Squishy Robot Simulator: Physics Settings *
|Areas of Science||
|Time Required||Short (2-5 days)|
|Prerequisites||Familiarity with VoxCAD software. We recommend completing our introductory VoxCAD project first.|
|Material Availability||This project requires the free VoxCAD software and a computer running Microsoft® Windows®.|
|Cost||Very Low (under $20)|
AbstractIn our introductory VoxCAD project, we provided you with a template file that included default material properties and physics simulation settings. These settings include friction, gravity, and temperature — all of which can drastically change how fast your robots move. However, we did not explain what exactly all these physics simulation settings meant, or how to change them. You can access the physics settings through the Physics Settings tab after entering the Physics Sandbox mode, as shown in Figure 1:
Figure 1. Access the Physics Settings tab in Physics Sandbox mode, which you enter by clicking the Physics Sandbox button in the toolbox at the top of the screen.
We highly recommend watching this video tutorial as an introduction to the different physics settings:
For reference, we have listed the available settings here. Note that you can also hover your mouse cursor over the text describing each setting in the VoxCAD window to read a description. Note: this page was created in July 2013 using VoxCAD version 0.9.9. Future versions of VoxCAD may add or remove options, or change the exact locations of different buttons in the program. The general concept should remain the same, so this page should still serve as a good introduction to the physics settings.
These are always available toward the top of the Physics Settings tab:
- Stop condition determines whether your simulation will stop automatically, or wait for you to hit the Pause button. There are several different options for stop conditions.
- Time step changes the amount of time between each step of the simulation. A smaller time step will make the simulation slower but more accurate. In general, you want to keep the time step as small as possible.
- Ground damp ratio determines the "damping" (similar to friction) between objects and the virtual "world" surrounding them. A low ground damp ratio will enable objects to move around with relative ease, like moving through air. A high ground damp ratio will make it more difficult for objects to move, like moving through water or syrup.
- Enable self collision: This checkbox determines whether different objects will bounce off each other. If left unchecked, objects will pass through each other.
- Collision damp ratio determines the amount of energy lost in collisions. A low collision damp ratio will make the simulation more "bouncy" when objects collide with each other or the ground. You must check the enable self collision checkbox to use this control.
These settings are available under the Environment sub-tab:
- Enable temperature: This checkbox enables simulation of temperature, which will affect materials that have a non-zero coefficient of thermal expansion. When checked, you can set the model temperature in °C using the slider bar or the text box to the right.
- Vary temperature: This checkbox enables temperature oscillations, with an amplitude set by the Temp ( °C) slider (or textbox) and a period set by the Period (sec) slider (or textbox). Materials with nonzero coefficients of thermal expansion will alternately expand and contract if this option is turned on. A bigger period means slower oscillations, and a smaller period means faster oscillations.
- Enable gravity turns gravity on or off in the simulation, with a value in meters per second squared (m/s2) set by the slider bar or text box. Note that "down" requires a negative number for gravity — if the number is positive, your objects will fall "up," away from the virtual floor.
- Enable floor turns the floor in the virtual world on or off. If you disable this while gravity is on, objects will "fall" through space.
These settings are available under the Other sub-tab:
- Bulk damp ratio: This value adjusts the damping between connected voxels — a higher bulk damp ratio is like having more friction at each bond. A low bulk damp ratio will make your model more "jiggly".
- Enable velocity limit: This checkbox enables you to limit each voxel's maximum velocity.
- Maximum voxel velocity determines the maximum velocity at which voxels can travel. You must check the enable velocity limit checkbox to use this control.
Remember, this is an abbreviated project idea, so exactly what you do next is up to you. Here are a few suggestions:
- Import the robot simulations you used for the introductory VoxCAD project. What happens to your race as you change the period of the temperature oscillations? Does it change the speed of your robots? Does the race have a new winner, or does the order stay the same? Do some robots have a maximum speed that only occurs at a certain frequency? If so, look up the concept of resonance.
- Can you design a robot that completely changes the way it moves depending on the magnitude of the temperature oscillations? For example, can you design a robot that bounces with low temperature changes, but rolls with high temperature changes?
- How does changing the different damping coefficients affect the speed of your robots?
Ben Finio, Ph.D., Science Buddies
- Windows is a registered trademark of Microsoft Corporation.
Cite This PageGeneral citation information is provided here. Be sure to check the formatting, including capitalization, for the method you are using and update your citation, as needed.
Last edit date: 2017-11-06
- Hiller, J. (n.d.). VoxCAD. Retrieved December 20, 2016, from https://sourceforge.net/projects/voxcad/
- Hiller, J. (2011, April 27). VoxCAD tutorial 5: Simulation. Retrieved March 27, 2013, from http://youtu.be/9DjrLWaCgTE
News Feed on This Topic
Ask an ExpertThe Ask an Expert Forum is intended to be a place where students can go to find answers to science questions that they have been unable to find using other resources. If you have specific questions about your science fair project or science fair, our team of volunteer scientists can help. Our Experts won't do the work for you, but they will make suggestions, offer guidance, and help you troubleshoot.
Ask an Expert
If you like this project, you might enjoy exploring these related careers:
Robotics EngineerHave you watched "The Transformers" cartoon series or seen the "Transformers" movies? Both shows are about how good and evil robots fight each other and the humans who get in the middle. Many TV shows and movies show robots and humans interacting with each other. While this is, at present, fantasy, in real life robots play a helpful role. Robots do jobs that can be dangerous for humans. For example, some robots defuse landmines in war-stricken countries; others work in harsh environments like the bottom of the ocean and on the planet Mars. At the heart of every robot is a robotics engineer who thinks about what a robot needs to do and works with several engineering disciplines to design and put together the perfect piece of equipment. Read more
Mechanical EngineerMechanical engineers are part of your everyday life, designing the spoon you used to eat your breakfast, your breakfast's packaging, the flip-top cap on your toothpaste tube, the zipper on your jacket, the car, bike, or bus you took to school, the chair you sat in, the door handle you grasped and the hinges it opened on, and the ballpoint pen you used to take your test. Virtually every object that you see around you has passed through the hands of a mechanical engineer. Consequently, their skills are in demand to design millions of different products in almost every type of industry. Read more
Computer Software EngineerAre you interested in developing cool video game software for computers? Would you like to learn how to make software run faster and more reliably on different kinds of computers and operating systems? Do you like to apply your computer science skills to solve problems? If so, then you might be interested in the career of a computer software engineer. Read more
Computer ProgrammerComputers are essential tools in the modern world, handling everything from traffic control, car welding, movie animation, shipping, aircraft design, and social networking to book publishing, business management, music mixing, health care, agriculture, and online shopping. Computer programmers are the people who write the instructions that tell computers what to do. Read more
News Feed on This Topic
Looking for more science fun?
Try one of our science activities for quick, anytime science explorations. The perfect thing to liven up a rainy day, school vacation, or moment of boredom.Find an Activity
Explore Our Science Videos
Make Your Own Lava Lamp
Walking Water Experiment
Paper Rockets - STEM Activity