Unlike many robots, cunning plan was fully designed on paper/computer before manufacture. However as building commenced these plans became changed as problems arose. Firstly the old wheels (from B&Q), slipped as soon as any torque was put on them. Secondly the drill gearboxes needed a UNF tap set??
A minor setback happened a few nights before Robot wars when I blew up one of the cooling fans, but a replacement was easily found inside Mr Pentium.
However the main problem arose during Robot wars when any impact ripped the shell of the chassis. The problem was that the nuts on the chassis were held on by epoxy resin (due to time), and these were easily ripped off. You won't be able to see the corrective double sided tape on tele.
HEIGHT: 160mm
WIDTH: 470mm
LENGTH: 630mm
WEIGHT: 11.4kg
TOP SPEED: 15mph (approx.)
CHASSIS MATERIAL: ¼" plywood
FRAME COVERING: 1mm aluminum sheet for sides and top, 1mm steel for front and back
BACK WHEELS: 6" pneumatic tyres
FRONT WHEELS: 50mm diameter castors
MOTORS: Two 12V Black & Decker drill motors
SPEED CONTROL: Two Proline 200A speed controllers
RADIO CONTROL: Futaba 4 channel FM
|
Motors |
£7.00 each |
Black & Decker shop (BMJ Power) |
|
Gearboxes |
£16.00 each |
Black & Decker shop (BMJ Power) |
|
Main wheels |
£20.95 per pair |
Slough Model Shop |
|
Caster wheels |
£4.07 each |
B&Q |
|
Speed controllers |
£49.99 each |
Ripmax |
|
Servo reverse/mixer |
£9.95/£29.95 |
SM Services |
All the screws, bolts, sheet metal and aluminum blocks (motor mounts) were obtained from the University stores and therefore the cost=?.
The two motors work unloaded at 3.5A and are driven by 200A speed controllers. Overkill? Perhaps, they were brought with the future and upgrading in mind. In case of overheating they are mounted on extra heat sinks with cooling from two PC chip fans.
The speed controllers are driven through a servo mixer and reverse. A mixer controls the elevator and flaps on a remote control plane, but can be used to drive independently driven wheels. At first I was using two forward/reverse channels to drive the wheels independently, but the mixer takes the two signals and combines them so one channel is used for forward/reverse and the other for left/right, this makes the control easier and similar to a remote control car. If channel 1 is moved forward both motors go forward and vice versa with reverse. If Channel 2 is moved left one motor spins one way and the other motor spins the other way, i.e. the robot turns on the spot. If the robot is going forward and right the mixer compensates for this and the robot turns while moving. The reverse is needed as one channel needs reversing otherwise the speed controller thinks that one motor is going forward and the other reversing.
The chassis is made of ¼" plywood which makes it strong and light. The front and back of the frame is made of 1mm steel, while the top and sides are made of 1mm aluminum to cut down in weight and help with radio transmission.
The shell is held down by 4 bolts, 2 on either side of the robot.