Plexiglass Mar 30
After a frantic day of running around I managed to source some plexiglass at a local BAUHAUS store, and then preceeded to have an intimate evening with the laser cutter at HappyLab!
Laser cutting! Mar 29
Guys! Sorry I'm not there yet, I'm frantically laser cutting plexiglass. This is how the final product will look -
See you soon!
More prototypes... Mar 20
I did more 3d printing on the Ultimaker 2. It gave me some great, really solid and light pieces but I left it too late to print everything, so I will revert to laser cutting once again!
Version i-lost-count Mar 9
Still not quite there, so I don't want to waste loads of PLA and print the thing just yet. I am getting very close though, unfortunately this is turning out to be a bit of a nightmare task!
The whole system is much flatter now and the stability improvements are HUGE.
I also learnt a neat trick from Andrew Leek at the lab. When printing my gears I was struggling to remove the 'brim' support material, and he suggested that I printed a bit slower and without the fans. It worked a treat. The prints are coming out great and they have a super smooth base which is perfect for reducing friction.
Inventor Mar 8
After much faffing around I finally decided to model and simulate the robot with Inventor 2014
This is the first time I've used the software but with a little help I was able to grasp the basics.
I struggled with exporting the models for the laser cutter for a while, eventually I found that you can select a face and then 'export face as' and save it to a dxf. Once you do that you will probably need to open the dxf and save it as an older version (2000) if you wish to import it into Rhino/Illustrator/Inkscape etc.
3D Printing Mar 2
So today I started to replace plywood components with PLA. It made a big improvement to the sturdiness of the model.
This was the first of many iterations during the printing process. It quickly became apparent that this blue was far too high above the gears and was causing the legs to twist when they walked. I managed to remedy this but wish I'd spent more time simulating the movement in 3D software rather than guessing it from some 2D flash animations I made.
Before RobotChallenge I will redesign the gear system, using Inventor, as the motors are having a lot of trouble powering the movement of the legs. Now that I have access to a printer I can make much finer teeth on the spur gears, and even have them at angles as shown below.
I plan on making the central gear much smaller than it is now, and the two gears connected to the legs much larger. This will increase the torque of the system and mean that the legs move at a slower, more controlled pace.
I also plan on changing the gait (walk-cycle) of the robot. Right now it looks a bit frantic! If only I had simulation software like Disney Research's…
Strandbeest Mar 1
This was one of the clips that was at the back of my mind when I entered this competition.
A tale of Two Boards Feb 28
As you probably know, the Arduino Robot is infact two Arduinos (Leonardos) on seperate boards, that communicate as a master/slave over I2C(?).
The top board, the Control Board, behaves like a typical Arduino and it can send commands to the lower, Motor Board.
The Motor Board simply responds to commands, it can however run without being connected to the upper board. The issue is that with default firmware it has very limited functionality.
My electronics plans for this project are relatively straightforward. I want to send movement commands to the robot and receive feedback from sensors, such as strain on the motors and possibly things like temperature of the ground. For now I am happy testing the robot using just the lower board, but soon I will probably have to reflash it in order to use the IO pins without the upper board connected.
Algodoo Feb 24
After trying to get my head around lots of different software, I settled on using Algodoo (previously named Phun) for testing what my robot's walking motion might behave like. The nice thing about it, aside from seeing the actual motion path of the legs, will be that I can look at some of the forces involved and adjust the parts accordingly.
My main problem this month has been that my Mac is its last legs. Switching it off is always a gamble as I don't know if I'll ever hear that familiar boot chime again.
Anyway, I'm sharing this because initially I wanted to use Autodesk Inventor, a Windows application. If you are a student I highly recommend you to register for their student scheme where you can get every Autodesk product for free. After beating my HDD into submission and finally getting Boot Camp running I quickly ran out of disk space so eventually gave up and resorted to using kiddy physics simulators.
The video below shows my first attempt at creating spur gears (cogs) haha
My next step will be to try and export what I design in more powerful software in a format that Algodoo understands. Whilst there are a couple of projects out there - svg2phun and an inscape plugin called phn_output - they seem quite dated and only have Japanese documentation.
Wish me luck!
Joystick Feb 23
I decided to create a very simple mobile-friendly joystick.
My plan is to attach a Spark Core to the robot allowing it to both send and receive commands over Wifi.
The primary aim will be to have the ability to send movement commands… so to begin with I will implement 8-way joystick movement. Forward and Backward will simply require changing the direction of the motors, but left and right will mean that one side rotates forward whilst the other remains still or rotates backwards.
You can test the joystick in the area below. Click/Touch and drag, it should show your movement direction at the bottom of the window.
Mechanisms Feb 20
I researched a lot of different mechanisms, but finally settled on the proposed on http://mechanicalspider.com/concept.html
It is called the Klann Linkage, and is similar to the now famous Strandbeest, but seemingly simpler to implement and more suitable for motors.
progress pic.twitter.com/GuIs2ZJUpR— OFFRObot (@off_robot) February 6, 2014
Next stop, simulationville pic.twitter.com/I0C4HUcWuP— OFFRObot (@off_robot) February 11, 2014
I found an existing project, and wanted to see how the mechanism behaved so I took the cad files, modified them very slightly and then laser cut them out of cardboard.
I also created a Pinterest board to start collecting ideas. People often overlook Pinterest, or dismiss it as a place where people gather pictures of hairstyles and clothing, but I find it to be an incredibly useful visual bookmarking tool.
Break Feb 17
I'm going to be away until 27th Feb, but I will make sure I post anything that happens while I'm gone.
3D Model Feb 12
I was being slowed down by the new parametric tools so to give myself a bit of a 'confidence boost' I decided to model it quickly in Rhinocerous. A tool that I used frequently last year in Fab Lab Barcelona.
I asked the following question a few times
but wasn't getting anywhere with it, so I decided to make a scale model in Rhino with the promise to improve it in time.
Dissection Feb 6
Within no time I'd whisked my robot off to its new home at Fab Lab Sitges and was tearing to pieces.
Early on I decided that I'd try to discard the top (controller board) and create a dock solely for the bottom (motor board).
This will be more challenging as it will probably require adding some custom firmware to the microcontroller, but fingers crossed I don't think it should take too much effort. The upside is that it will be easier to move around because there is less size/weight to worry about.
It begins Feb 5
Woah! Today marks the beginning of the crazy project that is OffRobot!
Within a mere 48 hours of being notified that I was one of the 10 finalists, there was my robot. Neatly packaged and waiting to be played with. This is going to be exciting!
Hmm I wonder what this could be... pic.twitter.com/NPflo0FQEt— OFFRObot (@off_robot) February 5, 2014
Hi Feb 4
I should probably start off with a quick introduction… Hi. I'm John and I'm a programmer from the UK. Typically I'm found working with servers/websites and apps, although whenever the opportunity arises I like to challenge myself with physical hardware.
Last year I did the Fab Academy in Fab Lab Barcelona and I really fell for the city. Since then, together with my trusty dying macbook, I've been whizzing backwards and forwards between European cities in an effort to pursue some sort of 'digital nomadic' lifestyle.
I made this mini blog for a competition called Hack the Arduino Robot and originally decided to enter because I love playing with arduinos and have fond childhood memories of moving the little turtle around in LOGO. So the Arduino Robot seemed like the perfect fit!