Pan and Tilt Problems

[pryonic]

Hi,

I've just assembled my Pi Robot Camera kit, and aside from it now only going round in circles as one of the wires became detached from the motor (I'm borrowing a soldering iron this weekend!) the construction was relatively easy for a beginner like myself. However, I have had some issues with the pan and tilt kit.

I am powering the device using a Tecknet power bank I already had for charging my phone, with the Pi powered from the 2amp socket and Mini Driver connected via the USB cable I purchased from yourselves.

1.) Are the pan and tilt motors the same, or should one be used for pan and one for tilt? I couldn't see any distinguishing markings? I assumed there were, but was I wrong?

2.) When the power is switched on, and again as the device boots (possibly as Ino checks the sketch is loaded and reboots the Mini Driver) the camera jerks quite violently which if it keeps doing will damage the ribbon cable of the camera. It's the tilt motor which jerks the most, but they both do. Any idea what is causing this? I am not sure where to begin diagnosing this behaviour.

3.) It's possibly related, but during boot up and until I control the pan/tilt the servo motors seem to be active, they are making a noise but not really moving (after the initial jerk). It could be that they are trying to turn but are at their limit and the cable itself is preventing them turning.

4.) I'm not sure if the model of the servo motor has changed slightly, but I cannot securely mount the pan motor using the M2 Hex spacers as the cable comes out from the side of the motor where the spacers should sit. If I fully tighten the screws in the motor the spacer would damage the cable (see photo). Have I done something stupid? In the photos in the set up block post the cable appears to come from the bottom of the motor.

Thanks for any help you can give

[Alan]

Hi there,

Welcome to the forums. Apologies for the delayed reply.

In answer to your questions

1. The motors are the same so can be used interchangeably
2. The servo motors will twitch when first powered on, but this can turn into a repetitive motion if the power switch on the Mini Driver is not set to 'on'. This is because the Pi isn't able to provide enough current for the initial power on from its USB port.
3. Sounds like you do have the power switch on the mini driver set to on, also it's a good sign that the servo motors are holding a position as that suggests that firmware is running on the mini driver. The pan/tilt assembly should be pointing roughly forwards. If your motors are very far away from the centre then I'd advise unscrewing and repositioning the white servo horns.
4. You've done nothing wrong here, the fit with the cable has always been fairly tight. You should find that the base of the M2 standoff can slide out slightly however in the hole where it's attached to the blue chassis. You should hopefully be able to secure the pan/tilt assembly without overtightening the screws.

Hope that helps, are you able to move the motors and pan/tilt head from the web interface?

Regards

Alan

[pryonic]

Hi,

Thanks for getting back to me. I spent a lot of time googling and reading these forums and it turns out it was all down to my lack of knowledge. As an absolute robotics newbie I hadn't realised that a "servo" motor was an different to a "normal" DC motor and that I have to ensure I screwed the pan and tilt mounts on at specifc angle when they were reset - the violent jump was them trying to centre themselves when the sketch loaded.

In hindsight the third wire should have given it away that something special was going on with the motors - but it's been a learning experience! It might be worth putting something in the instructions explaining that the servos need to be centred?

I now have a fully working robot, and now the fun part of trying to learn how the sketch works starts.

Thanks for an excellent kit!