infraredledlight-sensorproximity-sensorsensor
I need a sensor which can count a fast moving object. I am thinking to use IR beam break sensor. But, I think there will be a problem with the sunlight as the Tx-Rx will be 4-5 meters apart.
I also need to consider the fast response time. IR sensor has better response time than LDR. Am I right?
EDIT:
Consider, the fast moving object is like a soccer ball (a bit smaller than a soccer ball, though). Its speed is between 15ft/s – 60ft/s.
There are a few ways you might get feedback from the kite, without using vision.
1) GPS. Don't rule this out simply because the kite's base might be in a different location each time you use it. To counter this, you simply need a GPS receiver on both the kite and the base. Take both readings, and convert them into Cartesian coordinates. The difference between these coordinates is the offset of the kite from the base. Note that while GPS offers fairly low accuracy, its resolution is better than its accuracy. The kite and the base will both have the same position error, and so the kite's location relative to the base can be (reasonably) accurately calculated.
2) IMU. A 9-axis Inertial Measurement Unit, will help. There are some pretty small, lightweight parts available, like the MPU-9150 from Invensense. If you use a Kalman Filter to combine the GPS reading with the IMU reading, you can hugely increase your position resolution.
(Sorry, that's a similar part, but the same size)
3) Load cells. The reason I asked how easily you could fly a kite with your eyes shut, is because this will give you some idea of how useful the information from Load Cells will be. Perhaps you wouldn't be able to fly the kite brilliantly, but I bet you could keep it in the air. Each kite string will need a 3-axis force measurement so that you know the exact force and angle of each string. Arrange the three load cells like this:
Each one has a string coming perpendicularly out of the top, in the direction of the load cell's maximum sensitivity. Tie the three strings together, and to the main kite string. The sum of the three measured force vectors will be the tension and direction of that kite string. Make sure that the angle between the strings is greater than the maximum angle of the kite string, otherwise one of the three strings may go slack, making for a false measurement.
4) Pressure. I'm sure you could learn a lot by measuring the air pressure at several points on the kite's inside surface. There are some tiny lightweight barometric sensors available, like the BMP085.
It's even available from Sparkfun on a breakout board. These sensors will also help you to measure the kite's altitude (if they're out of the wind), and you can even use them to measure the windspeed if you place two inside a pitot tube.
Four sensors and three Pitot tubes, plus one sensor on the ground, will give you wind speed and direction, and altitude.
Yes, there are optical sensors that can measure speed. I worked at the proving grounds for a major car maker. In the past, anyone testing cars on the oval used "fifth wheels" but these were falling out of favor as of ten to fifteen years ago. Now optical sensors that measure the how the correlation of random surface texture with itself changes over time.
A similar technique is being researched to measure blood speed in blood vessels with tiny probes inserted by catheter. Same math, very different application.
There is a possibility of taking the sensor out of a wireless optical mouse, but it's unlikely to work if the distance between sensor and moving surface is more than a few cm. "Few" might mean only one! But then, you could use a lens and change that.
But anyway, what sensor can you run out and buy today? If I had more time I'd look for specific examples, but try googling for "optical flow speed sensor" and see what comes up.
Best Answer
The best ways to make a light beam system work reliably in uncontrolled lighting conditions is to look at these two things: