Abstract: In order to realize the robust control of unmanned bicycle under different terrain conditions, different load conditions and different speed scenarios, a robust controller was designed by combining Linear Expanding State Observer (LESO) and Non-singular Terminal Sliding Mode Control (NSTSMC) method, and a physical prototype experiment platform was built to verify its performance. Considering the linear variable parameter (LPV) model of the unmanned bicycle, The coupling between the steering angle dynamics and the lean angle is eliminated by feed-forward compensation; the internal uncertainties and external disturbances of the system are combined into lumped disturbances, and a linear extended state observer is introduced to construct an improved LPV model that only includes the lean angle. A non-singular terminal sliding surface is chosen, and the equivalent control and nonlinear control of the controller are designed by using the improved LPV model. The results of numerical simulation and physical prototype experiments show that the unmanned bicycle can realize self-balancing motion on four different grounds: granite road, asphalt road, cement road and lawn. Its lean angle can be stabilized at [-0.006,0.006](rad) range; it also has strong robustness for the mass load within 16.5kg, the changing vehicle speed of 1.2m/s-2.4m/s, and the pulse interference generated when crossing the speed bump.

Key words: Unmanned bicycle, Balance control, Linear variable parameter, Linear extended state observer, Non-singular terminal sliding mode control