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I'm proud to present to you my best moc so far. I was building it for almost half a year. During this time I graduated, and my BSc thesis was about remote control of this vehicle.
Truck features all wheel drive, 4 wheel steering with different steering lock, full double wishbone suspension, remote controlled 4-speed gearbox with neutral gear, working winch, working fake R6 piston engine and working steering wheel.
Remote control
Vehicle is remote controlled by a mobile phone using Bluetooth connection. Both applications (mobile phone app and NXT app) are written by me in Java language (I used LeJOS to program NXT).
Gearbox
Gearbox uses 2 driving rings to shift gears, each of them is controlled by one NXT motor. After shifting gear motor locks in a fixed position to prevent slipping off a driving ring.
Gear ratios are:
- gear 1) 18.75:1
gear 2) 11.25:1
gear 3) 6.25:1
gear 4) 3.75:1
Two front axles are steered with different ratios which is 1:1,67 (z12 drives z20). System construction is strong, backlash is low and it is impossible to desynchronize axles steering.
There is a price for this toughness. Steering geometry isn't perfect, but it's good enough:
Software provides "return to center" and "endpoints" functions, which means that wheels can't turn to greater angle than the chassis is design to.
The steering wheel inside the cabin is connected to steering motor via rubber, so the cabin can tilt along with the steering wheel.
Propulsion system
As you know NXT has only 3 motor ports, and I needed to control 4 independent motors. To resolve that problem I used HiTechnic IRLink sensor which control PF IR Tower. Propulsion motor (single PF XL) is connected to that tower. I had been forgetting to turn off batbox so I have attached touch sensor to batbox. Now NXT program checks before exiting if the batbox is turned on, and if so, NXT indicates it by sound signal.
There is a winch capable of lifting the whole truck. It can be switched on by red lever near the drivers seat. The winch can operate independently of shifted gear, so there is a possibility to change gears while using winch.
Suspension
Volvo has double wishbone independent suspension on each wheel. Thanks to it truck is very stable and it's off-road capabilities are good.
Multimedia
Brickshelf gallery
Edited by Atr, 09 April 2010 - 04:13 PM.
What a great blend of TECHNIC, Model Team, and Mindstorms building!
