This robot is really an Idea that I have been thinking about for a while, but I don't know if I'll ever build it.

It's based around the idea of making a robot that's actually useful around the house or office, rather than just making a robot to that walks because it's hard/interesting to build and there aren't that many around.

Mainly I think that if a robot wil actually do anything to assist around any environment it should have some sort of manipulator. Even without any guidance system or even on-board power source, it could still be used for teleoperation in hazardous environments. However, there are many expensive commercial arms available, and also many cheap 'toy' like products, so this robot project will concentrate mainly on building a low cost but reliable arm mechanism on a mobile base.

I will be attempting to explain and draw the ideas for now as the robot only exists in my head so far...




My initial concept for the arm is to try to reduce the load on the motors as much as possible, while still being able to move it's manipulator through a wide area of freedom. If rotating shoulder joints are used to lift the arm, then when the arm is outstretched with a large load there will be considerable force on the shoulder motor and mechanism. A system of counter balancing etc could be used but this will be tricky to implement correctly. Therefore I've decided to use a giant linear actuator to lift the arm up and down on a vertical column:



The vertical green part is a giant screw thread that will be turned by a motor. The red part around it will slide up and down along with the rest of the arm:



In order to save further power, each joint of the arm will only bend in a horizontal plane. Each joint will be hinged with bearings to reduce friction, therefore it doesn't matter how heavy the load is at the end - as it will always be supported by the hinges and not the force of the motor.

Next, the arm will be attached to a wheeled base, the vertical lifting column will run most of the height of the robot:



Here's the arm in it's downward outstretched postition, of course there is space for another arm on its left hand side if required:



I'm not really sure of the physical dimensions yet, maybe it should be taller and thinner to reach the top of kitchen surfaces, but at the same time fit through doorways:



I'll post some more when I have the ideas and have drawn them, maybe some preliminary spec...