Investigation On Flutter Testing Model Suspension System Based On Underconstrained Wire-Driven Parallel Robots

In this paper,according to the urgent need of support device for wind-tunnel complete-model flutter test,a two-cable suspension system is designed based on the underconstrained WDPRs(Wire-Driven Parallel Robots).The kinematics and statics of the underconstrained WDPRs are modeled and simulated.Using ADAMS,simulation and analysis of the motion and stability of the model on two-cable mount system are carried out.The first-generation prototype of the mount system is designed and built,and aircraft model on the prototype is designed and manufactured,as well as the positioning and assembling device for the aircraft model.The variation law between rotation rigid body modes frequencies of the supported model and cable tension is given by experiments,and a new method of indirect measurement of rotate rigid body modes frequencies by cable tension is proposed and verified.First of all,the intrinsic coupling between the kinematics and statics of underconstrained WDPRs is expounded,and of which the geometrico-static model is established.The solving process and method of direct/inverse geometrico-static problems are discussed in detail,and different coordinate parameter representations of the direct geometrico-static problems are mainly introduced,as well as homotopy algorithm for solving nonlinear polynomial equations.MATLAB and DGP-Solver software are used to simulate the computing from the inverse geometrico-static problem to the direct geometrico-static problem,which provides a theoretical basis for the wire system design and motion control of the support device.Secondly,the design requirements of the suspension system are described,the basic structure of the suspension system is designed from the four aspects of motion control,pose measurement,tension measurement,and safety.Different suspending methods are compared and the two-cable mount system are selected,on which the motion and stability of the model are simulated and analyzed in ADAMS successively under the following three conditions:gravity,changing the stiffness of the suspension system with springs,aerodynamic load of the wind-tunnel test.Then the rack structure and pulley arrangement points were designed according to the wire-system layout.The design and assembly of the drive device and the design and selection of the visual device were completed.The first-generation prototype of the suspension system was built,providing a test platform for the follow-up related research.Once again,for the functional test and exploration test of the prototype of the first-generation suspension system under windless conditions,a universal model with built-in adjustable pulleys and civil aircraft structure shape was designed and manufactured;For the future case of suspending models with built-in rod type six-component force balance on the suspension system,a device that can reliably position and installation the model and balance is designed and fabricated.The model can easily adjust the position of the center of mass,change the direction and the connection mode of the wires.Finally,the effect of cable tension on the rotation rigid body modes frequencies of the supported model is experimentally studied,on the first-generation prototype,of which the variation law is given.The method of indirectly obtaining the rotation rigid body modes frequencies of the model by wire tensions is proposed and its feasibility is verified.This method has a certain degree of innovation.The relevant conclusions can provide reference for engineering applications,and accumulate practical experience for prototype improvement.This paper makes a pioneering research work on the complete-model flutter test suspension system based on underconstrained WDPRs,which lays a foundation for further research and development.