Hardware

The first step in building the Nucleon was putting the hardware all together.  This page contains a brief overview of the hardware and construction.    Computer and Electronics The control panel. The Nucleon uses a MicroATX computer with an AMD Sempron processor.  I decided to use a MicroATX over MiniITX because I needed the additional computing power for video and audio compression, and for future expansion. Specifications: Motherboard:  Biostar M7VIG 400 MicroATX Processor:  AMD Sempron 2400 Memory:  256 DDR Storage:  Lexar 1GB CompactFlash Next, I had to interface my computer with the motors, headlights, status LEDs, and switches. I finally settled on the Velleman K8055 USB interface, which is sold as a solder kit. For the motors themselves, these are controlled by the MD22 Motor Controller, which is controlled by two 5v signal lines from the USB interface. Everything from here was rather straight forward. I used a relay for the headlights, connected the voltage sensor to the analog input, and the LEDs to the digital outputs. After I had the whole thing working roughly on my desk, I then had to build the chassis and body. Chassis and Body The aluminum chassis. The chassis, body, and associated parts are made from aluminum and stainless steel. The first step was calculating the size of the frame.  I designed it so that the centre of each wheel is sits on a circle, allowing the machine to have a turning radius of 0. The chassis consists of 3/4" aluminum stock, which is welded, with the edges then ground down. Next, I put a 1/8" plate of aluminum over this frame. For the motors, I made 4 brackets from 2" angle 'iron', and then drilled the holes for the mounting screws and the shaft.  These brackets I then bolted to the frame. Lastly, I had to drill the holes for the various electronics, and add the rods for the board layers. The body, made from aluminum sheet. The body was a little more difficult.  I started off with a rough model in clay, and then I calculated the angles and size of each piece which I then cut. The chassis has two parts, an upper shell, and a lower base (to protect the motors from water and hitting). The seams were welded, then ground down.  I filled a few imperfections with body filler, did a final sand, and then prepared it for painting. Next, I cut the holes for the headlights, control panel, and camera. Finally, I painted the aluminum white.  I initially was going to chose a graphite silver, but then decided on white.  After painting, I polished the paint, and then the body was done.  It was time for assembly. Assembly of the Nucleon The chassis with the batteries. Now, it was time to to begin assembling it.  First I installed the batteries, and connected them in parallel. Next, I mounted the motors.  I used ferrite cores to reduce interference from the electric motor, and I soldered the wires on to the motor.  I then ran these wires to the approximate position of the motor controller.  Next, I fastened the battery charger, motor controller, and speaker amplifier down.  I wired the battery to a central DPDT switch.  This way I could switch between charge and run mode. The motor controller has an input for the power voltage, and can then power two channels.  Each side of the Nucleon is a seperate channel, to allow for skid steering.  The motor controller need 5v to operate, which I got from a 5v rail on the DC/DC power supply. Each channel is controlled by a 0-5v signal, with 0 being full reverse, 2.5 being stop, and 5 being full forward.  The signal is generated from the USB interface.  The first layer of parts. I used a 12v voltage regulator to power the speaker amplifier. Then I put the second layer of circuit boards down, which was the USB interface and the power supply.  For the power supply, this is fused between the DPDT switch. I connected the motor controller's 5v power line to a relay on a digital output, and the signals to the analog outputs.  I also connected the voltage sensor to the analog input, the information button to a digital input, and the LEDs to the digital outputs. Finally, the third layer was the motherboard.  I insulated this from the rest with plastic rod, and then screwed it down. Now, I just had to finish connecting everything. I plugged in the speaker, webcam, USB interface, VGA extension cable, additional USB ports (for control panel), and installed the WiFi PCI adapter. The Nucleon, without the body. For testing, I attached the wheels.  These are regular RC wheels, with a 14mm hex drive.  I had couplers from the motor shafts, which are secured with screws.  The only thing left is to put the body on, and wire in the switches and LEDs to the control panel. For a discussion of the operating system and control software, click here.