Test of ODrive motors and Board
After some experimentation with tiny N20 5V DC motors, the same type found in MG905 servos – I realise that they run just too fast. For the DC motor to work I have used a small 2N7000 / 2N7002 / NDS7002A — N-Channel Mosfet.
I will use a few of these DC motors in the forthcoming installation for the final project, however, because the RPM is too fast, I will be converting some of the servos I have into continuous and much slower, rotating servos.
This is achieved by cutting the physical obstruction on the main gear and disconnecting the potentiometer inside, replacing with 2 x 2.2K ohm resistors as voltage divider. I have also tested the more reliable MG906 metal gear servo with the PCA9685 16 channel controller board with an Arduino Uno. I drive the board with a 10A 5V fanless power supply with my own printed enclosure holding a dual pole 30A 240V switch.
I will now be looking at converting as many of the plastic geared servos as possible using surface mount 2.2K ohm resistors (+/- 1% accurate), on order from RS Components ; 100 for 70p!
Heres a short clip of 3 motors in action:
Hello – just to let you know what I am working on…
I am trying out a few things and they include
Lidar – Neato’s Lidar sensor connected to..
Robot Operating System (ROS)
cutecom to talk to the
Lidar Controller from GetSurreal.com
and tmux to facilitate dual screen operations and more
using rviz to display map of the room (up to 5 metres away)
prototyping control of Lidar unit using Arduino Mega
Aquired a Tripmate Router/NAS/Powerbank to avoid the university wifi
Installed different versions of Linux
(i) Ubuntu Mate (with ROS)
(ii) Raspbian Jesse (installed Processing and OpenFrameworks)
difficulty on combining OF and ROS! (help)
if I cant, I will use OSC and two Pi’s; one to sense the Lidar and the other to process in OpenFrameworks.
Any comments (not spam please) welcome! Thanks.
End of Year Project
I have looked into these areas so far;
- Autonomous robot with lidar sensor – no actual purpose, perhaps avoidance of objects in a room, mapping area etc.
Further extension of idea – automaton riding on the mobile vehicle, interactive with onlookers
I will learn a lot and it may result in an impressive installation
I ordered the parts anyway, I was curious and will continue with it in my own time anyway
Seems like a huge learning curve to throw all these paths into one project.
Is it art or an engineering project?
Terrifying learning curve
2. Small, not micro robot(s) large enough to mount small motors, scaled up into 5-10 robots to investigate flocking behaviours, emergence.
Good project to push computational content
Not very interesting, been done loads of times already, e.g. 1000 micro robot emergence flocking project by MIT other methods using overhead sensor  ref on plans at Github here
3. Using O-Drive and powerful brushless motors to animate a fast moving fully enclosed sculpture. E.g. dangerous sharp objects narrowly missing each other enclosed in a Perspex case.
minimal computational content, unlikely to progress with this.
Parts already sourced in any case.
Startling and highly dramatic piece, interesting.
Lidar and ROS operating system, investigate this with ODrive motor driver board and Lidar control board 
1.2 Cartographer  and SLAM library; Google’s mapping open source code for Lidar.
Useful course on SLAM and introduction to robot mapping
1.3 ROS Robot Operating System (best installed in Linux Ubuntu)
Investigate further into I2C and AtTiny with small battery, continuous rotating modified micro servos for power.
 https://github.com/ShapeLab/SwarmUI  https://github.com/swarminterface/Zooids  https://odriverobotics.com/  https://www.getsurreal.com/product/lidar-controller-v2-0/  https://opensource.googleblog.com/2016/10/introducing-cartographer.html  https://en.wikipedia.org/wiki/Simultaneous_localization_and_mapping  http://www.ros.org/  https://ubuntu-mate.org/raspberry-pi/
Go back 55 years. Eccleston Square. The room filled with nine-year-old boys, 6 of whose fathers were in the cabinet not far away – possibly in committee rooms or the House of Commons.
