Teacher Toolbox
This page will inform students of the possible benefits that scissor linkages can have on competition robots. Before reading this page, have students brainstorm when it could be beneficial to design a robot with scissor linkages and write these ideas in their engineering notebooks. Once students have written down their ideas, read through this page as a whole-class.
The VEX IQ build featured in the image is one example of using scissor linkages with the addition of a motor to power the lift. Because it is immobile, this example is not competition-ready but this one was chosen to highlight adding a motor to a Grabber-like device. Use the Motivate Discussion questions to get students thinking about other applications of scissor linkages for their robots.
Designing with Scissor Linkages
You can use a scissor linkage in your design when you need to change the shape and size of your robot to accomplish a specific task. Scissor linkages are often included in robot designs with Rack Gears and Linear Slide Brackets so that their motion can be controlled by a motor. This can be useful when it comes to designing a robot for competitions.
A scissor linkage is helpful in many robot applications.
- A scissor linkage can be used to increase a robot's height.
- If your robot needs to start compact, but stretch out horizontally, you can use a scissor linkage to increase its width.
- A scissor linkage can extend a robot's reach if the robot needs to pick up objects and then place them in different locations.
Motivate Discussion
Q: What do you think the motorized scissor linkage in the photo does?
A: It likely grabs or pinches something like the Grabber does but is powered by a motor.
Q: Do you think a robot like this is likely to win a competition?
A: It depends on the game but generally, this robot cannot drive around or do much other than pinch. So, it seems unlikely to score many points.
Q: Besides a chassis with a drivetrain, what else could be added to this scissor lift in order to make the robot more competition-ready?
A: Answers will likely vary but one of the best responses is likely that a platform could be added to the top of the lift. This would allow game objects or other parts of the robot to be moved up and down as needed. Other answers might include better ends for pinching and holding or a better base that would allow the scissor linkage to grab, hold, and move an object.
Q: How would you use a scissor linkage on a competition robot?
A: Answers will likely take inspiration from the three applications listed on this page and that is intended. Have students add their own details about how the linkage would function and how that would be a benefit to the robot's design.
Extend Your Learning
To expand on this activity, think about what type of game elements would be the easiest and most difficult to pick up and move with a scissor linkage. For some examples of actual competition game elements, visit the VEX website to see the current game elements and past game elements.
To connect this activity to robotics competitions, ask students to join a robotics competition team. More information about this year's competition can be found at the Robotics Education & Competition Foundation (REC) website. The VIQC Hub app is also available for download and is the ideal competition companion for teams, spectators, and event planners involved in the VEX Robotics Competition! See more information about and download the app here.
Motivate Discussion
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Conclusion
Conclude this section by engaging students in a whole class discussion. Ask students to share their thoughts on the value of scissor linkages on competition robots and summarize what they have learned from this section. Encourage students to share their comments from their engineering notebooks.