Tekstvak: Electronic circuits
IR Phototransistors SFH 303 FA and SFH 309 PFA
The output of this sensors is a current of a few µA. To avoid noise, this current is first amplified with a C547Btransistor (Darlington arrangement). (Following scheme applies for both types of sensors)

Note: The resistor on the PCB of the SFH303 was placed wrong, so this is corrected in red. 
The output of the transistor is then send to another PCB. For the SFH 303 FA, the signal is immediately send to the microcontroller as an analogue input. For the SFH 309 PFA however, only 2 digital inputs of the microcontroller were taken. These indicate which of the 4 sensors gives the highest voltage. Theretofore following scheme was used (comparator— AND— NOR):

Ping))) Ultrasonic Distance Sensor
The analogue signal of this sensor is immediately send to the microcontroller using a buffer. 
(InP = signal coming from Ping, OP = signal Ping to the microcontroller)

IR Reflective Sensors HOA709-001
The greyscale of the playfield is not sufficiently precise to obtain a lot of information. So, the two sensors are just compared to have an indication of the alignment of the robot towards the goal.
Sharp GP2D12 IR Sensor
These sensors give a voltage proportional to the distance to an object or the wall. Pay attention: if the object is less then 10 cm away of the sensor, the voltage level can be interpreted wrong. Therefore, the sensors were placed inside the robot. This distance is approximately 5 cm, due space shortage.

Note: The Sharp sensors in our robot are directly connected to the microcontroller. 
Note1: After problems with the Ping, we decided not to use this sensor. 
Note: The PCB files can be downloaded on the page ‘Results and thanks’.

Matthias Borremans, Joost Geeroms, Frank Jonckheere and Sara Van Rossem

Design and building of a football playing robot

   i, BallL
(handsome) intelligent Ball Locatorh

Project Mechatronics 2009-2010                   VUB