| River-Crossing Robots -- Design and Construction, Part 3 |
From "Robot Rivals"
episode DROB-107 |
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Work proceeds on building the river-crossing robots.
Activity Log: Harvard (Hours 5 - 6)
- Trevor attaches the two steering wheel assemblies to the center segment. These wheels are wired to separate speed controllers, which allows them to control the direction of the robot. One motor at each end of the extension segments will power the robot when the center segment is directly over the gap.
- Harvard adjusts the height of each wheel so that all of them touch the ground.
- Then the team fits the chain and installs the motor that powers the actuator. They use attachment chain, which has special fastening tabs. Harvard will use these tabs to attach the extension bars to the chain, which loops around the sprocket of the motor and another sprocket on the other end.
- Brian attaches the battery to the motor leads to confirm that the extension assembly works properly. When the chain turns, it forces the rails to slide. The robot expands from a length of three feet to five feet.
Activity Log: Kentucky (Hours 5 - 6)
- Kentucky utilizes a modular approach to speed up the building process. Darren incorporates two pulleys from the base of the exercise equipment into the drawbridge device.
- Rick removes a metal box from the exercise equipment, drills several holes into it, and mounts it onto the frame of the robot. It will serve as the housing for all the electronics.
- Casey and Buzz prep the rails from the exercise machine, drill several holes into it, and mount it onto the top of the robot. This addition will provide the frame with a cube structure and greater rigidity.
- Darren and Rick install the motors that will raise and lower the bridge and the twine that connects the two together.
Expert Corner Buzz discusses the relationship of drive mechanisms and chains to wheels or sprockets. Chains are used frequently to help create movement and mobility in robots. When building a robot, power must be directed from the motor to a wheel, a sprocket, or a similar device. Ways to accomplish this may include a pulley or timing belt. Another good option is a strong, durable chain (figure A). Chains are found in many mechanical devices we encounter on a daily basis. Examples include a garage door opener or even a V-6 automobile engine, which uses a strong timing chain to keep the camshaft synchronized with the pistons. Chains are also used in industrial applications, such as a connecting chain for a conveyor belt. Typically, in order to fit a chain to a robot, several steps must be taken. First, the chain must be broken with a chain breaker to create two usable ends on the chain (figure B). The chain-breaker uses a small piston to push the pin out of the links (figure C). Then, a master link fits the two unconnected chain links back together.
RESOURCES :
Robot Builder's Bonanza
Model: 0071362967
Author: Gordon McComb
Build Your Own Robot!
Model: 1568811020
Author: Karl Lunt
Robots, Androids and Animatrons : 12 Incredible Projects You Can Build
Model: 0070328048
Author: John Iovine
Personal Robotics : Real Robots to Construct, Program, and Explore the World
Model: 156881089X
Author: Richard Raucci
Mobile Robots : Inspiration to Implementation
Model: 1568810970
Author: Joseph L. Jones, et al
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