Introduction
The purpose of this module is to develop a model for your actuator.
Steps
- Decide as a team what kind of actuator you will use. This semester you may choose any actuator or energy storage device you like, including
- A stretched or wound spring
- A preloaded beam
- A deformed elastic shape
- A motor, gear motor, or RC Servo
- Shape Memory Alloy
- … (see the professor to get something else approved)
- Develop a model which accurately captures the principal dynamics of the actuator.
- For metal springs, you will need to know the spring constant as well as any nonlinear hard limits (as in when a compression spring bottoms out).
- For elastic materials, you may need to capture
- nonlinear stress/strain or force/displacement curve
- rate-dependent loss (can be modeled as viscous damping)
- For motors, you will need to include:
- Coil resistance & inductance
- inertia
- input voltage
- gear ratio
- Measure or identify as many of the parameters as you can using scientific methods.
- Develop an experiment that measures force and/or motion of a system powered by your actuator, while controlling for or reducing the impact of unmodeled effects.
- include a picture and/or video of the experiment.
- run the experiment and collect data on how it moves when the actuator is activated.
- Include the actuator model developed above within a system-level model that includes the rest of your experiment
- include the masses or inertias that your actuator is connected to
- include other system compliance and damping effects as needed
- include the kinematics of the surrounding mechanism (such as the lever arm, external gear ratio, pulley diameter, etc)
- if there are unknown parameters, consider using an optimization step to identify the parameters
- Plot and compare the results of your model with simulation results.
- (Optional) If necessary, use optimization to improve your parameter estimates, and re-match your model to a second set of experimental data.
Discussion
Write a detailed description of how you accomplisehd each of the steps above. Be sure to include discussion on the following points:
- Assumptions you made
- Ways you eliminated unmodeled effects in the experiment
- Model elements you decided to approximate or simplify
- Description of your experiment
- Description of your system-level model
- Analysis of the quality of your model to capture the dynamics of your actuator, as well as a discussion of any optimization used to better fit your model.
Rubric
Description | Points |
---|---|
Actator Model | 20 |
Experimental Setup | 20 |
System Model | 20 |
Discussion | 20 |
Figures | 10 |
Images | 10 |
Total | 100 |