Sensor Calibration
Re-purpose Old Scanner Bed
Introduction
What do you do with an old scanner bed? I stripped it down and made a testbed controlled with an Arduino and a motor controller shield.
Project Description
Moving the sled back and forth is easy but you have to be able to stop. I used an optical interrupter at one end and a distance sensor at the other.
The idea was to see if distance measurement would match the specs for an IR sensor, and then I added a new laser sensor and made some test runs.
I added safety measures to the test bed to protect against over-running the limits of travel. At the optical interrupter end, I added a micro-switch that kills the power to the motor and sends a signal to the processor. At the end where the sensors under test are, I added a push-button with a circuit to debounce the output to be appropriate to use an interrupt on the processor.
I only used 9V for the motor power so a simple voltage divider could cut that in half to 4.5V to use as a signal for the processor. The motor could run at 12V but that would be a power waste, since 9V propels the sled nicely.
The data collected showed the IR sensor was very erratic and of course, non-linear as its specs show. The laser sensor was very stable and linear. It is the clear winner and a good candidate for future electronic projects.
Sensor Cal
Intro Video:
Test Data Video:
Test Results
IR sensor non-linear and erratic.
Laser sensor linear and accurate.