A typical input variable is identified for each of the following examples of dynamic systems. Give at least one output variable for each system

(a) Human body: Neuroelectric pulses (b) Company: Information

(c) Power plant: Fuel rate

(d) Automobile: Steering wheel movement (e) Robot: Voltage to joint motor

1.10 Hierarchical control has been applied in many industries, including steel mills, oil refineries, chemical plants, glass works, and automated manufacturing. Most applications have been limited to two or three levels of hierarchy, however. The lower levels usually consist of tight servo loops, with bandwidths in the order of 1 kHz. The upper levels typically control production planning and scheduling events measured in units of days or weeks.

A five-level hierarchy for a flexible manufacturing facility is as follows: The lowest level (level 1) handles servo control of robotic manipulator joints and machine tool degrees of freedom.

The second level performs activities such as coordinate transformation in machine tools, which are required in generating control commands for various servo loops. The third level converts task commands into motion trajectories (of manipulator end effector, machine tool bit, etc.) expressed in world coordinates. The fourth level converts complex and general task commands into simple task commands. The top level (level 5) performs supervisory control tasks for various machine tools and material-handling devices, including coordination, scheduling, and definition of basic moves. Suppose that this facility is used as a flexible manufacturing workcell for turbine blade production. Estimate the event duration at the lowest level and the control bandwidth (in hertz) at the highest level for this type of application.

1.11 According to some observers in the process control industry, early brands of analog control hard-ware had a product life of about 20 years. New hardhard-ware controllers can become obsolete in a couple of years, even before their development costs are recovered. As a control instrumentation engineer responsible for developing an off-the-shelf process controller, what features would you incorporate into the controller to correct this problem to a great extent?

1.12 The PLC is a sequential control device, which can sequentially and repeatedly activate a series of output devices (e.g., motors, valves, alarms, and signal lights) on the basis of the states of a series of input devices (e.g., switches, two-state sensors). Show how a programmable controller and a vision system consisting of a digital camera and a simple image processor (say, with an edge-detection algorithm) could be used for sorting fruits on the basis of quality and size for packaging and pricing.

1.13 Measuring devices (sensors, transducers) are useful for measuring the outputs of a process for feedback control. Give other situations in which signal measurement would be important. List at least five different sensors used in an automobile engine.

1.14 One way to classify controllers is to separately consider their sophistication and physical com-plexity. For instance, we can use an x–y plane with the x-axis denoting the physical complexity

and the y-axis denoting the controller sophistication. In this graphical representation, simple open-loop on/off controllers (say, opening and closing a valve) would have a very low controller sophistication value and an artificial-intelligence (AI)-based intelligent controller would have a high controller sophistication value. Moreover, a passive device is considered to have less physi-cal complexity than an active device. Hence, a passive spring-operated device (e.g., a relief valve) would occupy a position very close to the origin of the x–y plane and an intelligent machine (e.g., sophisticated robot) would occupy a position diagonally far from the origin. Consider five control devices of your choice. Mark the locations that you expect them to occupy (in relative terms) on this classification plane.

1.15 A dental hygienist assures a patient that they have nothing worry about the x-rays taken of the mouth as everything is digital now. Critically discuss the hygienist’s statement and how it should be interpreted.

1.16 You are an engineer who has been assigned the task of designing and instrumenting a practical system. In the project report, you have to describe the steps of establishing the design/ performance specifications for the system, selecting and sizing sensors, transducers, actuators, drive systems, controllers, signal conditioning and interface hardware, and software for the instrumentation and component integration of this system. Keeping this in mind, write a project proposal giving the following information:

1. Select a process (plant) as the system to be developed. Describe the plant indicating the pur-pose of the plant, how the plant operates, what is the system boundary (physical or imagi-nary), what are the important inputs (e.g., voltages, torques, heat transfer rates, flow rates), response variables (e.g., displacements, velocities, temperatures, pressures, currents, volt-ages), and what are important plant parameters (e.g., mass, stiffness, resistance, inductance, thermal conductivity, fluid capacity). You may use sketches.

2. Indicate the performance requirements (or operating specifications) for the plant (i.e., how the plant should behave in normal operation). You may use any available information on such requirements as accuracy, resolution, speed, linearity, stability, and operating bandwidth.

3. Give any constraints related to cost, size, weight, environment (e.g., operating temperature, humidity, dust-free or clean room conditions, lighting, and wash-down needs), and so on.

4. Indicate the type and the nature of the sensors and transducers present in the plant and what additional sensors and transducers might be needed to properly operate and control the system.

5. Indicate the type and the nature of the actuators and drive systems present in the plant and which of these actuators have to be controlled. If you need to add new actuators (including control actuators) and drive systems, indicate such requirements in detail.

6. Mention what types of signal modification and interfacing hardware would be needed (i.e., filters, amplifiers, modulators, demodulators, ADC, DAC, and other data acquisition and control needs). Describe the purpose of these devices. Indicate any software (e.g., driver software) that may be needed along with this hardware.

7. Indicate the nature and operation of the controllers in the system. State whether these con-trollers are adequate for your system. If you intend to add new concon-trollers briefly give their nature, characteristics, objectives, and so on (e.g., analog, digital, linear, nonlinear, hardware, software, control bandwidth).

8. Describe how the users and operators interact with the system, and the nature of the user interface requirements (e.g., graphic user interface or GUI).

The following plants or systems may be considered:

1. Hybrid electric vehicle 2. Household robot 3. Smart camera

4. Smart airbag system for an automobile

5. Rover mobile robot for Mars exploration, developed by NASA 6. Automated guided vehicle (AGV) for a manufacturing plant

7. Flight simulator

8. Hard disc drive for a personal computer

9. Packaging and labeling system for a grocery item 10. Vibration testing system (electrodynamic or hydraulic)

11. Active orthotic device to be worn by a person to assist a disabled or weak hand (which has some sensation, but not fully functional)

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Component Interconnection