The ability to move in any direction and turn on the spot is a helpful feature on robots that operate indoors around other objects. [James Bruton] demonstrated one possible solution in the form of a robot chassis that can move in any direction with three ball-shaped wheels.
The video after the break is part two of this series. Part one covered the ball wheels themselves, consisting of a pair of half-spheres that can rotate independently with a small roller in the center of each and a driven shaft through the center of the sphere. Three of these are arranged at 120° intervals around the center of the robot, with the main shafts driven by geared DC motors using belts. To move in a straight line some basic trigonometry is used to calculate the required relative speed of each wheel. An Arduino Mega is used to do the necessary calculation when receiving input from the wireless controller.
The motion is remarkably smooth, and we’d be interested to see how it compares with Mecanum and Omniwheels. It seems like the perfect platform for [James]’ Really Useful Robot. He hinted that he might mount a trash bin on it in the future. We would love to see an automatic trash-catching robot, similar to [StuffMadeHere]’s robotic basketball hoop.
That’s a really cool mechanism. Seems like it could benefit from a lower CG by moving the motors to the sides of the legs rather than the top, and possibly putting the battery down in the bottom of the central column. Again, really neat setup.
A brief look through [James’] stuff didn’t turn this up: Is R.U.R. a play on Čapek’s play?
What to do today, build a new robot or fix the dish washer. Hmm. Robot it is.
Awesome video but he really left us hanging with that dishwasher…
I built a similar robot a few years ago. A rubber wheel drove the 4″ hard plastic balls. It was based off of a FIRST robotics team efforts a few years before that (so like 2014 – 2017). Its cool to watch it drive. Mine is good on those rubber floo tiles, but too much slip on hardwood and not enough power on carpet.