Satellite for Optimal Control and Imaging

Mission Objectives

The SOC-i mission will carry an advanced guidance, navigation and control (GNC) payload capable of reorienting the spacecraft while satisfying multiple pointing constraints. SOC-i will also carry an Earth imaging camera, enabling it to take pictures of specified ground locations.

The mission will operate in space for 6 months, and will be supported by a UW ground station being developed in the Aerospace Engineering Research Building. It is a stated goal of the mission to be completely open-source, maintain code on our team's GitHub page .

Guidance Navigation and Control

The experimental GNC system is capable of reorienting the spacecraft while guaranteeing hard pointing constraints and minimizing the change in angular momentum stored in a set of three reaction wheels. In the figure below, the green cone represents a navigation sensor's field of view, while the red cone represents the camera's field of view. Reorientation maneuvers must be executed such that (i) the sun vector remains inside the green cone, (ii) the sun vector simultaneously remains outside the red cone and (iii) actuator and slew-rate limits are not violated. The satellite must compute these solutions on-board without any pre-loaded solutions or ground intervention.

The payload leverages previous work done at the UW in this area. In particular, we adapt methods from (Kim et al, 2010) and (Lee and Mesbahi, 2013) to formulate the problem. Solutions are obtained in real-time using the ECOS solver running on the main flight computer. Our implementation is an on-going process, but will use elements of optimal control theory or Successive Convexification .

Software

See the open source GNC code based in Matlab/Simulink.

System Validation

Read about our experimental GNC system validation

Publications

See our publications to read more on this topic.

Imaging System

We have selected the uCam-III from 4D Systems as our on-board camera. The camera will be mounted on the long-axis of the 3U chassis. More to come as we develop the system!

Project Partners