Orientation control of Atlas: A novel motion simulation platform

This paper describes the mechatronic design concept of a motion simulation platform called Atlas capable of delivering unlimited rotational motion. Atlas’ novel actuation system uses three actuated omni-directional wheels to rotate a spherical capsule that houses the occupant, the cockpit, and the simulator equipment. The unique actuation system allows the spherical capsule to be rotated with a continuously variable angular velocity about a continuously variable axis of rotation. The design process and challenges involved in the development and control of the Atlas simulator are discussed in this paper. To date, an incremental three-phase development approach of the Atlas simulator has resulted in desktop, half-scale, and full-scale prototypes of the simulator. The desktop proof-of-concept model and the focus of this paper, Atlas Lite, is used to test the basics of Atlas’s novel actuation, sensing, and control technologies. This paper introduces the actuation system concept and its implementation on Atlas Lite and a unique vision-based sensing system based on color markers used to estimate the orientation of the spherical capsule. This paper also describes a new nonlinear kinematic controller that allows the spherical capsule to track an arbitrary trajectory. Results from the implementation on Atlas Lite indicate the orientation controller and actuation system allow the spherical capsule to track representative aircraft motions from traditional flight simulation software.

► A novel motion platform with unlimited rotational freedom is developed.
► A vision based orientation sensor is designed and implemented on a small scale test platform.
► A quaternion based kinematic controller guarantees bounded tracking error.