AtlasMeter Testing Continued

I fixed the lost steps issue by taking inspiration from my CNC machine. Since they don't have infinite acceleration, CNC machines use trapezoidal velocity profiles to slowly ramp in and out of movements. My camera dolly also can't accelerate infinitely, so I applied a trapezoidal profile to the velocity of every camera move. After a bit of tweaking, I was no longer losing significant number of steps. I tested from 10 to 204 frames and every time the dolly moved the right distance. However, the dolly now travels a little slower (the move step function now takes a delay parameter and therefore takes more CPU time). I need to implement variable speed movement to save time in setting up the start and end positions of the dolly.

AtlasMeter Testing

After running the timelapse dolly several times, I've uncovered several bugs in the code and hardware (and fixed them). I added a screw to mount the camera (without the mount the camera slowly shifted around) and fixed some time display bugs. For some reason, the dolly consistently misses steps, and the more frames there are the more steps are dropped. At the end of a 240 frame run that was supposed to travel over the entire length of the dolly the camera was nearly a foot short of the set end position. I'll have to fiddle around and add some constant to the steps per frame to get the right distance.

I noticed that the camera moved slightly faster in the beginning than at the end and didn't have a very consistent speed  in the middle. There must be more steps dropping or some play in the belt. Also, I need to remember to not move the camera too much per frame or the video is choppy.

AtlasMove Rev.0 Complete

My timelapse dolly project, named AtlasMove, has finally become a functional prototype. I just finished programming a rudimentary menu system for setting up the timelapse parameters. I still need create clamps to hold the belt at each end of the slider to keep the belt taught.

Front side of the circuit board

Back side (a little messy)

Camera Dolly: Parts

All the parts I ordered for the motorized slider are coming in slowly. The motors from All Electronics are really nice. One annoying quirk about the stepper motor is the 2 mm female connector. Why it couldn't have been 2.54 mm, I'm not sure. In the end, I just bent a set of standard headers into the correct width. Interestingly, the gear motor had a 2 mm male header with far more pins than was needed for the encoder and motor power. On the back of the header was a 8 pin SOIC chip. Upon closer inspection, I found out that it was an I2C EEPROM (M24C02). I hooked up (poorly soldered) wires to read the EEPROM but found that it was empty (the entire thing was filled with 255 and 254). I wrote some data to it to verify that it was functional, and I was able to read my data back. I'll have to find a use for it later.

Pulley, belt, camera cable, motors, and linear slide	Stepper motor (and jerry-rigged connector)
Gear motor	EEPROM on gear motor header (motor wires desoldered)

Camera Shenanigans

I've recently been tinkering with DSLR cameras and timelapses. Seeing all the videos of timelapses and especially the "holy-grail" timelapses from day to night have gained my attention. I've been looking into the subject for quite a while now but only now am I really delving into the details. The timelapse controller I've been working on for a while is currently parked because I decided to get more acquainted with the basics of timelapse before getting into bulb ramping. I bought a simple timer remote and am experimenting with several scenarios. I've also shot one timelapse of the stars at night. To add motion to a timelapse, I've decided to also build a two-axis motorized dolly (linear motion and one rotational axis) using the 8020 slider that was supposed to go on the CNC. The parts are slowly arriving and I hope to build it up and test it soon.

 

Night Sky Timelapse from Jeffrey Ni on Vimeo.

Ham Radio: KK6QZZ

Just a quick update for the holidays. After nearly two years of putting it off, I finally took the test for a Technician ham radio license on December 9th. I passed with one question wrong and my call sign is KK6QZZ. I initially wanted to get a license for high-altitude balloon tracking and now I can begin to move forward with this project. I'm not sure if I want to build my own APRS transmitter or just buy one. I'll see how this pans out.

Mechanical Iris

Thanksgiving break began, and I spent the last couple of days designing and cutting out a mechanical iris. I got some practice with Autodesk Inventor and using my CNC. The entire thing was designed in one part file, then exported to an assembly, where I added constraints to simulate the movement of the mechanism. Then, the face of each part was exported as a DXF file and converted into a toolpath with V-Carve.

Closed

Opening

Open

The simulation looks great, but how would the actual device turn out? Since my machine is not rigid at all, the the cuts were significantly off (when compared to other DIY CNC machines). But in the end, the final product wasn't half bad.

Cutting out the fins and support ring.

Closed

Opening

Open

A quick video showing the opening and closing:

I would say this project is a success. I'm still working on getting the machine more rigid. I made some rails out of 8020 and v-groove rails and bearings.