Research On Evaluation Method Of 6-DOF Motion Simulator

A six-degree-of-freedom(6-Do F)motion simulation platform can generate complex motions with six degrees of freedom;therefore,it is usually used to mimic the motion of various carriers.In the development of the airborne gravity gradiometer,it is necessary to verify key technologies and evaluate the instrument's performance in the dynamic environment of the carrier.This study investigates the simulation of various base motions,on carriers such as airplanes,automobiles and ships,using a 6-Do F platform as the moving base,with the aim to provide a dynamic test environment for gradiometers.This study mainly addresses two problems,one is to obtain the motion data of a vehicle and analyze the characteristics;the other is to simulate the motion of the vehicle using the 6-Do F platform in the laboratory,and evaluate its simulation fidelity.In order to meet the requirements of dynamic testing of gravity gradiometer,the motion simulators were first investigated,using the MISTRAL 800 platform as the simulator.Then the sensors including accelerometers and inertial navigation systems were characterized and selected for the tests.Finally,a field vehicle test was conducted,obtaining the motion data of the carrier,including acceleration and attitude angle.In order to meet the data format requirements of the platform,the acceleration data is converted into displacement data.The two methods of time domain integration and frequency domain integration are compared;consequently it was discovered that the frequency domain integration is more suitable for practical use.The test results show that the 6-Do F platform can simulate the acceleration data well from 0.2Hz to 10 Hz range.According to the actual motion and analysis of the carrier,it is verified that the main component in the low frequency band(less than 0.2Hz)of the acceleration is the component of gravity acceleration generated by attitude Angle.For the evaluation of motion simulation fidelity,several mainstream evaluation methods are investigated.According to the specific application environment,the sensor-carrier loop and the sensor-6-Do F platform loop are established.The output data of 6-Do F collected by the sensor are selected as the evaluation index to evaluate the simulation fidelity.From the frequency domain,it is obtained that the simulation fidelity of the 6-Do F platform is 93 %.In this study,the instruments and sensors are selected,the motion data are collected,and the movement of the carrier is simulated by the MISTRAL 800 platform.Through detailed analysis of the simulated data,the fidelity of the 6-Do F platform is finally obtained.This study lays a foundation for the dynamic test of airborne gravity gradiometer,and provides a deeper understanding of the dynamic performance of the 6-Do F platform.