Dynamics of Step-climbing with Deformable Wheels

Wheeled-mobile robots operating in human environments typically encounter small steps. Surmounting steps is normally not considered when determining peak torque needs, yet it can be the maximum requirement. This work looks at the statics and dynamics of this situation to determine the necessary peak torque. It finds that using a dynamic model that includes the wheel elasticity is essential for properly representing a real-world tire. When torque is increased using a step function, energy is stored in the tire—higher tire elasticity eases climbing. Knowledge of this phenomenon could facilitate the use of smaller actuators. The model is numerically integrated and results are found to agree with experiment.