1.3.1 Lab 1 - Introduction to Resources and Tutorials[an error occurred while processing this directive]
2. Go to a laboratory (EC 616), or home computer and run ‘Netscape Communicator’. Go to ‘claymore.engineer.gvsu.edu’ and look for your account under ‘students’. You should be able to find a page that starts with ‘YOUR_NAME_GOES_HERE’.
3. In Netscape (with your home page showing), select ‘edit’ from the tool bar, or under ‘file’ select ‘edit’ or ‘edit page’. You will be asked if you want to save the page. Create a ‘temp’ directory on the computer. This directory will be used to temporarily hold your web page files. Make sure that the files will be saved in the ‘temp’ directory, and then ‘save’ the files. An editor will start on the screen.
5. The editor behaves much like Microsoft Word, with some subtle differences. At this point add your name, and change your email address to your river account. You can change your email address by clicking on the email link, and then clicking on the chain link near the top of the screen.
6. To upload the changes you have made to the website, select ‘publish’. You will need to indicate the file name as ‘index.html’, the destination as ‘ftp://claymore.engineer.gvsu.edu/home/YOUR_NAME/public_html’. You will also need to enter your user name and your password (DO NOT SAVE THE PASSWORD - SOMEBODY ELSE CAN GET ACCESS TO YOUR ACCOUNT). You should see a message that indicates files have been uploaded successfully.
7. Use Netscape, not the editor, to see if the changes have occurred. Your changes may not show up on the browser. This is because Netscape does not reload pages every time to look at them. Pages are often stored for up to 1 month on the PCs hard drive, and reused when you look at them. There are two ways to update the screen before this time limit - click on the reload button.
8. Next we will add links to your home page. First, run Mathcad, and create a simple file, and then save it in the same folder/directory you saved. Use a file name that is all lower case such as ‘test.mcd’ - any upper case letters cause problems in Windows 95.
9. Get your home page back in the Netscape editor. Someplace type the word ‘GVSU’. Use the mouse to select what you just typed, and then click on the link button. For the link name enter ‘http://www.gvsu.edu’, and apply the change. This will now be a link to the Grand Valley home page. For your Mathcad file type something like ‘Mathcad file’, highlight it, and add a link to ‘test.mcd’. This link will connect to your Mathcad file.
Working Model 2D, Mathcad and the Internet will be used in this course. In some cases students have not been exposed to one or more of these software packages in the past. This session will be used as a refresher for those with little prior exposure, and as a tutorial for those with no experience.
Mathcad is a software package that allows us to do complex calculations both numerically and symbolically. To learn it initially will require a time investment. But, when doing calculations later, it will save a significant amount of time and reduce calculation errors.
Working Model 2D is a software package that allows us to set up systems of multiple rigid bodies. We can then apply forces, moments, etc. and then see how the system dynamics are effected. In comparison, Mathcad will allow longer, precise calculations, whereas Working Model allows faster results with reduced accuracy. Working Model also presents a visual simulation - this allows a more intuitive understanding of a dynamic system.
6. Go to a search engine and find a website for a major business that is related to your co-op position and add a link to it on your home page. Explain how the business is related to your co-op position.
The essential purpose of engineering is to apply principles of the arts and sciences to solve real problems. Scientific principles tend to evolve over time, but the essential principles and written works are valid for a number of decades or centuries. As a result, books can be excellent resources for this knowledge. The applications that make use of the basic principles tend to be more revolutionary. As a result, printed books have a value for teaching the fundamentals, but the ’state of the art’ must often be found in magazines, journals, etc. To put this in simpler terms, when we look for scientific resources, we will often use sources over a decade old. When using engineering resources, most will be less than five years old. Until recently, print has been the major means of exchanging information, and libraries have been the traditional repositories of printed materials. To deal with the extensive number of publications available in a library, we need to learn how to search for needed information, and what resources are available.
New technology has changed access to library materials. Libraries pool resources and share materials. Internet technology has also helped increase accessibility. In particular internet tools allow the entire library catalog to be examined without visiting the library. There are also a number of resources that can be searched and retrieved over the internet.
1.3.2 Lab 2 - Computer Based Data Collection[an error occurred while processing this directive]
To obtain the greatest computing power and flexibility we need to write computer programs. But, traditional programming languages are not well suited to designing user interfaces and dealing with data flows.
