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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This chassis looks amazing!

Ill most definitely be buying one of these soon!

Oh boy, I am really considering in getting one of this!!!!!!!!    :D

The weather has cleared up so I will make some videos today and post them. Goind down stairs is easy, up would be easy with a slower gearbox and better motor controller. I keep giving it too much power and it flips over :(

For this reason I am looking at offering it with a choice between two different gearbox ratios.

I don't have words.....   absolutely amazing!!

Would be awesome if we have both gear-ratios available on the vehicle, and the possibility to choose one or another considering the obstacle/road .. something like this  :D  

(in case you can't watch the video tell me and I will sent it to you.... or search for the Traxxas Summit)

Unfortunately adding 6 gearboxes like that would make the chassis way too expensive. With a good motor controller you can slow the speed down and maintain good torque.

true!! to bad!!  :-)

edit: could you give some advice on a good motor controller? 

I am going to design a FET motor controller for this but it wont be ready for a while.

In the video I just used a Mr. Basic controller but my assistant Rose replaced the 2A relays with 20A relays and the BD681 was replaced with FQP45N03L Nch FETs. This was much cheaper (and uglier) than some of the admittedly very nice expensive units sold by Pololu.

Any Nch FET will do as long as it can handle at least 20A, and has a suitable pin configuration. The FQP45N03L just had to be put in back to front so that the Gate connected to Base. The Drain connected to Collector and the Source connected to Emitter.

 

When aproximately will your controller be finished? I just wanted to know because I plan on ordering this chassis, but will hold off until the controller is available if its still within the introductory price period.

Sorry, I dont mean to be rude - I just want to save on shipping!!

I am looking at using a couple of servo ICs to drive FET "H" bridge's effectively treating the motors as continuous rotation servos. This seems the simplest and cheapest way to control the motors since all microcontrollers can drive a servo and it only requires 2 output pins. I hope to have the PCB ready for testing by the end of the month but then I'll be away for about 3 weeks so no promises.

Wow! That is just amazing. I'm stunned.

Great job and thanks for the offer to LMR members. I think I'll be placing an order soon.