Xueshan Gao

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.

Floor‐cleaning robot using omni‐directional wheels

Purpose – The purpose of this paper is to present an omni‐directional floor‐cleaning robot equipped with four omni‐directional wheels. The research purposes are to design a robot for cleaning jobs in domestic, narrow and crowded places and to provide a robotics‐study platform in a laboratory.Design/methodology/approach – The robot system using Swedish wheels, one dust collector (brush) switching device and a sort of air‐bag sensing device is designed. The kinematics and the motion control conditions of the robot are analyzed. Specifically, a design method of wheels is described.Findings – The configuration of the robot, parameters of the wheel and controlling methods are studied and demonstrated. The smooth locomotion capability and high‐working efficiency are verified by experiments.Practical implications – The robot can perform its work in semi‐autonomous and tele‐operated mode. Moreover, the robot can pivot around, avoid obstacles and is provided with automatic power management system.Originality/value...

A multi-DOF two wheeled inverted pendulum robot climbing on a slope

Two wheeled inverted pendulum (TWIP) robot is widely used in various applications for its zero turning radius, small footprint and other advantages. However, the traditional TWIP robot can not keep upright when climbs or descends on a slope, which makes the operator sitting on the robot feel unsafe and uncomfortable. This paper introduces a Multi-DOF TWIP robot, which adding a movable weight to the standard TWIP robot. This robot can maintain the robot body upright when the robot climbs or descends a slope, also when accelerate or decelerate. The complex full dynamics model of the robot is derived from the Largranges method, and then a simplified method is proposed. Controllers for balance and velocity control are designed separately based on the simplified model. Simulation and real experiment demonstrates that this method proposed in this paper is effective.

A powered ankle-foot orthoses for ankle rehabilitation

Ankle rehabilitation training becomes a tough question for the patients with ankle joint injuries especially with the hemiplegia after stroke. Here a novel powered ankle-foot orthoses which can provide ankle dorsiflexion and plantar flexion assistant using electric motor is proposed in this paper. The mechanical structure of the orthoses including wearing parts, ankle joint hinged part, driving unit, transmission mechanism and sensing units is mainly described. In order to obtain the ankles moment-angle relationship, the dynamics model of the ankle-foot is established. In addition, for the motor control of ankle-foot orthoses, motion path is planned based on the human walking gait and the simulation. This study provides a new method for ankle-foot orthoses design and has great significance for ankle rehabilitation.

Optimal trajectory planning for robotic manipulators using improved teaching-learning-based optimization algorithm

Purpose The purpose of this paper is to propose a method of optimal trajectory planning for robotic manipulators that applies an improved teaching-learning-based optimization (ITLBO) algorithm. Design/methodology/approach The ITLBO algorithm possesses better ability to escape from the local optimum by integrating the original TLBO with variable neighborhood search. The trajectory of robotic manipulators complying with the kinematical constraints is constructed by fifth-order B-spline curves. The objective function to be minimized is execution time of the trajectory. Findings Experimental results with a 6-DOF robotic manipulator applied to surface polishing of metallic workpiece verify the effectiveness of the method. Originality/value The presented ITLBO algorithm is more efficient than the original TLBO algorithm and its variants. It can be applied to any robotic manipulators to generate time-optimal trajectories.

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.

Dynamic model and balance control of two-wheeled robot with non-holonomic constraints

Two-wheeled mobile robot is known for advantages on performing better manuever in a confined space. It is a typical mobile robot with some features such as complexity, highly nonlinear, instability, multi-variable and strongly coupling. This research is aimed to design and develop the dynamic model and balance control strategy of the robot. A Gibbs-Appell equation is applied to build the dynamic model of two-wheeled robot in this paper. The virtual prototype model of the robot and the state space model with feedback are obtained. The experiments based on the simulation model and actual model are implemented. They show that the state feedback controller carried on the robot model in the posture and the speed is effective and the dynamical balance process is stable. The nonlinear dynamics model based on non-holonomic constraints and pole placement algorithm on the basis of the dynamic model are effective.

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.