Study on Low Noise Wallclimbing Robot Based on Negative Pressure Suction
|School||Harbin Institute of Technology|
|Course||Mechanical and Electronic Engineering|
|Keywords||Wall climbing robot Safety analysis Negative pressure suction system Control system|
Wall climbing robots, being able to move on the vertical wall, can carry tools to clean a wall, spray shell structure of ships, detecting oil storage, aircraft and bridge where it is hard to reach or dangerous for mankind. Advanced special devices for reconnaissance purpose in dangerous area are demanded by security department. Carrying camera and mike, wall climbing robot as a scout can sneak to guilty place from wall surface and then transmit pictures and voice to control center, which plays an important role in anti-terror, reducing the danger and protecting the security force efficiently.Due to the special application circumstance, good adaptability on wall for guaranteeing the safety of the robot, high moving speed to reduce time moving to the goal place, low voice are specially demanded to prevent from detecting by criminals. A wireless portable wall climbing robotic system for reconnaissance purpose was developed to meet the specification of the project, which size is 320x280x150mm, the weight is less than 5kg, the locomotion speed is more than 10m/min, the working duration is 45-70min, the noise in 1m is less than 70dB. Based on analysis of safety attraction, the least negative pressure value is deduced while the robot is static and dynamic moving on the wall. Since negative absorbing process model is the base of negative pressure adhesion system design and negative pressure control, A mathematical model of the transient sucking process was made with bond graph theory by reasonable assumptions, and simulations were made by 20sim software. Since the locomotion system model is the base of locomotion control, it was made after analyzing the stress impacting on the locomotion system between the wall and wheels.Low noise and high efficiency suction equipment and sealing mechanical part of small fiction and good adaptability on wall were carefully studied as key technical problem of the wall climbing robotic system for reconnaissance purpose. After analyzing the mechanics of noise, a stable pressure generating radical fan of high efficiency was designed with the Computational Fluid Dynamics (CFD) tool keeping in mind of requirements of a wall climbing robot after pneumatic thermodynamics analysis. The sealing system should automatically prevent leakage between the robot and the wall and reduce the flow mass to keep the fan working under the expecting condition based on fluid dynamics. The sealing system has advantages of low friction and efficient seal performance. To reducing noise further, sound insulating and noise deadening ways were taken after analyzing the noise reducing principle.The control system of wall climbing robot is based on ATmega128 processor which implementing sensors data fusion, motor control and wireless communication. Pressure and posture control are important content of research on wall climbing robot. This paper proposed a two loop pressure fuzzy control system which inner loop is current loop and the outer loop is pressure loop after studying the fluid flow leakage influence on the state of the control system. A composite posture control system was designed after analyzing the pressure and weight influencing on the posture. Simulations and experiments were conducted and the result was presented to confirm the control system satisfaction on the application.At last, the experiment setup was built to evaluate the performance of negative pressure suction system, general abilities of wall climbing robot. Experiment results show valid analysis and design of robot. Wall climbing robot can move at a high speed, stably attract on wall and accomplish reconnaissance mission successfully. The theoretical and experimental result of research on wall climbing robot will contribute to further perfect the performance of robot design. At the same time, a wall climbing robotic system for reconnaissance purpose can be used as a novel equipment for secure department in urban area.