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Police V2
Sumo robot circuit 1
Sumo robot circuit 2, Sumo robot 2 PCB, Sumo robot 2 PCB Layout, Build Info
The original Police Sumobot (Sumo Robot) was not quite up to scratch, for a start it didn't have a 5 second delay timer, which it needs for competitions. Secondly the side sensors were always sticking out, which meant that it didn't meet the required size.
The other problem I was having was with the wheel size... they just weren't quite getting the grip needed and kept struggling at points on the sumo-ring.
The new version sports some great features:
- Removable front scoop for access to the electronics
- Side sensors which are released from a servo at the start of a match!
- Two front optical edge sensors
- More power!! switch
The servo with the side sensors is also 'plug and play', I can simply pull it out and run without it. To achieve this I have used a chopped up IC holder (I ran out of socket pins), I mounted pins inside the robot as the male end, and pins on the servo as the female end.
When the 5 second timer gives power to the main circuit, the servo activates and spins, this releases the side sensors which are held by hook on the servo arms. The servo's posotive power line has a switch in it which is closed to begin with, when it has spun around the switch opens and cuts the servo's power.
The circuit operation is pretty simple. When switched on the motors are powered through the relay, at this point the relay is not active and so the motors are connected to the normally closed (NC) pins of the relay. If a side sensor is triggered, the respective capacitor charges and feeds a current to the respective transistor. The transistor then allows current to flow
and hence completes the circuit for the magnetic relay coil. The coil in the relay now activates causing the motor connected to that coil to recieve an inverted supply (ie, its posotive becomes its negative, and negative becomes posotive), therefore causing the motor to spin in the opposite direction. This will continue until the capacitor fully discharges, at which point the transistor will turn off, and the relay will reset to its
previous state. If a front edge sensor is triggered, both capacitors will charge, however one will not charge as much due to the LED setup, this cause the robot to reverse and then turn at the end of its reverse because one motor remains in reverse for longer. If at any time the robot reverses towards the edge the capacitor will be shorted, causing it to go forwards again.
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