I’ve spent some time attempting to justify continuing with Android1 – ‘Pinocchio’, named due to it’d largely wooden appearance. However, it’s just too big and heavy, it took one little step but then the other leg broke.
So now I’ve decided to build a much lighter android with more joints like a human. I will be taking parts from the first android as I go to save money, but this one will be made from Aluminium, It should turn out around 5’5” instead of 6’7” like the last one, then it can ride in my car and fit through door ways.
This is the legs so far…
The parts laid out, knee, and ankle joints:
A few things together, plus the feet. It is really very light as it’s all made from Aluminium extrusion:
Took me about 2 weeks to get this far. The concept is that each joint is independent, so it’s ankle, knee and hip all have separate motors. Each joint has a large curved ‘half moon’ sort of thing which the motor runs on. There are toothed belts on each runner and matching toothed gears on the motors.
The hips will be next which have two degrees of freedom allowing it to pivot sideways at the hips and ankles to shift it’s weight onto each foot. This way it’s body no longer needs the swinging shuttle in Android 1, this makes the construction a lot easier.
I have now added the hip assembly so the Android can sway from side to side in order to shift it’s weight on to either leg like a human. I have also added a ‘spine’ to mount everything else on including the computer taken from the other android:
The PC power supply will be stripped down and put into a smaller aluminium box, this time I will use a laptop 2.5”IDE disc as they are much smaller and lighter. It can already pose into all the positions required to walk ‘freeze frame’, I will use a simple position feedback system for the joints so that set positions can be programmed and recalled in the right order. It will have arms that swing around to help balance a little, although it should work without them. At the moment it’s 140cm / 4’7” tall (without it’s head), so it should end up about 5’5”.
In the last few weeks or so I have moved further towards getting the android to move. I’ve added the ball joints for the arms and some speakers to the top to it can speak while it’s waiting for the head to be made.
I have redesigned the mechanism that pulls it from side to side so it uses a belt and pulleys instead of the wooden runner, it also has bungees to help it centre once the weight is off to one side. I’ve designed and built the control electronics that turns each motor into a servo. Currently I can turn a knob to one position and the joint will move there and stop, I just need to fit it to all the leg joints. After that I’ll decide if I will define fixed reference positions for the joint to move to, or if the reference position will be controlled dynamically by the computer:
I’ve added the power supplies to the back of the android. On the right of the picture is the PC power supply fitted into a smaller lighter box, on the left are some PWM controllers for the motors. The middle box is there to house the mains connecter.
I have now added the rest of the circuits that turn the cordless screwdriver motors into servos:
These are controlled by radio control style servos driven by a PC serial interface on it’s back:
The pan and tilt assembly and the arms are also driven by servos and the same board:
Close up of shoulder and head assembly. I have used a Logitech Quickcam as an SDK is available, this will form the basis of the vision recognition:
The whole thing, stands at 5’5” / 165cm tall:
*This project has now ended, see Android project 3*
My name is James Bruton, I live in Southampton, UK.
Please note that this is my personal project website, I have no products for sale, most of the information is provided so that you can have a go yourself... Read More