In this study, a four-axis platform capable of rolling, pitch, and yaw rotation was created for rehabilitation and exercise. Based on this, a virtual coach and a virtual reality game system were developed. The virtual coach is a 3D person model created with the Unity program that allows the user to exercise in the correct posture with the virtual coach, and recognizes the correct posture with the Kinect. Additionally, a virtual reality game has been developed, and in conjunction with this, the actual platform also moves to increase the rehabilitation effect. The upper body and lower body movement and plantar pressure measurement were used to associate with the four-axis platform to maintain strength and balance the body.

The motion platform supports the trainee in experiencing a sense of reality in virtual space by performing a motion on the available degrees of freedom for a motion that mimics a specific motion in connection with a virtual reality content or a simulator. The required specification of the motor and driver of motion platform is determined by the target specification for the upward motion of the motion plate. The reason is that the weight of the upper plate always applies gravity in the direction of the downward motion. As a result, the downward motion has an excessive specification compared to the upward motion specification, resulting in an unbalanced motion specification. Additionally, a problem may occur in which a volume increases from the application of a high specification driving unit. In this paper, the motion platform was designed capable of three-axis motion in roll, pitch, and gravity directions using a compression spring to apply a load compensation mechanism. Based on the design results, the specifications of the compression spring for motion platform to satisfy the operating specifications do not excessively move the upward and downward direction derived by the analysis.