The Base module (BM) provides
- beacon + heading assistance (v1)
- charger (v1)
- calibration (v2)
- USB (v1)
It is laid on the floor and is powered by the nearest outlet.
The robot must have the corresponding localization hardware and software. These elements should be as light (physically and for resources) as possible.
The guiding assists the robot to come and connect to the base. The connector includes a USB connector and power lines, with nearly zero insertion force. Once connected the robot can charge its batteries and connect to an external USB host.
Calibration services may be implemented for different kind of sensors.
Beacon and guiding assistance
The beacon is supposed to be used in this way. It is plugged in an outlet and laid against the wall. It starts rotating the head on a mast at a precise height. For v1 this height is 30 cm.The system must provide guiding facilities towards the connector to a distance of 1 meter and with a precision of 7.5 degrees or better. The connector design should ensure a mechanical guidance to the contacts. As it is initially designed to be against a wall, and cover 180 degrees, this gives 24 steps for a standard stepper motor.
The beaconing system must be very simple so that the robot consumes as little resource as possible.
Inrared (IR) is the most simple solution for the moment. The robot needs a receiver with minimal hardware to decode the IR signal.
For v1, the beacon is a fixed frame of 8 bit at 1200 b/s on a 20 kHz IR signal. The robots will need :
an IR receiver + amplifier + filter , a clock, a shift register + some logic to decode the frame and interact with the software. If the processing is through interrupt, there is no need for a latch. Polling is however the solution of choice as interrupts are generally scarce. Polling a latched frame detection is however problematic as there is a larger lapse between receiving the frame and reacting to it than with interrupts.