Liman Yang

Network-Based Coordinated Motion Control of Large-Scale Transportation Vehicles

A series of large-scale transportation vehicles have been developed to transfer huge and heavy objects. Such a multiaxle vehicle has a complex steering system that consists of a large number of independently controlled steer axles. To achieve smooth and accurate steering motion without slipping and sliding, real-time and coordinated control of the steer axles is essential. Based on the networked control system (NCS), a multimode steering control scheme is proposed. Through kinematical and dynamic analysis of the steering system and utilizing the inherent real-time data-sharing features of the NCS, a cross-coupled control algorithm is developed to improve the steering accuracy. The effectiveness of the network-based steering control method is verified through simulation and experimental results

Design of robust sliding mode control with disturbance observer for multi-axis coordinated traveling system

This paper deals with the robust control strategy for multi-axis coordinated motion system. Firstly, the adjacent cross-coupling error control method was introduced to reduce the synchronization error. Then, the sliding mode control (SMC) law based on the mathematical model of the plant was adopted for restraining parameter perturbation. Furthermore, addressing the unknown torque disturbance, a disturbance observer was proposed. The switching gain of the robust control algorithm can be set as a smaller value so that the chattering on the sliding mode plane can be decreased. The simulation results have proved the effectiveness of the proposed control algorithm.

Posture Measurement and Coordinated Control of Twin Hoisting-Girder Transporters Based on Hybrid Network and RTK-GPS

In this paper, a typical application of multimobile robots, i.e., twin hoisting-girder transporters cooperating to transport a giant concrete girder, is studied. An overall solution based on the hybrid network communication framework is presented and the key issues, such as the accurate posture estimation and coordinated control of the two independent transporters forming a team, are researched. In order to obtain the relative distance and orientation angle between two transporters while traveling, a measurement data fusion method using real-time kinematic global positioning system for kinematic locating and in-vehicle speed sensors for speed measuring is proposed. Furthermore, a distributed master-slave coordinated control strategy based on the hybrid network framework is proposed to meet the reliability and accuracy requirements. The application results show that the deviations of the relative distance and the orientation of two transporters during working are not more than 0.1 m and 0.2deg, respectively, and it can meet the requirements of the technological specifications.

Analysis of delay and traffic load in networked control system

Time delay and delay jitter are the critical issues in system design of networked control systems (NCS). Aiming at the particularity of control network, the conceptions of loop-delay and network-delay are proposed in view of control and network, and their intentions, properties and acquiring methods are compared. The theoretical analysis and mathematic description about characteristic and evaluating index of network-delay are presented. Furthermore, the traffic load composition and estimating method are discussed. Taking the double-motors synchronization control system as an example, the simulation of corresponding NCS is implemented. The validity of above mentioned methods is verified

Multi-source information fusion augmented reality benefited decision-making for unmanned aerial vehicles: A effective way for accurate operation

Augmented reality UAV multi-source information is obtained by overlaying a variety of other sensors and the database data in the airborne video of CCD sensor. More substantial and credible information display can then be obtained. Our research includes the establishment of binocular stereo camera, improved feature matching algorithm with high matching speed and robustness, pose measurement methods making control operators observation immersion better. The method used for manipulation of augmented reality provides enhanced decision support information to improve the personnel control decisions speed and accuracy.

An Efficient Flexible Division Algorithm for Predicting Temperature-Fields of Mechatronic System with Manufacturing Applications

This paper presents a new thermal-field modeling method referred to here as a flexible division algorithm (FDA) for predicting the temperature fields of a mechatronic system, and its real-time applications where thermal effects have a significant influence on the performance and reliability of the final products. This algorithm, which takes advantages of the flexible division in 3-D space to deal with the spatial distribution of thermal fields, is built upon physical laws to derive the governing equations in state-space representation that facilitates the reconstruction and control of the thermal field being analyzed. Three numerical models (involving both Cartesian and cylindrical coordinates) are illustrated to highlight the effectiveness and usefulness of the FDA for real-time modeling and computing. In the context of a thin-walled component machining application, the FDA is evaluated numerically and validated experimentally. Its solutions agree well with results computed using commercial finite-element analysis (FEA) software, confirming its ability to obtain accurate results, but with significantly less computation time, and its effectiveness as a complement to FEA when real-time computing of a physical field is required.

