How do I give a radio control car autonomous control

[ScaleRobotics]

You are right, you need a wide road for the RCAP as it is. And no, it is not autonomous, but it includes many of the items that Kenjones1935 is asking about, like an example of a connection to the receiver that allows either transmitter control, or switched to "autopilot" mode, where the pic controls the servo. But I would love to see more examples as well!

Here is 4 or so trecks down a the straight, wide (1/1 scale) roads. Another good place would be a soccer field.

[Kenjones1935]

Thank you all for your encouragement and suggestions.

My vision is a car that can be raced using the regular RC control on a circuit defined in the basketball court of the middle school gym but then the track leads underneath the fold down bleacher seats. The student running the RC can not see under the stands. Remember that under there on the floor are many supporting structures. The car must avoid these on its own.

A different vision is to have the same track on the gym floor, but including a maze made from, say, cardboard boxes that the car must navigate. We could put Xmas tree lights over each of the exit holes in the boxes. In autonomous mode the car could sense the lights.

RC cars have beautiful model suspensions. They go very fast and are quite indestructible. From the point of view of developing STEM thinking they are missing a formal language and repeatable controls. I are trying to marry the two.

Ken

[mackrackit]

Maybe just leave the RC part intact. Add another RC channel and another board.
The second board would be for auto.
The added RC channel would be to switch power from one board to the other.

[Kenjones1935]

Yes, this idea might work.

My problem is that I do not know the details of the I/O signals of the various parts of these 'bots. With LEGO RCX the outputs to the motors come directly from the encapsulated microcontroller system. The motors are not as powerful as those in a RC car. The commands available to the RCX from the ROBOlab program have seven levels of power.

The RC cars, on the other hand, are driven by a 7.2 volt battery pack through a box called a "speed control". Speed control gets its signal directly from the RC receiver. I think it is treated as a servo. Is this pulse width modulation?

I am hoping to borrow an oscilloscope soon.

Ken

[mackrackit]

This might help some.
http://ww1.microchip.com/downloads/e...hapter%205.pdf
and the suggestion up in post #2 also.

But yes, PWM is how speed is controlled. How your car is setup I do not know. Maybe if you gave a brand/type someone here might know off hand?

[Kenjones1935]

Still finding it difficult to find the I/O details of my radio control receiver and my electronic motor speed controller. What is on those three wires (white, red and black) between the receiver and the ESC?? Also what is the information format on the three wires (blue, red and black) between the receiver and the servo?

RC receiver: FUTABA FP-R122JE am 2 channel BEC

ESC: NOSRAM Tomahawk Reverse 93050

motor: MABUCHI RS-540RH/SH

[John_Mac]

I have done a lot of work on Autonomous control of RC cars, helis and airplanes. My applications have mostly been on stabilization and waypoints for aircraft using in inertial measurement unit (IMU) board. On the RC car, I ripped out the simple RC controls and replaced them with a Specktrum RX.TX system. I used a PIC processor to convert the throttle PWM signal into something the existing H Bridge motor controller understood and replaced the steering servo with a standard RC servo. I have a camera on a servo controlled pan and tilt servo system, and added things like the Parallax PING sonic distance sensor, and compass module and a GPS (but this only works outside). There are a lot of things you can think of adding.

Looks like you already have a real RX/TX system with a BEC/ESC to a motor. The signal going from the RX to the ESC; Red/Black/Blue(sometimes different color) are +V/GND/Signal. Signal is a Pulse Width Modulated signal whose width tells you how much throttle to apply. Typically this signal will be 3.5v (or so) and a width of 1.2 to 1.8 usec, depending on throttle setting.

Autonomous control will depend on what you want to do and what sensors you need to accomplish it. Waypoints won't work indoors with a GPS, but you can memorize a track, detect obstruction, follow a wire or tape track, lots of things.

A very sophisticated version of indoor automony is a laser scanner that basically maps its environment, but very pricey. You could try a sonar version of this using the PING sensor, lots of math and geometry involved.

Good luck and have a lot of fun with your students.

John