The R2 Project Part 2

Blogpost from Luke Laurie’s Teacherblog: https://lukelaurie.wordpress.com/

Last time, I talked about how I was building the drivetrain for the remote controlled R2. Click here for Part 1.

It’s really important to me that this robot is mobile, and able to drive on smooth ground or carpet, while also being able to overcome bumps and dips. Being able to turn smoothly is extremely important.

At first, I had a wheel base of two wheels in the rear two legs providing the mobility, and a single immobile wheel that could roll or slide on a turn. The sliding worked acceptably on smooth surfaces, but just couldn’t cut it on the rug.

So, I researched Omniwheels. I found some very cool robots people have built out of LEGOs using omniwheels, and some omniwheels that you can even buy. (I can’t vouch for any of these wheels or the vendor) I love that the internet is full of people’s cool technology projects.

I found a fairly simple Omniwheel design out there somewhere, and attempted several modifications, but in the end, I settled on the design below. This wheel seems pretty effective at allowing R2 to drive forward and backward in a fairly straight line without too many bumps, while also turning pretty smoothly. For now, this is what I’ll use, but I may consider other options.

 

Advertisements

The R2 Project Part 1

Blog Post from Luke Laurie’s Teacher Blog: https://lukelaurie.wordpress.com/

My son received an R2-D2 aquarium as a gift a while back, but we never had it set up with fish. After siting around for a while as a decoration, I got the idea of putting some mechanical and electronic components into it and turning it into a robot. After all, I teach a robotics science class, and have a lot of LEGOs and other parts lying around. By doing this work around my students, I could show them a thing or two about design and troubleshooting a robot project like this.

To start, I needed the thing to be able to move, and I decided that it would be most fun if he could be remotely controlled. So I got out some VEX robotics materials that were going unused, and set about designing a driving base to match the R2 shell.

I started with a design that had large enough wheels to be pretty quick, but could still carry significant weight. I used some LEGO wheels for the front, which worked OK, but they had to slide around when R2 turned, and would most likely get stuck on carpet. The rear wheels were also too large to fit inside the R2 feet, so they wouldn’t do.

Deciding that the rear wheels were two big, I switched to smaller wheels that had about 1/2 the circumference. If I attached these directly to the motor in the same way as the larger wheels were connected, my robot would cut its speed in 1/2. That would be too slow for my taste.

So I put a couple of gears on there- a larger one with about 60 teeth attached to the motor, and a smaller one with about 30 teeth attached to the wheel axle. Bingo- the robot speed was right back up to the same speed as with the larger wheels, I just lose a little energy and add a little noise because of the gears.

 

MESA: Rules for Robotics Competitions

Blog Post at https://lukelaurie.wordpress.com/

LEGO Sumo Robots, UCSB 2001

Since the year 2000, I have been working with students on the Central Coast of California, teaching them to build and program robots, mostly using LEGO Mindstorms. Last year, several MESA centers across California piloted rules I developed for UCSB’s RoboChallenge program. These rules are designed to enable students using most kinds of robotics formats to build Tug O’ War Robots (for Junior High) and Sumo Robots (for Senior High).

It appears that some schools and MESA centers will again be using these rules for Demonstration events during their MESA competitions. I’m posting these draft rules to make it easy for students, teachers, and MESA coordinators to find them,along with some additional resources that will be helpful. The rules have not been modified since written in early 2009.

Tug O’ War (Junior High)

Tug O’ War draft MESA rules:

MESA Draft Rules for Junior High Tug O’ War (MS Word)

Tug O’ War Tutorial and Video:

http://homepage.mac.com/mrlaurie/robo/tugowartutorial.html

Tug O’ War Blog Page:

https://lukelaurie.wordpress.com/2009/05/11/tug-o-war-robots/

Sumo (Senior High)

***Note on Sumo: The size of the Sumo board in the rules is somewhat small. A larger board makes for more exciting matches. I prefer a board that is approximately 4 feet in diameter, painted black, with a white border about 4″ wide.

Sumo draft MESA rules:

MESA Draft Rules for High School Sumo (MS Word)

Sumo Tutorial and Video:

http://homepage.mac.com/mrlaurie/robo/sumotutorial.html

Sumo Blog Page:

https://lukelaurie.wordpress.com/2009/05/20/sumo-robots/