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.

6WD_Silver_chassis_3__small_.jpg

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.

6WDnew3.jpg

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:

4_wheels-1.jpg

 

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Getting replacement tires or wheels is a real hassle. I visited two local shops but nothing they had would work. Searching the RC website is a challenge because they do not list by dimensions.

Are these wheels for a 1:8 scale RC truck? What are the hub dimensions? 

There are shops that sell replacement wheels.

Robot Shop: http://www.robotshop.com/dagu-all-terrain-wheels-four-pack-3.html

SparkFun: https://www.sparkfun.com/products/10555

Pololu: http://www.pololu.com/catalog/product/1555

There are probably some other shops as well. You can also buy replacement brass adaptors that allow the wheel to mate to the motor drive shaft at some of these stores.

The wheel is a standard RC type but I could not tell you which one as I haven't played with RC cars in the last 20 years.

I've spent quite a bit of time looking around on the internet for some CAD models of the 6WD Chassis. Are these made available anywhere? I've found the drawings with basic dimensions, but it would be a huge time saver not having to remodel everything.

Thanks,

Mitch

Sorry.

We cannot release these drawings otherwise it is too easy for some less reputable companies in China to copy the design. We have already had one product illegally copied.

Hi, I've attached a Rugged Audio Shield to the Wild Thumper Controller and it uses the SPI library to receive commands from the controller board. I'm using the ICSP header to communicate to the shield and it works great. However, now my left motors are stuck on unless I change my stick to max speed in reverse. I'm wondering if this is due to pin D11 being the default MOSI pin used for SPI. I've done a continuity test on the ICSP headers to the the digital pins and it looks like they aren't connected, but I'm wondering if the library is trying send MOSI signals to the H bridge. Could this be what is happening? The velocity is constant. Thanks

Wild thumper pinout:

#define LmotorA             3  // Left  motor H bridge, input A
#define LmotorB            11  // Left  motor H bridge, input B
#define RmotorA             5  // Right motor H bridge, input A
#define RmotorB             6  // Right motor H bridge, input B

#define Charger            13  // Low=ON High=OFF

Arduino SPI pinout:

 ** MOSI - pin 11
 ** MISO - pin 12
 ** CLK - pin 13
 ** CS - pin 4

yes, you cannot use an ISP interface because only certain pins on the Arduino can be used for PWM and pin 11 is one of them. You cannot re-define LmotorB because pin 11 is hardwired to the "H" bridge.

The best way to interface another controller to the WildThumper controller is I2C or serial.

crap, well everything seems to work great using the ICSP pins. The audio shield works and the controller still receivers commands from my wireless controller, but left motors are stuck forward. Do you know if its possible to disable the D11 SPI assignment somehow? If the MOSI ICSP pin and D11 aren't shorted, how does the ICSP get the MOSI data? Thanks

Sorry but pin 11 is hardwired to the ISP socket and the H-Bridge. It is also internally hardwired in the ATmega chips to the ISP internal hardware. The WT controller was never designed to be controlled as an ISP device and you are the first person I know that has tried.

Go I2C, much easier.

If I find a feasible way to go I2C I might try, but it seems there is only a fully functioning library for the Rugged Audio Shield that relies pretty heavily on SPI. If I can ever find R46 (must be on underside of PCB?) I'm debating just cutting the D11 connection to prevent the MOSI signal from reaching the H bridge and possibly add a little wire from D10 instead and edit the IO pin file. It looks like if you substituted D10 for D11 and D4 for D13 then SPI would work no problem with this controller. Something to try if you ever make a revision. Thanks for the help!

I'm sorry but most likely all you will do is damage the board and void any warantee you have. That's a lot of trouble to go to to use an incompatible shield.

You would be much better off buying an Arduino board to plug the audio sheild into and then use I2C to link that Arduino to the WT controller. Use the WT controller as a slave for motor control, aditional sensor inputs and a servo driver. Use the new Arduino as the main controller.