PTZ (Pan tlilt zoom) DSLR camera tracker with liftoff detection project

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mikec For the Panasonic FZ150 You should be getting 14 ms shutter delay in prefocus (see https://www.imaging-resource.com/PRODS/FZ150/FZ150DAT.HTM ). Nice: 12 fps continuous shooting!
Nobody else has ever been able to duplicate that 14 msec number; I have no idea how imaging-resource got it. The actual pre-focused latency is thought to be about 90-100 msec.

Here's my first sequence of shots at 12 fps using the Sharp GP2Y0D810 sensor and an Aerotech Arreaux on an E15-7. Worked well, but it is a bit of a pain getting the sensor positioned within 4 inches of the rocket, I can see the appeal of the lidar. I may play with the ultrasonic sensor, though I have some doubts about beamwidth, range accuracy, and immunity to the noise of the liftoff.

arr1.jpg
 
Using a cell phone as the tracker is a cool idea. For some reason, I never thought about an app being able to process live video from the camera, but I just realized that it is the way "augmented reality" apps work.
Obviously image analysis can be done at some level on phones, but AFAIK most AR apps are just using the phone's orientation sensors and a simple video overlay. It's not like phone hardware is especially magical relative to what you can do on any other small computer platform, and I find the phone development environments needlessly painful to use (YMMV).

Tracking a colored blob is pretty easy, but controlling a zoom lens and tracking bright exhaust, then tracking smoke all the way to apogee is many many times harder. But it's a fun problem to think about.
 
So, I did some more work on the trigger this Fall. A disappointment and a positive surprise.

The LIDAR is ok for low power detection, but at a high angle in the sky for high-powered rockets, or very bright sky, it gets false positives due to sunlight. So that is a disappointment.

However, the RF link has worked great and much better than I expected. It is very low latency and allows cameras and triggers to be positioned without stringing wires between them.

I am going to look at filtering or m of n sliding window detection on the Lidar. Also, I am going to revisit the laser trip detection on the fin. Position it with a goose neck base about the fin and have an RF link to a remote camera(s). The problem with this before was having to string a wire from the sensor to the camera.

I'm going to write one program that runs both on the sensor module and the camera module. It will have a manual override, so that if the sensor doesn't trigger and the rocket is lifting off, you can trigger it manually. I'm using the Adafruit Feather M0 RFM69HCW Packet Radio - 868 or 915 MHz (3176)

upload_2019-12-17_8-17-24.png
 
I created a PCB (my first!) for the trigger circuit and RF link.

Options for different sensor inputs (high-low or low-high trigger).

Camera and aux output.

Same circuit and code on another tx and Rx unit.

Poll feature will query other nodes for connectivity.

Arm will activate sensor. Subsequent trigger sends trigger message to all nodes.

Trigger override push button (or foot switch) . Commands all cameras to activate. Nodes do not need to be armed.

Used kicad for circuit layout. Seeed studios for board


Now back to the tilt unit, or maybe I will make a Bluetooth link and an app.

Photo shows armed. Other photo shows trigger and breadboard design nodeIMG_0778.jpgIMG_0774.jpg
 
man that's cool!

i wonder if you could use a mic for a trigger, rockets are pretty noisy. Like you would setup the camera pointed at the rocket, detect launch via the sound, then automatically rotate the gimble at a rate matching the expected flight acceleration profile.

edit: if you got real fancy you may be able to use those directional mics like in an Amazon Echo and use the sound for tracking.
 
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Definitely worth exploring.

There are these cheap sensor modules out there that have a comparator and a threshold built it for a digital output. They are like $2-5 on ebay and amazon (cheaper that you can build!!). For example, https://www.waveshare.com/sound-sensor.htm

There are a whole variety of sensor types available, for example, IR sensor (https://www.waveshare.com/flame-sensor.htm), pictured on the left of my recent post with the photo Google
IR Infrared Obstacle Avoidance Sensor Module for Arduino


I have a rev2 pcb board done for the trigger portion. It will be able to accept a variety of sensor inputs, high to low trigger, and has a second input for low to high. The parts will come in and I will start testing. I'm working up a little instruction manual. But I plan to open source it.

Thanks for your suggestion.
 
