Determining Random Vibration Response of Terrestrial Rovers from Ground Inputs

Abstract

Terrestrial rovers will play an important role in space exploration on the Moon and Martian surfaces. Before a rover is launched there are several series of testing, and design changes to ensure the rover will last the life of the mission. Currently the Canadian Space Agency (CSA) works with companies such as Neptec to test prototype rovers at the CSA’s Mars Emulation Terrain (MET). This allows engineers and scientists to test new designs and equipment to handle the terrain that could be faced on another planet’s surface, by modifying suspension and damping systems. The current method of building prototypes and testing them on the MET is useful but costly and does not fully represent the surface topology that the rovers will encounter. The current work presents the foundation for determining a representative vibration input for a given terrain type, with a single model determining the vibration response of a lunar test rover. More specifically the vibration over a known aggregate was determined in the form of a power spectral density (PSD) to be used as an input to a finite element (FE) model, to give the response PSD of the rover. The predicted PSD of the rover was compared to the experimental PSD, and was within the probability of 3𝜎 of occurrence at specific frequencies thus verifying the FE model. It was determined that at low frequencies less than 1000Hz, the method of double integration was more reliable for generating vibration displacement trend data from accelerometer data for the rover and at high frequencies, above 1000Hz, the Omega arithmetic method was more reliable. Additionally, when the magnitude of the displacement is needed the omega arithmetic method should be used. The FE model is able to predict the absolute excitation and payload excitation for a given terrain PSD input, and can be used in the next step toward future modelling of the vibration inputs of a planet’s surface given its terrain’s topology.