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TITAN 6WD robot chassis

TITAN is a large 6WD chassis designed for big robotic projects.

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The TITAN is a large 6WD robot chassis designed for projects such as a snow plow or fire fighting robot.

The TITAN robot chassis is a much larger version of the Wild Thumper chassis I designed 6 years ago. The TITAN is designed for large robotic projects such as a snow plow or fire fighting robot. The original prototype (black chassis) worked well but needed some small improvements. This post is about the TITAN MkII chassis which is bigger, stronger (I weigh 140Kg) and can use a wider range of motors.

The chassis is constructed from 3mm thick 6061 aluminium sheet that has been cut, folded and riveted. The battery bays between the wheels can hold up to six 12V @ 12Ah SLA electric bike batteries or some fairly hefty lithium batteries depending on your application.

Each wishbone section contains a brushless motor with a planetary gearbox. The chassis utilizes the same suspension system as the Wild Thumper with the center sections being a standard independent suspension while the front and rear are free floating to help keep all 6 wheel on the ground.

The wheels use are 13 inch ATV wheels. As you can see there is a big difference compared to the original Wild Thumper wheel.

Currently I am using a Spider controller to control the chassis. The Spider is essentially an Arduino Mega2560 but with a 3A switchmode power supply that allows it to run directly from the batteries (24V). The Spider controller is a good choice as it has enough IO pins and internal timers to control all 6 motors.

Each motor has 3 hall effect sensor outputs (5V) which make ideal encoder inputs. By monitoring these inputs the Spider controller can adjust the speed of each motor individually and measure speed / distance traveled if required.

TITAN fire fighting robot!

My TITAN fire fighting robot is a good example of a practical application for the TITAN robot chassis. I have take a cheap fire fighters water cannon and mounted it onto the TITAN chassis.

Making a pan/tilt mechanism for the water cannon was a bit of a challenge. In the end I decided on a simple linkage system. It is cheap and easy to maintain.

It does not have a lot of range for panning left and right but since the entire chassis can rotate the pan feature is really just a way to improve the accuracy of aim.

I used two 24V DC motors with 60:1 worm drives for the pan/tilt mechanism. Each motor shaft has a couple of small magnets and an AS5600 12bit rotary hall effect sensor (contactless potentiometer) to provide feedback on the position of the output shaft.

The pan/tilt motors are driven by a simple motor driver which I originally designed for an animatronic Chinese dancing lion. This motor driver uses two BTN7971B half bridges. The original driver (shown here) used a PTC fuse but I have since replaced it with a 10A, self resetting circuit breaker.

The problem with the PTC fuses is their "on" resistance was too high and limited the maximum current available to the motors. The circuit breakers use a bi-metal switch which has a much lower resistance.

  • The long haul from prototype to product

    Russell Cameron05/13/2016 at 01:27 0 comments

    13th May, 2016

    Late 2014 my boss mentioned he wanted to build a robot snow plow. I suggested a large version of the Wild Thumper chassis as a good place to start. As we had many other projects in the pipeline the 1st prototype wasn't built until mid 2015.

    The chassis was designed to be more than just a snow plow and has many mounting points for accessories to be bolted on. The prototype used low powered motors, only 60W (2.5A @ 24V) which are great for extending battery life but limits it's ability to carry heavy payloads over rough terrain.

    late 2015 we decided to build another 3 prototypes. The MkII design is slightly longer to accommodate bigger wheels. The wishbones are also bigger to accept larger motors.

    The fire fighter shown here is still using the 60W motors and the payload is about 40Kg so it does struggle with the rough terrain.

    The next step for the fire fighter prototype is to replace the PVC parts with aluminium, water proof the electronics and add some thermal insulation. We will also need to upgrade the motors and will probably change the wheels for a solid rubber wheel.

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