|A trip to the hardware store discovered "carpet strip", which is wooden strip with angled nails poking through the front surface. It is ordinarily secured "nails up" to the floor to grip the backside of carpet. Now, we were going to try using it to grab the front of the carpet and pull our car along by applying strips to the stationary and moving parts of our car. Here, the boys are modifying the drive to accept a stronger angle bracket, as well as installing the carpet gripper strips.|
|The bottom view of our new and improved car.|
|We briefly modified the unit to have a stationary gripper in the back, and the moving gripper in the front (both had been in front). This solved the problem of the vehicle getting stuck with the stationary gripper hanging in air on the curved section of track, but now we toppled backwards on the vertical section. The problem is that we had 3 points of contact (rear, stationary middle, moving front), but had to follow a surface that varied from curved to flat. The boys decided to use a moving middle gripper.|
|Here is our latest version: a slippery rear support, a floating middle support, and the moving front gripper. It worked much better, but the new floating middle support kept binding and falling off.|
|Here is our next version, with the floating middle support on the end of a long hinged arm. It worked much better, but the motor labored whenever the front gripper tried to move forward. Greg identified the problem as the blunt front surface....|
|...and sanded a bevel on the front surface. This should solve the problem of binding.|
|Eureka! With rubber bands to provide mild outward force on the middle gripper, and the front gripper sanded, we can actually climb the wall! For the first time ever, we are beginning to think we might have something to enter in the trials (which are only a week away!). All we need to do now is improve our carpet-strip grippers (they still slip every now and then).|
|The improved grippers were made by cutting the ends from Safety Pins and epoxying them into an angle bracket, which I suppose makes them "Dangerous Pins". Actually, the entire crawler is beginning to resemble a medieval torture device...|
|Here we are, happy campers all with our final version of the
crater crawler which reliably crawls to the top of the crater over and
over... Even Rigel is stunned that it actually works!
This is Kenneth's last meeting with us, as he will be out for several months with foot surgery the following morning. We're sad he can't be with us at the competition next week, but we're glad we were able to complete our project together as a team!
Crater Climber - the Movie! It grinds up vertical surfaces, it'll give you tetanus in a heartbeat, and it's coming to invade your town! AAHHHHH!
Click here see a movie of the crater-climber in action! (Warning - 2MB AVI video). Click on the image after it loads. Turn the sound up all the way for full effect.