OKAY,

With the help of the new-to-me oscilloscope I saw what I had been suspecting. The PIC's HPWM signal is not structured like the RC receiver signal. This explains why the PIC has not been able to command a smooth gradation of steering servo positions or wheel driving torque.

The RC receiver produces a pulse every 20 milliseconds (50 Hz). The pulses are between 1 and 2 milliseconds long. The PIC's HPWM machine produces a pulse every 3.8 milliseconds (263 Hz). The pulses are between 1 and 2 milliseconds long.

This matches scalerobotics comment of yesterday. It also matches the PBP textbook. Now that I understand what it is saying.

What I have does give me steering and wheel drive control. It is more bang/bang than I would like. It goes FAST. Which leads me to the problem of getting the car to steer left soon enough when approaching a corner in the wall.

The RC versus PIC control toggle works. Under RC control the car reacts like the original system. RC channel 3 provides the toggle signal. The PULSIN command does a fine job differentiating short from long PWM on this incoming signal. The code then controls the AZ8222 Subminiature DIP DPDT Relay via the SN7407N DIP MOS driver. This DPDT switch selects either the PIC output or the RC receiver output to send to the electronic speed control and the steering servo.

I'll make a video when I get the kinks out. I am afraid my prototyping technique is not robust enough to withstand the bumps needed to straighten out the feed back loops.

Thanks again for your help and encouragement.

Ken