Adding a manually controlled servo gimbal for use as a head tracking gimbal is relatively simple if using a flight controller running a common firmware (Betaflight, iNav, ect.), but there are a few important considerations when adding to an existing build or pre-built.
Seem like too much work? Our store sells a selection of Fully Pre-Built Gimbal Drones!
What You’ll Need:
- 3D printed parts designed to fit your frame (Open-Source Designs by Medlin Drone). Good-Value 3D Printer: https://amzn.to/3yB2s57
- 1x Digital Metal Gear Servo. Large smooth servo LDX-218: https://amzn.to/3fMmrqi (you will need a 25T servo horn if purchased from somewhere other than the Medlin Drone Store). Smaller and lighter but less smooth servo EMAX ES08MD: https://amzn.to/3xyv3qy.
- 2x Ball Bearings 10mm OD, 5mm ID, 4mm Thick: https://amzn.to/3xuCsqJ
- 1x 25-35mm M3 Standoff 5mm OD: https://amzn.to/2X2kFLr
- 2x M3 Screws: https://amzn.to/2WVjpd7
- 1x Servo Linkage Wire (Optional, a paperclip will work): https://amzn.to/3ApEuKQ
- 1x FPV Camera Wire Extensions (Optional, for analog cameras you can just extend wires, good silicone wire: https://amzn.to/2X9gbSZ). For DJI, you can replace the camera cable with a Mavic Pro Replacement Camera Cable: https://amzn.to/3DYZt9F Fat Shark Shark Byte comes with a long enough cable. Any digital camera will require more work than an analog setup, you may need to move your VTX forward in the frame. Protected camera extensions available for analog and DJI at the Medlin Drone Store!
- 1x Servo Cable Extension (Optional, can just cut off servo plug and solder directly to FC): https://amzn.to/3AnGl2z
- 1x Wire Shrouding (Optional): https://amzn.to/3BRFIiE
- 1x 100uF 16V Capacitor (Optional, helps smooth servo movement): https://amzn.to/3fK1oV6
- 1x Head Tracking Unit (Recommended) – Video for Open Source DIY Head Tracker – Huge shout out to the creators of this!! Arduino Nano BLE: https://amzn.to/2VGh3Om. Pre-Built Head Tracker available at the Medlin Drone Store! Here’s a tutorial for Adding a Head Tracker to Your Setup.
- Unless using crossfire or another receiver with ability to output an individual PWM signal the flight controller must have an available UART with a built in ‘timer’ (a LED pin or unused motor output pin will work), 5V output, and ground.
- You will probably need to extend the connection wires to the FPV flight camera (the Medlin Drone Store has extension cables for all major camera manufacturers, both analog and digital).
- Depending on the frame design you may run into an issue where the gimbal interferes with the propellers, this can usually be solved with spacing the gimbal upwards or forwards.
That’s it! Otherwise, you should be able to implement this on your drone, unless you are using the DJI FPV drone… that already has one on it… but let’s not talk about that.
The build will vary depending on frame design, but here are some tips:
- Start by adding servo connection to Flight Controller and testing servo control, no point in going further until you confirm this. I recommend using a male servo connector so that you can easily switch out servos, a servo cable extension can be cut in half to get a male connector.
- If extending the FPV camera wires or using an extension cable, it is better for the wires to be longer than necessary than shorter, especially in a crash.
- Route the FPV camera wires such that they intersect (or nearly intersect) the gimbals axis of rotation, this ensures the wires are not being pulled/pushed during gimbal operation.
These are the general steps you will need to follow to add a servo gimbal to a FPV drone, either via a Medlin Drone kit or via components you sourced yourself, the exact setup will vary from frame to frame and preference.
Joshua Bardwell made a video on adding a servo to a FPV drone, if you prefer that format follow his video for the portion of this tutorial related to servo control setup.
- Locate an unused LED pin or unused motor output pin on your flight controller, as well as a 5V and ground pin. These will be how you power and control the servo. If using TBS Crossfire you can just use the 3rd or 4th output pin/map as a PWM channel output to control the servo and skip the steps related to Betaflight setup, for example setting the 3rd output map to “CH7” will output a PWM signal for channel 7 on the 3rd output pad.
