Key Technology Research On Wall Auto-cleaning Robot

Cleaning the facades of skyscrapers is not only a heavy workload but also tedious, time-consuming, dangerous, and suitable for automation. Even to present, most work is done by workers in suspended scaffoldings or nacelle. Wall cleaning robot has not been used widely yet and the practical process is restricted by its weight, cost, safety, versatility, adaptability to wall surfaces and other factors.The research in this dissertation aims at providing city construction industry with a highly efficient wall climbing robot for cleaning glass or tile wall automatically in order to enhance the wall adaptability of robot, improve cleaning quality, increase working efficiency, increase energy-saving and environment-friendly performance, reduce operating costs and improve the working condition of workers. The key technology of the wall auto-cleaning robot was studied in depth on the moving system, adsorption system, cleaning operating system and the relational integration mechanism with the robot body, locomotion characteristics, control system and path planning in this dissertation.The technical difficulties of wall climbing robot and wall cleaning in developing the wall cleaning robot system were analyzed in depth. A wheel-legged wall auto-cleaning robot with both wheel-legged and wheeled moving modes was designed using modular design method, which consisted of wall climbing robot, cleaning operating system and relational connection mechanism, safety device and control system.According to general design requirements of wall cleaning robot, three kinds of adsorption and motion system design plans of wheel-legged wall auto-cleaning robot adopting multi-sucker vacuum adsorption were presented in this dissertation, which all integrated functions of adsorption, motion, overstepping obstacle, transition from surface to surface and pose adjustment. By comparative analysis of the three plans, the joint motion system design plan with both wheel-legged and wheeled movement mechanisms was adopted. On this basis, the basic conditions of reliable adsorption and movement of the robot in two moving modes were achieved by mechanical analysis.The detailed design of the selected adsorption system was completed, which as design of vacuum coupling delivery and adsorption system included the design of adaptive multi-antrum vacuum sucker and negative pressure synchronous distributor and the selection of vacuum generator and high-pressure gas source. Each sub-vacuum chamber in sucker was connected to common-chamber by a vacuum valve, and rubber seal with good deformation ability was installed around the sucker, therefore independent and effective absorption of every sub-vacuum chamber and every sucker was ensured. Sucker was connected with arm of wheel-leg through ball hinge, which made the sucker self-adaptive to wall. Meanwhile aiming at complicated work environment, three design plans of negative pressure synchronous distributor as key connection mechanism between wheel-leg and vacuum generator were proposed and comparatively analyzed.The detailed design of the selected joint motion system was completed, which included overstepping obstacle capacity analysis and design of wheel-leg mechanism, wheel mechanism design, transmission design, cylinder and its auxiliary guide-bar mechanism design. Among them, three sets of wheel-leg sucker mechanisms were driven by a motor and corresponding chain, which made the robot with one moving degree of freedom in the direction parallel to the wall and solved the"slanting track"problem and improved movement accuracy. Two sets of wheel mechanisms were driven respectively by one motor, which adopted inclinometer for pose closed loop control and realized swift turn of robot. The above-mentioned joint motion system effectively integrated with adsorption system can cooperatively complete functions of adsorption, movement, closing to obstacles, overstepping obstacle, transition from surface to surface and pose adjustment of robot in the process of operation. This integrated motion and adsorption system made the wall climbing robot with strong adaptive ability to wall like legged robot and with high velocity like wheeled robot by simple and lightweight structure. Based on the above-mentioned work, the processes of planar motion, pose adjustment, overstepping obstacle and transition from surface to surface of wall climbing robot were analyzed in depth.Aiming at the current situation of most wall cleaning robots operating only top-down one-way without the function of sewage purifying and recycling, three kinds of cleaning operating system with the functions of two-way (or four-way) operating, sewage purifying and recycling were successfully designed using modular design method and improve operational efficiency largely. Among them, due to the increase of water spraying process, dual-chamber cleaning operating system with two-way operation ability combined the detergent wash, brushing, water spraying and scraping cleaning modes and maximized the cleaning effect. In addition, aiming at the characteristic of wheel-legged wall auto-cleaning robot with displacement fluctuation in the direction perpendicular to wall, elastic connection mechanism self-adaptive to height for flexible integration between cleaning operating system and robot body was designed and made the cleaning operating system self-adaptive to wall roughness, height fluctuation of robot body and adsorption pressure fluctuation, which made the robot have functions of constant pressure operation, unique constant pressure overstepping obstacle and effective cleaning of window frames. The elastic connection mechanism can also be used to connect operation system to other robots, which has a certain universal significance.Kinematics and dynamics analysis and modeling is the basis of robot control. The Sheth-Uicher transform was used to build the kinematics equations of wall climbing robot respectively in wheeled and wheel-legged moving modes. The positive and inverse solutions of the kinematics equations were gained and kinematics simulation aiming at several typical motion states was carried out, which provided the theory support for motion control of the wall climbing robot. On this basis, theoretical research on position and pose conjecture arithmetic of the robot respectively in both moving modes was completed. Furthermore, Routh equation, Maggi equation and Appell equation were used to establish the dynamics model of the wall auto-cleaning robot in two moving modes. The positive and inverse solutions of the dynamics equations were gained, and three kinds of dynamics equations were comparatively analyzed. Dynamics simulation was carried out and provided the necessary conditions for selection of the motor and dynamic control of the robot.At the same time using path planning method of mobile robot for reference, a complete cover path planning method considering main movement direction and integrating grid method with heuristic search algorithm was proposed and can be used for wall cleaning robot with two-way (or four-way) operation capability, which significantly reduced trajectories overlap and improved the performance of path planning.In short, the wall auto-cleaning robot with strong adaptive ability to wall and strong overstepping obstacle in this dissertation is simple, flexible, lightweight, fast, accurate, versatile, easy to control, suitable for a variety of walls of different materials and regular shapes. The integrated adsorption and motion system, cleaning operating system and elastic connection mechanism adaptive to height, etc. can also be applied to many other robot systems. Wheel-legged wall climbing robot as load and mobile platform can evolve into other special service robots for inspection, derust, spray-paint, anti-terror, etc. by combining with other operation tools, which owns broad market potential.