At the front on a table is a pristine pile of squared paper, cut accurately and sitting immaculately in a cube, about a foot tall. The tea lady, Mrs Grice walks in with trembling hand – a green cup and saucer – 2 biscuits. Badger thanks Mrs Grice.
“CENTRIFUGAL FORCE!” he shouts – swinging the teacup and saucer, inches from our faces in a balletic flourish. Mrs Grice had left the room. This is mathematics. Now, ushering another boy up from the rows of desks in the classroom (Petty A) – putting his finger on the pile of neat squared paper, he is told to make a little circle with his finger. The paper starts moving at the top, transferring some of the force to the paper below. The cube gradually transforms itself into a twisted spiral. We sit in silence, fully engaged. “The Commonwealth Institute roof is similar… “Mr Badger explains, no, not far from our house in Kensington. I remember the roof spans all, straight, making up the beautifully curved lines of the roof. Now stand here, at the front. Halve the distance from you and the door. Move to that point. Halve it again. Move. You will never reach the door.
Badger had a nickname for me.
I would drift off and look at the leaves being burnt outside in the square – the smell of the 1963 Autumn in SW1. “COMPUTER! What is 6 squared?” I would have to stand up and shout the answer. I never forget how he avoided the chalk and the endless soporific drone all my other maths teachers put me through. Mr Routh, Mrs Behets, and finally, when I ran out a few years later during a lesson in calculus as the windowpane acid really kicked in, Mrs Jacobson.
My father – a man of many contradictions – a major in royal corps of signals during the war, heading up a section of men his job in ciphers was to encrypt messages in the 8th army. After the war, he took over his uncle’s gallery in Leicester square (which he hated)… and told me of how he could determine if the number on the tube train carriage (usually a long number, I am not sure!) if it was a prime or not from when he boarded the train at Gloucester Road to by the time it got to Hyde Park Corner. Hugh, a disappointed man, he often beat me and forbade me from motorcycles and art schools. He failed the motorcycles, for I then rode them for the next 46 years, the art seeped in and out over the years until now, when I have given it time doing an MFA.
One afternoon my father surprised me with a little demonstration of computational art without a computer. He took a a page from that Sunday’s paper, a photo of the Queen. He drew a grid in pencil over the photo, lining up the dots to measure it out accurately.
Then, taking a fresh sheet of paper out of the Queen Anne desk next to me, he took a compass and drew the edges of the same grid, the same carefully arranged dots, with the compass, transferring the straight grid lines of the photo into a series of curved lines. Each tiny square of the grid was transposed into the curve grid, as to distort the queen’s face.
I wish he had done more of that and beat me less.
The spirit of Mr Badger lives on as I rediscover the joys of mathematics without the boredom. My father – who also told me to go to the ICA and see a wonderful exhibition, Cybernetic serendipity at age 14.
Testing the mechanism and stepper driver with an EasyDriver. I have used a LN298N H bridge board but I found the latter method less bulky and convenient. I am going to introduce a second stepper to incorporate movement about the y axis to move my object.
The supported object is heavy so I have to test the Nema17 stepper to see if it is strong enough.
I liked watching this film. It discusses how, as humans, we feel compelled to create art – the film shows us graffiti removal teams in Portland Oregon unconconsciously creating art as part of their work to remove graffiti tags inn an industrial area of the city.
I admire the film’s clarity and how it informs us on a subject in a convincing way. it was part of a project undertaken as part of a degree course by Matt McCormick in 2001 and is narrated by Miranda July.
ATiny is a great little chip, low power, cheap to set up and compact. No Serial.prinln is available however so all testing is done on an Arduino Classic.
I tried out a little joystick I bought as a ‘bundle’ of sensors etc from China.
Fairly simple, using a more limited array of pins to connect to; two pulse width modulated pins and the rest as disgital pins (or use the PWM pins if you want.)
I used two digital pins and two PWM pins (see Fritzing diagrams)
I made a programmer board to plug into the Arduino as this was easier to carry about and re-use. Credit to Brian Lough on YouTube. Really Good Video.
Video and more pics to be uploaded very soon!