The good, the bad and the ugly

The good: And there is light.

Front sensing box light on

While adjusting the first pilot sensing device (unit 1.0 beta #1), the team has been working on several parallel tasks for making possible to start to collect pilot data by the end of this week. Most of the issues concerning the current design are hardware related, while some industrial design concerns persist and they need to be addressed in future iterations of the case design. The overall goal of this phase of the project is fixing the critical issues which can avoid to users from collecting data in a regular operation of their bikes. We assume that better adjustments of the physical design and software implementation can be done, but the priority is collecting data, as well for being able to provide a meaningful feedback process in between the evaluation of the data gathered data, the testing of the thesis and assumption which were taken when the project started, and the improvement of the sensing devices.

From a construction a very physical perspective, the anchoring of the back sensing box to the rack needed to be improved. During the last trip, the original plastic clamps weren’t able to support the tight tension from the screws and they broke apart. For this purpose, new metal clamps were placed, and it seems now the anchoring will be able to stay for much longer. Additionally, the installation is easier, because of the lower number of screws, and the joint is somehow flexible as it depends on the flexibility of the own metal folded plate.

Back sensing box with new metal clamps

 

The bad: Without information, you’d go crazy. (Arthur C. Clarke)

However, no doubt, the most demanding and critical issue is the random, inconsistent, and malfunctioning of the custom gas sensors board. It is critical because, at least in this first model of the sensing unit, the detection of different profiles of gases and pollutants in the air is considered to be an important factor affecting the stress of riders and as well important and useful to distinguish in an indirect way, without the use of image, different kind of vehicles close to the bike. Many different issues happened during the different testing performed for understanding the behavior of the gas sensors.  560 kΩ resistors were replaced by 470 kΩ resistors, ADC’s boards show memory allocation issues, higher voltage is not only better in terms of resolution of signal but as well in stability of the sensors, inconsistent sensors and amplifier flows, etc. The way of debugging and testing the devices for allowing the correct calibration has finally been done by testing one by one the custom boards.

Custom boards for gas sensors

Given that the objective is at least having 3 functioning bikes by the end of the current week, it was possible to discard completely wrong and messy boards and just focusing on the ones which were showing consistent data, although not calibrated yet. The flaws of the sensors were so evident enough that even at this preliminary phase with our custom vacuum device, it was able to detect major failures of the tested sensors.

Left, well-functioning sensors displaying stabilized read under controlled atmosphere. Right, mal-functioning sensors displaying extremely noisy and inconsistent readings.

 

Stable readings (1, 3 and 4) and unstable readings (2)

After identifying the usable sensors, the next step is calibrating them in the official Atlanta gas sensing station which is providing quality air feedback for public institutions in the Metropolitan Area of Atlanta.

The ugly: I just want to say one word to you—just one word …“plastics!” … There’s a great future in plastics. (Mr. McGuire in “The Graduate”)

Concurrently, while gas sensors have been adjusted, the work has proceeded for getting the whole system working for the new two sensing units to be mounted during the week on bikes. New cases, boxes, and electronic component have been assembled and they have already gone on testing. With regard to the strictly physical components of the units, some issues have been detected, but still, they are not extremely important to avoid the pilot data collection. At least three additional design iteration should be needed to nail down the design of the devices. Different plastic materials and printing technologies have been tested, and still some other additional ones need to be tested. However, for the development and prototyping purposes, this exploration is useful and allows to detect design issues.

 

New parts for the units 2 and 3

Although the issues encountered during the hardware adjustment, we have been able to deliver the first sensing units for being used by external users which will provide important and meaningful data for improving the whole system and above all, data for modeling the riding condition the project is willing to study and understand. The second unit is already running and the third one will be soon too, by brave volunteers willing to help to collect the data.

 

This first deployment of the sensing unit is focused on adjusting the sensors, designing the pipeline of the data cleaning and processing, and finally to plot a basic data modeling able to encompass the theoretical background considered in this project and related to the quality of the biking infrastructure and affection of traffic into riders’ stress levels.
By the end of this week, we expect to have the gas sensors calibrated after 24 hours test at the Atlanta air quality facilities. It will allow us to equiped definitely three bikes with the sensors and being able to start to collect the data and to perform the first data analysis and data modeling from those pilot data.

Seeing like a Bike: new system architecture

Goal accomplished. Currently, the team has been able to redesign the whole architecture of the system. It has been done by minimizing the size of the rear box, reducing the number of microcontroller boards involved in the connectivity of sensors, and relocating some of the sensors.

The original layout had a big box with independent compartments for batteries, air quality and GPS and proximity sensors. In each case, each module was virtually independent, with its own microcontrollers and architecture. The new layout integrates into a single case, located in the back of the bike, all the required sensors with a simpler and more consistent architecture based on a single Arduino UNO. This redesign provides additionally an important energy saving, so just one battery may be necessary. This is an important outcome of this new architecture, as the power banks are proportionally the heaviest and largest elements of the whole system. Finally, the GPS sensor has been relocated to the front unit as orientation is a critical factor for those sensor, as it requires a direct vision of the sky, and for simplifying the connection of an already relatively overloaded Arduino UNO board in the back.

Goals for next week. As next steps, the implementation of the new communication protocols between the back and the front unit is the most complex task. By now, each of the units independently is able to work and collect data as expected. From a more physical point of view, details of the final layout of the rear sensing box are still needed to be decided, this is the reason for the still prototyping outlook of the case. Several iterations into the particular position of boards and typology of connections between the different components are expected. With regards to the front unit, a redesign of the case is as well required as the addition of the GPS module connected to one of the external USB ports of the Raspberry Pi. In general, the goal of the next week is to develop a new functioning prototype for the rear and front units, and able to collect data with two main objectives: being able to calibrate the sensors and being able to systematize the construction of the 9 sensing units which will be mounted on different bikes for gathering data by the end of the summer.

During this week, Myeong is working into the communication protocols for being able to collect the data from all the sensors in the storage of the front unit, Erica is assembling and preparing components already decided for the multiple planned units, Noel is working on the redesign of the case of the front unit, and Javier is focusing on the final design of the rear unit.