INTRODUCTION

Inspiration

LEAPFROG Research

One of our group members, Thanh Tran, has been working on a research project for the past two years that aims to develop a fully autonomous flight vehicle that can navigate extraterrestrial surfaces. The vehicle's attitude control system (ACS) currently utilizes paintball tanks to dispel cold air from various points to lift and balance the vehicle. There are several obstacles with this approach: first, these tanks don't generate enough thrust to stabilize the vehicle for long enough. Second, these tanks rely on fuel to generate air, which is a costly resource to have to rely on when exploring extraterrestrial surfaces. To combat these issues, we are exploring another flight stabilization method: reaction wheels.

acs_leapfrog.mp4

Interest

Why Reaction Wheels?

In spacecraft, reaction wheels are often used for attitude control because they save fuel by replacing thrusters that would otherwise be required and are also advantageous for small-angle adjustments. Although it would be difficult to generate enough torque via reaction wheels to propel large spacecraft, this approach is suitable for a smaller vehicle such as the LEAPFROG lunar lander. First, however, we'd like to test out the approach on an even smaller scale: this project aims to solve the inverted pendulum problem with reaction wheels as our form of actuation to serve as a model that can later be implemented into the LEAPFROG vehicle. Hence, our project is named after this lunar lander that we are attempting to contribute to.

Goals

The end goal of our project is to create a working model of the inverted pendulum problem using reaction wheels. Although this is an existing and common controls problem, we hope to make it our own by:

Implementing hardware and software from scratch to more accurately support and model the LEAPFROG vehicle than traditional models,
Utilizing a larger wheel to stick size ratio to generate enough torque to propel the LEAPFROG lunar lander,
Designing and 3D printing our own parts to make the mechanism modular and allow flexibility with switching out parts.

Intent

Application

We realize that it may be difficult to imagine how a self balancing stick will translate to a flight stabilization system. Indeed, the aim of this project is not to create a mechanism that we can immediately attach onto the LEAPFROG lunar lander to enable it to fly better. Instead, we aim to build a system that will help us gain a strong understanding of how reaction wheels work such that our model can serve as a basis for more intricate design problems. In this video, we see how reaction wheels are used as an attitude control system to make adjustments to the mechanism's roll, pitch, and yaw. In the future, we would like to utilize reaction wheels to make such adjustments but in the context of an inverted pendulum where the forces from the wheels are also used to propel the vehicle upwards in flight.

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