Moving Platform Deployment of MEMS Accelerometers for Gravitational Gradiometry

使用现代加速度计测量高频地震活动现在可以检测到地球运动达到新的低噪声模型定义的地震噪声极限。随着这一限制的达到，研究的目标是在更苛刻的环境、更便宜的部署和更紧凑的设计中进行部署。实现这一目标的成功途径之一是基于MEMS的设备。一项需要结合这三项技术的重要科学努力是部署不测量地震，而是与NASA的洞察任务相匹配。这是使用帝国理工学院开发的微加工单晶硅加速度计实现的。短周期或称SP的加速度计设计得又小又轻，半径相当于一英镑硬币。它被证明可以承受1200克10毫秒的半正弦冲击，以及-80摄氏度和+60摄氏度之间的温度。因此，该项目的目标是开发一种基于无人机的平台，可以使用之前开发的SP加速度计远程探测地球以下的空洞和/或密度的巨大变化。一种拟议的应用是不将加速度计(S)安装在固定物体(例如行星)上，而是部署在移动物体(例如无人机)上。然而，在部署无人机期间，可能会遇到以下挑战：1.拒绝无人机动力2。实时比例因子匹配3.未对准噪声注入4.其他噪声源因此，该项目的主要目标是开发模拟电路和分析代码，以补偿这些挑战，并允许从无人机平台探测地下空洞。通过模拟和后处理初步演示单个组件的成功，将使整个系统的可行性得以展示。一旦开发了完整的原型，将进行传感器在非惯性参照系中检测静止质量的重力信号的演示(例如，在6个有效维度上经历平移和旋转加速)作为概念验证。这将展示该系统在有利条件下(如无风)持续实时测量纳米g信号的能力。

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.