Abstract: Omni-directional wheeled robot for lower limbs rehabilitative training needs to track trajectory which is set by doctors.The uncertainties of the robot and the disturbances caused by trained patient affect the tracking performances. A nonlinear robust L₂ controller is presented to solve disturbance rejection problems.Kinematics model of lower limbs rehabilitative training robot is presented,thereby,a kinematics model of the position error system is established.The tracking and uncertain disturbance rejection are formulated as an L₂ control question to design control law with backstepping algorithm in a built storage function.A trajectory tracking controller meeting the disturbance rejection requirement is constructed. Simulation and experiment results show that the proposed controller is effective.