I had lying around an old R/C car an thought it would be cool if my new robot also becomes radio controlled. I took apart the thing and there were four wires on the PCB.
*Black Ground
*Red Voltage
*Brown cable going to motor
*Blue cable going to motor
I used my volt meter to see what voltages there were on the motor. When I drive forward there comes 5 volt on the motor. If I drive backward the current reverses, and the motor turns the other way. So I could just connect these wires to my microcontroller and if one of these wire becomes high I know if my robot has to move forward or backward.
No problemo so far. Now comes the confusing part.
I thought that for left and right a similair thing would be on the board. Two wires which can reverse the current so that one way the car steers left and the other way the car steers right. BUT. there were no two wires. There were only two copper-like wire things that went from the PCB to something (dunno what this is). The weird thing is, I measured the current on this lines and when I steer left or right, no current is on these lines. Also my R/C car only steers left or right when it is also moving forward or backward. I always thought R/C cars where steered by a servo. But this is not the case here. I searched on the web for how it is done then, without a servo, but I couldn't find any usefull items.
Can someone please tell me how this steering thingy works, so I can hook it up to my microcontroller. My guess it that it works with some magnetic field thing or something.
There are plenty of ways There are plenty of ways that they can steer without a servo. However - can you take a picture of whare the wires leads to? What is where you’d expect a servo?
Are you sure there’s no CURRENT on the two lines you measured? See my guess is that the steering is done by a solenoid. (A coil with a lump of iron up the middle whose position depends onthe amount of amps whizzing through the coil.) Unlike the VOLTAGE driven devices you are probably used to, solenoids are positioned by CURRENT. If you put a load (say a 1K resistor) across the wires in parallel with your DMM in Volts mode do you see a voltage?
I’m absolutely not questioning your knowledge, but I do know that a lot of hobbyists deny the existance of current!
While you’re taking pictures, take a picture of the “thing” the wires used to connect to. (Oh, wait. Fristy already said that. No need to do it twice.)
NB - slightly confusing. I think it would be safe to say that cars can ONLY steer left or right while moving forwards or backwards. This applies to real cars, too!
If all else fails, mount the whole R/C car on your robot. Position a couple of microswitches beside teh wheels of teh R/C car so that when they turn they hit the switches. Attach the switches to your MCU.
It is indeed exact the same It is indeed exact the same as the picture above taken by Drixx. Thanks for the information, I measured again and indeed there runs current through the wires. And with the resistor I measure Volts. I think I can hook it up to my microcontroller now. Thank you very much for your fast help.
I think you misunderstood what I am trying to do. I am not trying to let my microcontroller control the RC car. I rip out the PCB from the RC car and attach it to my microcontroller on my robot. So my robot becomes radio controlled. When for example I press forward on the remote control a 5 volt signal goes from the PCB to an input pin on my microcontroller. My microcontroller then will know I want the robot to move forward and the microcontroller moves the robot forward. Similair for the other directions.
