On the capability of wheeled mobile robots for heavy object manipulation considering dynamic stability constraints

Abstract

In the current research, the maximum mass that can be transferred by a Wheeled Mobile Robot (WMR) equipped with a manipulator will be found. Once such a multibody system carries a heavy payload, it may turn-over. Thus, a very important problem of how to design the motion of the wheeled robot in order to prevent its turn-over or, in other words, to maintain its dynamical stability appears. The solution of this problem is the main focus of the present study. Toward the solution of the aforementioned problem, a pseudospectral approach, which is based on powerful direct optimization technique, will be utilized. To tackle the loss of postural stability during object manipulation, which may have potentially severe concerns, a proper dynamic stability margin measure will be exploited to superiorly estimate and remove the risk of fall. The stability constraints will appear as inequality constraints that will then be transcribed into an equality constraint to solve the problem. Using the provided direct search method, an algorithm will be suggested to find the maximal mass that can be manipulated by the considered robot. The obtained simulation results reveal the success of the provided novel methodology to assess the manipulation capability of the considered WMR while considering dynamic stability and actuator limitations.