NASA CanSat CompetitionTechnical Document2020

Spin Stabilized Camera

A technical guide on camera stabilization methods for CanSat satellites, exploring both software and hardware approaches to counteract spinning during descent.

The Problem

If you want to use a camera in your CanSat, you better be prepared for spinning video. Your CanSat will be spinning due to parachute and wind. There is nothing to stop it from spinning.

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Spinning video without stabilization

So, what if you want to make it stabilized? There are two main approaches: Software Stabilization and Hardware Stabilization.

1

Software Stabilization

Understanding Video

Videos are fast-played images. You basically show 30 photos in 1 second. In every frame you change the image little bit. It's super fast so a human eye can't see the interrupts. It looks like moving.

16 x 16 pixels illustration

1.1

By Selecting a Point from Image

You can select something from the image. For example, you choose eye of the Mario and then you track its position. Then you can position the other pixels.

Drawback: This method means lots of effort for small processor, you need some serious memory and processor.

1.2

By Getting Yaw Value from Sensors

If you put gyro sensor to your spinning system then get the yaw value, you can know how much you need to tilt your image (or 2D array). But you still have a lot of work.

Let's calculate the effort needed:

  • Resolution: 640 x 480 = 307,200 pixels
  • Per frame: 307,200 × 24 bits ÷ 8 = 921,600 bytes
  • At 24 FPS: 921,600 × 24 = 22,118,400 bytes/second

This is for uncompressed video. Even with compression, it's too much data for small processors.

2

Hardware Stabilization

You can turn the camera physically. If your CanSat spins in Clockwise direction, you can turn the camera to Counterclockwise direction so image doesn't move.

YawRollPitch

Aircraft rotation axes

cameracansat

CanSat with counter-rotating camera

"My awesome paint drawing" - Original caption from 2020

Requirements:

  • Gyro sensor - to read yaw values
  • Electric motor - to spin camera in opposite direction
  • Separate battery - camera must be unattached with wires (they would tangle or break)
  • Motor encoder/decoder - to turn motor exactly the same degree that CanSat has spun

Method Comparison

Software

  • ✓ No additional hardware
  • ✓ Can be done post-processing
  • ✗ High computational load
  • ✗ Requires powerful processor
  • ✗ Large memory requirement

Hardware

  • ✓ Real-time stabilization
  • ✓ No processing overhead
  • ✗ Additional weight
  • ✗ More complex design
  • ✗ Separate power needed

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