Rev2 board of the camera trigger board/rf link is ready for testing.

I need to populate an LED D5 (ordered the wrong part), and there is a header for an eventual bluetooth module/ Smartphone app. I need to order the proper on-off switch. Note that the silkscreen for the lipo is backward.

Thanks to everyone for suggestions. The board can accommodate a variety of liftoff sensors. I started to put together a trade-off matrix. The sensor of choice may depend on which parameters are most important to the user. If one can accommodate a launch rail with a switch built in, or is ok with gluing a foil on your rocket's fins for a pair of alligator or paper clips, those ave very compelling choices. The microphone sensor that Chad suggested is worth a look. You can get one for $5 from China (waveshare, etc), cheaper than you can build.



Presentation1.jpg thumbnail_1.jpg thumbnail_2.jpg
 
I plan to opensource the board and software. I'm working on writing up some documentation. I will post details to those interested once more mature, and I have tested out the board more.

The BOM for a board node using an adafruit RFM95 module 1 mile range, without PCB and bluetooth module is $60. You can Knock $10 off using the RFM65 module (Adafruit 3176) with a 500 meter range and possibly more by not populating the parts of the board you don't care about.

One board node will give control to a local camera only; Two will give you a sensor and a remote camera over the RF link. Three will add another remote camera or a monitoring node.

A single board design/software supports separate node functions of sensor, camera trigger and monitor.

A node has two camera outputs and an aux output (e.g, for the future pan/tilt part, ha).

There are two sets of sensor inputs, low/high and high/low trigger, each with gnd and +3.3V terminal connections.

There is an output to turn on a laser or other device.

The three push button switches are to:
Arm sensor (once armed a sensor trigger will fire camera)
Poll other nodes
Force a camera fire manually without sensor.

Arm and force trigger have terminal blocks for optional foot switches (or other input control).

At the moment, unfortunately, the frequency is hardwired in the software. It is crying out for a bluetooth smartphone link for configuration and monitoring. This will be in the future someday
 
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man that's cool!

i wonder if you could use a mic for a trigger, rockets are pretty noisy. Like you would setup the camera pointed at the rocket, detect launch via the sound, then automatically rotate the gimble at a rate matching the expected flight acceleration profile.

.

I got a cheap sound sensor with a LM393 comparator built in from Amazon (5 for $5.49). I must say the sound sensor is looking pretty promising. One can set the threshold so normal talking will not trip it. A clap or low shout will activate. The nice thing about sound is that the sensor orientation toward the rocket is not that critical. Lasers, LIDAR, ultrasound require careful placement and alignment fixtures (aka hassle to set up).

I will test against real rockets, both Estes and HPR at the next launch. Assuming the latency is low, which it should be if it is only three feet from the rocket, it should be good. Thanks, Chad for the suggestion.
sound_sensor.jpg
 
Sorry to be negative, but I think pure audio triggering is going to prove complicated, since igniters often pop long before ignition, there can be chuffing, etc. Happy to be proven wrong on this.
 
I've been testing the RocketTrig system with good results. The trip wire and laser/photodiode sensors work the best, and I have assembled an articulated fixture for the latter. The Lidar works well under some circumstances, but can be sensitive to background light and is expensive. The microphone sensor that I had had a very high latency. Not sure why.

Only thing I'm not happy with is the antenna. Maybe a helical coil type?

I'm the type of person that likes to have spares. Something breaks, reach in the range box and replace it. I assembled 6 of these, although I only need three. Dunno. Is this hoarding?

Here are some photos.IMG_1583.jpg
 

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No its prudence...anything can break at any time, especially the more complicated it is. I have been following this for a while looks like its coming along nicely. Once you get it up and running the way you want maybe offer it as a Eggtimer style kit.
 
Once you get it up and running the way you want maybe offer it as a Eggtimer style kit.

Ahh, good idea. But more a kin to the old HeathKit kits, as the components are all discrete.. I could provide the board and user manual/instructions and a few compents that Mouser doesn't have and flash the microcontroller. Then I could give you a Mouser BOM and just order the componets youserlf, customizing it a bit (e.g., leave off a few componets for features you don't care about). It's all discrete components, so it would be a jiffy to solder.

