滑动爬壁机器人英文文献和中文翻译(3)
This paper presents the conception of SWCR’s adsorption performance, discussing technical means and theoretical methods to improve its adsorption performance in the two aspects mentioned previously. The paper is arranged as follows: Section 2 discusses how to turn as much as possible adsorption force into driving force.
Section 3 builds thermodynamics and hydrodynamics models of centrifugal-impeller based suction system, seeks
ways of improving the utilization rate of power. With the aid of computational fluid dynamics (CFD) simulation, section 4 puts forward a design method for SWCR-specific centrifugal impeller, aiming at improving efficiency under a certain flow rate. Section 5 introduces a prototype “BIT Climber” developed by our laboratory and discusses related tests. Finally, experimental results, conclusions and future work are given in section 6.
2 Distribution of Given Adsorption Force
Adsorption force Fa of SWCR refers to the force perpendicular to the wall caused by pressure difference between inside and outside of the chamber. Usually, when robot adheres to the wall, Fa is balanced by three forces together, as shown in Fig. 1
Fig. 1. Equilibrants for adsorption force
(1) Supporting force on driven wheels is Fsd, which can be turned into static friction force and is the only source of robot’s propulsion and load capability, it’s a necessary part of adsorption force.
(2) Supporting force on passive wheel is Fsp.
(3) Supporting force on seal is Fss.
Ideally, balance force for Fa contains only Fsd, because Fsp and Fss can not be transformed into load capacity and mobility, moreover, when the robot moves, Fss will bring additional sliding frictional resistance. From this point of
view, the ratio ηa of Fsd to Fa should be as large as possible. However, the existence of the passive wheel not only brings on simplification of the robot’s locomotion mechanism and reduces the complexity of control, but also prevents lateral sliding of wheels to ensure control precision[19–20]. And Fss can increase the flow resistance of sealing device, which is favorable to reducing the adsorption power.
2.1 Locomotion mechanism
Four kinds of locomotion mechanism are raised as shown in Fig. 2, a, b have lower utilization rate of adsorption force, but they have the advantages of simple structure and control method.
Fig. 2. Diagram of mobile mechanism
If the robot needs an independent implementation of a long time task, the pursuit of low noise and high adsorption performance requirements, c or d type should be chosen, because they have high utilization rate of adsorption force.
2.2 Sealing device
After the selection of locomotion mechanism, the issue of seal’s pressure allocation needs to be considered. shows that, the smaller ks gets, the bigger supporting force will be allotted on driven wheels. Moreover, the frictional resistance of sliding seal will getreduced as ks does, so that the value of Fa that is necessary to make the robot adhere reliably can be made smaller, which is helpful for power saving. However, a too small will cause a sharp reduction in flow resistance, which would substantially increase the suction power and have apernicious influence on suction system’s aerodynamic performance. QIN, et al[25], studied the effect of ks on suction power of an SWCR robot which uses a pneumatocyst ring as seal, it turns out that, when ks is within 0.35–0.50, the suction power can be maintained at a relatively low level. The labyrinth-type sealing element could keep ks at a lower range.
3 SWCR Suction System Using Centrifugal Impeller
This section will take suction system as research object, in-depth study the formation principle of adsorption force, describe fluid state changes in the suction circuit from the thermodynamical and hydromechanical point of view, present the factors that determine the value of Fa and theoretical method to lower power consumption under the same Fa.
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