, a navigation system generates the desired drive parameters (i.e. heading and velocity) and the associated controllers drive the corresponding actuators. Traditionally the controllers are required to be tuned using knowledge of the limitations of the mobile robot. Inverse Simulation provides a means of generating the required control signals with no need for controller tuning. The use of Inverse Simulation is suitable in cases where the cost of the mobile robot or actuators is high, desired drive requirements need to be met or for situations where tight tolerances on the trajectory are to be achieved. In this paper the benefits of applying Inverse Simulation to the control of a mobile robot are discussed and appropriate results presented.

Numerical stability of inverse simulation algorithms applied to planetary rover navigation

“…For the Differentiation method, (1) is discretized N times over a time interval Τ into the form shown in (2), where dt is the discretization step.…”

“…The model of the rover has been presented in [2,3,19] and has been experimentally validated [19]. It is briefly described here for completeness.…”

“…First, a path to the destination is determined as a series of waypoints. This information provides the desired trajectory for the Inverse Simulation, which in turn generates the required guidance commands (control inputs) to follow the trajectory [2], [3]. The method can be applied in situ: given a series of waypoints or a defined trajectory, the rover can calculate the necessary control inputs or offline: operators define the trajectory, the control inputs are calculated and then sent to the rover.…”

“…Inverse Simulation has also been used as a model validation method [1], [8]. Previous research has demonstrated the potential for Inverse Simulation as a guidance and control method for wheeled rovers [2], [3].…”

“…Inverse Simulation is a model based, numerical, iterative process where step changes in the various controls are applied until the predicted response matches the desired response [1]. Applied to rover navigation, the desired response is a trajectory or path to a goal destination [2], [3].…”