Mecanum Omnidrive: What is it, how we did it and how well it worked Chad Hine Eastman Kodak Company MAK Robotics Team #211 Rochester, New York 14650-2110, USA

Outline MAK Robotics Team This Year’s Game Why We Used Omnidrive? Why We Used Mecanum Omnidrive? What Is It? How Did We Build It? How Did We Control It? How Well Did It Work? Lessons Learned Questions

MAK Robotics Team Kodak first sponsored a team in 1994 with two other local high schools. In 1999, MAK (Marshall And Kodak) was formed. We hold fall seminars and tutorials to teach the students about robotics. We have won numerous awards for quality and innovative designs. We have between 10 and 15 volunteers from Kodak on the team. There are currently, 20-30 students from Marshall each year. We also have 5 teachers/administrators helping from Marshall.

This Year’s Game Crowded field with 6 robots and 9 goals.

Why We Used Omnidrive? We wanted something different! Not just the same old tetra stacker. Robot maneuverability was voted on as the top priority (over speed and power). Flat playing field allowed many different omnidrive designs. Kit finally included four matching motors capable enough for drive wheels. Looked like a fun challenge. We like winning awards.

Why We Used Mecanum Omnidrive? Brainstormed various ways of doing omnidrive. Ideas included: regular omni wheels mounted at 45 degree angles, tank turret, wheel turning, tripod-omnidrive, and more. Only major difference with Mecanum over standard drivetrain is the wheels. Mecanum was overall the quickest and easiest to do given enough manufacturing capability to be able to make the complicated wheels. Mecanum gave us the most options in case it did not work (just replace the wheels with standard wheels). Mecanum was also the lightest of the omnidrive solutions. They looked really cool (important to students).

What Is It? It is a way of driving a “platform” in any direction, without slowing or turning. It uses omniwheels with rollers mounted at a 45 degree angle from the main wheel. Software controls how quickly each of the four wheels move in any direction.

What Is It? Standard Omniwheel Mecanum Omniwheel

What Is It?

What Is It?

What Is It?

How Did We Build It? Used http://robotics.ee.uwa.edu.au/eyebot/doc/robots/omni.html

How Did We Build It? There is nothing special about the base other than the wheels being mounted equidistant from each other. This is not necessary, but greatly simplifies the software. The wheels were completely designed in UG by a team member. The hubs were created by stereolithography using nylon. The shafts were manufactured by another team member. The “cone” rollers were molded in the mold shop using polyurethane. The “center” rollers were purchased. The wheels were completely assembled by the students.

How Did We Build It?

How Did We Control It? Used a single joystick. When you push forward, it went forward. When you push left, it went left. When you push diagonal, it went diagonal. etc. 8 different wheel direction modes: Slope of Yellow dot says we are going diagonal. Since X and Y are positive, we know we are going forward-right diagonal. Distance from origin is how fast we will travel in that direction. Red square is “dead” zone – meaning don’t move.

How Well Did It Work? Realistically, six weeks to design, build and test something this new and innovative is not nearly enough time. We had major problems controlling the robot. We had robustness issues with the stereolithed hubs. We had very bad power and speed in the “cork-screw” directions. We had minor problems with the small wheel base this design forced on us. Overall, our robot placed very well. We had very good power and speed in the “straight” directions. Our drivetrain won us Most Innovative Design Award. Our uniqueness earned us spots in the playoffs in both competitions we attended.

How Well Did It Work?

Lessons Learned Try to make all 4 drive motors face the same way to negate motor bias. Spend much more time on the software algorithms. Use LUTs to help keep motors around same speed. Use sensing devices and feedback to force the wheels to drive at the exact same speed. Make the stereolithe hubs more robust. Adding an individual suspension system to each wheel would greatly help over rough surfaces.

Lessons Learned

Questions?

Thank You To all the hard working Kodak volunteers that made this possible: John Pochan Charles Patton Jaime Lange Norm Morrill Jim Olds Scott Phillips Joe Kabasta Don Hammen Mike Schafer Joanne Begy Jeff Lange To our generous sponsors who make this possible every year: Glen Pearson George Wacker Jim Stoffel Essie Calhoun

Thank You