All posts by Tanay Nandgaonkar

Vibrant Alley – Revitalizing Dead Spaces



The urban environment combines various spaces and paths that are used by people everyday. However, the access to such spaces is filtered through different times of the day, particularly at dusk and night. These restrictions begin to construct an issue of accessibility to desired or needed spaces. Such locations can be defined as “dead spaces” or undesirable paths due to a lack of safety or control in the space. Therefore, the idea of this project is to design a system that allows for dead space to be accessible.

Our proposal is to create a space that can be desired as an accessible path for people, particularly in the interests of safety. To do so, we want to improve lighting as a means of attracting people into a space. The lighting is then a customary element of control for the user. In other words, the person walking through the space controls the motion and angles of soft light beams simply through their position in space. Conceptually, the number and angles of light being generated produce a canvas of light surrounding the user as well as creating a lit path for them to follow, and hence a desirable and safer space for one to use.

In our prototype, we purposes LEDs and servo motors to direct the lights based on an object’s position in the grid, but on a full scale model, a brighter beam would be necessary for the project.

In the first video, a close up of one servo can be seen–the motor’s movement redirects the light to each location.

In the second video, the motors can be seen sweeping from the left side to the right–they are alternately pointing to the leftmost pad, then the center, then the rightmost, with a short delay in between. Although we could not get the motion detection to work completely correctly, the motors do have the capacity to point to specific coordinates in a coordinated manner.

Screenshot 2014-12-15 11.42.22

finalvid [Concept Video]

-Tessa Crawford, Angelo Razo, Mathew Hoffman, Tanay Nandgaonkar

Detecting occupied space using gridded motion sensors

This tutorial will show how to identify the coordinates of the space encompassed by objects within a grid. By using two axes with evenly spaced PIR motion detectors, multiple moving objects can be identified. In addition, when multiple objects are close together in the space, the coordinates will include any area covered on two sides by the objects themselves.

Note: Although this tutorial will use 3 total PIR detectors, the number of sensors can be expanded for larger grids with minimal changes to the code.


Figure A: Gridded PIR Sensor System



The gridded PIR sensors should be set up as shown in Figure A. In the next few diagrams, the circles represent objects in the grid, and the X’s represent the squares whose coordinates will be returned by Arduino via the serial cable. The red lines show which PIR sensors are set off by the objects.

Figure B: One Object Detected


If one object is present in the grid, it will set off  PIR sensors attached to the closest column and the closest row.

Figure C: Two objects detected in a line


If two objects in a straight horizontal/vertical line are detected, each object will be detected and the coordinates returned will only be those where the objects are located.

Figure D: Three objects detected (not in a line)


If the objects encompass a certain area on two sides (e.g. if a group of people is walking through a gridded area), the space that they enclose will also be returned as a coordinate value.

This will allow for the response to change when a group enters the space. If the group is neatly ordered in a straight line, the returned coordinates will similarly reflect a straight line. However, if the group is disorderly and spread out in the space, the returned coordinates will reflect the total area encompassed by the group.

Figure E: Objects Along a Diagonal Line


If the objects are placed along the entire diagonal, then all possible coordinates will be returned. According to the initial behavior, each returned value should be encompassed on two sides. In the diagonal case with all coordinate pairs returned, this is technically true, but some of the squares will be two squares or more removed from the actual object, which may encompass more space than desired. In order to fix this problem, additional sensors, such as force sensors on squares outside the diagonal, will provide enough input to double check the presence of objects in those areas.

This is an optional addition, but for our purposes, we will be focusing only on the PIR motion sensors in this tutorial.

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