# Accurate Pan/Tilt Unit **URL:** \ **Category:** Support\ **Created:** [13 November 2017 23:08 UTC](https://forum.core-electronics.com.au/t/accurate-pan-tilt-unit/1819 "2017-11-13T23:08:51Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![Lars20656](https://avatars.discourse-cdn.com/v4/letter/l/d6d6ee/32.png) [@Lars20656](https://forum.core-electronics.com.au/u/Lars20656)\ **Post date:** [13 November 2017 23:08 UTC](https://forum.core-electronics.com.au/t/accurate-pan-tilt-unit/1819/1 "2017-11-13T23:08:51Z")
Hi, I have a project in mind which requires a fairly accurate pan/tilt device. I’m planning to attach a laser pointer to a pan/tilt controller, hanging in a roof. I want to be able to quickly and consistently direct the laser beam onto specific locations on walls 4-5 meters away, with at least ±5 cm accuracy. I’d like to be able to control it from a regular PC running Linux via USB or similar. Can anyone recommend good solutions to this problem? Cheers, Lars ---
**Author:** ![Sam](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/sam/32/99_2.png) [@Sam](https://forum.core-electronics.com.au/u/Sam)\ **Post date:** [13 November 2017 23:15 UTC](https://forum.core-electronics.com.au/t/accurate-pan-tilt-unit/1819/2 "2017-11-13T23:15:46Z")
Hi Lars, Sounds like a great project! Because a laser isn’t very heavy, the [Pan/Tilt Kit from DFRobot](https://core-electronics.com.au/pan-and-tilt-kit-black-anodized-no-servos.html) would be perfect. It’ll allow you to choose any of our [standard servos](https://core-electronics.com.au/components/motors/servos/standard.html) to use with it and give you the accuracy that you need. As far as controlling it from your computer. You could use an Arduino board (or any other board with a serial port) and just control it via the serial monitor. For example, you could create a bunch of strings which the Arduino accepts as commands. When that string is sent via the serial monitor it could snap to a known location. Or you could use a cartisean coordinate system which can be entered via the serial terminal (x,y). ---
**Author:** ![Michael\_R](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/michael_r/32/435_2.png) [@Michael\_R](https://forum.core-electronics.com.au/u/Michael_R)\ **Post date:** [13 November 2017 23:52 UTC](https://forum.core-electronics.com.au/t/accurate-pan-tilt-unit/1819/3 "2017-11-13T23:52:01Z")
For the absolute in _smooth_ pan/tilt control, it will be worthwhile looking into brushless motor gimbals. Backlash in a servo’s gearbox probably won’t make it repeatable over those distances. Over 5m it only takes 0.6 degree error to put you out 5cm. ---
**Author:** ![Lars20656](https://avatars.discourse-cdn.com/v4/letter/l/d6d6ee/32.png) [@Lars20656](https://forum.core-electronics.com.au/u/Lars20656)\ **Post date:** [13 November 2017 23:54 UTC](https://forum.core-electronics.com.au/t/accurate-pan-tilt-unit/1819/4 "2017-11-13T23:54:43Z")
Thanks Sam, I had a look at your standard servos, but I’m not sure how to tell if they’ll be accurate enough. I can’t find any numbers on their angular resolution. To get an accuracy of a few cm, beaming a laser on a wall 5m away, I’d need an angular accuracy/resolution of about 0.25 degrees or so. ---
**Author:** ![Lars20656](https://avatars.discourse-cdn.com/v4/letter/l/d6d6ee/32.png) [@Lars20656](https://forum.core-electronics.com.au/u/Lars20656)\ **Post date:** [13 November 2017 23:57 UTC](https://forum.core-electronics.com.au/t/accurate-pan-tilt-unit/1819/5 "2017-11-13T23:57:09Z")
Thanks Michael, do you have any recommendations/links when it comes brushless motor gimbals? My budget for this part of the project would probably be limited to a couple of 100AUD max. ---
**Author:** ![Sam](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/sam/32/99_2.png) [@Sam](https://forum.core-electronics.com.au/u/Sam)\ **Post date:** [13 November 2017 23:57 UTC](https://forum.core-electronics.com.au/t/accurate-pan-tilt-unit/1819/6 "2017-11-13T23:57:23Z")
Haha, that’s my bad, I misread the distance and for some reason thought you meant 40-50cm. You are both quite correct. How quickly does it need to move positions? ---
**Author:** ![Michael\_R](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/michael_r/32/435_2.png) [@Michael\_R](https://forum.core-electronics.com.au/u/Michael_R)\ **Post date:** [14 November 2017 00:01 UTC](https://forum.core-electronics.com.au/t/accurate-pan-tilt-unit/1819/7 "2017-11-14T00:01:49Z")
I don’t, sadly. I’ve never experimented with them but they appear to be the go-to for accurate and smooth pan-tilt. There’s a plethora of projects built around them, typically for cinematography. there are loads of products specifically designed drone-footage so they can be easily driven by regular servo signals. Nothing that core carries though. Check out some brushless gimbals on RC drone sites as a starting point. ---
