Adaptive Controllability of OmniDirectional Vehicle Over Unpredictable Terrain Ka C. Cheok, Micho Radovnikovich a Gregory R. Hudas, James L. Overholt b Paul Fleck c a Dept. of Electrical and Computer Engineering, Oakland University, Rochester, MI, USA b U.S. Army RDECOM-TARDEC, Warren, MI, USA c Dataspeed, Inc., Troy, MI, USA ABSTRACT In this paper, the controllability of a Mecanum omnidirectional vehicle (ODV) is investigated. An adaptive drive controller is developed that guides the ODV over irregular and unpredictable driving surfaces. Using sensor fusion with appropriate filtering, the ODV gets an accurate perception of the conditions it encounters and then adapts to them to robustly control its motion. Current applications of Mecanum ODVs are designed for use on smooth, regular driving surfaces, and don’t actively detect the characteristics of disturbances in the terrain. The intention of this work is to take advantage of the mobility of ODVs in environments where they weren’t originally intended to be used. The methods proposed in this paper were implemented in hardware on an ODV. Experimental results did not perform as designed due to incorrect assumptions and over-simplification of the system model. Future work will concentrate on developing more robust control schemes to account for the unknown nonlinear dynamics inherent in the system. Keywords: Mecanum wheel, omnidirectional vehicle, wheel slip, adaptive control, robust control, wheel slip, controllability awareness 1. INTRODUCTION Omnidirectional vehicle (ODV) platforms using Mecanum wheels have very good mobility and maneuverability because they are able to move in any direction. This extra mobility over conventional drive systems has the potential to be very useful in both military and domestic applications, but needs to be adapted to the task at hand. The main problem with Mecanum omnidirectional platforms is that their dynamics are often delicate and are greatly affected by disturbances caused by irregular driving surfaces. The control algorithms must be carefully calibrated to match the physical dimensions of the platform as well as the anticipated performance environments. Therefore, current implementations of omnidirectional vehicles are used mainly on hard and smooth ground. There is a relatively small number of papers discussing research of Mecanum ODVs, and very few of them account for wheel slip at all. If slipping is accounted for, it is simply handled from a closed loop control point of view, and the system does not actively characterize the slip conditions. 1 If dynamic slip characteristics can be effectively estimated and used to adjust the control laws of the ODV, it is hypothesized that an ODV can be as robust when traveling over irregular terrain as a conventional vehicle. This paper presents control systems to address the adaptive control 2 problem for a Mecanum ODV. The systems were simulated in Matlab and Simulink, and certain algorithms were implemented on an experimental platform.