A Robotic Walker Based on a Two-Wheeled Inverted Pendulum

This paper presents the design and control of a robotic walker based on a two-wheeled inverted pendulum (TWIP) developed to assist mobility-impaired users with balance and stability. Traditional walkers use three or more contact points to create a solid base to augment a user’s balance. A TWIP walker can support a user’s balance through balance control. A robotic walker prototype has been developed to illustrate its ability to assist human gait and exploit the maneuverability of a two-wheeled mobile platform compared to multi-wheeled system. Presented is a linearized mathematical model of the two-wheeled system using Newtonian mechanics. A control strategy consisting of a decoupled linear quadratic regulator (LQR) controller and two state variable controllers is developed to stabilize the platform and regulate its behavior with robust disturbance rejection performance. Results are shown using a physical prototype to demonstrate the ability of the decoupled LQR controller to robustly balance the platform while the state variable controllers regulate the platform’s position with smooth, minimum jerk, control when used by a person during standing and walking.