| With the development of economy, it is becoming more and more important to ensure the power system running safely and stably. There are many problems demanding prompt solution, such as energizing everyday maintenance of grid, repairing the fault in time, building power system defense architecture to deal with all kinds of challenges. Most countries around the world have paid more attentions to live-working that is overhauling, changing component and testing on high-voltage equipment without power cutting. The live-working mode for distribution network that is the most direct and close to users in power grid, depends on people mostly, which is high-risk and labor-intensive. To avoid accidents in manual living-working and improve work efficiency, it has immediate practical significance and important value in development of live-working repair robot instead of traditional manual deicing.Although many kinds of live-working repair robots have been researched in our country, structure design, power drive system, dynamic modeling, control methods and other various aspects, have not formed any mature theory systems, and still remain explored. This paper presents a live-working repair robot for the development of safe equipment for emergency rescue and recovery, which can live-work for safety emergency repairing and routine maintenance. The main contents and results are summarized as follows:(1) According to the overhead lines environment of distribution systems with lOkV voltage and smaller, an overall new mechanical configuration of emergency repair live-working repair robot is designed, which include mobile lift platform, hydraulic robot arm, special live-working tools. An engineering mobile lift platform applicable to complex conditions of field road is designed based on insulated bucket arm car. A large load, high dielectric strength, high power density, multi-DOF hydraulic robot arm is developed to fit for the demand of high insulation degree and low quality load, which can working in the complex space environment. Many kinds of live-working special tool with standard mechanical and electrical interface are designed to realize standardized operation of live-working repairing and maintain.(2) According to the special demand for control system of live-working repair robot, a control system adopted the structure of layered hierarchical is developed which can divide into upper layer. Then tasks management, tasks planning, master-slave control and self-control can be reach by tasks reasonably allocated and coordinated. The master control system is analyzed and designed by UML-based object-oriented technology. And the master control software with the feature of simultaneous multi-threading and multiple-ports communication network has resolved the critical resource competition problem of concurrent interactive multi-subsystem, which integrates detecting the robot motion parameters, visual localization and tracking, master manipulator teaching and reappearing, and information processing and statistics. The live-working repair robot can move flexibly and reliably with multi-DOF and process information from multiple sensors in real-time under the control of slave control system based on TRIO multiple axes motion controller. To ensure the insulation grade, the communication between master control system and slave control system is by fiber and an isolation transformer is adopted in power line to achieve electric isolation.(3) The live-working repair robot is analyzed on kinematics by D-H method, and a dynamic model is built in the perspective of live-working repair robot and working object as a whole. The kinematics and inverse kinematics analysis to the 6-DOF hydraulic robot arm of live-working is conducted forward. In light of the actual live-working environment, this paper analyzes the live-working movement space and optimizes the structure of the robot arm. Lagrange method is used to build the dynamics equation and the integrated model for robot arm and power line as flexible load is built to prevent accidents arising from the rebounding and inertance, according to the scene of operating on power line, which provides a basis model for compliant control strategy when operating flexible load. Based on the simulation results of the co-simulation in ADAMS and MATLAB, the moving range, moving velocity and joint driving force and other important parameters of each joint were obtained, and the results show the effectiveness of the proposed kinematic model and dynamic model.(4) The master control strategy and self-control strategy based on multi-sensors is researched to ensure the high efficiency and reliability of the live-working. In the master control strategy, force reflex control strategy is improved to decrease the influence from size scale effect, the superiority of which is verified by testing. In the self-control strategy, the combination of coefficient method and curve-fitting method is used to compensate the robot arm’s own gravity based on force analysis result for the robot arm, so the measurement accuracy of contact force is enhanced. The approaching velocity of robot is controlled by the vision-based optimal control method before touching the object. A novel impedance-based explicit force control method is proposed during the contact process and experiment results show that the method improved the force tracking accuracy and reliability when robot contacting high stiffness environment.(5) According to the actual condition of overhead line in distribution power network, a live-working object identification method based on auto-resizing-threshold Canny edge detection and three straight lines and circle detection by Hough Transform is proposed, which can overcome the difficulties of complicated background of overhead line, low-contrast working objects, and much interference from the light, etc. A hex nut recognition method is proposed and validated in the case of uneven light, including these steps:edge detection by Canny edge detector with continuous adjustment of the threshold, searching for three straight lines with angle 60 degrees between each other through Hough Transform, circle detection by Hough Transform. The combination of moving-target location method based on binocular vision and the parameter calibrating method from the world coordinate system to camera coordinate system is used to obtain the 3D position of the working object in robot coordinate system that sets the stage for self-control motion based on visual servo.(6) To avoid the dual-arms working problems of force control out of synchronization and possibility of collision, a dual arms force control compliant model and a dual arms collision avoidance control method based on C-Space method and A* searching method is proposed. A general compliant model is built to resolve the problem caused by different kinematic structure of dual arms and provide theory basis for the force control of asymmetric redundant driver robot. According to the working space of the live-working repair robot, the dual arms collision avoidance problem is converting to collision-free trajectory planning problem. The collision free library of one arm against the other one is built based on C-Space method, then A* searching method is used in searching for the path to the destination in the collision free library. So that the coordination control of dual arms for collision avoidance is realized, and it further improve the safety in working process of the live-working repair robot. |
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