Introduction: SKY CAM an Aerial Camera Solution
This Instructable will walk you through how I made a remote control (Semi Autonomous) Cable Cam system for my GCSE Electronic Products Project at School and hopefully enable you to be able to create your own system! This is intended as a rough guide on the principals as each system is different depending on the requirements. For this project you'll need a reasonable understanding of electronics and CAD CAM (Computer Aided Design/ Manufacture) although don't be put off as simplified versions can be made.
- My client needs a system to get aerial film of a variety of activities and events.
- The Problem is that where Drones/UAV’s would typically be used to get this footage, it is unsafe and impractical to use these over people, inside, or in typical sporting terrain such as wooded areas or a sports hall, because of the danger of injury should the system fail and limited space can make It impossible to operate such systems.
Based on this I set a Design Brief:
- Design and make a product to capture aerial footage using a safe and cost effective system that can be remote controlled and move between two fixed points.
As most Commercially available Cable Camera systems come in at about the $4,000 plus mark. I wanted to make a system that would make this kind of advanced camera work available to more creators and hobbyists on a tighter budget.
What you'll need to complete this project :
Access to a 3D Printer (Housings)
Access to a Laser Cutter (Main Body of the rig and for the Control panel cutting and etching)
Be able to make PCB's as almost all of them in this project are custom designed.
Additionally these are the main specialist components that I used:
Membrane Switch (The ENT menu scroll Button)
Dyneema Cable (Choose Length depending on where you plan to use the system)
Yellow Flight Case ( For the controller, although any enclosure could be used)
Step 1: Overview
The Cable Cam consists of three main parts:
The Actual Rig (The part that carries the cameras and drives along the cable)
The Controller (Contains a Microcontroller and an RF Transmitter)
The Cable (Supports the rig and allows it to be run between any two reasonably sturdy points)
Step 2: How It Works
As you can see in the pictures above the Rig Relies on friction in order to transfer drive from the wheel onto the cable (Green Line). It can be difficult to achieve the right balance of friction so I used the below methods to achieve optimal tension and friction.
Primarily the arrangement of the the wheels forces the cable down and over the drive wheel as seen in the diagram above. This is a very good method as it allows the two outer wheels to take the full load of the rig onto the cable (Meaning you can mount reasonably heavy cameras or equipment onto the rig) be sure to READ STEP 7 before trying to use your own system!
However the three wheel arrangement relies heavily on the cable be at a very high tension which is ideal and easy to achieve with my rigging method however it may not always be at the optimal tension. To cope with this the load bearing wheels both sit in a slot system that allows them to be moved up and down to vary the tension in the rig. It also acts as a basic safety system- If the cable becomes over tensioned for any reason then the out rigger wheels slide up to reduce pressure on the rig and drive wheel, hopefully preventing damage to the motor.
So when you're designing your own rig using the tri arrangement of wheels is an excellent method for ensuring drive onto the cable.
Step 3: Controller
To make the Controller you need to start off by getting the measurements with some digital callipers and making a rectangle in CAD (Fusion 360), I then laser cut it in card. This will allow you to get the measurements correct as well as letting you position all your components before you cut in your final material.
For My control panel i cut it in 3mm Dual Layer Laser plastic which is how I got the engraving's to be white. one issue with this 3mm plastic is that it's pretty flexible. To counteract this I used 5mm black acrylic with large cut outs in the support the back of the panel as can be seen above. Then in each of the four corners I drilled a 3mm diameter hole and put a machine screw through the two plastics and secured it with an M3 Dome Nut on the top of the panel which holds it together nicely. It also adds to the rugged aesthetic of the control panel.
One advantage of using a flight case similar to the above is that your panel can be a friction fit. Just push it in tightly and it will stay in, however if you need to remove it for any reason you can still click it out with a bit of force!
Step 4: Electronic Systems
There are two main Systems in this project which are outlined below. You can also get an understanding of how they integrate with the flowchart above.