Most computer programs are written with lines of program and compiled to execute. LabVIEW allows you to “write” programs using graphical symbols. This graphical programming approach allows systems to be designed by connecting the symbols with "wires" (i.e., lines).
• To obtain the greatest computing power and flexibility we need to write computer programs. But, traditional programming languages are not well suited to designing user interfaces and dealing with data flows.
• The connector for the card can be found on the back of the computer. It will have a connector with pinouts like the one shown below. A ribbon cable will be used to make electrical connection to the connector in the back of the computer.
To read the data into a computer we write programs, and use "canned" software to help with the task. LabVIEW allows us to write programs for data collection, but instead of typing instructions we draw function blocks and connect them. How we connect them determines how the data (numbers) flow. The functions are things like data reads and calculations.
In this lab we will be using Labview to connect to a data acquisition (DAQ) board in the computer. This will allow us to collect data from the world outside the computer, and make changes to the world outside with outputs.
When interfacing to the card using a program such as Labview, there must be ways to address or request information for a specific input or output (recall memory addresses in EGR226). The first important piece of information is the board number. There can be multiple DAQ boards installed in the computer. In our case there is only one, and it is designated device ’1’. There are also many inputs and outputs available on the card. For analog outputs there are two channels so we need to specify which one when using the output with 0 or 1. For analog inputs there are 8 channels, and as before, we must specify which one we plan to read from using 0 to 7. For digital I/O there are a total of 24 pin distributed across 3 ports (1 byte each). Therefore when connecting inputs and output we must specify the port (PA=0, PB=1, PC=2) and the channel from 0 to 7. Note is that we can make the ports inputs or outputs, but not mixed - in other words we must pick whether a port will only be used for inputs or for outputs.
The voltage levels for the inputs and outputs are important, and you will need to be aware of these. For the digital outputs they will only ever be 0V or 5V. But the analog inputs and outputs will vary from -5V to 5V. This is build into the board. If we exceed these voltage limits by a few volts on the inputs, the boards have built in protection and should be undamaged. If we exceed the input voltages significantly, there is a potential to permanently damage the board.
2. Enter the LabVIEW program (layout) schematically shown below and connect a signal generator to the analog input (ACH0). (Note: there is a pin diagram for the connector in the Labview tutorial section.) Start the signal generator with a low frequency sinusoidal wave. Use the ‘DAQ Configure’ software to test the circuitry and verify that your hardware is operational. Then run your Labview program. Record the observations seen on the screen.
3. Connect the multimeter as shown below. Test the circuit using the ‘DAQ Configure’ utility. Enter the LabVIEW program schematically illustrated below and then run it. You should be able to control the output voltage from the screen using the mouse. Record your observations.
4. Connect the digital input and output circuits to the DAQ card and use the test panel to test the circuits. To do this, run the ‘DAQ Configure’ utility, double click on the ‘PCI-1200’, run the test panel window and ensure that the inputs and outputs are working correctly. Create the LabVIEW screen schematically illustrated below. This should allow you to scan an input switch and set an output light. When done, quit the program and run your LabVIEW program.
1.3.3 Lab 3 - Sensors and More Labview[an error occurred while processing this directive]
Sensors allow us to convert physical phenomenon to measurable signals, normally voltage or current. These tend to fall into one of two categories, discrete or continuous. Discrete sensors will only switch on or off. Examples of these include,
1. Sensors will be set up in the laboratory at multiple stations. You and your team should circulate to each station and collect results as needed. Instructions will be provided at each station to clarify the setup. The stations might include,
Theory: The industrial motors and controllers to be used in this laboratory are manufactured by Allen-Bradley. The controllers are Ultra 100 drives, and the motors are Y-series brushless servo motors.
1.3.4 Lab 4 - Motors[an error occurred while processing this directive]
DC motors will apply a torque between the rotor and stator that is related to the applied voltage or current. When a voltage is applied the torque will cause the rotor to accelerate. For any voltage and load on the motor there will tend to be a final angular velocity due to friction and drag in the motor. And, for a given voltage the ratio between steady state torque and speed will be a straight line.
The basic equivalent circuit model for the motor is shown below. We can develop equations for this model. This model must also include the rotational inertia of the rotor and any attached loads. On the left hand side is the resistance of the motor and the ’back emf’ dependent voltage source. On the right hand side the inertia components are shown. The rotational inertia J1 is the motor rotor, and the second inertia is an attached disk.
