Sphere bots get some new skills

Spherical robots , or in this case RC vehicles are pretty versatile. They travel about the same on most terrains, including water in some cases. That’s not to say that they travel particularly well on those terrains though. The common problem is that they can’t really climb over bumps very well, until now. We’ve seen a few versions of sphere bots, but they all seem to need fairly level smooth surfaces, aside from that one that went in the water. We hadn’t seen any that really had the oomph necessary to climb stairs though. Actually, we still haven’t seen that, but he says it can in the interview you can watch after the break.

Comments

  1. Pard says:

    I made a sphere bot using a hamster ball and a series of motors with weights on them. They are fast and fun. Would love to see how this thing conquers stairs.

  2. cyc4015 says:

    not gonna lie, i’m way more interested in the tank

  3. anyone catch the obligatory automated dorm room door at 1:45 lol

  4. McSquid says:

    @ cyc

    2nded

  5. Caleb Kraft says:

    the tank looks awesome.
    In one of our previous posts we showed a tiny bit of a radio controlled sphere I hacked together with RC car parts. It was sloppy, but worked. It would barely go over anything though.

  6. mars says:

    Oooh, a tank!

  7. cyc4015 says:

    also, i imagine what makes the ball manage obstacles so well is that it weighs a freaking tonne

  8. lackofmotive says:

    appears as though they used something (a pen?) tucked under the rubber for better traction. would a final design include many of these ribs around the sphere?

  9. monkeyslayer56 says:

    @cyc4015
    3rded

  10. Tim says:

    cyc4015: Nah they seemed to be saying it uses gyroscopes to provide a kind of solid base to push off. I guess you could also use a momentum wheel in the same plane as the axle if you wanted. That might actually be easier.

  11. Dan Cardin says:

    It uses gyroscopes to navigate the terrain so well.

  12. Daley says:

    I’m with the others – screw the ball, I want the tank! Oh yeah, and I’ll take one of those pressurised air-cannons mounted on it too ;)

  13. Steohan says:

    @twistedsymphony: i live in the dorm at MIT where that automated door is! you can actually open/close it with an iPhone app. :)

  14. kuhl says:

    i basically want to be an inventor too, and have the resources to just tinker.

  15. trialex says:

    Agree with others previous comments – it’s easy to make a sphemical bot with plain motors and drive it around. You can never get great steering, or more importantly stopping control with these designs though

    This implementation really is excellent – the gyro seems to make it much more stable and controllable.

  16. john says:

    @kuhl: i’m sure a lot of readers hear have the same goal

  17. Greg says:

    That’s me in the video, I’m glad you guys like it. I’d be happy to answer questions about it (or tanks or cannons or dorm room door actuators).

  18. Jonathan says:

    @Greg: real nice !

    Is that the hydraulic door opener that uses the building water supply as a source? Great out-of-the-box thinking :D

    How do the gyroscopes help? Are you using two like this [http://blog.makezine.com/archive/2009/09/how-to_use_hard_drives_for_image_st.html] to add ‘inertia’ to the pendulum part? Or just electronic ones to do automatic closed-loop stabilisation?

  19. Greg says:

    It certainly is. Making it hydraulic was more fun than just slapping an electric linear actuator on there. And it has the added benefit of being manually overridden and incredibly quiet in operation.

    The gyroscopes work by storing huge amounts of angular momentum. They are used in way that makes them whats called control moment gyroscopes (http://en.wikipedia.org/wiki/Control_Moment_Gyroscope). They arent used for stability like in that example with harddrives. Their stored angular momentum is dispensed to create extra torque.

  20. sunny185 says:

    Nice idea)

  21. _matt says:

    Two words:

    AWESOME

  22. Gizer20 says:

    So your robot still changing the gravity center to move arround, but when is stuck in a hole or something similar you use the gyroscope to create extra torque and get out from there no?

    By the way, awesome robot where do you get the sphere?

  23. Jonathan says:

    @Greg: indeed, hydraulics rock :)

    So I suppose (also from the pictures) there are two gyros spinning in the horizontal plane, I think you are only using them as a angular momentum storage, and then simply driving the ball against this momentum-heavy pendulum. (since attempting to tilt them will cause them to react by tilting left to right in opposite directions, which they cannot)

    But how about simply attaching the gyros to the inside of the sphere on left to right gimbals, without using a pendulum, and then tilting them?
    This should create forward torque I think, and would sound more like a CMG to me, no?
    Not sure about turning though…

  24. Mic says:

    Hack a segway and use its guidance system to buffer out all the wacky movements to give better control?

  25. Greg says:

    @Gizer20: Yes the robot still shifts center of mass for normal motion. The stored momentum gives the pendulum more than just gravity to push against to create torque. It uses both at the same time.

    The shell is actually a polycarbonate gumball machine globe.

  26. Greg says:

    @Jonathan: The gyros are actively driven to rotate left/right to generate the precession torque. So they are in fact used like CMGs.

    The reason you can’t just use CMGs is because you can only store so much momentum. By conservation of angular momentum, you can only generate a certain amount of torque*time before your CMG system is ‘depleted’.

    Steering is accomplished using the pendulum, but can be supplemented by the CMGs as well (in a slightly different/more complicated configuration).

  27. Greg says:

    @Mic: The control system for this robot is significantly more complex than for the segway. I’m building a custom system with an IMU and encoders on all the parts. I’m also developing the dynamic equations of motion mathematically, which are all delightfully non-linear. After that I’ll be able to write the software to cancel out all the wacky movements.

  28. Andrew says:

    This is ingenious. Nice work!

  29. Dan Cardin says:

    @Greg: how is it that the gyro you have on the table is staying up? Is the lighting in the video obscuring something that I should be seeing or is it just a metal stick with the spinning ball parts on the end…and standing up on its own?

  30. Mic says:

    Greg you’re absolutely right. What I meant to convey was the idea of compensation. You would obviously need a more complicated and specialized system, but my proposed concept has merit. Something designed to measure and compensate for g forces. I mean you’re right it is more complex, but you still need a computer to measure forces and to compensate for the ones that mess up your control inputs. That’s what I tried to say, but, a segway is a lame example as you have said =P Awesome creation, serious props man.

  31. Madmaxx says:

    @ Dan Cardin

    the stick with the ball has a gyro in the ball. when the gyro is spinning, it keeps itself positioned in relation to its original position and resists changes in yaw thereafter. once the gyro stops, the whole assembly falls.

  32. Dan Cardin says:

    Well, thats nifty then, since it seems to defy gravity.

  33. Greg says:

    theres more videos by gyroscopes.org that demonstrate some pretty cool gyroscopic precession.

  34. none says:

    i made a sphere bot.. it had a hamster ball with a hamster inside. it rolled away and never came back :(

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