AutoBot

Discussions around autonomous, semi-automatic and intelligent robots and systems.

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Lincoln
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AutoBot

Post by Lincoln » Tue Jan 23, 2018 6:10 pm

Hi, as the name says, i'm now making a autonomous robot. Not for combat of any weight class, just for fun and possibly for showing off at "EM field"
Development on a new pcb is now underway, i'm already a good way towards completing the schematic.

The plan at the moment is to make an automatic robot out of a remote control off road car i have (1/10 scale) but then i will probably make a new version of ManoeuvraBot (about beetle size metal flipper with 3 omni directional wheels) as the new pcb shall have 4 motor drivers each technically capable of 30 Amps, but the pcb probably won't be designed for anywhere near that much current, but the idea is so we can use any motors we find lying around and they should work.
7003314mdrivers.png
7003314mdrivers.png (102.44 KiB) Viewed 2135 times
The new board will have connections to a raspberry pi zero, this is because we may use some form of AI and that will need the processing power of a raspberry pi and not the little microcontroller that runs the robot.

I know more details but this post is long enough already. questions welcome, it shows people want to see more updates on this project.
but i will point out this will not be small in any way, i'm designing it to be hand solderable unlike our tiny "SmartBoard" (see details here, http://www.robotwars101.org/forum/viewt ... 0&start=30) so this is kind of a second version of that but it will not be for ants.
Team RobotMad, home of the Smart robots, and very mean pots :)
Chris and Lincoln Barnes

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MarkR
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Re: AutoBot

Post by MarkR » Tue Jan 23, 2018 8:38 pm

That is so cool.

I'm looking at ways of incorporating a Pi Zero into an antweight fighting bot.

My initial plan is to wire it up to the Dasmikro ESC, power it from the Dasmikro's regulator and output PWM signals to drive the main motors. Servos (e.g. weapon) can be driven directly from a Pi's GPIO (in my experience).

I then plan to use a MPU6050 IMU breakout board to provide gyro and accelerometer. I could use a mpu9250 to give magnetometer too, but I've tried it before on a larger robot and get random results, probably because of interference from nearby motors and metal objects on the robot, it's likely to be worse on a smaller robot.

The Pi Zero W of course has built-in wifi and bluetooth, so no separate radio module is needed.

Another option would be the "Motozero" board https://thepihut.com/products/motozero which definitely has enough power to drive two motors (indeed, it will drive four) at modest currents, but unnecessarily large and heavy; I could get a Motozero anyway, it comes as a kit, then discard the bits which aren't needed (huge terminal blocks, IC sockets) and add low profile header to connect to the Pi Zero. But then I need a voltage regulator too.

for larger or autonomous robots I've also been playing with other sensors, the laser ranging time-of-flight modules are so awesome (The http://www.st.com/en/imaging-and-photon ... 53l0x.html VL53L0x ) - and cheap - but tricky to interface with in software.

Another sensor is the optical flow sensor from an optical mouse; I've been trying to hack these too. The pound-shop sells optical mice which actually work. Examining the PCB, it would be moderately easy to remove the unnecessary parts and strip it down to just a sensor with usb interface.
Robot: Betsie - RaspberryPi controlled flipper bot with gyro stablisation - too clever for her own good?

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Lincoln
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Re: AutoBot

Post by Lincoln » Tue Jan 23, 2018 9:31 pm

Nice idea but my first thoughts are that a pi zero is still very big for antwights and quite heavy too.

You should give designing your own pcb a go it's genuinely a good experience and fun if your a nerd and are avoiding doing A level work.
you can then use a microcontroller to do everything necessary for antwights with non of the unnecessary things that come on a pi zero such as hdmi and all that.
i use the mpu9250 but we don't really use the magnetometer except to recognise when the robot is upside down, to thus tell the software to reverse the gyro inputs. The software is the main bit of the time taken in getting a working antwight when you make your own pcb. i don't know if your really a software guy or if the idea of writing software puts you off then probably don't want make your own pcb. disclaimer, my dad writes all the software i do the hardwear.

my new pcb is designed to run without the pi zero w, so even though the pi has wifi and bluetooth im adding my own so that it doesn't always need the pi. the pi is there to explore the possibility of AI.

we have been looking at lidar type sensors but they are all a bit expensive at the moment. so it will probably have IR and ultrasonic sensors instead.
Team RobotMad, home of the Smart robots, and very mean pots :)
Chris and Lincoln Barnes

