Camera falling rig

Description

Simple falling rig for a small action camera like a GoPro or a Rollei. It is designed to drop the camera with a certain speed from a bridge or from a cliff. 
The assembly is not the easiest and requires different tools as well as some basic skills in building electronics, but don't be scared, everything will be explained in this description.
The maximum speed of the rig depends on different factors like the voltage of your power supply / battery, the size of the pulley (reduction ratio) and the used 555 DC motor.
Of course you can use the winch itself for other small payloads, depending on what you need.

Check out my YouTube video about it to get an idea of what kind of shots can be done using this contraption.

Bill of materials 

3d printed

•  Electronic box 

  • Cover plate

  • PCB holder

  • box lower - case 

  • cable clamp (optional) - i used hot glue 

• Battery holder 

• Winch 

  • baseplate 

  • roller

  • rope guide and its pulley 

  • motor pullery 

  • indexer pulley 

  • indexer cover 

  • arm 

• ACM - action cam multi orientation mount 

  • top arm 

  • 2x lower ring part I 

  • 2x lower ring part II 

  • center beam 

Hardware 

• Baseboard - wooden or other material -> length depends on what you want, width min. 150mm 

• M4_threaded rod 120mm

• M4 threaded rod 50 mm 

• 608zz bearings

• M4 nyloc nuts

• M3 x 30 screws

• M3 nuts

• M3 x 12 countersunk screws

• 3,5 mm Wood screws

• Self tapping M2 screws

• 50-100 m fishing line 

Electronics

• ESP8266 Amica Board

• MP1584EN DC-DC 3A Power

• L298N Motortreiber Modul mini

• L-298N Motor Drive Controller Board Modul

Electronics

I choose the simplest way I could imagine. The smaller L298N mini board was implemented between the ESP8266 and the L-298N drive controller in order to shift the 3.3 V to 5 V and then to the motor supply voltage.
I decided to go this route because I had other projects where I could use the mini driver board for small motors. A simple logic level shifter would be the more correct approach.
The attached electronics.PDF contains more information about how to connect everything and how to wire the electronics up. 
Used pin out -> The Pin ID i drew in the schematics are not fixed! You can simply change to other pins by changing a few lines of the code! You shouldn't use any boot pins. (D0,D3,D4,D8)  

Adding an inline fuse to the wires from the battery to the main electronics is highly recommended as those battery packs are able to deliver high amount of currents any shorts within the electronics may lead to an fire hazard! 

As shown in the pictures I added some small 10-100 nF caps to the inputs of the encoder to decouple any noise from the sensor wires.  This is just optional and is only required if the DC motor (brushes) induce to much noise to the sensor inputs. 

Code and web interface 

Programming of the ESP8266 using the Arduino IDE is well documented on several websites and YouTube HowTos, thus i wont describe this here. 
Simply download the .ino file and open it with the Arduino IDE. 
Change the input and output pins depending on your setup. Usually you only need to set the following parameters. 

Update the PID settings depending on how the winch reacts to your payload. (There are a lot of descriptions out there how to setup a PID correctly, just google for it...) 

The winch is controlled using a simple web interface on the esp8266. 
After burning the code onto the ESP8266 and powering everything up you can simple connect to the esp using the wifi access point with the credentials you entered inside the Arduino IDE. 

After connecting to the ESP8266 AP simply open a web browser and enter 192.168.4.1, a screen like that one shown below should open. 
You can change the values depending on your needs or simply put in a target position and let it run. 
The direction depends strongly on how you hook the light barrier sensors up, in case - is running forward and + backwards, either change the wiring of the sensors or switch the Encoder A and Encoder B pin in the software. 

Printing 

Used material: PLA 
Layer height: 0,2 mm 
Nozzle diameter: 0.4 mm 
No supports and no adhesion -> already added in CAD! 

Printing large flat surfaces laying down on the print bed isn't good practice at all! Thus i usually add support fins and a heavy chamfer on one edge. For the post processing simple wiggle the fin a few times and it should pull of the part. The little connection spots will remain on the surface but they shouldn't be an issue for further assembly. 

All parts should be rather easy to print, i printed them mostly on a low quality bed slinger machine with poor mechanics. 

