added research

2 files changed, 96 insertions, 4 deletions

diff --git a/doc/base.tex b/doc/base.tex
index ecc3c8d..9c1c908 100644
--- a/doc/base.tex
+++ b/doc/base.tex
@@ -6,7 +6,6 @@
 \usepackage{siunitx}
 \usepackage{amsmath}
 \usepackage{csquotes}
-\usepackage{parskip}
 \usepackage{unicode-math}
 \usepackage{fontspec}
 \usepackage{tabularx}
@@ -27,7 +26,10 @@
 
 \bigskipamount=7mm
 \medskipamount=4mm
-\parindent=0mm
+% \parindent=0mm
+\parskip=1ex
+
+\def\tightlist{}
 
 \title{\doctitle}
 \author{
diff --git a/doc/research.md b/doc/research.md
index 1a616f9..ba697a8 100644
--- a/doc/research.md
+++ b/doc/research.md
@@ -1,4 +1,94 @@
-# test 1
+# Problem statement
 
-this is a test document in markdown that will get converted into latex
+The following is the original project description (translated to English):
 
+> I would like to bring to market a vehicle that can drive independently from A
+> to B. The vehicle must take into account traffic rules, road signs, traffic
+> lights, etc. Research is being conducted using a small cart, the Pololu Zumo
+> 32U4, on which a camera module Nicla Vision is mounted. The aim is to
+> investigate the most appropriate method of recognizing the road, traffic
+> signs and traffic lights. This should be demonstrated with a proof of
+> concept. The cart does not need to drive fast, so the image processing does
+> not need to be very fast. Assume one frame per second (or faster).
+
+# TBD: The big question
+
+## Communication between the Nicla and Zumo
+
+In order to make the Zumo robot both detect where it is on a road, and steer to
+keep driving on said road, some sort of communication needs to exist between
+the Nicla and Zumo. As mentioned earlier\footnote{dit is nog niet benoemd}, all
+machine vision-related tasks will happen on the Nicla board. Because the Nicla
+board is the first to know how much to steer the cart, it makes sense to have
+it control the cart by giving the Nicla a 'steering wheel' of sorts.
+
+This section tries to answer the question "What is the best protocol to use
+over the existing UART connection between the Nicla and Zumo?". After a
+brainstorm session, we came up with the following specifications for the
+communication protocol:
+
+1. **Low bandwidth**  
+   Less data means more responsive steering
+2. **As simple as possible**  
+   The Nicla only needs to control speed and steering
+3. **Easy to mock and test**  
+   The cart should be able to be controlled using a mock driver and the Nicla's
+   output should be testable (preferably using unit tests)
+4. **Adaptive to noisy data**  
+   The cart should gradually change speed and steering direction as to not slip
+   or cause excessive motion blur for the camera module on the Nicla
+5. **Adaptive to Nicla failure**  
+   If the Nicla crashes or can't detect anything, it will stop sending control
+   commands. In this case, the Zumo robot should slowly come to a halt.
+
+Where possible, it's generally benificial to re-use existing code to save on
+time. Existing code exists for a custom binary protocol and a text-based
+command protocol. Both of these were designed without bandwidth or latency in
+mind, and mostly focus on robustness in the case of temporary disconnects or
+noise on the communication lines, so a new protocol needs to be made.
+
+To address specification 1 and 2, the command length is fixed at 1 byte. This
+means that UARTs built-in start/stop bit will take care of message start/end
+detection, since most software interfaces for UART (including Arduino) string
+multiple sequential messages together even if they're not part of the same UART
+packet.
+
+To mock messages from the Nicla to the Zumo robot, a simple USB serial to UART
+cable can be used, along with a small C or Python program to convert
+keyboard/mouse input into steering/speed commands. A small software layer can
+be implemented on the Nicla to log the semantic meaning of the commands instead
+of sending actual UART data when run in a unit test.
+
+A PID controller can be used to smoothly interpolate between input
+speed/steering values. This would also introduce some lag between when the
+Nicla knows how much to steer, and when the Zumo actually steered the wanted
+amount. Smoothing the speed/steering values does make it virtually impossible
+for the Nicla to make it's own input data unusable because of motion blur, so
+the lag needs to be handled in some other way as directly controlling speed
+values without interpolation would lead to a garbage-in-garbage-out system. The
+simplest solution to motion blur is limiting the maximum speed the Zumo robot
+can drive at, which is the solution we're going to use as speed is not one of
+the criteria of the complete system\footnote{Problem statement
+(\ref{problem-statement})}.
+
+In the case the Nicla module crashes or fails to detect the road or roadsigns,
+it will stop sending commands. If the Zumo robot would naively continue at it's
+current speed, it could drive itself into nearby walls, shoes, pets, etc. To
+make sure the robot doesn't get 'lost', it needs to slow down once it hasn't
+received commands for some time. As mentioned in section \ref{TODO}, the Nicla
+module is able to process at about 10 frames per second, so 2 seconds is a
+reasonable time-out period.
+
+\def\communicationConclusion{
+The complete protocol will consist of single byte commands. A byte can either
+change the cart speed or steering direction, both will apply gradually. When no
+commands have been received for more than 2 seconds, the Zumo robot will
+gradually slow down until it is stopped. Exact specifications of commands are
+provided in the protocol specification document\footnote{dit document bestaat
+nog niet}.
+}
+\communicationConclusion
+
+## Conclusion
+
+\communicationConclusion