Let's Make Robots!

Manoeuvrabot


Manoeuvrabot is intended to be highly manoruvrable - hence it has four omni-wheels which can each be driven independently from a 4 channel motor controller. Initially it is remote controlled but eventually we aim to add some degree of autonomous operation with various sensors.  This is documentation of the first phase of development.

 

 

 

Omniwheels and motors are from www.bitsforbots.co.uk

 

Motor control uses 2 micro dual serial motor controllers from www.pololu.com (unfortunately this specific model is now discontinued, but there is a new generation alternative available). 

Remote Control uses Spektrum DSM2 SP9545 satellite receiver controlled from any compatible transmitter (e.g. DX5e, DX6i , DX7, DX8). This is a particularly excellent solution for remote control where a microcontroller with serial input is involved as it can be interfaced directly without the need to decode PWM signals for each channel and it is very cheap.

Main microcontroller is a Microchip pic18F2680 with custom controller software. (Time to design, build and programme this are not included in the duration of this project as this component has been reused from earlier projects.) 

As you can see in the video the omniwheel arrangement isn't working completely satisfactorily at present.  When one pair of wheels is turning under power the others should allow the robot to move by the orange segments spinning round but this doesn't always happen.  Perhaps we need some form of suspension to keep all wheels equally in contact with the ground. If anyone has encountered and overcome this issue with an omniwheel robot we'd love to hear how you did it. Thanks.

 

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How did you attach the wheels to those motors? Are those little plastic tubes I can see?

The adapters to connect the motors to the wheels are actually made from metal and they are an excellent fit.  They also came from www.bitsforbots.co.uk although I don't believe they are shown directly as parts on the site.

We discussed what we were trying to achieve with John (from bitsforbots) and he was able to provide the complete set of parts.

I've noticed most omni wheel robots have 3 wheels instead of 4, with 3 wheels balance is never a problem, and one less motor = more battery life, I'd consider removing one wheel and making the chassis a triangle unless you want lots of grief and wasted time on suspension.

That’s the way to do it, -and it would look so much cooler.

Have a look at this http://letsmakerobots.com/node/18908

Thanks for the tips and suggestions from everyone so far, we'll give them a try.

If you mount the motors on a flexible chassis that acts as suspension that might solve your problem. Polymorph could be useful as it is quite springy when it is thin.

-Love the name of your bot man...