Introduction
The purpose of this module is to lead you through the process of collecting data on your system for use in fitting your model
Course Resources
- Optimization Module
- Experimental Validation Module
- Dynamics Module
Instructions
- Attach 3 optical tracking markers to the fixed base frame, at the same camera depth as your experimental setup. They must not be colinear, and would best be arranged orthogonally (as in x-y vectors)
- Measure the distance between all three markers.
- Measure the distance from your camera to the center of your experiment’s z-plane.
- Attach at least one marker to the output of your energy storage device / actuator so that it can alwyas be viewed by the camera. Attach more markers if you intend to capture flexibility, bending, or compliance.
- Attach your camera to the fixed/rigid frame using a tripod or fixed camera mount.
- Take a practice video and run it through your capture software to ensure the markers are always visible.
- Start recording. Use high-quality mode.
- Trigger your energy storage device or actuator with a step input. The input signal must be measurable (voltage & current, distance, force, etc) or calculable (mass, energy).
- Track the motion of your system until it stops moving. Make sure motion is planar.
- Export/save the video to your computer
- Using open source motion tracking software export the x-y position of all markers over time.
- Using the base frame markers as reference points, size and rotate your data to get x-y values in SI units.
- Using the model-fitting example in the optimization module, feed in the marker position data of the system output to the output of the model.
- Supply all known or measurable values
- Run the optimization to identify unknown system parameters
Discussion
- What optimizaiton method did you use?
- What worked? What didn’t work?
Suggestions
To add a known force, attach a known mass to a string, let it deflect and settle, then cut the string.
To displace a known distance, pull the device in a known direction with a string, measuring the displacement. Let it settle, then cut the string.
If measuring voltage and current, a power supply’s current reading may not be sufficiently fast enough to capture transient responses
If measuring anything that has a digital readout (but no serial output), make sure the readout is visible by the camera. You can then convert the voltage reading manually using the video time as a reference.