Assembly 

Lets go to the fun part, shall we? 

1. Mount the battery holder to the base plate using 4 3mm wood screws.
   I cut a few pieces of 1 mm copper sheet metal to roughly 7x15 mm. 
   After pressing these sheets through the openings in the backside of the battery holder i solder a cable to the required connectors. 
   !!! Add a fuse to one of those cable to limit the current in case of any short circuits!!! 

   

2. The electronics are a bit more complicated. 
   First glue two 15 pin female dupont connectors into the grooves on the backside. 
   Solder the connecting wires for all other components to these connectors. Run the wires for the DC-DC converter and for the mini motor driver shield trough their corresponding openings. Solder those shields according to the schematics attached. Then simply press the shields into the PCB holder, they should snap in place rather easy. If not you can trim cut the edges of the breakout PCBs a bit for an easier fit. 

   

   Route the wires to the battery, the sensors and to the motor driver shield through the openings on the short edge of the box. Use either the cable clamp or some hot glue to strain protect the wires. 

   

   Place the PCB holder in the box and use 4 M2 self tapping screws to mount it. Make sure that you don't squeeze any wires in between the standoffs and the holder. 
   After programming the ESP8266 you can press it into the female pin headers (!!!Check for correct orientation!!!) and close the lid of the electronics box. 
   The lid is designed with grip fins and has a very tight feeling to it while closing! You need to press it rather hard on the box, don't be scared, it will not snap and the fins ensure that everything will hold together reliable! 

   

3. The winch... start by mounting the base to the wood base plate using 4 3 mm wood screws. 

   

   Make sure that the motor mount is on the longer side of the board! 
   Use two M3x12 bolts to mount the 555 motor (or similar) to the mount and add the motor pulley to the shaft using screw clamp. 

   

   Next is mounting the winch roller. Screw a Nyloc nut to the M4 threaded rod on one side, then add the first bearing to it. Run the rod through the base from the left side, add another nyloc nut to the rod, the hex side of the nut needs to face inwards, then add the roller and press the nut in the left side of the roller. When the rod reaches the end of the roller press another nyloc nut into the ressed area on the roller and screw in the threaded rod. Now add the PU drive belt to the roller and screw the threaded rod through the right side of the base adding the second bearing and another nut. 

   

   Then add the indexer disc to the axel and the last nyloc nut which should place the indexer right between the flanges of the lightbarrier holder.

   

   Mounting the front arm is a bit tricky. Add 3 M3x25 screws to the corresponding holes and use a pair of needle nose pliers or tweezers to screw 3 nuts onto the screws. As i didn't resess the nuts inside thier cavitiy using some hotglue to fix them is highly recommende. I simply added a little bit of spray grease (WD40) to the screws prior to pushing them through the holes, after screwing the nuts onto the bolts i used a generous amount of hot glue to fix the nuts. The screws should break loose from the hotglue rather easily when properly greased. 

   

   Add another bearing to the rope pulley and press the rope guide onto the arm. Push the 50 mm M4 threaded rod through the arm, the guide and the bearing and use two nuts to mount everything togehter. 
   I desgined the rope guide to be easily replaceable for further development, in this simple configuration the rope tends to pile up on one side of the roller. 

   

   
   After installing the lightbarrier sensors (i simply used hotglue to mount them onto the fork) add the indexer cover. I recommend to wrap/glue the cover in aluminum foil, this will keep all the IR light out of the sensor area and prevent the sensors from missreading the position. The cover is mounted using to M3x25 and two M3 nuts. 

   

4. Camera mount - this desgin is very flexible and it strongly depends on what and how you plan to shoot your videos. 
   The simplest version consists out of the top arm and one of lower ring parts.
   This setup allows you to shoot downwards and horizontally. 

   

   If you want to do more complex things like shooting at an certain angle or shoot tworards the sky while dropping the camera i recommend to print all ring parts and experiment a bit with different setups. The full ring allows you to tie three pieces of rope to the camera and film twoards the sky while remaining vertically aligend. 

   

   Thats it. :) As mentioned above, it is not the easiest build and it does have some improvised solutions to it but it is working and quite fun to play around with.