An Introduction to Embedded Control

• What is embedded control?
• Why is embedded control important to me?
• Why is embedded control important to my career?
• Can I see the laboratory studio?
• What work can I expect from this course?
• What is the LITEC Blimp?
• What was the LITEC Smart Car?

What is embedded control?

Microprocessor controlled system have become ubiquitous in our day-to-day lives. In addition to the microprocessor's familiar role as the central processing unit (CPU) in a computer, it is well suited to serve as a dedicated controller for various applications. A microprocessor used in a specific application is called a microcontroller. The embedded control field is simply defining the need for a microcontroller in a specific system and developing the hardware and software necessary for proper use and functioning of the microcontroller.

Why is embedded control important to me?

Embedded devices are all around us, in many common items that we use. From the time you woke up this morning, you’ve probably interacted with at least five different systems which utilize a microprocessor and didn't even realize it. For example, most of you have a digital alarm clock which may have a small microprocessor in it. If you switched on your late-model stereo, then you’ve probably interacted with another microprocessor. If you cooked your breakfast or lunch in a microwave, then you’ve communicated your cooking instructions to its microprocessor. If you chose instead to eat in the school commons and paid by a credit account, then a microprocessor in the card reader of the cash register processed your transaction. If you drove to class and your car has fuel injection, then your car also utilizes a microprocessor. If you talked on your cell phone today, your voice went to a microprocessor which had it converted to a digital signal to be transmitted to a cell tower.

Why is embedded control important to my career?

The purpose of this course is to introduce you to the development of an integrated embedded control system. Through this experience, you will gain an understanding of how such systems are designed and integrated into a typical consumer product. Whether your future job requires you to develop cutting-edge sound equipment, design fuel-injection systems, or monitor the ozone layer, the chances are very high that you will be involved with embedded control to some degree. Therefore, with microprocessor-controlled systems playing an increasingly vital role in the world we live in, this course can give you, no matter what your speciality, an enormous advantage over those engineers who have never designed an embedded control system.

The applications of embedded control are limited only by one’s imagination and there is a growing opportunity for engineers to utilize embedded control to solve a variety of important problems of today and in the future. In the future, you will continue to see embedded control appear in almost every household item. Some products may actually become feasible because of an inexpensive embedded control system. For this reason, engineers from all areas and with different specialties will at some time in their careers be involved with the development of systems that utilize embedded control.

Can I see the laboratory studio?

The LITEC Studio Classroom (Note: This file requires Apple Quicktime)

Using Quicktime's ability to create virtual world movie files, we have linked laboratory images together to produce a dynamic image of the studio. You can use the mouse to move the view and see where you will be doing your design work for this course.

What work can I expect from this course?

The lab assignments will introduce you to several topic areas of embedded microprocessor control, and then will help you to integrate what you learn at each stage into a working control system. Since the goal of the final lab exercise is to integrate what you have learned and actually built in all of the previous lab exercises, it is essential that you keep up with the work. The specific lab assignments are located in the course manual. These include the necessary reading assignments, both in this manual and in the other sources, as well as relevant interactive tutorials since much of this information may be new to you. It will be necessary for you to read the assigned material before the start of each laboratory session, and it would be enormously advantageous to work through the tutorials in advance of the lab session. Moreover, the required reading material will be considered fair game on exams. Throughout the course, homework will also be assigned along with short in-class exercises to assist you in preparing for the lab exercises.

A number of different microprocessors have been specifically designed for embedded control applications. In this lab, you will be using one of the most popular 16-bit microprocessors specifically designed for embedded control, the Silicon Labs C8051F020. Considering its size, the C8051 is both powerful and flexible and has proven ideal for many demanding consumer applications.

What is the LITEC Blimp?

The blimp is the new semester project for LITEC students. It was first prototyped in the classroom during the Spring 2005 semester by only one section. The design and project work were further refined during the Summer 2005 session. Starting Fall 2005, the blimp will be the centerpeice of the LITEC studio.

