Month: March 2019

Sid Lathar, A1 | Progress Report #3

Accomplishment:

Following previous week’s report the method was implemented into the Hello world app. The app can now use Google Maps API to get current coordinates of the phone and get the nearest intersection to it.

Changes to schedule:

The progress is on schedule.

Upcoming work:

By next week I plan to implement the following features into the app:
– Basic UI to toggle intersection search (right now it’s ongoing as long as the app is running)
– Plan the layout for the app
– Research on communicating with the Pi

Accomplishments this week:

• Designed signal light patterns. Since at full capacity, the LED strip can consume 12 – 15 A at 5V, we need to be careful about turning on all of the light s at the same time. Therefore, I designed some light patterns that try to be conservative on the number of LEDs used.

Above: brake light is the entire panel, but at low power
Below: Turn signals, we are not using all the lights.

• Listened to other presentations, and received feedback from Prof. Ken about what steps to take in the future, which include batteries and weight specs.
• Received LED matrices, wrote code to interface with the matrix.
• Drawing diagrams and helping write the design review paper.

Concerns:

• The LED matrix code is not hard to write in terms of turning 2D data[][] into 1D serial data to be interpreted by the Arduino, but the problem is that if we want to store signals that are very specific, a single 16×16 bit-vector to describe a signal is very expensive, if we have around 100 such signals. This is made worse, since the Arduino Nano also has a very limited memory. One possible solution we may have to consider, is to offload the signal memory to the Pi, and then have the Pi send over communication the signal that the Nano should be displaying. This can be cached, for better performance, so we don’t have to fetch 256 bits every time we want to display a signal.
• We are bit worried about how much battery power we need. We are currently thinking about one on the bike and one on the jacket, the Pi and the LED matrix are the two biggest energy suckers.

We had presentations this week, and were able to see many aspects of how even projects that were well underway and seemingly on a good track still could use some design reflections and feedback.

For our team specifically, we mostly missed out on specifications for our battery life and weight. This is a very important aspect of our product, as the first two things a consumer are probably going to consider in our product are:

• Will the battery life last long enough?
• Will the device be bulky and unwieldy to put on the bike/my body.

Our plan is to conduct some sort of competitive analysis on other similar situations, and the other is to conduct a small user test to see how people respond to weight and battery life. We met with Prof. Ken Mai as well to talk about other ways to find solutions for our problem.

We also received a concern about how we plan to measure the brightness of our LEDs, but for now, we are going to assume that we light all of the LEDs at 100%, and we are going to use the candela ratings that the datasheeet gives us. If we need to adjust the brightness to an in between, we can consider buying a sensor (around 6.99) to test it out.