PBP projects for R/C models

[Kenjones1935]

When I toggle from radio control to PIC control I would like the car not to go through a sudden change of commands. I would like the PIC to know what the RC receiver had just told the electronic speed control and the steering servo so that at the instant of toggle it can duplicate these commands.

Hopefully a solution is while in RC mode to loop two PULSIN commands looking at the signals the radio receiver is sending to the ESP and the servo. The technical question I have is, "How do I process the input from a PULSIN to create a HPWM that is equivalent?"

The PBP textbook description is not clear to me.

Ken

[Kenjones1935]

The question I was trying to ask was this.

All my code is a continuous loop. The PIC is way fast compared to the fifty pulses per second which is the specification for the radio control car PWM.

I am doing many HPWM commands within a fiftieth of a second. What does that look like on the output pin? Actually now that i have an oscilloscope I can find out for myself.

Ken

[ScaleRobotics]

The question I was trying to ask was this.

All my code is a continuous loop. The PIC is way fast compared to the fifty pulses per second which is the specification for the radio control car PWM.

I am doing many HPWM commands within a fiftieth of a second. What does that look like on the output pin? Actually now that i have an oscilloscope I can find out for myself.

Ken

Hey Ken,

We would not know what it looks like, because we have not seen any code. We really do not know any details, HPWM settings, or oscillator settings even. But you do seem like you are getting along pretty well. This might help us answer your previous question too! I would be curious to see your oscilloscope measurements as well. The only way I know to use HPWM for the 20ms period HPWM, is to slow the oscillator down to 0.5 mhz . And the resolution kind of stinks using that method.

But I have a feeling you are using an "unkenventional" method, which is cool. Just would like to hear some details of what it is.

Thanks,

Walter

[Kenjones1935]

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

[Kenjones1935]

Here is a video of my RC car taken today at our Radio Control Hobby Shop's race track.



Why does my code take so long to see and react to the information from the proximity sensors? There are no long PAUSE statements in my code. I am using HPWM to create the PWM control signals. Maybe I should take all the comments out of my code and post it for your consideration.

Ken

[Kenjones1935]

Here is my code as seen by WINDOWS notepad application. It does not make the PBP commands into capitals.

Were is the big delay?

Ken

[mackrackit]

WOW!!! That is cool!!! Very nice job so far.

After a quick look at the code I see a lot of things going on between range checks.
Just wondering what would happen it you setup a timer to trigger an interrupt routine.
The interrupt routine would be the range check. That way the range would be know almost instantly for corrections.

Or add range checking in between the IF/ENDIF statements. Places like this

aftermain:
gosub skidandreverse                           
frontfreetostopreverse = frontfreetostopreversesetup
 

if rangefront < frontfree then 'turn left as there is something ahead in front

gosub SteerFullLeft

goto main 
endif



IF rangeright = 0 then
endif

if rangeright > outertrack then 'turn right as we are too far away
gosub SteerHalfRight
endif


if rangeright < desiredtrack and oldrangeright < rangeright then
gosub SteerStraight  
endif 
        
          

if rangeright > desiredtrack and oldrangeright > rangeright then
gosub SteerStraight  
endif