The Robot Warehouse

This is still very much a work in progress so check back from time to time to see where its got to. 

The basis of the project is to provide a demonstration area where model robots can simulate an much larger scale automated warehousing operation. To this end a grid of wires as been created, 8x20, which will be used to provide guidance to small robots acting out the roles of picking and transport vehicles.

The wires have been laid out with the design below in mind.

The one end of the grid wire is connected to a common connection, with a separate connection for vertical and horizontal grids. In practice this common connection may be a positive, ground or switched connection depending on the method of control. A perimeter wire has also been included that will indicate the bounds of operation.

In construction, all wires have been brought back to a single 40-pin connector at the side, with common connections using more pins to ensure lower contact resistance where higher currents are expected.

The operation of the board is not fixed, but several solutions will be experimented with, the first to be tried will be option 1.

1. A 34kHz signal will be applied to a switching circuit and applied to individual wires on the board. A detector on the robot will follow a wire until it encounters an active crossover of wires, when it will stop and communicate, via radio, with the switching computer its location. New instruction and a new switched wire combination will then be issued for the robots continued journey.
2. A 34kHz will be rapidly switched between wires and the robot will detect this, reporting back to the switching controller, via radio, its location and receiving new instructions as appropriate.
3. A serial data signal will be switched between wires, received by the robots as both location information and potentially instructions. The robots will report back to the controller via radio.

The perimeter wire will carry a separate signal which if detected will indicate an error condition, where the robot is about to go out of bounds, and remedial action will be needed, which may be automated by the robot or controller, or by operator intervention.

While simulating an automated warehouse is the intention, the configuration may also be repurposed for fun problem solving in the the style of the Sokoban game, with controller competing against human operators to complete a puzzle.

The board was made from a 1220x 600mm hardboard sheet which was reinforced around the edges underneath, and supported in the middle, with a raised edge to provide a hard stop for robots to prevent them falling off a table or trestles.

The wire layout was then drawn onto the board and wires laid out in the required pattern. Each wire is 5cm from the adjacent wire and the perimeter wire is 2.5cm away from the outside guidance wires. These distances were the closest convenient distance after experiments were carried out with a detector design and wire currents and voltages of 50mA and 5V respectively, values which could easily be accommodated by available microcontrollers and associated experimenters circuits. 

All the wires were laid out to be as flat as possible, only crossing where designed, and then routed back to teh 40-pin connector and soldered on, the connector being soldered to a piece of matrix board first to give it a mount. To secure the wires near the connector, stacked cable clamp were designed and 3D printed to fit.

The whole is covered with a sheet of clear acrylic plastic to provide a running surface for the robots and also to retain any drawn design on paper underneath, such as the Sokoban course.