Control of the Twowheeled Inverted Pendulum (TWIP) Robot Moving on the Continuous Uneven Ground Uneven terrain is common in natural environment. The TWIP robot has demonstrated its rapid movement ability in even ground in previous works. This paper explores control of the TWIP robot in the continuous uneven ground except the step case. The sinusoidal function and the piecewise linear function type ground surface are taken as an example to explore motion characteristics of robots on complex terrain. As for the robotic system, continuous or step changes of slope are the main types of disturbance to it. To cope with these disturbance, a Sliding Mode Control (SMC) is used to design the nominal controller due to its insensitivity to uncertainty. Then, the Extended Kalman Filter (EKF) is adopted to estimate the slope of unknown terrain without any ground information from sensors but according to motion state of robot and the Equilibrium Point Estimation (EPE) is then achieved based on the obtained slope angle. In simulation, the TWIP robot moves on these two types of uneven ground surface to track the reference position or velocity trajectory. The comparative experimental results have demonstrated that SMC combined with the EPE method can enable TWIP robot to locomote on some limited uneven ground with higher stability and dynamic performance, compared to the single LQR and the single SMC method. Also, the proposed algorithm has been conduted successfully on the WIPBot robot to travel upward and downward slope.

Walking Control of Biped Robots on Uneven Terrains Based on SLIP Model Having humanlike legged structure, biped robots are regarded as the most promising robots that can take the place of human to work in the environments designed for human beings. To this end, it is the premise for biped robots to achieve stable walking on uneven ground. This paper presents a control strategy for a biped robot based on springloaded inverted pendulum (SLIP) model, which controls the joint torque of the robot by obtaining the errors of length and angular position of virtual spring legs. Additionally, this paper proposes a new control method of adjusting the length of legs to enable the robot to achieve stable walking on unstructured terrains, such as staircases. In the end, the simulation results corroborate the effectiveness of the proposed approaches.