Heavy Duty ATR Mechanical Description
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| General Description |
 The Heavy Duty ATR kit is an extremely rugged well built robot. It was originally designed for a university that requested a rugged robot outfitted with encoders, but without the need for the full enclosure that comes with the deluxe ATR.
The robot's chassis is very rigid to support large weights. The wheels are driven with timing belts (similar to the deluxe ATR), but can also be equipped with chains for heavier loads. .
The wheels are axle mounted and supported using two sealed ball bearings. Each of the four axles are driven by a large gear mtor via a cogged timing belt to yield a very smooth and slip free mode of operation. The timing belts will jump/slip when heavily loaded (>25lbs) where as the chains will not. The chains should only be selected if the robot is going to be used for loads greater than 25 lbs since they require lubrication and are noisier. With chains, the powerful IG42 Gear 252 rpm motor and standard tires 50lbs is no issue. For added capacity the tires can be foam filled and a lower gear ratio motor can be used. The ends of the shafts are exposed on the inside and a bracket is supplied for mounting encoders to each shaft/wheel if desired.
The motors and transmission allow this robot to climb walls. The wheels of this robot are our Tamiya 6.75" Dia. All-Terrain Tires. The wheel hubs have a hex coupling that matches to our axles for a slip free engagement. The robots dimensions are ~20.75" wide and ~19.75" long (wheel to wheel edge). The base is about 12.25" x 16.25". The robot has a ~2.25" clearance.
| Click on image for larger views |
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| Bottom CAD view showing gusseted design, encoders, motors, belts and pulleys |
Side CAD view with wheels and outside plate removed. |
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| Frame |
The frame is made of 1/8" thick aircraft grade aluminum. The design uses all laser cut parts with mortise and tenon design for precise alignment and mating of the parts. The frame is ribbed and gusseted making it very rigid. The chassis is completely welding using TIG and MIG.
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| Motors and Motor Mounts |
This ATR is only set up with our IG42 large gear motors. The standard motors are 252 RPM. The motor to wheel gearing is 14:18. The wheels are 6.75 inches in diameter.
So... 252*14/18*3.14*6.75/12 = ~350 fpm (4mph) travel speed (of course the motor speed is nominal at 24V the batteries usually run about 27 volts so the RPMs are probably faster and then if there is a lot of load on the motors they will run slower, etc. etc.) Any ways, its a pretty quick and powerful robot. If you want more power you can choose the 122 RPM motors for about half the speed and twice the power.
The chains will give you a 10:15 ratio.
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Large IG42 Motor (252 RPM) |
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Large IG42 Motor (122 RPM) |
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| Wheels and Drive Shafts |
The wheels of this robot are our Tamiya 6.75" Dia. All-Terrain Tires. The wheel hubs have a hex coupling that matches to our axles for a slip free engagement.
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| Hardware |
The final item you need to make you kit complete is a hardware package.
It includes nuts, bolts washers, nylon spacers (for isolating your electronics and controller boards), cable ties, and cable hold downs.
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Hardware Package (mounts most components to the base robot base). |
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Servo Standoff Hardware Package (used to mount servos onto the base of the robot). |
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