The Rig Side:
- RF Reciever
- Microcontroller Board
- Motor Driver
The Controller Side:
- Control PCB
- RF Transmitter
The Motor driver is a Transistor Based H Bridge that works by switching on alternate pairs of the four transistors that allows the motor to be run: Forwards, Backwards and also act as a break by feeding back EMF into the motor. Instead of using relays I used an Optocoupler (16 Pin 4 gate) to interface the PICAXE Microcontroller with the transistors ensuring that the Microcontroller isn't damaged by the higher current of the motor driver.
On the rig at each end there is a micro switch that allows for the rig to know its position along the cable at all times, allowing for autonomous features and also stops it from hitting the end of the line. It can determine it's location because during the start up procedure it runs the maximum length of the cable and records the end and start points. Then it can calculate its position at any time based on how long it been moving along the cable
Step 5: Drive System
In oder to be able to drive the rig at high tensions and at reasonable speed you'll need to use a high torque geared motor. I used an electric screwdriver motor and designed a housing for it in CAD (Autodesk Fusion 360) works really well for me. Above you can see that I included cable ducting and air vents, as well as mounting holes.
The measurements need to be extremely precise otherwise you may experience gear box failure. (I did in my initial testing phases, there was some excess space inside the housing that allowed the gearbox to come loose and fail so watch out!)
Step 6: Motor Driver
I decided that i would build a custom motor driver for my project that would enable me to interface the motor with my Microcontroller and run it forwards and backwards. Additionally in my final system I was also able to use back EMF to act as a brake on the motor. See above for the Motor Driver research and incremental development. After my research I finally used FET's interfaced with an Optocoupler as the pictures explain!
Step 7: Rig
Step 8: Software
The system has two Microcontrollers one on the rig and one in the control panel.
The Code for all the systems is written in BASIC on the PICAXE program editor.
If you wish to replicate I advise you look to the flowcharts as this will allow you to implement it on any platform regardless.
The original code shown here was an early stage development code and has been removed as it is unhelpful.
Step 9: Finishing Details
- To give the product a professional finish I was able to use a Roland Sticker Cutter (Dr Stika) to cut Vinyl Sheet into text for branding.
- Additionally you can use strips of tape to indicate the correct orientation for the power packs on the power unit. This lets you easily switch out the battery packs without getting them the wrong way up.
- I Polished the Aluminium spacing tubes on a bufffing wheel to add the the sleek aesthetic of the device. this only takes a couple of minutes and gives a really nice finish
- Try to polish the Aluminium tubing before you cut it too length as it will save your fingers from the buffing wheel!
Step 10: FILES:
Second Prize in the
We have a be nice policy.
Please be positive and constructive.
You should be able to build a similar program for Arduino or other system if you look at the system flowcharts!
Excellent design and documentation. Questions:
Was the gearbox from the electric screwdriver?
How did you connect the gearbox output shaft to the drive wheel? (pulleys shown all have an internal bearing)
Looks like you have to remove the support wheels/ shafts to attach the unit to the cable. I would think that a quick release pin here would be helpful.
Does it have enough friction on the drive wheel to operate on sloped line? Would think that you would need more contact angle on the drive wheel or even a multi-reeved system.
1) Yes thats it a 3.6v electric screwdriver with a planetary gear system just off amazon!
2) I had to both drill out the hole by 0.5mm for the drive shaft and that allowed for a secure friction lock and then I simply used superglue to lock up the bearing and added epoxy just to be safe as its a high load part.
3) because of the nature of the system and the way the rig is set up you can just feed the cable through, but you can actually simply release the load bearing wheels then slide the cable past the drive wheel and on to get it on.
4) Yes, there is absolutely no problem in terms of friction which i was pretty suprised with, the three wheel system really works very well and the sliding outer wheels allow you to adjust accordingly. But theres definitely enough friction, from time to time its been too much with a highly tensioned centre cable so I've had to use the adjusters to let some slack into the system!