Fuquan Dai

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.

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.

Dynamic adaptive equilibrium control for a self-stabilizing robot

For Coaxial two-wheeled self-stabilizing robots, severe vibrations and fatal injury may occur when changing the center of gravity (CG) position, a feasible way for smoothly controlling the dynamic equilibrium in this condition is proposed in this paper; both the movement tendency and the height of system CG are concerned. A hybrid controller based on adaptive and full state feedback control is designed for the equilibrium control. Under the adaptive controller, the height of system CG is estimated and amended in every control-cycle, and stable control effects are achieved along with the states feedback controller. Influence of the height of CG on the dynamic equilibrium is analyzed. The authors present the simulation as well as the model experiments, which show the self-stabilizing robot could be controlled smoothly by the mixed controller whether the height is changed by the loads or not and it can return to balance in approximately 2.5s when it is disturbed.

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.

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.

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.

Development of a dual-mode mobile robot system for practical applications

This paper addresses a Coaxial Couple Wheeled Robot platform with a dual-mode for practical applications both as a personal transporter and a robot patrolman. This CCWR has two modes: the patrol mode as CCWR-P and the transporter mode as CCWR-T. In order to achieve fast switching between the two modes, modular design approach is adopted, and mechanism as well as the designed controller are developed and demonstrated. The system is divided into four separate parts, and independent functional modules can be quickly assembled for different target applications. Integration hardware is focused here, as well as the implementation of the controllers. For the robot control, a compact states feedback controller is proposed in this paper, and then the robot can track the desired inputs. Finally, the running experiments indoor and outdoor proved that the robot platform can move smoothly with the two modes and furthermore the robot can execute the tasks of transporting and patrol.

Motion control for a walking companion robot with a novel human–robot interface

A walking companion robot is presented for rehabilitation from dyskinesia of lower limbs in this article. A new human–robot interface (HRI) is designed which adopts one-axis force sensor and potentiometer connector to detect the motion of the user. To accompany in displacement and angle between the user and the robot precisely in real time, the common motions are classified into two elemental motion states. With distinction method of motion states, a classification scheme of motion control is adopted. The mathematical model-based control method is first introduced and the corresponding control systems are built. Due to the unavoidable deviation of the mathematical model-based control method, a force control method is proposed and the corresponding control systems are built. The corresponding simulations demonstrate that the efficiency of the two proposed control methods. The experimental data and paths of robot verify the two control methods and indicate that the force control method can better satisfy the user’s requirements.

Modeling and LQR control of a multi-DOF two-wheeled robot

A multi-DOF two-wheeled robot is considered, the research is aimed to develop the dynamic model and balance control scheme of the robot. A balance weight is involved to compose a new DOF, the dynamic model of the robot is established with Lagrange equations. To facilitate the modelling and design control scheme, the dynamic model is simplified and the displacement of balance weight is chosen as control input instead of state variable. With the dynamic model, a LQR controller is designed for achieving the desired velocity of the robot while stabilizing the central body. Simulation and physical prototypes are established to prove the veracity of the model and confirm the validity of the designed controller.