So, by now I should’ve had the first part of code ready to be tested, but unfortunately there was a delay in getting the PIC and PICKit. I went ahead and assembled the chassis and drive system which I will be using.
I cheated a little and bought a neat little kit. I say ‘cheated’ because that doesn’t include any designing, only had to research a few options and choose one closest to my needs. I chose this kit from Tamiya, which comes in three parts. The gearbox-motor assembly (first picture), the universal mounting plate (forms the base/chassis for the whole thing and the tank-tracks. The second picture shows the complete assembly. This little gearbox/motor kit has two configurations for two different ratios; 58:1 and 204:1.
Here are the technical specs for the gearbox:
• Gear Ratios: 58:1 207:1
• Motor: FA-130
• Motor RPM: 12300 (9710 Maximum Efficiency)
• Motor Voltage: 1.5-3V (1.5V Recommended)
• Motor Stall Current: 2.1A
• Free-run current: 150mA
• Motor Stall torque: 36 g-cm
I bought mine from MicroRobotics in Centurion. Click on the link to find out more about them. They distribute +Arduino boards and +Atmel Microcontroller and programmers and a host of other electronics. I also bought an h-bridge from them, which will enable the microcontroller to drive the motors.
I could not help myself, and had to test the tank drive system after I had assembled it, so I stripped the control circuit off a robot kit I had built previously, the Hexpod obstacle avoiding robot (Shown below)
The tank drive worked perfectly and a lot smoother than the leg drive system of the Hexapod and this was the result of the test system:
The only snag I have picked up is that the robot doesn’t run in a straight line, but that I will sort out later. It could be that the one motor is being driven harder by an imbalance in the electronics. I will first go ahead and concentrate on the fun part of building and programming the control system, then we can find out if there really is a problem with the drive system.
Getting up to speed with my dormant programming skills proved harder than I anticipated. See the next post in this series: Microcontroller Basics
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