Author: jwasserm

The past week, I’ve been working on the game state tracker and some integration tasks such as getting the camera to take pictures within our python program as opposed to just from the command line. Cody and I spent a good amount of time on this task that shouldn’t have taken so long. We were getting an error that the camera was busy and couldn’t take the picture. We ended up earning this was because we had initialized a cv2 camera instance we were thinking of using and forgot to comment it out.

I had already written the functions for most of the intricacies of the game state tracker, so the rest was just interfacing with the MQTT protocol that Denis set up. Today, we tested the whole system together and it went quite well. I found a couple bugs in the check_board function I had written in terms of calculating the start and end column for a horizontal word. But after fixing that, when we pressed the “Check” button on the individual player touch screen, we got the point total and validity back! We are still deciding the convention we put in place for submitting words, whether we should require a check beforehand or not.

I am glad at the place we are in now, and hopefully we can finish up the home stretch in a relatively smooth manner. I’ve been working on the final report for the past three weeks, editing from the design report, so I think we should get that done soon.

These past couple weeks, Denis and I put a lot of work into the user interface with the individual touch displays. It took some trial and error with the driver to get the desktop of out RPi 0s to show up on the lcd display (which was quite frustrating) but we ultimately got the desktop to show. The touch portion was touch and go (no pun intended) for a while where it would randomly work or not work on boot. We think we found the problem with a race condition on boot up that would sometimes permit the touch functionality and sometimes  not. Denis and I laser cut a box for the battery pack and buck converter to fit in. The display then rests on top of the box for a clean wireless look.

I made the front end of the user facing app user tkinter graphics where I made a keyboard, tile display box, player scores, “check”, “submit”, and “hint” buttons, and then ultimately a page for hint results. This will be how players interact with our system.

For this upcoming week, we really need to finish integration, mostly of the cv with the rest of the system. I think we are in a good place to have everything done by the demo.

It’s safe to say I gained a lot of new skills throughout my Capstone experience this semester. First off, I was able to write the hint generation algorithm from help from the article https://www.cs.cmu.edu/afs/cs/academic/class/15451-s06/www/lectures/scrabble.pdf. I spent many hours rereading this to understand how the backtracking algorithm worked and researched more into the ins and out of the directed acyclic word graph. Furthermore, I had no prior experience with tkinter graphics so I read specs and watched videos on how to make a simple app and then expanded on it from there.  Finally, when debugging the issues we were having with the RPi 0s, I read many posts from Raspberry Pi Forums from people who were having similar issues to us. Often times, it would take many iterations of Forums to find a possible fix, which gave me good experience of dealing with this type of hardware.

This past week I wrote and debugged functions for validating a new board and calculating the score for that new move. The check_board function takes in the board with the possible new word placed in it and a list of the squares that tiles were just placed (should be in order left to right or up to down). The function find the new board made, looks it up in the dawg (much quicker look up time than a simple linear search in the dictionary). If it’s not in the dawg, the function returns a tuple of (False, 0), meaning it’s not a valid word and scores 0 points. If it is a word, the new board, start and end position of the word, and tiles added are passed into the calculate_score function I wrote which only includes the score and letter multipliers for tiles that are newly placed (accoding to official Scrabble rules). The total score for the new word is updated in check_board. If the placed word is horizontal, the function goes through each letter and does word validation and score updating on the new word made vertically if there is one, and vice versa for a vertical main word.

Denis has been able to refactor my hint logic and put it on the Pi for communication with the Pi 0s. This will be used for our demo next week.

I completed my tasks on time so far, and in the coming weeks, I will pick up some integration tasks in terms of interfacing with the LCD displays and interfacing the output of Cody’s cv with the input of the check_board function.

Verification:

For the scoring, I ran tests where I placed different words (horizontal and vertical) on the board (2D list) and verified that the computed score was correct. I also varied the “tiled_added” list so make sure that letter and word multipliers weren’t added to already filled in squares. I did a similar practice with the check_board function.

For the hints algorithm, I used a unit testing approach where I tested each function on it’s own before testing the whole hint generation since it is a complex algorithm. Timing wise, the hint generation takes about 0.05 seconds on my computer. On the Pi, processes seem to run 8 times slower, but this is still well within our time allotted of 1.4 seconds (design requirement).

Last week, I finished up the hint logic, fixing some of the last little bugs as well as generalizing the algorithm to the vertical direction. Denis is now able to run the hint logic on the main RPi and can send receive hints with the RPi0s.. Also, I set up the gooseneck camera mount. I laser cut a platform (rectangle with four holes in it so that I could zip tie  it to the top of the camera mount we bought). I then was able to clip the ring light onto the platform. The RPi and RPi camera rest on the platform and the camera is looped through the ring light. The picture below is what the mount + platform looks like (without the RPi on it). The other picture is what I took from my phone camera. Just from that, we can see how the ring light really helps eliminate shadows that we were seeing before.

Last week, I wrote a preliminary scoring function where letter and word multipliers are taken into account (but haven’t tested it yet). This upcoming week, I plan on testing the scoring function as well as writing the function that takes in the newly placed tiles and validates/scores all the newly created words.

After this week, I feel more confident that we are running on schedule, but we must not let up and finish strong this last month of the semester.

This week I made a lot of progress with the hint generation. Right now, we can find all the horizontal words possible given the state of the board and rack. There is still one bug that I need to fix dealing with anchor squares which also have a filled square to the left. I just need to remove those anchor squares from the anchor list so that invalid words don’t propagate through, which shouldn’t be hard to fix. I also need to generalize the algorithm to the vertical direction. The hard part was already done in the horizontal direction, so the vertical functions should be easy to implement as they are just the transpose of the horizontal functions. Shown below is a snippet of the list of valid words, along with there start and end square, that the backtracking function returns.

Last week, I mentioned I was a bit behind on hint generation. I was able to catch up this week and made some good progress. Shown in the attached file, I added a function which updates cross-checks after a word is played. The next step is to implement finding prefixes and suffixes given an anchor square. I need the data structure of the language for that. The article we are basing the algorithm off uses a Directed Acyclic Word Graph. I found an open source implementation of the DAWG and will discuss will discuss with the team tomorrow when we meet what the think of using it.