Motor Drive Circuits
The GBot used two Igarashi 33GN2732 geared motors for the drivetrain. Both of these motors were characterized to determine the minimum PWM frequency that they could be driven with. They had electrical time constants of 302.2 us and 218.37 us which gave them minimum PWM frequencies of 3.31 kHz and 4.58 kHz, respectively. For the implementation of these motors, a PWM frequency of 5 kHz was used.
To drive each of these motors, a TLE 5206 H-Bridge was used. This H-Bridge offered a low internal resistance when high amounts of current were flowing through it as well as an undervoltage lockout of 5.6V, which would not have presented a problem with the 7.2V battery supply voltage that was used to power the motors. The above diagram depicts the circuit schematic for the TLE 5206 connected to the right motor, and the circuit used to supply power to the left motor was identical except for changing the input ports to reflect the E128 pinout connections.
To drive each of these motors, a TLE 5206 H-Bridge was used. This H-Bridge offered a low internal resistance when high amounts of current were flowing through it as well as an undervoltage lockout of 5.6V, which would not have presented a problem with the 7.2V battery supply voltage that was used to power the motors. The above diagram depicts the circuit schematic for the TLE 5206 connected to the right motor, and the circuit used to supply power to the left motor was identical except for changing the input ports to reflect the E128 pinout connections.