Goals, Aspirations & Risks
This is an ambitious project with many challenges and risks. It is (unfortunately) just a hobby with the resource constraints that this imposes, but assuming I don't go bankrupt, go to jail or die; I'm am putting every reasonable effort into progressing this project. It is both a creative outlet and a tool for personal growth. Below is a non-exhaustive list of what I hope to achieve (both short and long term).
- Sci-fi styling allowing novelty features where I want, rather than requiring a good reason. 70's and 80's childhood of Star Wars and Alien(s) having a big influence.
- Large enough to operate outdoors and in limited human environments. Think R2-D2 size rather than table-top or carpet rover. This does mean costs will be higher though.
- Develop programming and electronics skills; motor control, control loops, sensing, user interfaces.
- Develop mechanical skills; 3D modelling, 3D printing, gearboxes, levers and actuators.
- Learn to use Linux & ROS (on-board Raspberry Pi(s) with Arduino ROSnodes, monitoring/control via laptop and custom remote).
- Investigate higher level behaviour algorithms, machine vision, mapping, speech recognition, speech synthesis and maybe even AI.
- Four stowable wheeled-legs allowing staged experimentation with modes of travel. With increasing difficulty:
- Compact 4-wheel slow manoeuvres. -- Fairly easy to do, just the physical size makes it more "interesting".
- Expanded (stable) 4-wheel manoeuvres. -- As above.
- Compact 2-wheel balance. -- I'm fairly confident I can get to here.
- Expanded 2-wheel balance? -- Unnecessary or transition to #5?
- Upright 2-wheel balance (think Boston Dynamics' Handle). -- The transition will be the difficult bit.
- Quadrupedal walk. -- Numerous gaits to try.
- Bipedal walk?
- Investigate possible practical applications of a similar platform. I'm thinking of SAR and disaster relief with appropriate sensor and equipment load-outs. Power provision? Drinking water generation? Load carrying? Environmental monitoring and warning?
To date, I've been collecting lots of parts and doing some ground work. This includes:
- 3D modelling with Fusion 360 (I do have some Solidworks experience).
- Re-inventing the wheel trying to develop a scheme to network multiple Arduinos over UART, until I rediscovered ROS.org.
- Discovering how alien installing anything on a Linux system is and particularly how error-prone the ROS install is (EDIT: I now think is due to my RPi. I thought it was a RPi2 when in fact it is an older B+).
- Purchased a cheap router and made a wall-mounted fold-down router table to aid in chassis construction.
- Evaluating various actuators (brushed DC gearmotors, BLDC, pneumatic and RC servo), sensors, NeoPixels and LCD/OLED displays.
- I made a crude solar tracker (pan & tilt mechanism that automatically faces the brightest point visible to it) for possible solar PV development on the robot.
- Working on how to best approach some of the more complex leg mechanisms and ensure the actuators will be powerful and fast enough with the range of motion for what I want to do. I do like Pneumatic Artificial Muscles, there's something about them...