PBP projects for R/C models

[Kenjones1935]

Please suggest your ideas on competitions that could be implemented with my PIC and/or RC controlled hobby level car. Right now all it does is go through a left turning maze. Programming for both right and left turns is the most obvious extension.

What if I added different sensors and maybe some kind of emitter. I am thinking of a game of tag. Somehow the rest of the cars in the group would need to know which car is "IT".

What fun could be had with a group of these cars?

Ken

[Kenjones1935]

I have installed a second battery pack -- four AA batteries now power the PIC and all the electronics except the radio receiver. The original 7.2 volt NiCad battery power only the servo, the electronic speed control and the radio receiver.

The inconsistent behavior in autonomous control may have been because of noise, but then it could be because of slow reaction time relative to speed travel. Not sure yet.

I need suggestions on how to prototype this package. There appears to be shops that offer short run PC cards. PCB-POOL advertises in the SERVO magazine. You all have any preferences?

Ken

[mackrackit]

I have used these folks.
http://www.expresspcb.com/
Only thing I do not like is you have to use there software. But very happy with the three boards for $51.00. Nice work and quick turn-around.

[Kenjones1935]

Mucho frustrations followed by some successes. The PC board proto challenge is beyond me for now. Created instead a car that toggles itself between radio and PIC control without using a third radio channel and negotiates a maze that includes both right and left turns.

The auto toggle is a function of the car being out in the clear - not in or too near the cardboard maze. The right and left turns were pretty obvious after numerous stupidities.

I hope to post a video next week.

Thanks again for all your support.

Ken

[Kenjones1935]

I think the code is pretty solid. Now the problem is response time, size of maze passageways and RC car speed. A fraction of a second does not seem very long when the car is up on blocks, but it is enough time at speed to crash into a far wall when it should have detected a turning opportunity and done its thing.

I think I need:
1. Techniques using PICBASIC Pro for recording data in memory that can be read back into my PC for analysis. How do I do this? I have not the faintest idea what app to use.

[mackrackit]

This is a tough one.

If the trouble is speed and timing then using more MCU cycles might make it worse.

You can look at writing data to the on-board EEPROM.
http://melabs.com/resources/samples/pbp/eeword.htm

[ardhuru]

I think I need:
1. Techniques using PICBASIC Pro for recording data in memory that can be read back into my PC for analysis. How do I do this? I have not the faintest idea what app to use.

This thread might help:

http://www.picbasic.co.uk/forum/arch...p/t-13317.html

Regards,

Anand

[Kenjones1935]

Thanks for your attention and replies.

I think the PIC is plenty fast enough. I think the SFR05's are responding quickly enough judging from their flashing LED's. My guesses are either SFR inconsistencies and/or weakness in my jury rigged PWM signal.

The servo and the speed control want PWM pulses at 50 per second. I have not been able to do that with my PIC. I get the pulse width correct, but I can not get the rep rate down to once each 20 millisec.

Ken

[ScaleRobotics]

After reading about some of Bruce's cool projects with the 18F2431 series chips, I have been playing around with them for a little while. One thing that caught my eye is that they can do Power Control PWM as low as 19 hertz (while running at 40 mhz). Something you have to bring other chips OSC down to 0.5 mhz to do. This, and a few more of it's features, make it pretty nifty for creating PWM servo output. I mocked up a quick test, and have been able to do about 10bit PWM 1 to 2ms pulses at the proper 50 hertz spacing on 3 pins with the 18F2431. The larger chips of this series can do 4 pin PCPWM. I will post a little code once I get it cleaned up a bit.

[flipper_md]

on the power topic, I've read that most current electric R/C plane systems uses a BEC to run all servos/receiver from the main battery pack(Mostly LiPo these days).
BEC usually have a safety function that will choke power to the motor, but keep servos alive in case that you are running out of juice.

[Kenjones1935]

I'll catch you all up a bit.

I have changed tack.

I am trying to go from a hobby level car with PWM controls to a toy level car most of which have simple DC wheel and servo controls. The purpose is to reduce the cost of kitting for school students. In addition to reducing the cost, DC control of two wheel drive makes it easier to implement a sporty racing-like skid steering.

I purchased (at K-MART) two 1/10 scale toy cars on sale each for $25.95. Their original prices were $50. The 1/10 size gives me more room for adding microchip electronics. The wheels and the steering if driven simply by DC with reversing current are easily controlled using DPDT relays controlled via current drivers by my PIC .

WRONG! The steering servo contains both a DC motor and an angle measuring device which is read by the electronics that comes with the car. A total of six wires go to this servo. Where can I read how this works? Should I just go back to the store and buy 'proper' toy level cars? Your suggestions would be greatly appreciated.

Thank you thank you for the oscilloscope. Without it I would not have the faintest.

Ken

[mackrackit]

A total of six wires go to this servo.

That sounds like a stepper.
A picture of the setup might help...

[Kenjones1935]

Toggling between autonomous control and radio control is much more complicated for the toy level car than for the hobby level car. Why? Toy level drives the steering servo and the wheel motor each with DC in both directions. This requires four wires. There is no common ground. Hobby level cars use pulse width modulation signals for these two jobs. Only two wires are required. The grounds are common.

Toggling between PIC and R/C in toy level requires switching eight wires - four from the radio receiver and four from the PIC. The same operation on PWM wires requires switching only two wires.

Hmmmmm...... That's a pretty good argument for sticking to the expensive machines.

Ken

[Kenjones1935]

I have some Radio Shack solderless prototyping boards. With 22 guage solid wire I can create a fairly robust kit. I need to connect ten signal wires from the PICkit 2 to the solderless board. The Digi-Key S5752-12-ND header might work. The question is whether 22 gauge solid wire will fit and stay in this device. If not #22, then what gauge will work? Or is there a crimp-on male connector that will do the job.

What did the Microchip engineers have in mind when they designed the PICkit 2 printed circuit board? Any ideas?

Ken

[mackrackit]

22 gauge will be snug and if you do your breadboarding like Darrel does it all should stay put.
http://www.picbasic.co.uk/forum/atta...2&d=1278267329

[ScaleRobotics]

What did the Microchip engineers have in mind when they designed the PICkit 2 printed circuit board? Any ideas?

A compact USB device that programs all their MCU's, using 5 to 6 connections?

But what do you mean Ken?

On a tangent, here is what they were thinking for the pickit3: