Soccer (or as it is more widely known - football) has often been considered the most popular sport in the world. Wherever you go, there are kids on the street or in a park kicking around a ball, jerseys from the most popular football clubs can be seen in every major city, and the truest World Cup truly does include most of the nations on this earth. It seems fitting that Motes would enter the arena of sports through soccer. The idea behind Motes and wireless sensor networks is to create a device that will become ubiquitous throughout this planet enabling us to live in a smarter more connected world. Soccer has connected people from all over, at all ages with all levels of skill for generations, and now Motes have made their way into this arena with a little bit of fun!
Embedded systems are increasingly becoming connected through wireless networking. These devices now form the basis of many of today’s consumer products including cell phones and video game controllers. In the CSE466 “Software for Embedded Systems” class in the Department of Computer Science & Engineering at the University of Washington, students used the design of a multi-player video game as motivation for the principal concepts in wireless embedded systems. Each student in the class designed an accelerometer-based game controller and then, the class as a whole, developed a multi-player video game that allowed 28 players (the number of students in the course) to play simultaneously. How did they do it? With Motes!
Computer Engineering curricula have traditionally included the interfacing of sensing and actuation devices to microcontrollers but have not emphasized wireless communication. This time students at University of Washington undertook the task of updating the platform used in this course to Crossbow's Imote2 which runs an embedded Linux operating system and developing a multi-player video game using controllers modeled on the, then just introduced, Nintendo Wii video game controller. Previous courses had used the MICA Mote platform, but the Imote2 offered a device with greater capabilities.
Each student designed their own Wii-like accelerometer-based 2-D game controller. An LCD screen was added so that game state could be displayed on the user’s controller during the game. The Imote2 platform offers users an expansion connector for attaching sensing and actuation hardware. On one side, students attached the basic ITS400 Imote2 sensor board which includes a 3-axis accelerometer, temperature sensors, a humidity sensor, a light sensor, and a 4-channel A/D for further additions. On the other side, students designed their own board to provide some actuation known as the "SuperBird". A cell phone-size color LCD screen as well as sound generation capabilities, a speaker, microphone, and audio jacks. This board also included a cell phone camera, jog dial, USB host port, barometer, and a heart rate sensor and is the form factor of a large cell phone. While not all of the board’s capabilities were used in this particular application, the board was designed to be flexible enough to accommodate a variety of projects (such as a video phone, music player, etc.) in the future. The Imote2 platform is based on Linux and students were provided with the device drivers for their project implementation.
Students decided on utilizing controllers that could move a player in two dimensions. Soccer quickly emerged as a game that could be varied to accommodate the project requirements, namely, that it should involve every student simultaneously and require only two-dimensional control of each player. In addition, students wanted to have some collaborative elements between players that would spur real team play - soccer being a true team sport! The game was developed in steps. Development began with the basic player controller, that is, the mapping of values from the accelerometer to an X-Y velocity vector. A communication protocol needed to be devised on top of the basic MAC of the 802.15.4 radio to handle the communication between players and the game coordinator. To ensure that there was some inter-player communication, the “captain” of the merged players (the player with
the highest number) collected all the moves of the constituent players and reported that result to the game coordinator. The scheme was basically round-robin. The game coordinator polled the first player for its move and waited for a response before proceeding to the next player. If a player was too slow in responding, its movement was ignored for that round. This provided some timing constraints on the implementations to quickly handle packets from the game coordinator. The boards were programmed to allow students to control players in the virtual
soccer-like game. Tilting the board would cause the player (represented
by a dot on the field) to go in the corresponding direction.
On the final day of the course a 30-minute soccer match was held between the two sections of the class. A video of the match and an explanation of the project can be seen here:
GOOOOOAAAAAAAALLLLLL for CSE466 at University of Washington!!
Comments