Star Tracker Functional Test (Matlab)

Introduction

Test Description: Testing the function of the ST-16RT star tracker (EM) using the provided Matlab functions.

Completed: 17/03/2025

Documented by: Riley Sweeney

Resources Required:

• Tools: 

• Hardware and Equipment: EM star tracker, variable power supply, USB to RS485 adapter, computer with ST GUI and matlab installed, flashlight

• PPE: Use ESD bracelet and mat when handling any electronic hardware.

Verification Activities: R-LIB-ADC-003-6367, R-LIB-ADC-005-5877

Pass Criteria: The star tracker shall collect an image when commanded.

ST Matlab Test Set-Up

This test will follow a similar setup and procedure to the test using the GUI, however this will allow viewing the resulting image. Since the star tracker is quite sensitive to ambient light, it will be placed in a box with a light shining through a pinhole to avoid oversaturation.

1. Connect the RS-485 adapter to computer via USB. Drivers may need to be installed to enable function.

2. Connect the ground and power pins on the RS-485 adapter to the power supply.

3. Connect the RS-485 port to the star tracker.

4. Set the power supply's voltage to 12 V to represent the voltage it will receive from LI Bus.

5. Place the star tracker inside a box, with the lens pointing toward the pinhole.

6. Close the box to reduce the ambient light.

7. Turn on the power supply.

8. Launch Matlab.

ST GUI Test Procedures

This test will ping the star tracker and take an image using the provided Matlab functions.

1. A ping will first be sent to the star tracker to confirm the interface between Matlab and the star tracker. This will use the "pingComPortST16RT2" function. Inputs for this function include "comPort", "nspAddr", "fullPing", and "unitNumStr".

2. Call "pingComPortST16RT2". The results should include the unit number and the processor serial number.

3. With a successful ping, a picture can now be taken. Prior to this, turn on a flashlight and point it through the pinhole.

4. Call the takeApicture function. Note that within this function, the image size can be specified (max is 1024x1024). Note that larger images will take longer to process and plot.

ST Matlab Results

The above image shows an 800x800 pixel image showing the ambient light in the lab coming through the pinhole.

The image above shows a 300x300 pixel image with a flashlight shining into the pinhole.

This image shows ambient light entering a pinhole to the left of the original pinhole shown in the previous figures (this pinhole was covered).