Friday, July 14, 2017

Rock Paper Scissors Using LSTM

Recently I have been doing a lot of research into using LSTM for data compression (in cmix, lstm-compress, and tensorflow-compress). In 2011 I made a website about Rock Paper Scissors AI. I realized that LSTM should be good at playing RPS, so today I made a small demo to do that:

Saturday, May 20, 2017

Solar Panels

My wife and I recently bought a house in the San Francisco Bay Area. We are getting solar panels installed on the roof of the house. In this area it is a great financial investment - there is a lot of sun and the electricity rates are high. There is also a 30% federal tax credit for solar installations.

Determining the best size of the system to install depends on your electricity usage. Producing more power than you consume is less profitable.

We got quotes from three different companies. The quotes are surprisingly different:

System size: 2.7 kW
Estimated annual production: 4,036 kWh
Cost before rebate: $11,394
Cost after rebate: $6,381
Price per watt: $2.36/W

System size: 2.61 kW
Estimated annual production: 3,526 kWh
Cost before rebate: $10,559
Cost after rebate: $7,391
Price per watt: $2.83/W

System size: 2.61 kW
Estimated annual production: 5,050 kWh
Cost before rebate: $7,050
Cost after rebate: $4,950
Price per watt: $1.9/W

SunWork has by far the best price at $1.9/W. Not only that, but their system is estimated to produce far more kWh than the two other companies. Their system uses microinverters instead of a central inverter. Microinverters have a longer warranty: 25 years instead of 10 years. They are also more efficient than a central inverter. With a central inverter the system only produces as much as the least efficient panel. Microinverters allow each panel to independently perform the DC-AC conversion and also allow you to monitor the performance of each panel.

Another reason SunWork estimates a larger annual production is because they did a better job of optimizing the layout of the panels on our roof. Each company had a different layout:




SunWork managed to squeeze all nine panels onto southern facing parts of the roof. Sunrun had cool software which created a 3D model of our roof and automatically detected vents and surrounding trees (useful for modelling shadows). For all three companies the panel placement seemed to be done manually - combined with some software to estimate annual output.

Update: SunWork panels have been installed! Here is a dashboard to monitor our system output.

Update#2: The final price was lower than their initial quote: $6,565

Thursday, February 11, 2016

Trackball Mouse

A couple years ago I bought this neat mouse on Amazon. It is surprisingly useful. I can use it to remote control my computer from my bed. It is also useful for controlling my Avegant Glyph when not sitting at a desk.

Wednesday, February 10, 2016

Avegant Glyph Review

Two years ago I made a post about a device called Avegant Glyph. I ended up investing in the Kickstarter. The estimated delivery during the Kickstarter campaign was December 2014. I finally got the Glyph two days ago.

It is a very cool device, but fell short of my expectations. Initially I spent a lot of time trying to get the position of the display calibrated for my eyes. It was very difficult to calibrate - I couldn't get a clear view of the entire rectangular display. The nose pieces that came with the device keep the display too far from my eyes. I found that removing the nose piece helps me get closer to the display, getting a clearer picture. However, I still can't get a completely clear view of the corners of the display even with my eyelashes touching the lens. The device is also a bit uncomfortable without a nose piece.

Ignoring the calibration issues, the quality of the display is amazing. Colors are very pure and reading text is easy. The display quality looks much better than the Oculus Rift developer versions. However, the resolution of the display is not very high.

Originally I was hoping this could be used as a complete replacement for my desktop monitor. The calibration issues really prevent this from working well. It is annoying to not be able to see text in the corner of the display clearly with both eyes. I tried watching a movie with the device while lying down. This worked well. The weight of the device was supported by the bed, so it was not uncomfortable. The corner calibration issues were hardly noticeable while watching the movie (probably because focusing on the edges wasn't necessary).

Saturday, January 09, 2016

Raspberry Pi Thermostat Instructions

Here are some details on how I put together my Raspberry Pi thermostat.

My apartment's thermostat uses a very simple mechanism to control the heater:

Connecting the red wire to the white wire turns on the heater. Near the center of the thermostat is a glass vial containing some mercury. If the vial tilts to the right the mercury creates a connection between the wires. I attached the two black wires on the bottom and use the Raspberry Pi to control the connection between the wires. The original thermostat remains fully functional: the heater will turn on if either the Raspberry Pi or the original thermostat signal it to turn on.

Materials used: The relay module controls the connection between the two heater wires. GPIO output from the Raspberry Pi can turn the connection on/off. The connection is off by default - even when the Raspberry Pi is powered off. I SSH into the Raspberry Pi to control the GPIO pin over the Internet.

Friday, January 08, 2016

Raspberry Pi Thermostat

I connected a Raspberry Pi up to the heater in my apartment. Now I can control the heater over the Internet.

Update: more details posted here.

Tuesday, January 05, 2016

An Update on Baka

[previous post]

Although Baka Analytics has stopped updating, Baka is still alive. The occasional gaps in the data were due to Baka chewing through the wire which connects the magnetic sensor to the Raspberry Pi (which I had to fix several times). The outage since September 12 is a more serious issue: all of the USB ports on the Raspberry Pi stopped working. I think Baka caused this by urinating on the Raspberry Pi (which was stored next to his cage). I have ordered a replacement Raspberry Pi to use on another project, so it is unlikely I will restart Baka Analytics.

Baka's record was running 17.31 kilometers in a single night. In total Baka was recorded running 682.29 kilometers.