Eyes in the back of your back: Difference between revisions

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(New page: or, Vibro Vest. Name suggestions encouraged! Rachel and others are creating a vest that will allow the wearer to feel side-to-side movement behind them. This will be don...)
 
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[[User:rachel|Rachel]] and others are creating a vest that will allow the wearer to feel side-to-side movement behind them.  This will be done by a set of motion sensors connected to a touch display (of pager motors, at least initially).  The first prototype will have a one dimensional display so that up & down motion will not be detected, but this can probably be added later once some of the more pressing problems are solved.  We have not yet made a final determination on the prototype sensors but have had some success with ultrasonic rangefinders.
[[User:rachel|Rachel]] and others are creating a vest that will allow the wearer to feel side-to-side movement behind them.  This will be done by a set of motion sensors connected to a touch display (of pager motors, at least initially).  The first prototype will have a one dimensional display so that up & down motion will not be detected, but this can probably be added later once some of the more pressing problems are solved.  We have not yet made a final determination on the prototype sensors but have had some success with ultrasonic rangefinders.


* [[EBB Notes 1]]
* [[EBB Notes 2]]
* [[EBB Notes 3]]


== Current Status ==
== Current Status ==
Some functional if rough code for a Parallax Ping))) module has been produced.  This module is large and somewhat cumbersome, and appears to be quite inaccurate at distances greater than about 2-3 feet.  There is also a pair of MaxSonar-EZ1 modules which look interesting to try as well.
Full object is made but arduino is Broke due to plugging battery in backwards like an idiot.  Need to swap out for a new one, or reflash the bios, or Something...


I (Rachel) have a fairly detailed mental model of the armature but have not made it yet.
----
<strike>Parallax PING))) works but we don't like it so much.  Got a Maxbotics MAXSonar EZ-1 functional in its analog mode, with LED standing in for motor (the shift register not yet integrated) but have failed at reading its serial out.


Code:
Note: EZ-1's serial output is RS232 and most embedded systems expect TTL. -Reed
<pre>
/*
* Based on code found at http://arduino.cc/en/Tutorial/Ping
*/


int pin = 13;
Integrate the shift register (wait until sensor decision is made?  it would be cool to have an end-to-end thing...)
int pingPin = 12;
int ledPin = 11;
double periodFactor = .5; // percent of one second


void setup()                   // run once, when the sketch starts
I (Rachel) have a fairly detailed mental model of the armature but have not made it yet.
{
</strike>
//  pinMode(pin, OUTPUT);      // sets the digital pin as output
  Serial.begin(9600);
  pinMode(ledPin, OUTPUT);
}


void loop()                    // run over and over again
== Next Steps ==
{
* Try out IR sensor?  Daniela has lent us one, and I think there's some others in the bin plus of course the 900 PIR boards upstairs...
  long duration, inches, cm;
* Buy the other US sensor I found?  Its specs beat out both the Maxbotics and the PING))). Decide later.
 
  // The PING))) is triggered by a HIGH pulse of 2 or more microseconds.
  // We give a short LOW pulse beforehand to ensure a clean HIGH pulse.
  pinMode(pingPin, OUTPUT);
  digitalWrite(pingPin, LOW);
  delayMicroseconds(2);
  digitalWrite(pingPin, HIGH);
  delayMicroseconds(5);
  digitalWrite(pingPin, LOW);
  delayMicroseconds(2);
 
  // The same pin is used to read the signal from the PING))): a HIGH
  // pulse whose duration is the time (in microseconds) from the sending
  // of the ping to the reception of its echo off of an object.
  pinMode(pingPin, INPUT);
  duration = pulseIn(pingPin, HIGH);
 
  // convert the time into a distance
  inches = microsecondsToInches(duration);
  cm = microsecondsToCentimeters(duration);
 
  Serial.print(inches);
  Serial.print("in, ");
  Serial.print(cm);
  Serial.print("cm");
  Serial.println();
 
  pwm(duration);
}
 
void pwm(long microseconds)
{
  Serial.print(microseconds);
  Serial.println("ms");
 
  long offCycle = microseconds / 18;
  long onCycle = 1000 - offCycle;
  digitalWrite(ledPin, HIGH);
  delay(onCycle * periodFactor);
  digitalWrite(ledPin, LOW);
  delay(offCycle * periodFactor);
}


long microsecondsToInches(long microseconds)
[[Category:Sensebridge]]
{
  // According to Parallax's datasheet for the PING))), there are
  // 73.746 microseconds per inch (i.e. sound travels at 1130 feet per
  // second).  This gives the distance travelled by the ping, outbound
  // and return, so we divide by 2 to get the distance of the obstacle.
  // See: http://www.parallax.com/dl/docs/prod/acc/28015-PING-v1.3.pdf
  return microseconds / 74 / 2;
}
 
long microsecondsToCentimeters(long microseconds)
{
  // The speed of sound is 340 m/s or 29 microseconds per centimeter.
  // The ping travels out and back, so to find the distance of the
  // object we take half of the distance travelled.
  return microseconds / 29 / 2;
}
</pre>
 
 
== Next Steps ==
Next we'd like to see if the MaxSonar-EZ1 device has any better of a range than the Ping))).  Someone else has hooked it up to an arduino and posted code: http://www.flatline.net/journal/2007/12/02/arduino-reading-the-maxbotix-ultrasonic-rangefinder/

Revision as of 00:17, 27 April 2010

or, Vibro Vest. Name suggestions encouraged!

Rachel and others are creating a vest that will allow the wearer to feel side-to-side movement behind them. This will be done by a set of motion sensors connected to a touch display (of pager motors, at least initially). The first prototype will have a one dimensional display so that up & down motion will not be detected, but this can probably be added later once some of the more pressing problems are solved. We have not yet made a final determination on the prototype sensors but have had some success with ultrasonic rangefinders.

Current Status

Full object is made but arduino is Broke due to plugging battery in backwards like an idiot. Need to swap out for a new one, or reflash the bios, or Something...

Parallax PING))) works but we don't like it so much. Got a Maxbotics MAXSonar EZ-1 functional in its analog mode, with LED standing in for motor (the shift register not yet integrated) but have failed at reading its serial out.

Note: EZ-1's serial output is RS232 and most embedded systems expect TTL. -Reed

Integrate the shift register (wait until sensor decision is made? it would be cool to have an end-to-end thing...)

I (Rachel) have a fairly detailed mental model of the armature but have not made it yet.

Next Steps

  • Try out IR sensor? Daniela has lent us one, and I think there's some others in the bin plus of course the 900 PIR boards upstairs...
  • Buy the other US sensor I found? Its specs beat out both the Maxbotics and the PING))). Decide later.
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