Datasheet

Construction manual for robot kit NIBObee 01.12.2014
1.2 Motors
The robot is driven by two motors with 25:1 transmission. The motors are
driven by a H-bridge with a 14,7 kHz PWM-signal. The PWM-signal can be
regulated by odometry-sensors, thus it is possible to drive with constant
speed.
1.2.1 Odometry
The direction of rotation and the speed of the wheels is measured by two
photo-transistors and two IR-LEDs on the middle gearwheel of the
transmission. The speed is directly proportional to the frequency of the signal.
1.2.2 Motor bridge
The motor bridge is needed for current amplification and for voltage regulation
of the microcontroller signals. The motor is controlled by one of three possible
signal-combinations from the H-bridge: high/low (forward), low/high
(backwards), high/high (short-circuit). The short-circuit operating (freewheel)
is for better utilization of energy with PWM-control, since electricity does not
have to flow against the supply voltage in this case. Additionally the freewheel
stabilizes the torque for lower values.
It is possible to deactivate the motor bridge by removing the jumper JP7 for
test cases.
http://nibobee.nicai-systems.de 7
JP7 - motor-jumper