1.3.5 Lab 5 - Motor Control Systems[an error occurred while processing this directive]
Recall that by itself a motor is a first order system, but by adding a mass to it will become a second order system. A PID controller is well suited to controlling second order systems. But, tuning a PID controller is an art. The proportional gain sets to overall response. This should be tuned first so that the motor generally responds quickly, but doesn’t overshoot the goal. The derivative term should be set next so that the motor responds faster, and only overshoots the goal by an acceptable amount. Finally the integral portion is used to reduce the steady state error.
1.3.6 Lab 6 - Basic Control Systems[an error occurred while processing this directive]
We can develop a simple control technique for control of the velocity using the equation below. For this form of control, we need to specify a desired velocity (or position) by setting a value ’Vd’. The difference between the desired speed and actual speed is calculated (Vd-Vi). This will give a voltage difference between the two values. This difference is multiplied by a constant ’K’. The value of ’K’ will determine how the system responds.
1. Develop a Mathcad document that will model the velocity feedback controller given, motor parameters, desired velocity, an inertial load, and a gain constant. This is to be solved three different ways i) with Runge-Kutta integration, ii) integration of differential equations and iii) with laplace transforms.
1.3.7 Lab 7 - Basic System Components[an error occurred while processing this directive]
Recall that for a rigid body we can sum forces. If the body is static (not moving), these forces and moments are equal to zero. If there is motion/acceleration, we use d’Alembert’s equations for linear motion and rotation.
If we have a system that is comprised of a spring connected to a mass, it will oscillate. If the system also has a damper, it will tend to return to rest (static) as the damper dissipates energy. Recall that springs ideally follow Hooke’s law. We can find the value of the spring constant by stretching the spring and measuring the forces at different points or we can apply forces and measure the displacements.
In many cases we will get springs and devices that are preloaded. Both of the devices used in this lab have a preloaded spring. This means that when the spring has no force applied and appears to be undeflected, it is already under tension or compression, and we cannot use the unloaded length as the undeflected length. But, we can find the true undeflected length using the relationships from before.
Next, recall that the resistance force of a damper is proportional to velocity. Consider that when velocity is zero, the force is zero. As the speed increases, so does the force. We can measure this using the approximate derivatives as before.
In the lab an ultrasonic sensor will be used to measure the distances to the components as they move. The sensor used is an Allen Bradley 873C Ultrasonic Proximity Sensor. It emits sound pulses at 200KHz and waits for the echo from an object that is 30 to 100cm from it. It outputs an analog voltage that is proportional to distance. This sensor requires a 18-30 VDC supply to operate. The positive supply voltage is connected to the Brown wire, and the common is connected to the blue wire. The analog voltage output (for distance) is the black wire. The black wire and common can be connected to a computer with a DAQ card to read and record voltages. The sound from the sensor travels outwards in an 8 degree cone. A solid target will give the best reflection.
3. Connect the computer to the ultrasonic sensor (an Allen Bradley Bulletin 873C Ultrasonic Proximity Sensor, see www.ab.com), and calibrate the voltages to the position of the target (DO NOT FORGET TO DO THIS). Write a Labview program to read the voltage values and save them to a data file. In the program set a time step for the voltage readings, or measure the relationship between the reading number and actual time for later calculation.
5. Place the spring inside the damper and secure the damper. This will now be used as a combined spring damper. In this arrangement the spring will be precompressed. Make sure you know how much the spring has been compressed when the damper is in neutral position.
1.3.8 Lab 8 - Oscillating Systems[an error occurred while processing this directive]
1.3.9 Lab 9 - Filters[an error occurred while processing this directive]
We can build simple filters using op-amps, and off the shelf components such as resistors and capacitors. The figure below shows a band pass filter. This filter will pass frequencies near a central frequency determined by the resistor and capacitor values. By changing the values we can change the overall gain of the amplifier, or the tuned frequency.
As dictated by the ear, audio signals have frequencies that are between 10Hz and 16KHz as illustrated in the graph below. This graph shows perceived sound level, with the units of ’phons’. For example, we can follow the 100 phons curve (this would be like a loud concert or very noisy factory requiring ear protection). At much lower and higher frequencies there would have to be more sound pressure for us to perceive the same loudness, or phon value. If the sound were at 50Hz and 113 dB it would sound as loud as 100dB sound at 1KHz.
You may appreciate that these curves are similar to transfer functions, but they are non-linear. For this lab it is important to know how the ear works because you will be using your ear as one of the experimental devices today.