Design And Research On SMA Robot Hand Driven By Heat Pump

As an important branch of intelligent materials,shape memory alloy(SMA)has been widely used in various application scenarios due to its unique material properties.Generally,most of the related applications simply use one part of SMA's characteristics,which lacks a comprehensive consideration of energy efficiency,response rate,feedback and other issues.In result,it is hard to see massive production of concerning applications.As a special energy-saving device,heat pump can work to generate a temperature difference,which is exactly what needs for the actuation of SMA component.Also,with a forced thermal convection strategy,the use of heat pump can simplify device structure as well as improve the response rate of SMA component.Besides,heat pump can collect the residual heat during working process,which will greatly improve the energy efficiency of SMA component.Based on such an engineering background,this thesis designs a SMA robot hand driven by heat pump.The main purpose of the design is to achieve a high comprehensive performance,which includes device compactness,energy efficiency,response rate and feedback control.Firstly,a heat exchange system is designed based on the working characteristic of heat pump.Afterwards,SMA driving component and robot hand are designed,and related theoretical models are established to realize a controllable output.The main work of the thesis is listed as follows:In chapter 1,background and research status of this thesis are presented.The loading characteristics and driving methods of SMA component are analyzed,main fields and limiting factors of SMA applications are introduced.Working characteristic of heat pump is also elaborated for further research.In chapter 2,related theoretical models are constructed,which mainly include constitutive model of SMA material,motion model of robot hand and energy efficiency analysis model of heat pump.These models can provide a theoretical guidance for the subsequent device design as well as a theoretical analysis of the final experimental data.In chapter 3,design of the heat pump driven system is carried out.Specific type of heat pump and SMA component are designated,for which,concerning thermal convection devices are separately designed.During this process,many factors need to be well taken care of,which includes transfer of heat exchange medium,control of the working procedures,heat loss and manufacturing of the SMA spring.In chapter 4,a multi-joint robot hand is designed and assembled.As an execution terminal,it needs to work with a good cooperation of the previous heat pump driven system.Concerning work of this part includes choice of transmission methods,design of specific joints,and installation of sensors.In chapter 5,several experimental testes are carried out on the SMA robot hand,which mainly includes the mechanical performance test of the SMA spring,the response test of the robot hand,the working characteristic test of the heat pump,and the final energy efficiency test of the whole device.Feasibility of the device design is verified through these tests.Also,a comparison between experimental data and the simulation is carried out to make a theoretical verification.In the last chapter,The work done is summarized.Based on analysis of the experimental results,several proposals for improvement are made and some further prospective research ideas are raised.