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Re: AutoBot

Post by JeffSergeant » Wed Jan 24, 2018 4:56 pm

Lincoln wrote:
Tue Jan 23, 2018 9:31 pm
You should give designing your own pcb a go it's genuinely a good experience and fun if your a nerd and are avoiding doing A level work.
you can then use a microcontroller to do everything necessary for antwights with non of the unnecessary things that come on a pi zero such as hdmi and all that.
Second that! I designed and got a PCB printed for a bare-bones 'arduino' clone for a little project I did, with no experience and teaching myself I went from a working circuit on a breadboard to a PCB in my hands in a few hours of effort. if you can make something work on a bread-board, then converting it to a PCB is actually pretty straightforward. My trick, was to make a breadboard version of something, transfer it into a PCB design. Then rip apart the breadboard and re-make it based on the PCB schematic, it saved me a lot of bother!

No affiliation, but http://www.ragworm.eu is awesome for low-volume PCB runs; pricier than their Chinese counterparts but they do a free checking service; AND they're in the UK so turnaround is very quick. and 'Eagle' has a free express version for PCB layout; now owned by Autodesk, so the quality is only going to improve, just hope they stick with the freemium model)

Awesome tutorial from Princeton, I didn't use it but wish I had! http://www.princeton.edu/~mae412/HANDOU ... Eagle.html

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Lincoln
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Re: AutoBot

Post by Lincoln » Mon Jan 29, 2018 5:28 pm

just realized that as im using altim's free 'circuit maker' you can easily have a look at my progress on this pcb.
just go to circuit maker, its free. and search for 7003314, and while your there you can look at the smaller version from 2016 7003311
Team RobotMad, home of the Smart robots, and very mean pots :)
Chris and Lincoln Barnes

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Lincoln
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Re: AutoBot

Post by Lincoln » Tue Feb 20, 2018 8:49 pm

decided it's time for another update.

still designing the pcb, but very nearly completed the schematic and have started designing the layout.
here is my draft layout so far, in nice 3d renders.
7003314 draft top-min.png
7003314 draft top-min.png (87.19 KiB) Viewed 1968 times
here you can see the Pi Zero W on the left, then along the bottom from left to right is, the programing connector, the combined wifi/bluetooth module, 3.3V output connector, MPU-9250 sparkfun breakout board, micro B usb. up the right hand side are the motor driver outputs. then along the top is: 4 servo connector, 5V out, any (5.5 to 24) V in.
7003314 draft bottom-min.png
7003314 draft bottom-min.png (87.46 KiB) Viewed 1968 times
here you can see the motor drivers, 30 Amps each!, and the 2 mosfets for reverse polarity protection.

Our last board was mostly designed by chris (my dad) so this is kinda a personal project and while the software will still be done by my dad, im trying to do the heartware by myself as a learning experience and as something to look good on university applications.

As always, questions are welcome and encouraged.
Team RobotMad, home of the Smart robots, and very mean pots :)
Chris and Lincoln Barnes

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MarkR
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Re: AutoBot

Post by MarkR » Tue Feb 20, 2018 9:37 pm

Right I'm guessing that won't be on an antweight :)

A couple of questions:

* Why do you need a wifi / bluetooth module when the Pi Zero W has those already?
* Why use a breakout board for the mpu9250 when you could just stick the chip directly on your board? It is a qfn package which is possibly hand-solderable?
Robot: Betsie - RaspberryPi controlled flipper bot with gyro stablisation - too clever for her own good?

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Lincoln
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Re: AutoBot

Post by Lincoln » Tue Feb 20, 2018 10:09 pm

Yeah it's 10x7.5cm i did say in the first post this is not for antwights in anyway.

To answer your first question, the pi will only ever be put on if we ever eventually use some form of AI, thus it has its own wifi and bluetooth.
And to your second question, as i'm not that greatly experienced in soldering, very tiny pitch qfn packages are still out of my league, thus a breakout board.
Team RobotMad, home of the Smart robots, and very mean pots :)
Chris and Lincoln Barnes

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Re: AutoBot

Post by MarkR » Tue Feb 20, 2018 11:46 pm

Yeah, looking at a mpu9250 I used on another project, it is fairly small, but probably doable with a steady hand particularly if you have access to a magnifier of some kind. I know some people at Reading Hackspace who can solder such parts. The really problematic components are the ones which don't have pins *at all* - those need to be soldered using an oven and paste.
Robot: Betsie - RaspberryPi controlled flipper bot with gyro stablisation - too clever for her own good?

