Let's Make Robots!

"Wild Thumper" 6WD all terrain robot chassis


Vendor's Description: 


It's Here! Now with Video of it in Action on dirt using 34:1 gearboxes and new videos going down and up stairs and over snow with 75:1 gearboxes.

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Now available in silver!

Designed originally here on LMR specifically for robots, this 6WD chassis has wicked spiked 120mm dia. wheels and an anodized aluminium chassis made from 2mm thick plate. The chassis has 4mm dia. holes punched every 10mm to allow easy mounting of PCBs, servos etc. All nuts, bolts and screws are stainless steel. Brass fittings and suspension springs are nickel plated.

Two chassis segments between the wheels have been designed to hold 7.2V sub C battery packs (not included) as used in many RC cars. A total of 4x 7.2V battery packs can be fitted if necessary. These batteries are ideal for driving the 6V motors as well as inexpensive linear regulators to supply 5V.

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These photos show how even with one wheel resting on a large LMR mug (115mm high) all wheels are still touching the ground. It may not be a rock crawler but that's awesome for an off the shelf robot chassis.

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Ground clearance with the suspension lightly loaded is 60mm which is almost half of the total 130mm height when the topdeck is mounted on 25mm spacers.

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As you can see in this photo, with the top deck fitted you have a smooth deck to mount equipment on even when the chassis is flexed. Mounted on brass hex spacers, the top deck gives you room underneath to hide cables and PCBs to give your robot a cleaner more proffesional finish.

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The suspension for the front and rear is a single torsion spring. As the motor housings are connected to each other and not the chassis the front and rear can roll freely with the spring supporting weight and absorbing shock.

The steel cable is used to limit spring travel. The motor housings have 3 holes for each allowing spring tension and travel adjusment depending on the weight of the robot. Rubber grommets are fitted in the spring mounts to eliminate play while allowing the motor housing to roll.

The center suspension is similar but has 2 springs. Each spring connects from the motor housing to the chassis keeping the robot upright.

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The 6 powerful geared motors have steel gears and are fitted with powerful magnets to provide high torque. Top speed is about 6.6km/hr. These motors have a maximum stall current of 5.5A each so with 3 motors per side wired in parallel a dual "H" bridge rated for at least 17A per channel is required.

Rated voltage: 6V DC (min. 2V Max. 7.5V)
Stall current maximum 5.5A
No load current per motor is 350mA
Motor RPM is 10000 +/- 5%
Gearbox ratio is 34:1
Output shaft speed is 295rpm +/- 5%
Stall torque is 4Kg/cm

A 75:1 gearbox is now available!
This gives a top speed of about 3Km/hr and a massive stall torque of 8.8Kg/cm per wheel!!!

The chassis comes pre-assembled and weights 2.6Kg. Shipping cost to America or Europe will be approximately $48 USD.

Now available in 2 colour schemes:
Black with metallic red rims
Silver with chrome rims

Here is a preview of the 4WD version:

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Hi Chaltanya,

Did you read the page Oddbot linked to? It has a more elaborate description of the design and the building process. Written by Oddbot and herefor excellent reading material!

Hi, just wanted to know, how will the chassie behave if you drive it in snow, or trough alittle water?
At the moment you would need to put black automotive silicon around the wires where they leave the motor housing and a little bit around the front of the gearbox. In the near future I hope to have some custom seals made to solve this issue. I have driven it through snow without any problems.
OddBot, did you already have the motor controller available? Would like to know how much would it cost together with the Wild Thumper please  :)

I'm sorry but it is still being developed. We should have a sample in March. It will have a built in 5V 1A supply and a charging circuit to charge 7.2V battery packs using a standard 12V DC 1A supply. These are readily available in most countries.

 

I will have 10 for my shop :D 
I would buy one in a heartbeat, after seeing that video, if i had the money :(.
Aside from this monster chassis which is really nice ... what driver did you use in that video to handle so many amps?

For the demonstration video I didn't have a suitable motor controller so my assistant Rose assembled a Mr. Basic motor controller which we then glued some 10A relays to and replaced the power transistor with a couple of FETs capable of handling 45A. The relays are underrated and the whole unit is ugly as sin.

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The transmitter is an Xbee pro with two joysticks attached to analog inputs 0 and 1. The reciever is another Xbee pro configured to generate PWM outputs. These outputs are run through an RC filter to provide a picaxe 20X2 with 2 analog inputs.

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The 20X2 generates the PWM and relay signals. As the 20X2 is only capable of 1 PWM output I have written a simple program to generate the PWM signals. This only generates 4 speeds: 25%, 50%, 75% and 100% in forward or reverse.

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The video makes this thing look even better!!! 

If I ever decide to make an all terrain bot this is definitely the base I will choose!