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Archive for July, 2011

Arduino and MMA7361 (acceleration sensor)

July 11, 2011 23 comments

Needed components:

  • 1 Arduino board (Duemilanove, in this case)
  • 1 acceleration sensor MMA7361
  • some wires.

Pins connections:

  • ST (Self Test): Arduino pin 2
  • GSEL (g-Select): Arduino pin 3
  • 0GD (0g-Detect): Arduino pin 4
  • SLP (#Sleep#): Arduino pin Power (3.3V)
  • XOUT: Arduino pin A0
  • YOUT: Arduino pin A1
  • ZOUT: Arduino pin A2
  • GND: Arduino pin Ground
  • VCC: Arduino pin Power (3.3V)

The firmware application created for the Arduino board read the analog inputs (A0, A1, A2) and send the resulted information to the computer. On the computer a software application read the information which comes on the serial port and display it into a user friendly interface.

For each axis the acceleration value is displayed in [m/s^2] measurement unit and graphically using different progress bars (one for the positive values and another for negative values).

The analog inputs present some variation even the sensor is not moved, which make me think that it is not the best solution when it is necessary to have a high precision. Maybe I do something wrong but I could not see what could be. The single option to improve the analog readings was to make the reading of the same input multiple times (100 – 1000 x) and calculate an average value. If you have another better ideas please tell me :D.

At the beginning I want to use this type of sensor for monitoring the vibrations from a building structure (ex. walls), but now I’m not very sure that it is a very good idea. I will have to find another type of sensor, more precise.

Create the future – Design Contest 2011 – A building as a living body


This post contains the concept idea subscribed at the contest Create the future – Design Contest 2011 (http://contest.techbriefs.com/sustainable-technologies-2011/1690-a-building-as-a-living-body ) .

A building as a living body

An intelligent building is a building which is able to monitor and control its own functionalities, according to the building structure, indoor and outdoor environment. The functionalities and their characteristics are directly related to building scope (the activities accomplished by the occupants), but usually are the same. The most part of the necessary functionalities have been already determined, and they are mainly for ensuring the minimum energy consumption and the occupants comfort. Not to forget that the occupants’ productivity is dependent on their comfort. Since a building is related to its occupants, all the functionalities of the building could be determined from the occupants’ needs and abilities. This is the reason why it come the idea to view a building as a living body (e.g. human body). It is a new approach of considering an intelligent building.

The human body is full of sensors, most of them on the skin and inside different body’s organs, and actuators which receive and execute commands, and make possible the interaction between different parts of the body. So, a building should have: a lot of sensor and actuators integrated into its structure. Since the sensors are not cheap, to diminish the total cost of the monitoring and control system, the optimum number of sensors and their location has to be determined. Even the buildings structures are different they are organized in similar ways.

The next connections could be established between a human body and a building:

  • brain (the center of coordinating and monitoring all body activities) – BMS (Building Management System). A BMS monitors the existent conditions from the entire building and take actions for ensuring the required conditions.
  •  eyes – video surveillance system and lighting;
  • smell – monitoring air quality (temperature, humidity, carbon monoxide, carbon dioxide, hydrogen sulfide, ozone, particles) and react when the air quality is not proper for living (ventilation);
  •  taste – monitoring the energy quality and quantity  (e.g. current, voltage, active energy, active power, water, gas);
  • feel the inside/outside temperature – temperature sensors;
  •  feel the humidity – relative humidity sensors;
  •  feel vibrations or force – vibrations/force sensors;
  • ensure body temperature (e.g. perspiration) – ensure indoor temperature (heating, air conditioning);
  • protection against diseases – security systems.

All the psychic feelings represent input information, measurable by sensors. Analyzing the input information could be sent commands for ensuring the working plan of the entire building. As a human body have a working plan, same a building.

For implementing the idea, a solution based on using a wireless sensor network (WSN) is proposed (formed by coordinator, routers and end nodes). Only end nodes could have attached sensors and actuators. Such a network could be easily deployed in any building space, even if the building is already constructed. Each node’s base hardware could be easily implemented using a board as Arduino and a XBee radio communication module (at a cost of about 45$). And according to its destination the node could be completed with sensors and/or actuators.