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Lincoln
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Re: AutoBot

Post by Lincoln » Fri Mar 16, 2018 10:52 pm

finally the pcb design is done.
been having many issues with circuit maker crashing and other bugs but it completely done now pending PCBWay to check the files and then they will make 10 in a nice red color. i shal upload photos when i get them in a few weeks and then i can spend some of my easter holidays soldering them.

major changes recently are:
the addition of a I2C IO expander so we can use more sensors.
A 8 way logic gate to help control the interrupt signal from multiple sensors and the io expander being on the same bus.
4 neopixels on the board for a nice back light effect, that can then be be expanded via a connector.
as well as a chip to reverse the polarity of the signals to the Neopixels because the processor has a different default from the neo pixels.
and probably a few smaller changes i've forgotten.

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Lincoln
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Re: AutoBot

Post by Lincoln » Tue Mar 27, 2018 7:53 pm

the pcbs have arrived!
waiting on some components from mouser and then i shall solder one pcb to start with over my easter holidays. i've ordered components for 2 but had 13 made by pcbway, (i ordered 10????)

so the hearwere of the robot itself is now being designed. i've ordered some 25D gearmotors from pololu and 12mm hex adapters to be able to use wheels off of a 1/10th scale rc car.
i shall probably use "open beam" (15mmx15mmm extruded aluminum) to construct much of the robot. im attempting to make suspension, maybe even using pneumatic pistons instead of shock absorbers.
my dads work had a big clear out and i ended up with 2, motorized 2 axis swiveling cctv cameras. which im removing the electronics and camera from to have a motorized gimbal type thing on top of the robot so it can "look" around without turning the whole robot.

i still haven't thought of a perpous for this robot. but we are going to attach a geiger counter so guess it could be used for exploring radiation levels in different areas
you should be able to view some picture here https://photos.app.goo.gl/iA0UkrSumJv5aYq62
Team RobotMad, home of the Smart robots, and very mean pots :)
Chris and Lincoln Barnes

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Lincoln
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Re: AutoBot

Post by Lincoln » Sun May 13, 2018 5:20 pm

urrrm oops. kinda forgot to update this page.

well we made a prototype on a piece of wood, named plank-bot. put range sensors and neopixels on and got it to drive to stay a set distance from anything in front of it.this worked realy well.
next we tried hot air soldering the large motor driver chips on to a pcb, as before it was using a external motor driver board. this took some, practice, as we melted 2 pcbs before getting it right. we also have encoders on the motors going to a fpga that feeds the data back to the main board, but in adjusting the equations in the software it is now not as good as before so we need to fix that. other than that we have just started working on driving the cctv camera mechanism. and the cad for the proper version for the robot, thats not just a piece of wood, is coming along nicely.
Team RobotMad, home of the Smart robots, and very mean pots :)
Chris and Lincoln Barnes

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MarkR
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Re: AutoBot

Post by MarkR » Sun May 13, 2018 9:22 pm

That is brilliant.

I'm not sure whether you really need the fpga for shaft encoders, unless they're running really fast...

Right now I've got a working antweight flipper with Raspberry Pi + IMU, just waiting for me to get my lazy arse on and write the software.

In other news, there is a new laser range finder, the VL53L1X.

I bought some VL530X laser rangers last year, to test, and they are unbelievably awesome. But the new one is better!

https://www.pololu.com/product/3415

Max range 400cm!

This chip is so tiny that it needs a breakout board to be easily usable.

Also if you've used the ubiquitous sonar rangers, these laser things are at least 100x better in most ways. The chip inside must be incredibly clever, as according to my calculations, it's measuring differences in timing of less than one nanosecond.
Robot: Betsie - RaspberryPi controlled flipper bot with gyro stablisation - too clever for her own good?

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Lincoln
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Re: AutoBot

Post by Lincoln » Mon May 14, 2018 9:36 am

we have some of the short range and the 1m range versions of theses. but those 4m range ones look good. currently the plankbot uses 2 of the 1m rage ones at the moment.

we use a fpga for the encoders, mostly because the main processor dose not have enough spare io pins that we haven't already used. and it is pretty fast and the encoder is on the motor side of the gearbox so would be possible with the processor but difficult,so a fpga was just an easier solution.
Team RobotMad, home of the Smart robots, and very mean pots :)
Chris and Lincoln Barnes

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MarkR
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Re: AutoBot

Post by MarkR » Mon May 14, 2018 2:00 pm

Sorry to hijack your thread, but what do you think about this new H-bridge chip?

TB67H420FTG

It is tiny and powerful, but difficult to solder. I also don't know where to buy them.
Robot: Betsie - RaspberryPi controlled flipper bot with gyro stablisation - too clever for her own good?

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