Wenzeng Guo

Development of a coaxial self-balancing robot based on sliding mode control

A low cost coaxial self-balancing robot is proposed in this paper, the two wheels of which are placed coaxially for turning with zero-radius. Low cost MEMS accelerometer and gyro are selected to measure the posture information of the robot with a novel data fusion method. This data fusion method can overcome the shortcomings of accelerometer and gyro so that the precise posture information is obtained even with oscillation and impact. Based on the robots dynamics model established by Lagranges function method, two robust sliding mode controllers are designed for controlling the motions of the robot. Not only numerical simulation experiments using MATLAB Simulink and ADAMS but also physical experiments are conducted to confirm the effectiveness of the two controllers, and the results show that the robot performs well with precise measurement of the posture and sliding mode controllers.

Development of a transformable wheel-track mobile robot and obstacle-crossing mode selection

According to the terrain features of irregular environment, a novel mobile mechanism of the transformable wheel-track robot is proposed. The robot can adapt to the irregular environment by transforming the track configuration. The robot mechanism consists of a control box, two symmetric transformable wheel-track units and a sub-arm equipped with a single-direction wheel. The wheel-track unit is composed of two walking gear rings, a double four-bar linkage mechanism and a retractable track. Driven by a servo motor, each wheel-track unit can change its locomotion mode according to the environment. In the paper, the system structure and key mechanical points-positioning method of double four-bar linkage mechanism and retractable track are presented. Meanwhile, the step-climbing ability is analyzed separately in wheel mode and track mode. The result shows that, the structure of the robot is reasonable, which can quickly switch between two modes. If the step height is no more than 80mm, the robot can cross in wheel mode, and in track mode to climb higher steps.

Dynamics and stability analysis on stairs climbing of wheel-track mobile robot

A transformable wheel–track robot with the tail rod whose winding will coordinate the center of gravity of the robot is researched, and a theoretical basis for the stable climbing of the robot is provided. After a general introduction of the research, firstly the mechanical hardware and control hardware composition of the wheel–track robot is provided and the principles of its mechanical structure are illustrated. Secondly, through studying the fundamental constrains during the process of the robot climbing the obstacles, a mathematical model based on classical mechanics method is built to help analyze the dynamic principles of a wheel–track mobile robot climbing stairs. Thirdly, the dynamic stability analysis is carried out by analyzing not only the interaction among forces of track, track edge, and stair step but also the different stabilities of the robot when the track and the stairs have different touch points. Finally, an experiment of the modeling track robot climbing the stairs has convinced the effectiveness of the dynamic theories researched, which will be a beneficial reference for the future mobile robots obstacle climbing studies.

Obstacle-surmounting capability analysis of a joint double-tracked robot

This paper presents a robot with double tracks, composed of two segments connected with a joint in mechanical structure. As the angle between the two segments of the robot platform can be changed, the robot can work like a four-tracked robot for moving on many terrains. Change rule of the centroid position in obstacle-surmounting process is analyzed. Moving posture during step climbing are discussed, this is a typical case and is useful for designing the robot platform. The theoretical value of maximal obstacle-surmounting capability of the robot platform is obtained and compares with the test result. The effect of centroid position on obstacle-surmounting capability is obtained, which provides theoretical basis for centroid position control in obstacle-surmounting process. As a whole, reasonable mechanical structure and the good obstacle-surmounting capability of the joint double-tracked robot are tested by experiments.

A wall-climbing robot with gecko features

Geckos have an excellent locomotion ability on vertical wall surface. In this paper, a climbing robot with four magnetic tracks based on gecko-inspired method is presented. This robot can be used for inspecting and maintaining high conical towers in wind power stations. The configuration technical approach of the robot mechanical structure is given in bionics, and the stability when the robot stays on the tower wall in portrait orientation and landscape orientation is analyzed in detail. With the tracks and the redundant joints, the robot can adapt to the conical curved surface. Furthermore, the effectiveness of the design approach is simulated, and the experiment for the robot mobility and stability is verified in practical cases.

Strong Magnetic Units for a Wind Power Tower Inspection and Maintenance Robot

For developing a climbing robot which is used to inspect and maintain a wind power tower, the magnetic unit is one of the key components. Based on analysis of the working conditions of the robot, the approach in this paper is to use four common kinds of magnetic units for adapting to the conical surface. The magnetic circuit of these units is given by theory analysis and is simulated using ANSYS. Moreover, the magnetic force is analysed in detail and the results prove that the magnetic force is greatly influenced by the gap between the unit and the wall surface. In this paper, the design procedures and selection criteria based on the analytical results are given. Meanwhile, these units are compared with each other with the aid of ANSYS. From the results of this comparison, it can be ascertained that the unit using Installation C has the better performance. Furthermore, the effectiveness of the magnetic unit using Installation C is verified by a prototype. The simulations and experiments show that the magnetic unit can allow the robot to keep in contact with the conical wall surface as well as the plane wall surface.

The structure design and analysis of a wheel-track robot

This paper mainly introduces the system components of the wheel-track robot, mainly comprising a body structure and control system. Through the analysis of the driving power and the power of the selection of crawling, motor drive of the robot is chose. Variable structure adopts a screw rod transmission mechanism and the screw rod transmission structure is designed, and the simulation in variable structure verifies the screw drive design principle of rationality. Finally, variable structure of the robot in expansion and contraction experiments were carried out. Experimental results show that the correctness of the variable structure.

LQR controller design for two-wheeled robot with a movable seat

A two-wheeled robot with a movable seat is proposed in this paper, which can turn with zero-radius and whose seat can move up and down, front and back. Firstly, the overall structure and the control system of the robot is introduced; secondly, a new filtering method called RC and Kalman filtering method is designed to get the posture of the robot; then, the robots dynamics model is established by Lagranges function method and locally linearized; finally, the LQR controller is developed to make the robot walk straight on the flat ground and verified in MATLAB/Simulink. Simulation results show that the dynamic model and the LQR controller are effective.