MrDotBoto [Day 25.09.2006] - Big Wheels Keep On Turning!

I arrived into the office today to find a pleasant surprise! My motors and wheels for MrDotBoto had arrived! Now this was not only a welcome distraction from having to do my expenses, but also a big part of the project, which is getting MrDotBoto mobile.

Now, I don't have a chassis ready yet, mainly because I don't need one while I get the algorithms and code right for the sensor to motor movement, so instead, I grabbed an old hard disk mount I had lying around, and bolted the motor mounts to that. Now, the motor mounts are just a metal cut out which allows you to mount the motor to your chassis. Without the mounts, it would be very hard to get a good alignment for both motors to your chassis, and also, the motors are cylindrical with no grasps (bits of metal sticking out of the housing to mount them directly) so essentially, you would need to build your own mounts anyway (so why bother...).

The motors I'm using are Lynxmotion GHM-13 Gear Head motors, and they are perfect for the Serializer board, as they are 12V 3.8a motors, and the internal H-Bridge on the Serializer (the H-Bridge is what controls your motors, giving them power from the board) requires motors that are no greater than 12V and 4a. I'm also using the standard motor mounts for the Lynxmotion motors, and I've also got these wheels with the matching 6mm hubs. All this stuff is available from a Lynxmotion reseller, such as Robot Shop.

OK, so the next step in the process was to screw the mounts onto the hard disk plate, then screw the motors to the motor mounts, then connect the wheels/hubs to the motor axle. The hubs first need to be screwed onto the wheels, then they connect to the motor shaft with another small screw.

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Once these were on, the next step was to wire the motors to the Serializer board. Using the same wire that I used to connect the power supply to the Serializer board, I cut two short lengths, exposed the end wiring, then connected the wiring to the motors and the Serializer motor posts. OK, so firstly, the Serializer motor posts are not +ve or -ve, so unlike the power posts which do require you to connect the power the right way, the motor posts will accept your wires in any configuration. Best practice though is to keep your wiring the same, so that your code will be consistent, so I connected my black wire to the positive post on the motor and the red wire to the negative post on the motor, then connected the other ends to the Serializer motor posts as follows:


The key to doing this is so that when you give power to your motors in your code, then they turn in the same direction. That's why the wiring to the motors is the same (black = +ve, red = -ve) and the wiring to the Serializer motor posts are inversed.

Now, if you connect only one motor to the Serializer, it won't work. So make sure you have two connected. Also, the jumper bank needs to be full. When you get your Serializer board, only the first jumper pin set is closed, which controls the TTL Serial control, the other five enable the onboard H-Bridge, so if you plan to use it like I did, you'll need to close all five using jumper connectors.

So now the board was configured (jumper wise), the motors were wired, mounted and ready, so the last thing to do was add the code to my test harness. Now this couldn't be simpler. You simply:

Add your motors (I'm using the PWM component abstraction) :

Sent from Snipping Tool

Set up how they bind to your Serializer board and which posts are connected to which motor:

Sent from Snipping Tool

And then control how much power goes to them! I'm using a slider control as an accelerator pedal, so as I slide it up, it changes the power value to the motors! 0 power stops them!

Sent from Snipping Tool

So tada! Wheels are turning, MrDotBoto is burning! Next stop (after expenses) is to start getting the code working to correlate the Ir sensors to the motors!