Motor Control on a Heng Long Tiger (or similar)

[tsuki]

Hi. First of all - apologies if my first post is a stupid one or one that's been answered already.

I'm embarking on a robotics project that will be based on a tracked vehicle. Rather than trying to build my own chassis and cobbling together tracks and a drive train, I thought I could start with a pre-built RC tank and rip the guts out! Searching the 'net seems to suggest that Heng Long tanks are cheap and cheerful - since I'm not after realism, or even smoke/sound/BB firing, they sound like a good choice for me.

If I rip out the guts (including the main control board), I will have to provide the circuitry to control the drive motors myself. Does anyone know what kind of motors they are and how they can be controlled? (e.g. is it a simple "more current = more speed" affair, or are they servomotors that use a pulse train to set the speed, etc.?) I have found these threads - both give useful pinouts of the existing control boards, but no information on the motor connections.

Alternatively, does anyone know the protocol by which the RF reciever board talks to the main control board? That might help me decide whether it's a better idea to replace the main board or keep it and piggyback my electronics on top.

Thanks, and any advice you can offer (even "you're crazy, it'll never work") is much appreciated!

[Tankbear]

Hi Tsuki,

I'm not clued up with RC electronics but try answer some points with what i've learnt about the heng long electronics.

1) using a standard tank chassis might not be suitable. Basically the standard gearboxes are quite fast so if your robot is tall, as soon as you set off the inertia could well cause it to fell back. You can get round this with low ratio gearboxes which reduce the speed and increase torque which is probably more suitable.

2) each track will have it's own gearbox and motor. So if you ditch the HL electronics you may struggle to find alternative electronics which can control both motors as required. Someone else might say otherwise but like I say i'm not a RC geru.

3) Using the HL electonics (known as RX18) this controls the motors directly by varying the voltage for speed and polarity for direction.

4) The motors which come with the tank are 7.2v 380 motors. It is possible to upgrade them, I've got some 480 motors rated at 5amp each in one of my tanks and the HL electronics can handle the extra power no problem.

5) RF protocol no idea.

Hope that helps you.

Ian.

[tsuki]

Thanks for the info! The robot won't be particularly tall - barely taller than the tank it's based on, I would guess - so the gearing shouldn't be a problem.

I'll investigate circuitry to control the motors with variable voltage/polarity, and see if I can dig up more information on the RF protocol in case that's an easier way into the system.

[BZ123456]

I also build my project with HL tiger 1 base. I change the gear box with Mato 3:1 and also change the motor to speed 400. For electronic i use DBC to connect with my futaba fx-30. Now the platform move very smooth.