rwclough
Posts: 11
Joined: Mon Apr 01, 2013 2:51 am

Proposal for a small robot controller based on RPi Zero

Tue Feb 12, 2019 7:34 pm

The controller is a shield that plugs into a Raspberry Pi Zero. Its purpose is to control a small wheeled robot.

The shield provides the following features:
- 3 headers for I2C devices such as a SRF08 ultrasound rangefinder,
- 3 channels of ADC for devices such a Sharp IR rangefinder,
- 2 headers for servos (eg pan and tilt to point the above mentioned sensors),
- 2 motor drivers accessed via 2 screw-down blocks,
- 2 connectors for a servo battery and a motor battery,
- an OLED graphic display for debugging purposes or for showing what the Python program is doing while it is controlling the robot.

The Raspberry Pi Zero runs a Python program that communicates with micro-controllers on the shield. The commands/responses that the Python program sends/receives are ASCII strings.

This project could be described in MagPi over a couple of issues: parts list, Python program, etc.

mattmiller
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Joined: Thu Feb 05, 2015 11:25 pm

Re: Proposal for a small robot controller based on RPi Zero

Tue Feb 12, 2019 8:11 pm

What's the USP over the myriad other pi robot controller shields and HATs?

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mikronauts
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Re: Proposal for a small robot controller based on RPi Zero

Tue Feb 12, 2019 9:00 pm

When the pi0 was introduced, I quickly designed (and produced pcb's) for a Pi Zero form factor robotics hat that was FAR more feature full and powerful than what you are suggesting.

I never brought it to market as the RPF is limiting pi0 sales to such an extent that I would lose a lot of money marketing it.

I even tried contacting the RPF about buying qty.100 0's to bundle with my phat, but was basically ignored. Some told me to buy 0's one at a time, but the shipping kills that.

Unless you are Pimoroni, Adafruit etc (ie a Pi0 reseller) making money on phats for the 0 is basically impossible.

Fortunately other Pi models are different.
http://Mikronauts.com - home of EZasPi, RoboPi, Pi Rtc Dio and Pi Jumper @Mikronauts on Twitter
Advanced Robotics, I/O expansion and prototyping boards for the Raspberry Pi

rwclough
Posts: 11
Joined: Mon Apr 01, 2013 2:51 am

Re: Proposal for a small robot controller based on RPi Zero

Tue Feb 12, 2019 9:12 pm

Reply to mattmiller,
I have seen hats that provide a single function. For example, multiple USB ports, multiple servo controllers, DACs, ADCs, graphic displays. My contribution provides all the functions, on one hat, to control a small wheeled robot.
Cheers,
Ron

rwclough
Posts: 11
Joined: Mon Apr 01, 2013 2:51 am

Re: Proposal for a small robot controller based on RPi Zero

Tue Feb 12, 2019 9:15 pm

Reply to mikronauts,
I’m not in the business of selling PCBs. I’m interested in writing an article for MagPi magazine about building a small robot.
Cheers,
Ron

mattmiller
Posts: 2113
Joined: Thu Feb 05, 2015 11:25 pm

Re: Proposal for a small robot controller based on RPi Zero

Tue Feb 12, 2019 10:25 pm

I have seen hats that provide a single function. For example, multiple USB ports, multiple servo controllers, DACs, ADCs, graphic displays. My contribution provides all the functions, on one hat, to control a small wheeled robot.
I think your coming to the Pi robot party quite late on

Just as one example (out of many I could post) - the 4Tronix PiConZero

https://www.amazon.co.uk/4tronix-Intell ... B01E8MXQWY

mattmiller
Posts: 2113
Joined: Thu Feb 05, 2015 11:25 pm

Re: Proposal for a small robot controller based on RPi Zero

Tue Feb 12, 2019 10:28 pm

I'm sure magpi would be happy to publish another robot building/programming article as that sort of thing is its bread and butter but I don't think there's a need for another product in a crowded market unless it literally makes tea as well :)
Last edited by mattmiller on Wed Feb 13, 2019 11:34 am, edited 1 time in total.

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Gavinmc42
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Re: Proposal for a small robot controller based on RPi Zero

Tue Feb 12, 2019 11:59 pm

This is one of the better motor driver boards I have seen.
https://www.pololu.com/product/2753
But for me it is missing stuff.

An IMU chip - accel/gyro/compass, i2c connector for addon sensors, some servo 3 pin headers....
Ideally the addon board is about the same price as the Zero, that leaves no room for making money ;)
Too bad the Microbit does not have the Zero footprint, it has most of the stuff needed.

Zero based robotics is still pretty expensive and/or downright ugly.
These grabbed my attention, what could you make with a dozen or so of these?
https://www.adafruit.com/product/3871
Drivers only need to be transistor arrays?
Servos cn be expensive and tricky to program , generally needinga PWM chip
https://www.adafruit.com/?q=servo%20driver

I had thought a Lego compatible motor and driver and Lego shaped servo case would allow for more flexiblity.
I'm dancing on Rainbows.
Raspberries are not Apples or Oranges

mattmiller
Posts: 2113
Joined: Thu Feb 05, 2015 11:25 pm

Re: Proposal for a small robot controller based on RPi Zero

Wed Feb 13, 2019 11:31 am

This is one of the better motor driver boards I have seen.
?????
Its one of the most basic ones out there

You need to get out more :)

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