Big Rob – A Raspberry Pi powered robot

Jan 3rd, 2017 | By | Category: Robot cars, Top story

Big Rob is the latest robot I designed for off-road activities. The robot will be equipped with the latest technology like a precise navigation with the differential GPS architecture I built up. You will find more details about the differential GPS setup here. The big buggy tiers enable the robot to drive off road and not to get stuck in rough terrain like the little Raspberry Pi robots I already build and tested in the garden. The DC gear motors have a rotate speed of 35 RPM by 12V. The rated stall current is 1.8 A and the output torque is 15 kg/cm. This is strong enough for the big rob do drive around with all the equipment I will build into the robot. The case is big enough to store a large battery with 12 V and maybe round about 12 Ah from a motor cycle or small car. Not sure if I will only use a Raspberry Pi to control the robot. Maybe I will also add an NVIDIA Jetson TK1 developer kit for computer vision and autonomous driving capabilities.

The picture below shows two gear dc motors and the power train I built to mount the tiers and axels. The big buggy tier is mounted with a 24mm screw on the axel.

Big Rob - mechanic components

Big Rob – mechanic components

The next pictures shows two tiers and a dc motor with the mounted steel axel. I tried to find the best place to drill the holes into the plastic box to mount the dc motors, axis, ball bearings and tires. The plastic box was very easy to machine.

Big Rob - gear motor and power train

Big Rob – gear motor and power train

E-Book – How to build a Raspberry Pi powered robot

I published an e-book that describes how to build a Raspberry Pi powered robot. The basic are explained from the electronics, chassis design and how to program a motor driver with Python. With all this information from the e-book you are able to build your own robot if you like.

E-Book Ad:

Build a remote controlled car  with a Raspberry Pi

Big Rob – robot design

The idea of the robot design was to build a modular chassis which could be easily extended with an additional plastic box on top of the first box which is the chassis of the robot. The next pictures shows the robots chassis, the four dc gear motors with the four mounted tiers. The tiers are buggy 1:5 tiers with a diameter of 20 cm. Which is big enough for the robot to easily drive around in the garden and not too big for the dc gear motors.

Big Rob 4x4 dc motors

Big Rob 4×4 dc motors

On top of the chassis I could easily mount the GPS and WIFI antenna. Actual I am not sure where to mount the camera. I mounted the camera in the middle of the box behind the handle. Maybe I will use a pan and tilt kit for the camera in the future. But I do not have a dome housing for the pan & tilt camera which is water proof.

Big Rob front view

Big Rob front view

The next pictures shows a small Raspberry Pi robot I build last year and the big rob in the background.

Big Rob with little brother

Big Rob with little brother

I wired all the components and installed a Raspberry Pi 2 Model B to test the robot. In the middle of the picture on the top you see the small motor driver which is burned. Not sure what to buy next. But something which is able to deal with more than 10 A I suggest.

Big Rob prototype setup

Big Rob prototype setup

Video Big Rob

The video shows the first test drive in my office.

Summary

To build the robot was very easy. The plastic box was easy to machine with a normal drill. I drilled all the holes to mount the four dc motors, the ball bearings as well the hole for the axel. The dc motors are very strong and the robot could easily drive around. I decision to use two BTS7960B motor drivers was the right decision. The BTS7960B motor driver is easy to control with Python and strong enough to supply the two dc motors from each side of the robot.


Article list - Big Rob:

Big Rob – A Raspberry Pi powered robot
Big Rob – power train
Big Rob – Software comming soon


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3 Comments to “Big Rob – A Raspberry Pi powered robot”

  1. Hi,
    For that kind of power requirement, you’re going to need a pretty beefy controller board.
    Can I suggest taking a look at the Diablo from PiBorg: https://www.piborg.org/diablo which handles 55A per channel. Mind you, it’s only two channels. Same goes for the PicoBorg Reverse (which handles 10A total over two channels) https://www.piborg.org/picoborgrev.
    You could also try having a word with @CannonFodder on Twitter as he’s a Pi robotics expert who might be able to point you in the right direction and offer some guidance.

    Great to read about your projects – hope you manage to find a solution!

    Mike

  2. Hi, I think you were part of the inspiration for me to make a Web driven ex-RC car as per my blog attached. At one point I was working to the cardboard-car instructions, But I ended up using WebIOPi. It now works, I just need a separate power supply for the motors. One day I’ll post a video of it.

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