|Quantity||95.85 Length - Meter|
Fiber 0.25 microns diameter PMMA
|Record created date||March 31, 2013|
|Record created by||None|
We don't know.
creating prototype for PMMA joint-type transducer.
These activies are repeated in order to clarify the procedures of the Low-cost Tape Sensor design. The citations include these steps as well.
Tape sensor - introduction (done)
Tape sensor - gap optimization (IN PROGRESS)
Tape and flex sensor - comparison (IN PROGRESS)
Tape sensor - 3D printing (IN PROGRESS)
Tape sensor - manufacturing (STANDBY)
This is for Ronan
Created a low cost optical tape sensor that can be put on different structures to detect bending.
We'll apply it first on a hockey stick.
See project page
Started on Friday 27, 2012 After we created the prototype and made the demo for Zhu (Canadian Space Agency, beam deflection sensor) we realized that this device works in stretching and compression. I had the idea to create a very simple and low cost tape sensor using 250 um diameter PMMA fiber and kapton tape. The goal of this experiment was to build the first such prototype and test it. See design https://docs.google.com/drawings/d/17Wb68vkZPeV5jz1GJDJG-TXER2Ofy-1wyndfQbkgp10/edit The device was built and successively tested. See the video made with Daniel http://youtu.be/yKvdryt1iKk
04 JUNE 2013
Worked on the setup to fabricate the low cost Tape transducer. I continued in the same direction from where I left it. The device is now almost done, need to take some pictures and document how it works. This is still a prototype device, to produce a few of them in a systematic matter and test them.
I will use the enhanced LED 850nm Mosquito to test it. I need to make a project presentation to SENSORICA about this, in a week.
05 JUNE 2013
Did some mechanical work on the fabrication device. I finally put in place the micrometer screw and 2 springs to move the working plate. It seems to be solid. After this, I shifted my attention to the Y connector for the 250um diameter PMMA fiber. I created a separate labnotes where I marked 7 hours of work on this. The main problem was to create a mold/stamp for PCL, from which I make the connector. The idea is to stamp the Y grove into PCL, place the fibers into the grooves and apply optical clear epoxy to hold the fibers aligned in place. I started with clay, and moved to etching aluminum.
10 JUNE 2013
Produced a new low-cost tape sensor using Francois' design.
11 JUNE 2013
work on the tape sensor presentation
14 JUNE 2013
Created documentation for the low cost tape sensor, adding stuff on the website, and updating the document.
Gave training to Ronan on the Tape Sensor. I also created a labnote for him to collaborate on this project.
16 AUGUST 16, 2013
Worked with Rodrigo on a new tape sensor design. We are trying to implement the idea of optical gearing. See concepts here
One design use a concave lens (perhaps made with PDMS, using rounded lass rod/fiber as mold). See idea here
The other one uses a scattering (+ absorbent) medium within the gap between two fibers, using index matching gel with micron-size particles (silica powder or carbon powder).
See the design for the second choice here.
Rodrigo and I designed an experiment to compere intensity variation with gap between an air gap and a scattering (+absorbent) medium. We are going to create the setup and perform the comparison next week. The deliverable will be a white paper. See idea here.
23 AUGUST 2013
Worked on the low cost tape sensor with Rodrigo, helped him with the optical setup for some exploratory testing of optical gears. We are using 1mm PMMA fiber for these tests. This is in continuation of the previous work.
Before I start working on this project I review and restructure documentation - website and docs
I also communicated to SENSORICA about my work.
Project page link
Main doc link
There are a lot of docs that need to be updated around the Tape Sensor.
Optical Design - Tape sensor one in (glass) 3 out (PMMA)
with the melted glass fiber tip for a smaller exit cone within the gap.
Received the order from Thorlabs and assembled the optical fibers (3 out 1mm PMMA and 1 in, 125/62.5 glass) together.
It is not easy to assemble these fibers. I attached the together using a think metal wire. I also put them on a metal bar, but I am not too satisfied with that. Need another bar, probably with a groove in it. Also, the gap is not straight, the joint tube is a little too flexible.
The joint tube is a 2mm diameter transparent shrinking tube. No need to shring the tube around, it is tight enough.
I also prototypeed 7 fiber 250um diameter PMMA fiber, using a shrinking tube to hold them together. We already tried this structure using the 1mm PMMA fiber, and it is quite stable. I polished these fibers and it looks good.
I worked with Jonathan on the Tape Sensor.
I assembled the rod, from a cylindrical piece of wood, approx 1m long, which I had so buy. I made a groove in it using the Dremel.
I completed the prototype - glued the optical fibers in the groove of the wooden rod, sanded the rod and inserted it into the aluminum tube. Before inserting it into the aluminum tube we tested the prototype, and it seamed to work well. Some optical fiber preparation (cleaning) was required before connecting the fibers to the PDs and the LED. After the wooden rod was inserted into the aluminum tube I tested the device again. The sensor still works. We need now to find its axis. I also thought about the algorithm to extract the spatial information from the 3 intensities measured on the 3 PMMA collector fibers.
Jonathan helped mounting the PD on the circuit.
Microscopes were used for fiber preparation and for gap alignment inside the groove made in the wooden rod.
I continued to work on the demo for Zhu, which was dues on Friday - the day after.
I wrote the equations to extract spatial information from 3 intensities (need to scan the calculations and put them online!)
See document about the mathematical model and simulations
The LabView program (used for acquisition, data processing and display) required some modification, and the equation needed to be implemented - coded in the LabView program.
After these modifications I moved the setup on a different table that we chose for the demo, and wired everything.
I started testing the device and I encountered some problems. No spatial information could be extracted and the data made no sense within the model we were using.
I tried other ways to extract spatial information from the data, but things did not improve.
I discussed with Ivan and Daniel about the problem, and we realized that our model about the prototype was wrong. It turned out that compression and stretch of the joint were dominating the effects. The mirror tilting was was too small to be detected.
The 3 fibers ware applied off center within the aluminum tube. The intensity fluctuations with vending were max if the bending was done on plane containing the fibers. If the device was rotated fibers were 90 degrees no signal was detected.
So it turns out that this prototype doesn't work as expected, but this gave us other ideas about the hockey stick project (see smart sports equipment).