The Six Points Measurement Device With Six Bars For6-dof Motion Platform And Its Position Solution

Objects in space have six degrees of freedom,the position of objects in space can beuniquely identified when we know thesix degrees changes of freedom. Six degrees offreedom motion mechanism can move along in the directions of the three axes and aroundthe three axes of rotationsin space which arecalled six degrees changes offreedom.Measuring devicefor six degrees of freedom motion mechanism is used formeasuring the position of objects and also can followsix degrees of freedom motionmechanism to occur six degrees changes of freedom in space.Stewart platform model with six degrees of freedom is the most classical model ofparallel institutions with six degrees of freedom.In1965,Stewart platform wasfirstlyappeared on paper of Stewart, a British scholar. Stewart platform is a parallel typemechanical device,which has high rigidity, high precision, high load capacity, fastdynamic system response, no cumulative error and so on. Compared to the traditionalmotion institutions,six degrees of freedom measurement device can be usedto testautomobiletires parametersin order to achieve the goals of parameter optimization andimproving the reliability and durability of automobile tires. Six degrees of freedommeasurement device can test EMU bogies parameters, the test results can provide parameteroptimization for the structural design of the truck bogieswhich can improve the reliabilityand safety of the truck. Six degrees of freedom motion platform can be used to create aplatform shaker which can be used for the fatigue durability tests of the engine simulationsystems or transmissionsimulation systems and so on. We can say that six degrees offreedom motion devices have appeared in many corners inourlife,and parallel institutionswith six degrees of freedomhaveimproved the quality of our life.This paper proposesa new3-3hingepointsmeasurement device with sixbars for6-dofmotion platform.Compared to the existing six degrees of freedom measurement device, thismeasurement device simplifies the number of hinge points, eliminates the internal structurestress, maintains a high movement precision with the structural design, and has a very goodversatility. This paper analyzes the structural features of the six pointsmeasurement devicewith sixbars for6-dof motion platform, selects a suitable magnetostriction displacementsensor modelfor the measuring device and analyze the position changes occurring in thespace of the measuring device followed with measured device.In this paper,withthe relationship between two points coordinate valuesand the distanceof two points in geometryspace, therelationship was establishedbetween a moving coordinateplate hinge pointand a static coordinates plate hinge pointof a magnetostriction displacementsensor assembly. Through the theory above in this paper establishesthe mathematical modelof inverse kinematicsfor the six pointsmeasurement device with sixbars for6-dof motion platform,and alsoestablishesthe mathematical model of forward kinematicsfor themeasurement deviceby Newton iteration principle andthe mathematical model of inversekinematicsfor the measurement device.This paper completesthe simulation model ofthe inverse kinematicsandforwardkinematicsfor the six pointsmeasurement device with sixbars for6-dof motion platform byMatlab/Simulink software,and simulatesinverse kinematicssimulation model in the case ofgiving sinusoidal excitation for the positionparameters.With the data obtained by inversekinematicsto verifythe correctness of theforward kinematics simulation model for themeasuring devices.Finally,the tests were done with the real six pointsmeasurement device with sixbars for6-dof motion platform, we measure rod lengthswhenthe position of the measuring devicechanges followed by measured device and six rods lengths changes. And then we substitutedthe six rods lengths data into forward kinematics simulation model for the measuring device,we can verify whether the forward kinematics simulation model calculation results areconsistent with the occurred changes of six degrees of freedom in space of the measuringdevice.In summary,this paper proposes a newsix pointsmeasurement device with sixbars for6-dof motion platform, and proposed the inverse kinematics and forward kinematicsmodelsfor the measuring device.this paper simulatesinverse kinematicssimulation model in the caseof giving sinusoidal excitation for the position parameters, andfinally verify thecorrectnessof theforward kinematics simulation modelby real tests, it is also the verificationthat the six pointsmeasurement device with sixbars for6-dof motion platform can completeto measure the six degrees changes of freedom for motion mechanisms in space, and thefoundation for the application of this measuring device in the future is laid.