About this manual

The purpose of this manual is to provide you, the student, with the laboratory procedures necessary for conducting the control system experiments in the ASE 170P course. You should by no means treat this manual as the sole source of information for the design and implementation process. You should rely on lecture notes, reference text, as well as their own knowledge of control theory, to develop and implement your control algorithms. This manual is only intended to provide an organized method for performing the experiments.

Course Objectives

Course Policies

Doing Your Own Work

While you are encouraged to discuss theory and methods with other classmates, when it comes time to analyze, design, and implement your system, it must be done on your own. As an engineer you must always fully understand the problem you are trying to solve. Simply copying the work of others shows your lack of understanding of the problem. Remember, when you become an engineer working in industry, it is no longer just your grade that is at risk; your company's reputation, and more importantly other people's lives, are on the line. Any students caught in violation of these guidelines will be dealt with according to the university's policies on scholastic dishonesty.

Late Work

Any work submitted late without a valid reason will not receive credit. If a student has a valid reason why an assignment must be submitted late, he/she should contact the instructor as soon as possible.

Grading

When working in an experimental environment, results are always important, but so is your ability to communicate the information with others. Any work you submit should be neat, well organized, and easy to understand. Remember, your work is a demonstration of your ability to understand the material you are studying as well as a reflection of your organizational skills and attention to detail.

The following guidelines will help ensure that you receive as much credit as possible for your work:

Program Debugging

Some students tend to think of the instructor as a program debugging aid. You should try diligently to find your own errors before seeking assistance. Part of the objective of the computer assignments is to help you develop the ability to use the computer INDEPENDENTLY. You are not using the computer independently if someone else debugs your programs. You should only seek debugging assistance from the instructor if you have made a diligent effort to find your mistakes.

Model 210 Rectilinear Plant

The ECP Model 210 Rectilinear Plant holds three mass carriages which can be loaded with brass weights and connected in a variety of configurations using springs of varying stiffness. The adjustable dashpot can be used to provide damping for the system. A single drive motor provides actuation to the system via the first mass carriage, and position measurements are taken by quadrature encoders.

Figure 1: ECP Model 210 Rectilinear Plant

ECP Model 210

Model 205 Torsional Plant

The ECP Model 205 Torsional Plant holds three disks each of which can be loaded with brass weights at varying positions. The disks are connected through their centers by thin rods giving the system rotational stiffness. A single driver motor actuates the system via the bottom disk, and quadrature encoders provide angular position measurements.

Figure 2: ECP Model 205 Torsional Plant

ECP Model 205

A-51 Inverted Pendulum Accessory

The ECP A-51 Inverted Pendulum Accessory consists of a cylindrical weight attached to a slender rod. The position of the weight can be varied therefore changing the center of gravity of the assembly. The rod attaches to a low friction pivot joint whose angular position is measured by a quadrature encoder. The base plate allows for the accessory to be mounted on both the Model 210 and Model 205 plants.

Figure 3: ECP A-51 Inverted Pendulum Accessory

ECP A-51

PXI-1042 Chassis

The National Instruments PXI-1031 chassis provides a foundation to which a variety of PXI expansion modules can be added. This makes it a highly customizable measurement and testing platform.

Figure 4: National Instruments PXI-1031 Chassis

NI PXI-1031

PXI-8186 Real-Time Embedded Controller

The National Instruments PXI-8186 is a Pentium4-based, real-time embedded controller. In addition to having the ability to act as a Windows PC, the PXI-8186 can also run an NI developed, real-time operating system which allows it to work as a deployment platform for LabVIEW Real-Time applications.

Figure 5: National Instruments PXI-8186 Embedded Controller

NI PXI-8186

PXI-7831R Reconfigurable Multifunction I/O

The National Instruments PXI-7831R Reconfigurable Multifunction I/O is a module that can input and output both analog and digital signals. It is equipped with an FPGA (field processor gate array) which is configurable with the LabVIEW FPGA Module.

Figure 6: National Instruments PXI-7831R Reconfigurable Multifunction I/O

NI PXI-7831R

General Safety Precautions

Hardware Limits on the Model 210

Located near each mass carriage are two stop bumpers that prevent the carriage from exceeding their maximum allowable displacement. On each stop bumper is an electrical switch which sends out a signal when it is engaged. When the LabVIEW FPGA code receives this signal, it immediately outputs zero command voltage to the drive motor. This voltage remains zero until the error is cleared via the control loop VI's front panel. In addition to the limit switches, the FPGA code has been written to prevent overspeed / overvoltage of the drive motor. When the code detects overspeeding / overvolting of the motor, it will again output zero command voltage and remain there until the error has been cleared.

Hardware Limits on the Model 205

The FPGA code for the model 205 plant has been written to detect when the relative position between the first and second disks exceeds 3000 counts. This is to prevent damage to the torsional rod if a large torque is applied to the base disk. When this limit is exceeded, zero command voltage is output to the drive motor until the error is cleared. Just as with the model 210 plant, the model 205 also has drive motor over-speed/overvoltage protection incorporated into the FPGA code.