Thermal field modeling algorithm based on flexible space division for high-power, high-precision mechatronic systems

This paper presents a new thermal-field modeling method, referred to here as a flexible space division algorithm (FSDA), for design and real-time manufacturing applications of high-power, high-precision mechatronic systems where thermal fields play an important role in the performance and reliability of the final products. This algorithm, which takes advantages of the flexible division of three-dimensional space to deal with the spatial distribution of the thermal field, is built upon physical laws to derive the governing equations in state-space representation that facilitates the reconstruction and control of the thermal field being analyzed. Two numerical examples (involving both Cartesian and cylindrical coordinates) are illustrated to highlight the effectiveness and usefulness of the FSDA for real-time modeling and computing. In the context of a thin-walled component machining application, the FSDA is evaluated numerically, which consistently agrees well with results computed using commercial finite-element analysis software, confirming its ability to obtain accurate results with significantly less computation time and the complementary role to FEA that the FSDA can play when real-time computing of a physical field is required.

Path-following control for multi-axle car-like wheeled mobile robot with nonholonomic constraint

This paper deals with the path-following control of multi-axles driving car-like wheeled mobile robot (WMR). Addressing the issues of the nonholonomic constraint characters of the WMR, firstly, this paper analyzes the steering relationship of geometry and kinematical constraint of the multi-axles driving WMR, and establishes the dynamical equations. Then, using the guidance law that based on the guidance-based path-following principle to evaluate the tracking errors, the attitude angle for eliminating the tracking errors and updating law for path parameters are deduced. By stability analysis, the global uniform asymptotic stability of the system is certificated. Furthermore, the linearization robot dynamic model is derived by means of the nonlinear feedback linearization strategy. In order to overcome the torque disturbance, a sliding mode speed tracking controller with disturbance observer is proposed based on this linearization dynamic model. The simulation of tracking performance with the planned desired path which is constructed by cubic spline interpolation method is performed. The simulation results show that the proposed control strategy can achieve satisfactory path-following control performances.

Attitude measurement of driver's head based on accelerometer and magnetoresistive sensor

A head attitudes measurement system based on 3-axis micro-accelerometer and 3-axis micro-magnetoresistive sensor is designed and developed using for thermal imager setup of night-driving vehicle. The three attitude angles, i.e. pitch, roll and yaw, of drivers head are estimated relative to the driving vehicle in real time. In this system, the 3-axis micro-accelerometer detects the gravity field and the 3-axis micro-magnetoresistive sensor detects magnetic field. Euler orientation cosines matrix conversion theory and the relative algorithm are applied to the attitude calculation. Different from the conventional measurement to the earth, the reference coordinate system is mobile vehicle here. For this system, the geomagnetic field will be a disturbance, thus the oriented uniform magnetic field is built by permanent magnets and activity mechanical arms to eliminate the negative effect of the geomagnetic field. Moreover, the kinematical accelerations induced by the vehicles accelerating, decelerating or vibrating are considered as disturbances, and a dual-layer filter is designed to deal with them. Finally, the experiments on vehicle are carried out, and the three-dimensional attitude angles of the drivers head relative to the driving vehicle are measured. Results prove that this measuring system not only has small size and low cost, but also has quick response and high reliability.

Accurate mathematical model for describing electrohydraulic loading system of helicopter pitch adjusting hydromechanical servos

This paper deals with the establishment of the exact mathematical model for describing the electro-hydraulic load system which is applied to the earth-experiment of the hydromechanical servomechanism (hydraulic assistor) for the helicopter pitch adjusting. Based on the working principle analysis of the electro-hydraulic load system, the accurate mathematical model of electric-hydraulic loading system is established and the influence of the model on the system characteristics is deeply analyzed. It is proved that surplus force is concerned with not only the velocity but also the acceleration of rudderpost. Moreover, the traditional structure invariance principle is improved. Experiments in the paper validate the correctness of complex mathematical model, of which the guiding effect in eliminating the extraneous force is revealed also.