Let's Make Robots!

Sneak preview of T'REX robot tank chassis prototype

 

Inspired by the Rip Saw tank, I have designed a new robot chassis called the T'REX tank chassis. I finally received all the parts for the prototype chassis. The entire chassis including gearboxes and tracks are all metal. The tracks have been anodized a gun metal grey colour.

Check out the ground clearance on this beast! It can go over very rough terrain without getting stuck.

Dimensions:
Width: 235mm
Length:  350mm
Body Height:  60mm
Ground Clearance: 70mm 
Total Height: 130mm 
Weight: 3.6Kg

Motor Specifications:
Voltage: 12V
Nominal Current: 3A
Stall Current: 11A 

 

The T'REX motors are 12V and work best from a 3S LiPo 5000mAh or better. Each motor has a stall current of 11A so you need a beefy motor controller. The chassis included mounting holes for either a Wild Thumper controller or the new T'REX robot controller.


The new T'REX robot controller features:

  • Arduino compatible with ATmega328 processor @ 16MHz.
  • USB, ISP and FTDI  sockets for easy programming and bootloader burning.
  • Input voltage from 7V to 30V with 6V @3A servo power in high voltage mode.
  • Input voltage from 5.5V to 8.4V with servos powered directly from the battery in low voltage mode.
  • Battery monitor on A3.
  • 5V @ 2A output for powering external controllers (ideal for Raspberry Pi and other 32bit controllers).
  • Dual FET "H" bridge rated at 20A per channel (40A peak).
  • PWM controlled electronic braking independant for each motor.
  • PWM frequency of 32kHz for silent motor control.
  • PTC self resetting fuse for each motor.
  • Hall effect, factory calibrated current sensor for each motor.
  • 6x servo outputs (6V or battery voltage depending on power mode).
  • Built in 3-axis accelerometer with selectable 1.5G or 6G sensitivity.
  • I2C interface with voltage translation circuitry, works with 3.3V and 5V devices (ideal for Raspberry Pi and other 32bit controllers).
  • Bluetooth interface socket for optional bluetooth interface (ideal for mobile phone control).
  • Power, RX, TX, SDA, SCL and motor fault indication LEDs.


 

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I have had a number of people ask me how to add extra suspension for heavier loads. Although the T'REX was not designed for suspension adjustment the picture below shows how I would add extra suspension. 

I cannot say specifically which RC car suspension you need as it will depend on:

  1. Size
  2. Payload
  3. Availability in your country.

This is what I've wanted ever since the Wild Thumper came out.

I'm impressed with your designs, simple, direct and visually stunning.  Even if it did nothing I would admire its form.  A minamalist masterpiece.  I had considered getting an RC tank with metal parts and modifiying it myself but this saves me all the work and attendent frustrations, and did I mention it looks great?  I got one from Sparkfun and am itching to start working on lt.  But first I have my Thumper robot to finish and that will take months.  

This is a game changer.  I invite anyone to look at the other sub 500 dollar tank chassis offerings and there is no comparison.  Metal instead of plastic and a robust suspension system not to mention power to spare.  Dollar for dollar this blows away everything else I've seen.

I'm glad you like it. Some people have had trouble because it cannot handle heavy payloads without beefing up the suspension. If you do want to put a heavy payload on it then you will need to bolster the suspension with some RC car shock absorbers.

Hello,

Please, show how and where I must add RC car shock absorbers.

I need it to carry about 4KG.

I have been looking for years for a decent affordable tank base... Had about decided to give up and then found this bad boy. Even better I caught a hell of a deal on cyber Monday from spark fun. Looking forward to building it up. Also have to say you nailed the "Ripsaw" in terms of how it looks in motion, was the first thing I thought of when I saw the videos.

Have you done any setups with RC shocks? Any recommendations for components and/or configurations?
I'm glad you like the design. The tank has suspension already but if you add RC shocks then it will be able to handle heavier payloads without the treads coming loose. I can't recommend any specific shock, there is a huge range on the market and I haven't been into RC cars for over 20 years now. Originally the tank was designed to be used with the T'rex controller which can accept signals from an RC receiver, bluetooth or I2C. If you have a Rasperry Pi then the T'rex can easily be controlled by the Pi using the I2C interface which has voltage translation built in. Some of our customers mount a small WiFi router and webcam on the T'rex so they can control it from their PC.
i understand not being able to recommend specific components. How about how to configure an rc shock for use? is there an easy way to add them I am missing? Almost looking like I would have to re configure the legs away from the torsion springs. Haven't been able to find any projects where someone has done this but may just not know where to look. Any tricks on keeping the pins in the treads? Have mine up on a stand while sorting everything out and have to constantly police the pins in the treads. Do you know of a motor with encoders I could use in place of the ones that come with it? Understand If that is also something you cannot make a suggestion on.

How heavy are we talking about?  I'm thinking an ABS plastic pan/tilt (SPT200 from Servocity which I have on my Thumper) with Logitech C920 web cam minus the metal mounts, and an Arduino Tre (when it's finished beta) and maybe one or two Arduino Micros and a number of small lightweight sensors.  I am thinking less than a pound certainly much less than two.  

Out of curiosity what is the recommended weight limit before adding RC shocks? 

Will there be replacement panels available?  I forsee cutting openings and or drilling holes for my design, and as I'm sure you know what starts out as a bright idea becomes a better one during development and we are left wishing we had not started down one path when another becomes apparent.  It would be nice to be able to proceed without that worry.  "Don't let the perfect become the enemy of the good" and all that.

The original design was only intended to have a paypload of a 3S LiPo, a Raspbery Pi, T'rex Controller, and a camera on a small pan/tilt kit. Maybe 1Kg at the most on rough terrain.

The more weight you add the greater the possibility of the tracks coming off on rough terrain.

I doubt the distributors would carry spare panels but you can always try to buy them directly from the DAGU sales department.

I noticed HobbyKing is also selling the T-Rex.

If I purchase one, I'll probably buy it from SparkFun since after shipping is added, the price difference will likely be minimal and SparkFun is easier to deal with if one needs support.

It sure would be fun to see one of these drive through the snow during an Idaho winter.