Theoretical Analysis And Experimental Research On Near-singular Multidimensional Force Sensing Mechanism

For the urgent needs of multi-dimensional force sensing technology with different sensitivity in the fields of aviation,national defense and intelligent manufacturing,this paper based on the idea of “micro-force perception”,cleverly applies the near-singular configuration as a force-enhancing mechanism,and introduces the near-singular configuration into the design and development of multi-dimensional force sensing mechanism,to improve the sensitivity of different directions of the multi-dimensional force sensing mechanism.Taking near-singular flexible parallel multi-dimensional force sensing mechanism as the research object.Configuration design and configuration synthesis,stiffness model and force mapping model,performance analysis and structural optimization design,prototype development and calibration experiments are carried out.These works enrich the configuration of the multi-dimensional force sensing mechanism and provide new ideas for the application of near-singular multi-dimensional force sensing mechanism.Firstly,according to the characteristic that the near singular mechanism will produce larger internal force when exerting force/moment in some specific direction,the concept of near-singular isomerism design is introduced.Based on screw theory,the near-singular configuration is integrated with the flexible parallel multi-dimensional force sensing mechanism.Configuration design and configuration synthesis of near-singular multi-dimensional force sensing mechanism based on six-branch,eight-branch Stewart platform and SS branch are carried out respectively.Secondly,based on the deformation superposition principle and the deformation coordination condition,the stiffness model and force mapping model of near-singular multi-dimensional force sensing mechanism are theoretically derived,and the mathematical expressions are obtained.The mathematical model of the typical near-singular multi-dimensional force sensing mechanism is numerically validated by ANSYS Workbench,and the sensitivity amplification factor of the typical near singular six-dimensional force sensing mechanism is obtained.Then,the near-singularity performance index is proposed,and the performance index and sensitivity index are analyzed.The respective relationships between local structural parameters of near-singular multi-dimensional force sensing structures and near-singularity,sensitivity are discussed.Then based on the sensitivity index,the structural optimization design of the near-singular six-dimensional force sensing mechanism is carried out by joint simulation of SolidWorks and ANSYS Workbench.Optimization results increase sensitivity in a limited space.Based on the least squares method,the virtual calibration experiment of the near-singular multi-dimensional force sensing mechanism is carried out by MATLAB and ANSYS software.Finally,the prototype of the typical near-singular multi-dimensional force sensor is developed.The calibration system of the sensor is established,the calibration experiment scheme is formulated,and the calibration experiment of the sensor is carried out according to the calibration algorithm.The calibration matrix and nonlinear error matrix of the sensor is obtained.