Each student in PHYS 318 will participate in a team project that will involve using LabVIEW to solve a real-world problem. A summary of each project is described briefly below. Each of these projects can be written in using the dual-loop architecture of an event loop and a queued state machine from the audio analyzer experiment as a guide. One major difference is that the audio analyzer application was written in a manner where the application was continuously acquiring data but for these projects the applications will in general be idle and will acquire data for a finite period of time when the user presses an Acquire Data button. In addition, the address of the SVN repository for the project is provided.
Project Descriptions
- Photogates
Team Members: William Brunt, Leah Hartman, Galilea Ochoa-Vinalay, and Rachael Reynolds
A photogate is a composite device that consists of a light source whose output is collimated as a beam toward a photosensor. The output of the sensor is conditioned so that it will give a digital TRUE if the beam of light from the source to the detector is not blocked and a digital FALSE if the beam is blocked.
This team will design an application that will be capable of measuring the output of \(N\) photogates as a function of time and then performing some additional analysis on the resulting data.
One application will be to use the measured data and the solution to the following problem to compute a value for the acceleration due to gravity.
The acceleration of gravity can be measured by projecting a body upward and measuring the time that it takes to pass two given points in both directions. As an example, suppose a friend throws a ball straight up outside your window. You measure the distance\( h\) from the bottom of the lower pane of glass to the top of the upper pane of glass. You measure the time interval \(T_A\) the body takes to first rise past the bottom of the lower pane of glass and then drop past the same line on the way down. You also measure the time interval \(T_B\) the body takes to disappear past the top of the upper pane of glass and then reappear past the same line on the way down. Assume that the acceleration is constant (negligible air resistance), find an expression for the acceleration of the body in terms of the measured quantities. The initial velocity of the ball and the height from which the ball is thrown are both unknown.
Another application will be to use many sensors placed along a curved incline to measure the position as a function of time and compute the velocity as a function of time for a rolling object.svn://physics.wku.edu/phys318/projects/physics/photogates/trunk
- Sonic Ranger
Team Members: Austin Costello, Austin Forbes, and Maci Simmons
An ultrasonic ranger works by sending a series of pulses from a source and then measuring the amount of time required for those pulses to reflect from an object and return to a detector near the source. We will use an inexpensive HC-SR04 ultrasonic sensor. To use this one has to create a pulse of at least \(10\mu\textrm{s}\) duration on the Trigger line and then measure the duration of the return pulse on the Echo line. A counter input can be used to measure the pulse width. The duration of this pulse is proportional to the distance from the sensor to the object.
This team will inherit an existing application that uses the HC-SR04 but will need to make some modifications and improvements to the code. First, the existing application has an action engine for controlling the HC-SR04 but this VI has a blocked (password protected) block diagram. This action engine needs to be re-written. Secondly, the existing code could is not particularly well documented and would benefit from some work in this area. Finally, the team should consider adding an extra function to the code that will allow a set of position versus time data to be differentiated to show the velocity versus time.svn://physics.wku.edu/phys318/projects/physics/hc-sr04/trunk/
- Encoder
Team Members: Maddie Bunnell, Adrianna Burchett, and Bailey Stinson
An encoder is a device that can be used to measure position. They come in varieties to measure linear position (shaft encoder) or to measure angular position (rotary encoder). The most common type of encoder is called an AB encoder which gives two output pulse trains (labeled A and B) that are shifted in phase from each other by \(90^{\circ}\). By measuring the rate of pulses one can determine the speed of the object and by determining whether A leads B or B leads A one can determine direction. A slightly less common variety is one where the two outputs are designed in a manner so that motion in one direction produces pulses on the first output and motion in the other direction produces pulses on the second output. This style is sometimes called an up-down encoder.
This team will design an application that will measure data from a Pasco CI-6538 Rotary Motion Sensor (an up-down style rotary encoder) and use the results to perform a computation.svn://physics.wku.edu/phys318/projects/physics/ci-6538/trunk