The first goal of the students is to orient themselves with the microprocessor and coding techniques. Dealing with input, output, and interrupts allows the students to complete the future projects. Students are placed into groups of four and assigned to one of two main labs for blimp operation. With only four operational blimps, all code is first designed and tested on the smart car chasis. Half of the groups work on the steering control for the blimp, while the other half develop the speed control for the blimp. Two of the students in the steering group specifically develop the code necessary to steer the blimp, while their counterparts write the routines to read the electronic compasses mounted in the blimp gondolas. In the speed control group, two students find a way to set and maintain the speed of the blimp, and the other two operate the ultrasonic rangefinder.

Once the groups complete their individual basic assignments, the steering and speed groups are combined into groups of eight. The new groups must fully integrate all four procedures and operations onto a single smart car chasis. Only when this is done can the students port their code to operate on a blimp. Students actually see their code in operation at the end of the semester when the blimps are taken to the RPI Armory and flown.

As is standard engineering practice for a system as complex as the blimp, after a system-level design, you will design, construct, and test one subsystem at a time. For the hardware elements of most of these subsystems, we will guide you toward a solution which you are free to use in the final design. However, if think you have a better solution, or you want to try something different, you are encouraged to do so. RPI students are known to be exceptionally creative, and we encourage that creativity. However, keep in mind limitations of time and the availability of materials. Your goal is to produce the best product you can using the tools and materials available to you, and within the time constraints of a one semester course.

What was the LITEC Smart Car?

The Smart Car was the major project for LITEC students up to and including the Spring 2005 semester. Starting Fall 2005, all sections of LITEC will be working on a new project, the LITEC Blimp. We have kept the information about the Smart Car online so you can read about the systems many RPI students used to make the Smart Car function. Even though it has been eclipsed by the Blimp, the Smart Car will forever remain an important part of LITEC and RPI history.

The Smart Car was a model car with an optical line-tracking system and an on-board micro-processor to control the tracking and speed of the car. The development of this system was a foreshadow of the future trend in automotive technology, beside serving its true purpose: to teach the basic concepts of embedded control.

To develop the Smart Car, students were provided with a car equipped with an electrically actuated steering mechanism, a DC geared drive motor, and a battery. Students were also provided with a microprocessor kit small enough to be mounted on the car’s chassis, an electronics kit containing variable resistors, selected IC chips, optical sensors comprised of an infrared light emitting diode and photodetector, and an empty circuit board on which a circuit would be built to provide an interface among the microprocessor, the optical sensors, steering motor and the drive motor on the car chassis.

The students’ goal was to build the microprocessor-to-car interface circuitry and to develop the software, enabling the car to follow an optical track, along the floor of the lab, as accurately as possible, without straying from the optical track. The development of the system was spread over several lab exercises, each moving closer to the completion of the intelligent car. The optical track was simply a strip of white tape placed on the black track on the lab floor.

The optical sensor system was an arrangement of infrared light emitting diodes and matched photodetectors mounted at the front of the chassis of the car. The electrical signals from the optical tracking system were analyzed by the car’s on-board microprocessor and used to detect deviations from the track.

The steering mechanism consisted of a servo motor connected to the front wheels through push rods. A closed-loop steering control subsystem was developed to maintain the car on the track by periodically reading the signals from the optical tracking system and determining corrective steering action.

The car was powered by a DC drive motor mounted at the back. An optical disk tachometer was used to sense the speed of the car. A closed-loop subsystem was developed so that the speed of the car could be maintained as close as possible to the desired speed specified by the user.

Therefore, the basic system consisted of an optical tracking system to sense the track, a steering control subsystem to maintain the orientation of the car on the track, and a speed control subsystem to maintain a desired speed of the car.

With the basic system completed, many enhancements to the car were incorporated by the students. The car could be designed to follow a wall instead of a track on the floor; headlights could be mounted to indicate if the car was turning to the right or left; the car could be designed to sense marks on the track which could forewarn of a curve or obstacle ahead on the track, making preventive measures possible. The design and development of the smart car offered ample room for the creativity of students to be exercised.