Optimized Design Of Structure Of Lower-Limbs Exoskeleton Based On Finite Element Method

The lower-limb exoskeleton robot is a kind of typical man-machine integration system which is worn on the outside of the operators' lower limbs.As a combination of machinery,detection,control,information fusion and other robot technology,it provides power to help the normal people do some sports such as walking,running,mountain climbing,etc.This will contribute to enhancing the abilities and speed when people walking,as well as easing fatigue which appear easily in the case of large weight and walk for a long time.In order to carry on designing and analyzing mechanical structure of exoskeleton,this paper will use finite element as a research method.The paper will be divided into four parts.For a start,according to the biological anatomy,we need study human body anatomy biological structure and motion mechanism of each joint of lower limb.It can be concluded the form of movement and the scope of the activity of human hip,knee,ankle.On the basis of these analysis of human lower limb,the structure of exoskeleton will be modeled.With SolidWorks 3D modeling,we can begin to design the exoskeleton mainly including hip?knee?ankle?selection of driving system and load-bearing device.In addition,taking the wear safety and comfort of human body into consideration,we need to increase some degrees of freedom to fit the human body movement,as well as need to set the limit structure in some appropriate places.In the next place,the static and dynamic mechanical analysis of lower-limb exoskeleton will be performed.As the lower-limb exoskeleton as a whole by a number of components,multi-body structure,so the need to establish multi-body dynamics model.We can look lower-limb exoskeleton as multi-body structure because it is composed of multiple components.In order to obtain related mechanics data while standing and walking,what we should do is to use finite element method to analysis.As a finite element tool,Ansys Workbench can help us to conduct static analysis of the organization,thus drawing deformation and stress distribution under various operating conditions.Then,the mathematical model of the dynamics is derived by using the five-link model in the case of appropriate simplification.With the purpose of providing basis for the choice of drive system,a walking gait cycle is analyzed with torque andpower of hip and knee.For the second time,the model analysis of the lower-limb exoskeleton will be performed.Exoskeleton worn on the body,components may appear all sorts of vibration when walking.What's more,too large vibration amplitude can lead to exoskeleton structure fatigue damage.Therefore,to ensure that the design of the exoskeleton structure performance meets the requirement,we need the modal analysis to analyze the structure of the exoskeleton and calculate the natural frequency and natural vibration mode.To test and verify the results I have got form above FEM,I compare my results of structural finite element analysis with the structural data and conclusions from other literature.In the end,basing on the finite element analysis results that have been obtained through the above study,we are able to determine the optimization variables and constraints easily for structure optimization design and improvement.Since the original design is determined by reference to similar products through estimates,empirical comparisons or tests,the designed structure often do not meet the required requirements.In order to improve the optimization efficiency,response surface and sensitivity are used to study the influence of the design variables for optimization target.The optimization is launched under limits of design specifications,which aims at improving wear performance,but also to ensure strength and stiffness of structure.Only by this can we get a set of reasonable ? scientific and anthropomorphic mechanism design scheme of lower-limb exoskeleton.