Moving Platform Deployment of MEMS Accelerometers for Gravitational Gradiometry

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Measurements of high frequency seismic activity using modern accelerometers can now detect motions of the Earth to the seismic noise-limit, defined by the New Low Noise Model. With this limit reached, research has aimed at deployments in harsher environments, cheaper deployments and more compact designs. One successful route to achieve this has been MEMS-based devices.One important scientic endeavour which requires a combination of all three of these specications was a deployment not to measure earthquakes,but instead marsquakes with NASA's InSight mission. This was achieved using a micro-machined single wafer silicon accelerometer, developed at Imperial College. The short-period, or SP, accelerometer was designed to be small and light, with a radius equivalent to a pound coin. It was demonstrated to withstand a 1200g 10 ms half sine shock, as well as temperatures between -80C and +60C.The goal of this project is therefore to develop a drone-based platform which can remotely detect voids and / or large variations in density beneath the Earth using the previously developed SP accelerometer. One proposed application is to not mount the accelerometer(s) onto a fixed body (e.g. a planet) but instead to deploy onto a moving body (e.g. a drone). However, during the deployment of drones, the following challenges can be encountered:1. Rejection of Drone Dynamics2. Real-Time Scale Factor Matching3. Mis-alignment Noise Injection4. Other Noise SourcesThe key aim of this project is, therefore, to develop analogue circuitry and analysis code to compensate for those challenges and allow detection of subterranean voids from a drone-based platform. An initial demonstration of the success of individual components via simulation and post-processing will allow the viability of the full system to bedemonstrated. Once a full prototype has been developed, a demonstration of the sensors detecting the gravitational signal of a stationary mass in anon-inertial frame of reference (e.g. undergoing translational and rotational accelerations in 6 effective dimensions) will be performed as a proof of concept. This will demonstrate the systems ability to consistently measure nano-g signals in real-time under favourable conditions, such as no wind.