I keep finding little things to tweak.
 
Ahh, good idea. But more a kin to the old HeathKit kits, as the components are all discrete.. I could provide the board and user manual/instructions and a few compents that Mouser doesn't have and flash the microcontroller. Then I could give you a Mouser BOM and just order the componets youserlf, customizing it a bit (e.g., leave off a few componets for features you don't care about). It's all discrete components, so it would be a jiffy to solder.

I keep finding little things to tweak.

Thats probably not a bad way to do it.
 
man that's cool!

I've been testing the RocketTrig system with good results. The trip wire and laser/photodiode sensors work the best, and I have assembled an articulated fixture for the latter. The Lidar works well under some circumstances, but can be sensitive to background light and is expensive. The microphone sensor that I had had a very high latency. Not sure why.

Only thing I'm not happy with is the antenna. Maybe a helical coil type?

I'm the type of person that likes to have spares. Something breaks, reach in the range box and replace it. I assembled 6 of these, although I only need three. Dunno. Is this hoarding?

Here are some photos.View attachment 414994
 
It's been a while since I posted an update on this project. My two articles ran in Sport rocketry, Jan/Feb 2023 for the overall system and July/Aug 2023for a more detailed discussion of lift-off detection sensors and trade offs. All my circuits, board designs and code are on github: https://github.com/chrocket/RocketTrig . Since I wrote the article, several things have happened:

1) I have learned the Nikon Z9, a high end pro DSLR, has a motion sensor trigger mode built in. Press the shutter half way, when it detects motion, it fires. This is a top-of-the line camera, but someday this functionality will show up in other brands and trickle down to lower cameras.

2) Several people emailed me sensor ideas that are worth noting.

3) I had a eureka moment. I have a switched output through a bipolar transistor. This can be connected to a relay, and voila, I can create a remote launch controller. The infrastructure is all in place with the existing boards.

I will talk about (2) and (3) in separate posts.
 
Two people made good suggestions RE sensors.

Joel Mapes suggested, "a thin film pressure sensor placed under the edge of the rocket? Most rail systems have a ledge to hold off the rocket from the blast deflector, and a grippy clothespin can serve the same purpose on a launch rod.

The sensor could be sandwiched between two heat resistant layers (aluminum?) and gently stuck to the support or simply be held in place by the weight of the rocket."


And from Yev on the RIT rocketry team, "I have a suggestion about the break-wire. I think it could be simplified and end up with no modifications to the rocket if it were a breadboard header wire wrapped around one fin or railguide. They don't take a lot of force or distance to remove and feel pretty consistent."

Both good ideas.
 
So for the remote launch controller, I designed it with the following behavior, so I could fire the launch with a foot switch. This would give my hands free to handle cameras. The system can trigger cameras and launch rockets! I liked how the system worked so much, that I even worked up a new board that would better facilitate both camera control and remote launch control functions.

1) First of all, traditional toggle switch safety off and continuity circuits.

2) An "arm" command push button. This will arm the system for launch. Three conditions will disarm the system:
a) a 15-second time out occurs
b) the user presses a "disarm" push button
c) once the launch is fired, the system goes back to an unarmed state (For "launch", there is a panel push-button as well as a port for a foot switch).
The arm state sounds a buzzer and lights an LED.

3) Camera trigger method can be selected. User can select between launch fire or external sensor,

4) Launch (and camera trigger) will fire for a two second window. Hitting disarm will turn off the ignition circuit, if it is still on.

5) The disarm button acts to poll the cameras for a short time

6) System is housed in two small pelican case knock-offs, the launch controller and the remote note. The controller also contains a wired launch connection. This was a hail mary, in the event the RF launch part didn't work. But the remote launching capability works fine.

I also built a relay board. I found a nice really tiny relay, 12V 25Amp, Omron G8N-1U-AS. I used a MCP23017 I2C 16 channel GPIO expander. This gave more flexibility for inputs and outputs, as each channel can be programmed separately. I used 8 channels as outputs. These go to a ULN2308 8-channel driver. These can drive 500 mA, which can be a relay, LED, etc. Note that the prototype shown here does not use the relay or the relay board ... it uses a 12V automotive relay.

 

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