Theoretical And Experimental Study Of Planar Mobile Platform Drived By Single Centrifugal Force Generator

For some applications that have some restrictions on the moving space or special requirements for the working environment,the design using the general wheels or multiple legs to drive robot is often not suitable.Because the wheels and legs are often located outside the main body of the robot,it is needed transmission devices to transmit power from the power source to these actuator components.That will increase the complexity of the robot structure,limit the minimum size of the robot,and increase the difficulty of sealing the whole robot.It makes the device cannot meet the working requirements of some special environments,such as corrosion,radioactive pollution and so on.Using vibration-driving methods can eliminate the transmission and external moving parts.At present,the vibration-driving device is usually using piezoelectric technology,but it has high requirements for power supply system,which require external power supply.Therefore,it has to use cables to supply the power,which are not suitable for micro robots.In recent years,research on micro-robot driving platform using centrifugal force generator instead of piezoelectric crystal has emerged.However,the existing problems are as follows:in order to realize the planar motion of the platform,the existing design schemes often use multi-motor linkage control.Because the multi-motor linkage system is complex and needs to occupy additional space,the size of the platform is not easy to be reduced,which make it cannot meet the driving requirements for small and micro robots.To solve the above issues,aiming at realizing the controllable planar motion of the small and micro driving platform by using one single centrifugal force generator,the planar motion of centrifugal force driving platform using one single centrifugal force generator is studied in this thesis.The main work of this thesis is as follows:(1)In the early research of centrifugal force driving devices,variable centrifugal force was mainly used,and it was always generated by changing the radius of the rotation inertia mass by mechanical mechanism.For this kind of driving scheme,the feasibility of using one single centrifugal force generator to realize planar motion is evaluated by simulation and experiment.The research results further confirm that centrifugal force driving devices must be based on the existence of external friction.At the same time.it is found that this kind of variable centrifugal force driving scheme cannot achieve planar motion depending on only one single centrifugal force generator.(2)At present,small and micro robots usually realize centrifugal force driving by combining constant centrifugal force and variable friction force.For this kind of driving scheme,the feasibility of using one single centrifugal force generator to realize planar motion is evaluated by simulation and experiment.Simulation results and experiment results show that this kind of device can only realize controllable one-dimensional bidirectional motion with using only one single centrifugal force generator,and cannot realize planar controllable motion.(3)For the current driving scheme that combining constant centrifugal force and variable friction force,it is noticed that their common characteristics is that their centrifugal force acting points generally coincide with the center of mass of the mobile platform in this thesis.In order to realize the controllable planar motion of the mobile platform driven by one single centrifugal force generator,a design scheme using one single centrifugal force generator is proposed,its main feature is that centrifugal force acting point does not coincide with the center of mass of the mobile platform.The theoretical analysis,numerical simulation and experimental results show that the basic motion of the mobile platform driven by one single centrifugal force generator is planar motion.By controlling the rotation direction and rotation speed of the motor,a macroscopic Z-shaped motion path can be formed,so that the planar motion can be controllable.(4)Aiming at the condition that the influence factors of the driving effect of the planar mobile platform using one single centrifugal force generator are ambiguous,the influence of structural parameters and motion parameters on the driving effect was studied.The research results show that:increasing the inertia mass's rotation angular velocity,or its rotation radius,or its mass ratio will increase the motion speed of the centrifugal force driving platform;for the given structural parameters of the driving platform,there exists an optimal friction coefficient between the driving platform and the supporting surface,which can maximize the motion speed of the driving platform.(5)For the planar driving platform proposed in this thesis,its motion characteristics in horizontal straight pipes and curved pipes are also studied by the simulation and experiment.Through the simulation and the experiment,it is found that the driving platform moves along the axis of the pipeline when moving in horizontal straight pipes and bending pipes,but its direction of motion is not controlled by the motor's rotation direction.During the motion of the platform,centrifugal force generator always lies behind the platform's center of mass,so the desired direction of motion can be obtained by changing the position of centrifugal force generator on the platform.The obtained simulation results and experiment results can provide some reference for the practical application of this kind of driving platform in pipeline.Compared with the traditional driving method,centrifugal force driving platform has the characteristics of simple structure,easy miniaturization and easy sealing.Because the conventional motor is used as the driving power source,special power supply system is no more needed.Compared with the similar device using piezoelectric crystal,it does not need cables to operate,which embodies good engineering practicability and economic efficiency.This driving platform is not only suitable for narrow space,but also has practical application prospects in situations where the external environment is bad(such as corrosive,radioactive environment,etc.)which needs the robot to be sealed as a whole.