**Author:** ![Sam](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/sam/32/99_2.png) [@Sam](https://forum.core-electronics.com.au/u/Sam)\ **Post date:** [14 November 2017 00:10 UTC](https://forum.core-electronics.com.au/t/accurate-pan-tilt-unit/1819/8 "2017-11-14T00:10:54Z")
I’ve used brushless motors a bit for a few projects, but because they require more sophisticated drivers, they end up being a lot more expensive. ---
**Author:** ![Lars20656](https://avatars.discourse-cdn.com/v4/letter/l/d6d6ee/32.png) [@Lars20656](https://forum.core-electronics.com.au/u/Lars20656)\ **Post date:** [14 November 2017 00:16 UTC](https://forum.core-electronics.com.au/t/accurate-pan-tilt-unit/1819/9 "2017-11-14T00:16:14Z")
> [@Sam](#): > > Haha, that’s my bad, I misread the distance and for some reason thought you meant 40-50cm. You are both quite correct. How quickly does it need to move positions? It doesn’t need to move super fast… something like 90°/sec would be ok. ---
**Author:** ![Lars20656](https://avatars.discourse-cdn.com/v4/letter/l/d6d6ee/32.png) [@Lars20656](https://forum.core-electronics.com.au/u/Lars20656)\ **Post date:** [14 November 2017 00:20 UTC](https://forum.core-electronics.com.au/t/accurate-pan-tilt-unit/1819/10 "2017-11-14T00:20:56Z")
> [@Michael\_R](#): > > I don’t, sadly. I’ve never experimented with them but they appear to be the go-to for accurate and smooth pan-tilt. > There’s a plethora of projects built around them, typically for cinematography. there are loads of products specifically designed drone-footage so they can be easily driven by regular servo signals. Nothing that core carries though. Check out some brushless gimbals on RC drone sites as a starting point. When you buy a drone type of brushless gimbal unit, won’t that usually mean you’ll be paying extra for stabilization etc though? Since this device will be hanging solidly attached to a roof, it won’t really need stabilization, just consistent and fairly accurate pointing. ---
**Author:** ![Sam](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/sam/32/99_2.png) [@Sam](https://forum.core-electronics.com.au/u/Sam)\ **Post date:** [14 November 2017 00:49 UTC](https://forum.core-electronics.com.au/t/accurate-pan-tilt-unit/1819/11 "2017-11-14T00:49:41Z")
Given your budget, something that comes to mind, which I’ve used for a similar project, is you could mount potentiometers to the pivot points, and use a high-resolution ADC to monitor the values. Something like a 12-bit ADC should cover your 0.25 degree resolution. The only downside is that it restricts your rotation angle. But, provided you didn’t need more than ~270 degrees of movement (standard for most pots), you should be fine. That would allow you to have an absolute reading, simplifying your code, and you could use standard brushed DC motors. ---
**Author:** ![Lars20656](https://avatars.discourse-cdn.com/v4/letter/l/d6d6ee/32.png) [@Lars20656](https://forum.core-electronics.com.au/u/Lars20656)\ **Post date:** [14 November 2017 01:05 UTC](https://forum.core-electronics.com.au/t/accurate-pan-tilt-unit/1819/12 "2017-11-14T01:05:52Z")
Thanks Sam, 270 degree range is plenty. I’ll definitively look into this kind of solution. This being my first physical hardware project (I got a fair bit of software experience) I realise I have a lot to learn though. I was recommended these motors as part of a feedback loop system that may be able to give me the required accuracy: > **[Analog Feedback Micro Servo - Plastic Gear](https://www.littlebird.com.au/products/analog-feedback-micro-servo-plastic-gear)** > > It looks like a micro servo, it acts like a micro servo, but it's more than just a micro servo! We got a factory to custom-make these classic 'micro' sized hobby servos with a twist - the feedback (potentiometer wiper) line is brought out to a fourth... They could be attached to this pan/tilt bracket: > **[Unassembled Mini Pan-Tilt Kit (Without Micro Servos)](https://www.littlebird.com.au/products/unassembled-mini-pan-tilt-kit-without-micro-servos)** > > This unassembled pan-tilt kit is the perfect way to give your project customized full range motion! The pan-tilt can rotate roughly 180° from side-to-side and can tilt downwards roughly 150° (it may be less depending on the servos you use,... If it works, it would certainly be good value. What do you think? ---
**Author:** ![Sam](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/sam/32/99_2.png) [@Sam](https://forum.core-electronics.com.au/u/Sam)\ **Post date:** [14 November 2017 01:48 UTC](https://forum.core-electronics.com.au/t/accurate-pan-tilt-unit/1819/13 "2017-11-14T01:48:04Z")
Hi Lars, I haven’t used those servos before myself so I couldn’t really say. We’ve got both of those products available, but I couldn’t really advise on the resolution of that motor. ---
**Author:** ![Lars20656](https://avatars.discourse-cdn.com/v4/letter/l/d6d6ee/32.png) [@Lars20656](https://forum.core-electronics.com.au/u/Lars20656)\ **Post date:** [14 November 2017 05:01 UTC](https://forum.core-electronics.com.au/t/accurate-pan-tilt-unit/1819/14 "2017-11-14T05:01:30Z")
Ok, thanks for your suggestions guys. I will keep them in mind will continuing to do some research…