- You can choose to either use a male servo connector or to solder the servo leads directly onto the flight controller, some servos like the LDX-218 have a lead that has its own connector that plugs into the servo itself, for these you may want to just solder the lead to the flight controller since it has its own connector to the servo, the choice is yours.
- Plan on how you want to route wiring before soldering to the flight controller, and if using a capacitor consider where you want to place it. Ensure that the cables are long enough before cutting or soldering, check where the servo will sit on the frame and how it will be oriented to make sure your cables are long enough to reach.
- Generally servo wire leads have the 5V in the center, and the ground and PWM wires on the sides with the the PWM wire almost always being white.
- Solder your servo leads or connector onto the flight controller pads, with the PWM wiring going onto the unused LED pin or motor pad, the 5V to 5V, and ground to ground.
- If using a capacitor solder the capacitor to the 5V and ground pads ensuring the correct orientation (most capacitors have a gray line with a “-“ on the negative side).
- Go into Betaflight or iNav and follow the pictures bellow to set up your servo, Joshua Bardwell also made a video on this configuration.
- Now its time to test servo control, I recommend having the servo horn OFF the servo and using a smoke stopper for first plug in. THESE SERVOS CAN BREAK YOUR FINGERS please be careful. You wont know which way the servo is currently oriented until you have control of it, it would be easy to break things including yourself if you don’t use cation for this step, take the servo horn off so that no matter which way the servo spins it will not damage anything. Once you have confirmed you have control of the servo the rest is pretty simple.
- Now is a good time to think about how you want to route your FPV camera wires, or extend them if you need to. This will vary from frame to frame.
- Insert servo into the gimbal base.
- Check that the servo is plugged in and mount the gimbal base onto the frame, you will most likely need to have the top half of the gimbal disconnected to reach the front bolts.
- Insert the bearings into the bearing housing on the front of the gimbal base.
- Insert the M3 standoff into one side of the gimbals top half hinge, but only a little such that the hinge can still fit onto/over the bearing housing.
- Then line up the holes and press the standoff through the bearings and housing and through the other side of the hinge, there are other methods of doing this, like inserting the standoff first and then stretching the hinge over the standoff. Again, the choice is yours, some methods will be more or less frustrating to different people.
- Now screw a M3 screw into each end of the standoff to prevent the hinge from slipping off, gently snug them so that it isn’t compressing the hinge.
- Check that your FPV camera wires reach the camera, aren’t being pulled on when the gimbal rotates, and aren’t interfering with the propellers. I recommend having the wires pass through or near the axis of rotation to ensure they aren’t being pushed/pulled during gimbal movement.
- Next is to set up the servo linkage, it is useful to think about how far up/down you want the gimbal to rotate and decide where to you would want the servo linkage to connect to the top half of the gimbal, this will most like require trial and error, here is one of my setups for reference.
- I recommend using the Medlin Drone servo wire bending jig to bend the wire to the desired length. Clip off excess wire. I also recommend using a servo horn sleeve/insert to remove any free play in the linkage connection to the servo horn.
- Poke a small hole though the linkage connection tab in the desired location (again may take trial and error to find appropriate spot).
- With the servo horn OFF power on the drone and rotate the servo (via your transmitter, NOT by hand) all the way back/counterclockwise and disconnect power so that you know it’s in the furthest back position. This is where having control via a slider is useful, as described in the tutorial for adding a head tracker to your setup.
- Insert servo linkage wire into the hole in the connection tab and then into the servo horn, then insert servo horn onto servo, it should look similar to the picture above.
- Check that there is not excessive slop in the linkage, this can be caused by play in where the linkage connects to the servo horn, which can usually be solved by removing the linkage and slightly crimping with pliers the bend in the linkage that sits inside the servo horn. Also check that the hole poked in the connection tab is not so big that it introduces play in the linkage.
- Ensuring that your transmitter is on and has the channel controlling the servo in the same position as it was when you powered the drone off, carefully power on the drone and test the range of the gimbal. It is easy to break stuff at this stage, use your own judgment, Medlin Drone is not responsible for any broken parts or fingers.
- Once the gimbal is setup there isn’t as much need for caution, as it should maintain its current range of motion, but I still recommend respecting the servos power.
- Mount the FPV camera and connect the camera wires.
- Test that everything works and you are getting signal from your FPV camera to your VTX.