First successful prototype for undergrad physics labs

First prototype of Arduino for linear motion labs....

Arduino with sonic ranging module HC - SR04 (from the specs sheet):

Ultrasonic ranging module HC - SR04 provides 2cm - 400cm non-contact

measurement function, the ranging accuracy can reach to 3mm. The modules

includes ultrasonic transmitters, receiver and control circuit. The basic principle

of work:

(1) Using IO trigger for at least 10us high level signal,

(2) The Module automatically sends eight 40 kHz and detect whether there is a

pulse signal back.

(3) IF the signal back, through high level , time of high output IO duration is

the time from sending ultrasonic to returning.

Test distance = (high level time×velocity of sound (340M/S) / 2,

So what is the device doing?

The device measures the time that it takes for a sound pulse to return after bouncing off some surface and converts that value to a position.  Placing a card or hand in front of the transducer/microphone gives excellent readings as well.

Here's what a position vs. time [ x(t) ] graph looks like as I move the Arduino back and forth, bouncing the sound wave against the wall:

And the program can also output the position as a data file.  I loaded a data file into Excel:

It would be great to continue this project with the following steps:

1. log tabular data (see this and this)
2. plot v(t) and a(t) in addition to x(t) data in real time.
3. handle situation in case there is an erroneous spike
4. test the limitations of software/hardware.  Will the 40 Hz (25 ms) response of the HC - SR04 be appropriate?  How accurate/precise are our measurements?  Would using slightly better parts make a big difference?
5. test in actual lab scenario with a linear air track
1. how to arrange computers to be near lab setups?
6. develop some intriguing, real-world lab worksheet that guides students through the process as well as connects their experience to real-world applications.  Make an "instructor sheet" with concepts and ideas to plant as instructor goes around room visiting each lab group.

Resources:
Interfacing Code with the Physical World: A Crash Course in Processing and Arduino

How to visualize and save Arduino-sensed data

Longer-term questions:

1. How to make a direct real-world tie-in with as many labs as possible?
2. What activities will students respond most to?  What will be most intriguing?
3. Data analysis: should templates be provided?
4. Should these devices be ready to go or should students assemble?  (It can be as simple as plugging in 4 wires, and hitting upload to upload the arduino program.)
5. Value of written lab report: Students need to gain experience explaining and expressing scientific ideas concisely.  How can we emphasize this without placing an unreasonable time burden on the students (this is only a 1-hr credit)?  

Here's another cool idea that can be adopted (from Stanford undergrad labs):
Bernoulli's principle -- the sound can bounce off the top surface of a bucket of water, and thus flow rate can be calculated.  This can be related to the pressure at the level of a hole in the bucket, or the flow velocity -- and if a horizontal hole, the range that the water travels before hitting the floor!