Chair Technical Details

This is going to be short because I am tired. I might update this in the future.

People might be interested in the acutal components used on the show. So, here is the list and links to where I got them from.

First the controller that mixed the input from the joystick is custom. This is prot-type board that I developed for a wireless robot controller. It contains a TI tms320lf2406apzs DSP processor running at 40MHz. The board has a lot of functionality that this project did not require but there was one important piece that it did have that my other boards do not. The PC joystick interface. I designed this board to work with a PC joystick. The board even has a standard DB-15 connector with support for the Y-cable and two joysticks along with 4 buttons.

I reworked the board to add a simple RC circuit on two of the PWM outputs. The RC circuit worked along with the internal pull-up in the speed controllers to create a variable voltage source. This voltage is what controlls the speed controllers.

I wish I would have had more time but enhance the code. When the board is powered up you have to calibrate the joystick. This is done by moving the joystick front/back and side to side. Click the button when finished. The DSP is now mixing the input from the joystick. I was only able to wire the motors for a single direction. Reversing a series wound motor is difficult.

The electric motors are Series wound winch motors with ball bearings on both ends of the armature. They are a 3 post design, so they are Bi-directional and have neutral timing. They also have a nice shaft with a woodruf key. Alreay having the key way was important since I could not do any machining at the site.

Supplier Western Motors Service Company. Their motors seem nice, but don't call and bug them about personal projects. That is a direct quote from their webpage.

Part NumberDescription
W-914312 volt winch motor

For the speed controllers I wanted something rugged and reliable. After all, my but was going to be in the seat so I didn't want to loose controll and hit a wall. I choose to try out the controllers from Golf Tech Industries becuase even their most basic units have current limit which means they should be more reliable.

Golf Tech builds each unit as it is ordered. This gave me the oportunity to specify the minimum ramp time for the acceleration curve. I in a golf cart they don't want you burning rubber on the course so the deliberately create a slow on ramp for the PWM duty cycle. Since I want to do wheelies I got the shorted ramp time.

Here is Golf Tech Industries.

Part NumberDescription
GTK-2550Stinger 550 amp

The roller chain, sprockets and casters came from Grainger. Most of the Grainger stores did not let us film inside. Seems they think people might get supplies from Grainger to build something dangerous! I thought that was the only reason industrial supplies existed, for building dangerous stuff.

I don't know what casters we used, I just picked something that looked good from the shelf. Here is a list of other parts that I used.

The link to Grainger.

QtyPart #Description
12W092#35 roller chain 10 feet
15X290#35 master link
15X291#35 offset link
26L793#35 15 tooth sprocket for 3/4" shaft
41L7003/4" shaft collar locks

The rest of the parts are basically normal go-cart parts. They don't need to be special racing components so I purchased almost everything from Northern Tool. They sell go-cart and mini-bike components and have really good prices. Unfortunately they aren't too quick in the shipping department.

The link to Northern Tool.

QtyPart #Description
21334510" wheel with 60 tooth sprocket, 3/4" shaft
21394Slick tread tires (optional for looks)
21366Brake drum
213663Brake pin
21383Hand brake lever
21384brake cable