"Wild Thumper" 6WD all terrain robot chassis
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.
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.
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.
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.
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.
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.
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:
@ Tue, 2011-02-01 07:45
Measuring speed
Hi, I just got the wild thumper 6WD and I'm wondering how am I going to measure the speed in a direct form?... could you help with some ideas? or How do you do?... thank you.... P.S: I haven't bought the motor controllers yet, but for the application I'm building a good velocity measure for each wheel is very important
Thank you
@ Tue, 2011-02-01 16:51
Currently the easiest way
The easiest way would be to glue one or more small neodynium magnets on the inside of the wheels (inside of the tire, between the plastic rim and the foam insert) then use a hall effect sensor mounted on the gearbox to monitor the revolutions of each wheel.
Measuring the time between pulses will give you a direct measurement of speed.
@ Thu, 2010-11-11 21:00
When will the 4 wheel
When will the 4 wheel version come out
@ Fri, 2010-11-12 02:15
4WD Wild Thumper
Currently Pololu sell it in America.
http://www.pololu.com/catalog/category/88
@ Fri, 2010-11-12 23:14
If only it was cheaper
If only it was cheaper
@ Sat, 2010-11-13 03:37
Sorry
the combination of quality metal parts and weight (which translate into shipping cost) make it expensive.
@ Sat, 2010-11-13 13:11
Yeah
Yeah
@ Fri, 2010-04-02 23:26
Motor Controller?
Oddbot, can you update us as to the status of the motor controller? Im really anxious to play with my chassis, however Im holding off because I dont want to spend $120 on a controller capable of driving this beast. Also, I wanted to thank you for providing such a valuable resource to LMR members - I, (and everyone else, I'm sure) truely appreciate all youve contributed so far!
@ Thu, 2010-03-18 10:42
This just in
I received my 6x6 LMR Coffee Mug from China!
Click for high resolution.
It's 95 mm high. That's just 1 mm higher than my coffee robot will take, but I am in the habit of scraping off the last drop from the spout anyway. So, I'm pleased with it.
Now I'm off to reread the manual. Something tells me the tire threads are not all aligned...
@ Fri, 2010-03-19 03:09
Great!
I have found that the brass fittings can be a bit tight going into the wheels. You may need to wiggle them a bit as you press them in to ensure they go in all the way otherwise the wheel can sit at an angle making it wobble as it spins.
I hope you have a lot of fun with your new toys :D
I have often been asked how much payload can the chassis handle. The polymorph boxes weight 1.1Kg each. So it can handle as much as 6.6Kg (aprox. 14pound) but I would recommend no more than 5Kg (11pound).