1. The bidirectional communication refers to communication between the power surface (main large coil) to all the robots, and communication from an individual robot to the power surface. The former is accomplished by modulating the coil voltage / current, while the latter is accomplished by load modulating each robot's receive coil.
2. We used a multimeter to measure the approximate load current / voltage for the robots. For the contour plots in the paper, the load was just a resistor.
3. There are actually two PIC microcontrollers. One of them is in the power surface and is responsible for generating the 125 kHz (measured 112kHz) excitation frequency. The PIC's clock oscillates at ~40MHz, from which it generates the 125kHz drive signal via pulse-width modulation (PWM). The second PIC microcontroller serves as the robot's "brain." It is indeed responsible for the line-following behavior.
I hope this helps clear things up; however, I imagine that the paper is probably the most succinct source of information.
8:52 am
@ Amjath
1. The bidirectional communication refers to communication between the power surface (main large coil) to all the robots, and communication from an individual robot to the power surface. The former is accomplished by modulating the coil voltage / current, while the latter is accomplished by load modulating each robot's receive coil.
2. We used a multimeter to measure the approximate load current / voltage for the robots. For the contour plots in the paper, the load was just a resistor.
3. There are actually two PIC microcontrollers. One of them is in the power surface and is responsible for generating the 125 kHz (measured 112kHz) excitation frequency. The PIC's clock oscillates at ~40MHz, from which it generates the 125kHz drive signal via pulse-width modulation (PWM). The second PIC microcontroller serves as the robot's "brain." It is indeed responsible for the line-following behavior.
I hope this helps clear things up; however, I imagine that the paper is probably the most succinct source of information.