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York Jong

SENSORS - SHARP IR RANGE FINDER - 0 views

www.societyofrobots.com/sensors_sharpirrange.shtml

ir range rangefinder sensor

shared by York Jong on 01 Jun 07 - Cached
  • The Sharp IR Range Finder works by the process of triangulation. A pulse of light (wavelength range of 850nm +/-70nm) is emitted and then reflected back (or not reflected at all). When the light returns it comes back at an angle that is dependent on the distance of the reflecting object. Triangulation works by detecting this reflected beam angle - by knowing the angle, distance can then be determined.
  • The IR range finder reciever has a special precision lens that transmits the reflected light onto an enclosed linear CCD array based on the triangulation angle.
  • The Sharp IR has a non-linear output. This means that as the distance increases linearly (by set increments), the analog output increases/decreases non-linearly.
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  • To effectively use your Sharp IR Range Finder, you must have a voltage output versus distance chart to reference from.
  • One major issue with the Sharp IR Range Finder and that is going below the minimum sensor range. This is when an object is so close the sensor cannot get an accurate reading, and it tells your robot that a really close object is really far.
  • Another issue is the high narrowness of the IR beam. In reading sharp details and getting high accuracy, a thin beam is ideal. But the problem with a thin beam is that if it is not pointed exactly at the object, the object is therefore invisible.
  • A more advanced use for the Sharp IR Range Finder is to do mapping. To do this, you need at least one Range Finder, and at least one non-modified servo.
  • The sharp IR can be used as a quick and easy front non-contact robot bumper on your robot. Just place two IR devices in front of your robot and cross beams as shown. Ideally you would perfer to use rangers that have wider beams. Note: A single sonar can do this job just as well.
  • For example, a box in front of your robot might appear like this: 0 0 0 0 0 106 120 124 121 109 0 0 0 0 0
York Jong

ROBOT SENSOR INTERPRETATION - 0 views

www.societyofrobots.com/sensors_interpret.shtml

robot sensor

shared by York Jong on 14 Jun 07 - Cached
  • how to interpret sensor data into a mathematical form readable by computers
  • There are only 3 steps you need to follow: Gather Sensor Data (data logging) Graph Sensor Data Generate Line Equation
  • Some sensors (such as sonar and Sharp IR) do not work properly at very close range
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  • The way to get rid of noise is get a bunch of readings, then only keep the average. Make sure you test for noise in the actual environment your robot will be in
  • York Jong on 14 Jun 07
     
    Most roboticists understand faily well how sensors work. They understand that most sensors give continuous readings over a particular range. Most usually understand the physics behind them as well, such as speed of sound for sonar or sun interference for IR. Yet most do not understand how to interpret sensor data into a mathematical form readable by computers.
York Jong

Robotics -- Logo Products - 0 views

el.media.mit.edu/...robotics.html

5star collection logo robot toy

shared by York Jong on 19 Jun 07 - Cached
  • Many Logo-based and other robotics products produced by LEGO are distributed to schools in the USA by Pitsco.
  • This free-range turtle does not require connection to a computer. All the controls are on board.
  • The Cricket is a tiny computer, suitable for all kinds of robotics projects, that you can program using Logo.
  • York Jong on 19 Jun 07
     
    Logo has long been used to control mechanical turtles and other robotic devices. Here are some sources of equipment and related software.
York Jong

ROBOT BATTERIES - 0 views

www.societyofrobots.com/batteries.shtml

alkaline battery fuel-cell lead-acid li nicd nimh robot

shared by York Jong on 14 Jun 07 - Cached
  • Motorcycle lead acid batteries work great for larger low performance type robots. They are great for solar power robots too.
  • lead acid batteries have the serious problem of being very large and heavy, need to always be kept charged, and do not have the high discharge rates as the more modern batteries.
  • They have low power capacities, are heavy, have trouble supplying large amounts of current in short time periods, and get expensive to constantly replace
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  • Li-ion batteries have the same high energy capacity as NiMHs, power output rates of NiCads, and weigh about 20%-35% less. They also have zero memory effect problems, meaning you can recharge whenever
  • NiCad (Nickel Cadmium) batteries are good for small to medium size range robots. They have the highest current output, are more affordable than NiMH's, and can be recharged within one or two hours
  • A NiCad, over many charges, can only store less and less energy after each recharge. To prevent memory effect, whenever you wish to recharge your NiCad, you must first fully discharge it.
  • NiCad batteries contain toxic cadmium stuff, so save a squirrel and recycle/dispose of it properly.
  • NiMH battaries can last many more cycles than your typical NiCad battery.
  • they have good current output, and have the highest energy capacity. I would recommend them for small size robots and for powering circuits. Note, NiMH batteries usually take like 10 hours to recharge depending on various factors.
York Jong

A Bot With Peripheral Vision - 0 views

www.geocities.com/...PVRoller.html

5star beam behavior-based circuit electronics photopopper phototrope robot

shared by York Jong on 27 May 07 - Cached
  • I wanted to share an adaptation of the Schead v4, that I have been experimenting with. It is (for lack of a better term) a Master/Slave Schmitt Comparitor Head (M/S SC-H). With the addition of a 74 AC 240 or two (as motor drivers) and a pair of motors, you can put together an interesting little light seeking, wheeled robot with peripheral vision.
  • As long as the light reaching the photo-bridge of the Master SC-H is balanced, then the Slave SC-H acts as a regular, lone SC-H would. So, if one of the slave photo-diodes detects more light then the other, the inverter that controls the motor on that side changes states and is now the same as the inverter of the Master SC-H tied to the same motor. This turns that motor off and the robot will pivot around the stopped wheel toward the greater light source until the light on each sensors is balanced and the motor again begins to turn.
  • I am also using SCar to continue experimenting with Stacking separate Sensor/Behavior circuits onto a robot. I will post more as progress is made.
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  • The diodes between the  photo-diodes create a constant voltage drop between the inputs of the inverters. They cause  a dead band to exist between the thresholds of the two inverters. In a way they cause the circuit to act like a kind of window  comparator. Without these diodes both inverters would always be in the same state. With them, there is a small range where their outputs are in opposite states.
  • The Slave section has only two diodes (or one LED) between the photo-diodes. This makes it respond to smaller differences in light levels than does the Master part of the circuit
  • Basically, what I did was to stack one SC-H on top of another
  • I?m using a 74 HC 139 to direct the outputs of the M/S SC-H circuit to the appropriate motor(s)
  • Cheesy works very well. I?ve had fun making him chase a spot of light from a flashlight around on the floor. He has even been able to detect and react to the flashlight spot on the floor of the brightly lighted lab where I work.
    • York Jong
      York Jong on 03 Jun 07
       
      Stacking separate Sensor/Behavior
York Jong

BICORE ARTICLE - 0 views

www.geocities.com/...Bicorearticle.htm

4star beam bicore electronics robot

shared by York Jong on 26 May 07 - Cached
  • York Jong on 26 May 07
     
    The suspended bicore is the core of most BEAM devices. It's unique structure makes it very easy to customize for a wide range of uses. These uses vary from blinking LED's to servo-drivers to walkers.
York Jong

Introduction to Autonomous Mobile Robots - 0 views

www.amazon.com/...104-5150301-5775106

autonomous book mobile robot

shared by York Jong on 31 May 07 - Cached
  • York Jong on 31 May 07
     
    Mobile robots range from the teleoperated Sojourner on the Mars Pathfinder mission to cleaning robots in the Paris Metro. Introduction to Autonomous Mobile Robots offers students and other interested readers an overview of the technology of mobility -- th
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