Hongguang Wang

Estimation of Battery State of Charge With

Battery state-of-charge (SOC) estimation is essential for a mobile robot, such as inspection of power transmission lines. It is often estimated using a Kalman filter (KF) under the assumption that the statistical properties of the system and measurement errors are known. Otherwise, the SOC estimation error may be large or even divergent. In this paper, without the requirement of the known statistical properties, a SOC estimation method is proposed using an H∞ observer, which can still guarantee the SOC estimation accuracy in the worst statistical error case. Under the conditions of different currents and temperatures, the effectiveness of the proposed method is verified in the laboratory and field environments. With the comparison of the proposed method and the KF-based one, the experimental results show that the proposed method can still provide accurate SOC estimation when there exist inexact or unknown statistical properties of the errors. The proposed method has been applied successfully to the robot for inspecting the running 500-kV extra high voltage power transmission lines.

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The broken strand in the overhead ground wire (OGW), which is caused by thunder lighting, variation, etc., is a serious fault in power grid. The maintenance work, with high working intensity and risk is generally carried out in the high voltage live line by specially trained workers. This paper presents the development of a novel mobile robot designed for the OGW broken strand repair in power grid. The mobile robot with passive joints can run along the OGW and cross counterweights and splicing sleeves. After approaching the fault location, with the specialized tools, the robot first returns the broken strand back to the original position and then fastens the broken strand tightly through specialized clamp. With the consideration of practical application, safety and performance on obstacle-crossing and maintenance, the robot prototype has been developed. A calculation method has been proposed for the resolution of inverse kinematics with force constraints. Robot experiments in laboratory have been carried out and the results are shown in this paper.

Observer: Applied to a Robot for Inspecting Power Transmission Lines

The developments in mobile robotics have increasingly played an important role in the inspection and maintenance work of Power Transmission Lines (PTLs). This paper presents the research and development of the inspection robots for 500kV PTLs in Shenyang Institute of Automation, Chinese Academy of Sciences (SIACAS). An overview of the research work and the development of an inspection robot AApe-B, are introduced, respectively. The AApe-B can run on the Overhead Ground Wires (OGWs) and navigate different types of obstacles in remote and locally autonomous control mode. A novel dual-wheel-arm hybrid mechanism with the excellent locomotion and obstacle-navigation performance is designed, and obstacle navigation process is analyzed. An embedded control system which can withstand the strong electromagnetic interference has been developed. A lot of field experiments have been carried out, and the experimental results have shown that the inspection robot can reliably work during the 500kV Extra High Voltage (EHV) electromagnetic environment and possess the primary ability to implement the inspection task of the 500kV PTLs.

AApe-D: A novel power transmission line maintenance robot for broken strand repair

This paper focuses on the automatic generation of forward kinematics of a kind of modular reconfigurable robot. Based on the modularized division of robots and the communication between the host and the modules, a configuration recognition method is proposed. By using the graph theory, the method of topological analysis is proposed, and the assembly incidence matrix (AIM) and path matrix are derived. Subsequently, based on the results of topological analysis and the definition of module frames, the initial poses and twists of a robot are obtained. To deal with the multi-chain robots, the entries of the path matrix are employed to enable dyads to appear or not to appear in the kinematic equations. Then, the forward kinematics of the multi-chain robot is derived. An illustrative example and an experiment are presented. The results show that the method is valid and suitable for both single-open-chain robots and multi-chain robots.

Development of an inspection robot for 500 kV EHV power transmission lines

A novel mechanism for power transmission line inspection robot is presented according to the requirements of inspection tasks and characteristics of obstacles on power lines. Its configuration is introduced, and the kinematics equations and statics model are established. Then, the motion sequences for crossing the strain clamp are planned. Furthermore, the simulation of the navigation of the strain clamp has been carried out. The simulation results demonstrate that the mechanism has such characteristics as good motion stability, strong loading capacity and excellent obstacle negotiation capability.

Automatic kinematic modelling of a modular reconfigurable robot

A 5-DOF 5-UPS/PRPU parallel machine tool (PMT) is introduced. Redundant actuation is adopted in order to improve the positional accuracy and dynamic performance. A method for the measurement of positioning accuracy of PMT under dynamic condition is described in detail. It is based on Agilent 5529A dual-frequency laser interferometer which is capable of performing dynamic calibration. Based on the working principle of laser interferometer, the positional data of the moving platform are collected and the positional error data in accordance with ISO 230–2 standard of each virtual axis are obtained in high resolution. Meanwhile, the positioning accuracy of each axis is also descried with visual graphics. In order to investigate the influence of redundant actuation on the positioning accuracy of the machine, the linear positional error of X-Axis are both tested under the redundant actuation case as well as its corresponding non-redundant counterpart. These positional error data can be used for the positional error compensation model of machine tool.

Research on a novel inspection robot mechanism for power transmission lines

This paper proposes a robust guaranteed cost control method for a linear system with norm bounded time varying parametric uncertainties and external disturbance. Using the Lyapunov stability theory and linear matrix inequality method, a robust guaranteed cost control law is derived to guarantee that the closed loop system is not only stable, but also has adequately quadratic and H∞ performance levels for all the admissible uncertainties and external disturbance. A convex optimization problem is formulated to obtain the optimal state feedback controller which can minimize the quadratic and H∞ performance levels. Based on the model of the robot prototype for inspecting power transmission lines, simulation results verify the effectiveness of the proposed method.

Dynamic measurement of the positioning accuracy of redundantly actuated parallel machine tool

Power line inspection is essential to the smooth running of the power grid. In the past, the power line inspection was mainly carried out manually, which means the liners had to inspect the power line in the field or watch the inspection video taken by UAVs or inspection robots. The manual inspection method is with disadvantages such as long time consumption and high manual labor cost. With the rapid growing of power grid, the demand for the power inspection has been continuously increased, but the manual inspection method can hardly meet the requirements for the power inspection due to its disadvantages. This paper presents a computer vision-based method for the broken spacer detection. The method is mainly implemented in three steps. First of all, the spacer is recognized in the region of interest. Secondly, the image morphology is used to extract the image feature. At last, we determine the broken spacer fault by the analysis of the connected domain in the image. Experimental results have successfully demonstrated the effectiveness of the proposed method.

Robust guaranteed cost control of linear systems with norm bounded uncertainties and external disturbance

Considering the kinematic constraints and the path discreteness, a novel path planning method based on the feasible gait is proposed for an inchworm-like robot moving in a narrow space in this paper. Firstly, by analyzing the locomotion modes and the basic gaits of the robot, some arithmetic operators to describe the change of the position and orientation are defined, and a gait graph model is also presented. Secondly, making reference to the main idea of the partial dynamic window method, the path planning method is proposed, which include the environment modeling based on the dynamic partial grid map and the feasible gait searching algorithm based on the complete or incomplete traversal. Finally, some simulations and experiments are provided to validate the rationality and the validity of the path planning method.

A vision-based method for the broken spacer detection

This paper focuses on the kinematic calibration of a modular reconfigurable robot. To aim at low complexity and high generality, a new calibration method was proposed. Based on the definition of independent modules and the kinematics, the kinematic errors were divided into two categories, and will be calibrated respectively. The first category is the individual module errors, which represent the machining errors of modules; they will be calibrated directly by measuring tools. The second category is the assembly errors between consecutive modules, and will be calibrated by using Jacobian. A concept of virtual joint was proposed to deal with the cases that the axes of the errors are not coincident with any rotary joint. The proposed method decouples the errors and lowers the order of calibration equations, and thus has a simple representation and lower computational complexity. The results of the simulation show that the method is of validity, generality, and accuracy.