PBP projects for R/C models

[mackrackit]

You say looking down. Do you also have it looking for drop offs? Along that line maybe something like a seeing eye dog/bot?

[Kenjones1935]

There is a new car out that parallel parks itself. My car could do that if I put one sonar on the back bumper.

It could also detect motion if it were standing still. A relay race? I just thought of that. I like it....

Ken

[Kenjones1935]

The model level car is too expensive for middle school use. It seems to be too fast for my level of software and SF05 sonar sensing. I have found a commercially available electronic speed control that has no 'smarts', but that's $50 added cost to the package.

The 1/10 size gives me more room under the plastic car body for my solderless protokit plus an extra 4 AA battery package. This $50 toy car comes with a 7.2 volt rechargeable battery. There is still a mystery. How can the PIC detect that the RC transmitter is turned on? Presently turning on the transmitter with the trigger in a particular position stops the car in its tracks, but does not toggle to RC control.

All this sounds soo good. But.... go look at



It is not good. This has been frustrating. You can hear the car spin its wheels on the cement floor. I've not been able to get it to follow the wall. It turns too far when making what should be small adjustments. Could be my code. I'll share it if you want.

On the plus side this car cost $50 retail. It is light and very robust - as you can see. All my solderless kit easily fit underneath the plastic shell with holes for the sonar sensors.

As of right now It does seem that the model level car with the POT to adjust the speed is the way to go.

Ken

[Ioannis]

Hi Ken.

I would like to ask, is the steering servos linear in control or just like ON-OFF switch?

I mean can you control the amount of turn, or the angle that the car will turn? Or is it full right, full left and center?

Also I cannot see if you really have speed control over the car. It seems that it accelerates fully in every direction.

Anyway, sure it is very nervous in reactions. I will repeat my self and tell you to have a look at PID control. It is the only way to have smooth control of the speed and steering.

Ioannis

[Kenjones1935]

Yes, the difference between the 1/10 scale TOY cars and MODEL cars is proportional controls and $150. The original idea came from the URL below. In it is a 1/12 scale TOY car (cost about $25). He took out the radio control electronics completely.

http://letsmakerobots.com/node/696

I put my toy car up on blocks and used a large cardboard to simulate the presence of a wall on its right. I could not, even with me in control of the distance, get the car to steer straight ahead. Using my model level car it was easy. My code gives a window of 12 to 24 inches from the right hand wall for which the car should steer straight.

Ken

[Kenjones1935]

I think the model level car is getting close to understandable. Not so the toy. This video shows one under control, not the other.



One more step for the model level - get it more up to speed. This needs a bigger room. I've got that, but it needs cleaning. The toy level needs my understanding of the servo that drives the steering. Presently the car does not easily go straight hugging the wall. It just goes left or right. I will clean up and post my code.

Ken

[Ioannis]

It looks like your sensors are not detecting long distance and that is why it hits the walls.

Can you make a test program and see with RS232 or LCD the distance it actually measures? And then use both sensors as it may interefere each other.

Ioannis

[Kenjones1935]

I took the car to an old gymnasium this morning. I had adjusted the "frontfree" distance from four feet to five feet.
That's the proximity response from the front sonars which triggers the code to turn sharply left.
I left the potentiometer at the speed that was too fast for my garage. In the gym it negotiated the corners fine, but could not hug the wall.

I may need to recalibrate the steering, but more likely I need to restructure the wall hugging code.

Here's a link to the code I am presently running. The only difference between the toy car code and the model car code is the servo and DC motor driving commands. For the model code I use the HPWM PicBasic command. For the toy level I command certain pins to be HIGH or LOW.

http://www.employees.org/~kjones/HPI2_left_SyRen02.htm

Ken

[ScaleRobotics]

Yes, these are the same devices. 0.1" on the spacing. They are made for breadboards. More about them here:
http://www.schmalzhaus.com/UBW32/