Kinematic Modeling, Analysis, and Verification of an Essboard-Like Robot

The Essboard is a kind of unusual, portable, two-wheeled vehicle with a special structure and unique locomotion mode. The rider can drive the Essboard easily by twisting the two pedals using both feet. The device may inspire a new type of two-wheeled mobile robots; however, study on this special kind of mobile system is quite inadequate. In this article, we address the kinematics-the most fundamental issue-of an Essboard. The geometric model of the system is first established; then, the holonomic constraints on the two wheels and the holonomic equations are obtained. Finally, the nonholonomic constraints on the system are derived under the condition of pure rolling, and thus the accurate kinematics of the system are established for the first time. To verify the correctness and effectiveness of the established kinematics, a simulation using the virtual prototype technique is conducted, and to reveal its accuracy and advantages, a comparison with the previous model is made. A physical prototype of an Essboard-like robot is developed and employed as a platform to verify the theoretical models. The kinematics built and verified in this article are general and can therefore be applied to other similar monorail vehicles including bicycles and motorcycles.