The piezoelectric actuator is a device that features high displacement accuracy, high response speed and high force generation. It has mainly been applied in support of industrial machinery that requires precise position control.
The field of applications of piezoelectric actuators is comparable to that of electromagnetic actuators. Piezoelectric actuators are used for active vibration damping in mechanical structures where vibrations are undesirable. Vibration damping can be designed to reduce noise, fuel consumption and energy waste. The reduction of sound levels in helicopter structures has drawn a lot of interest recently, however the technology can be applied to other areas such as planes, wind turbines, motors, machine tools, laboratory tables (especially optical).
Application (Ji, 2010)
There are two methods of damping undesired vibrations in mechanical structures using piezo components: active and passive vibration damping. Passive vibration damping is a method, where the vibration is converted into electrical energy through the piezo effect and then stored or dissipated into heat, for example by means of resistors. In the active method, the piezo actuators generate counter movements in the control loop, which effectively damps the vibration. This is the preferred method as it is most effective, however it requires power and a complex controller.
The piezoelectric actuator has disadvantages compared to the electromagnetic actuator in terms of its displacement amount. However, it is advantageous from other aspects, including that of its displacement accuracy, generated force and response speed and energy efficiency as well as from the aspect of ease of proportional control and absence of electromagnetic noise.
The application piezoelectric actuator.
Particularly the advanced piezoelectric fiber composite due to the rapid development of smart materials and structures and active control technology in aviation and aerospace industry, to aircraft for performance enhancements such as flight control, aerodynamic force optimization, structure weight reduction, and overall aircraft design represents a new challenge to researches. It is considered as one of the key technologies for developing future flight vehicle. An approach with virtual control surface instead of conventional control surface to control aerodynamic force distribution and flight performance by use of piezoelectric fiber composite actuators distributed on wing surface.
Particularly, the design and implementation of increasing lift force, providing roll maneuver, decreasing induced drag and wing root moment in different flight environments by the same structure control platform are studied. The control effect and sensitivity are examined quantitatively.
Piezoelectric sensors
Piezoelectric sensors measure the electrical potential caused by applying mechanical force to a piezoelectric material. Piezoelectric sensors are used in a variety of pressure-sensing applications. Alumina ceramics, single crystals, and ultrasonic transducers are few examples of piezoelectric materials.
Piezoelectric sensors are used in structural health monitoring (SHM), where the integrity of mechanical structures is checked while in use. This is highly relevant where safety is an important issue e.g. transport structures, infrastructure and building structures. The continuous monitoring also holds an obvious financial advantage to traditional inspection of e.g. an airplane that requires a planned interruption of service and even a dismantling of selected parts.
Servo motor in robotics (verma, 2015)
Servo motors are actually a small module. Normally, its task is to move to and maintain itself at a particular angular position. Most servos are between 0 to 180 degrees.
It’s easy to control servos. It’s a mechanical as well as electronic module. It has a small potentiometer in the box itself to take feedback. It basically takes input from a signal wire in form of PWM signals. PWM is nothing but digital On/Off cycle. The duration of on time tells the servo about going to a particular angle. The duration is in few milliseconds. Then the potentiometer reading gives actual angular position at the moment. After that the motor is made to move accordingly with inbuilt motor drivers.
Due to control on angle based on feedback system, servos are extremely precise. They are used for making humanoids, bipeds, hexapods, controlling camera position, and a lot more things.
They are lighter and more reliable than stepper (no feedback) motors. The only problem is that servos have limited range. Only some servos have 360° non continuous operation support. Continuous rotation servos are quite a different thing and have encoders instead of potentiometer. Encoder is basically a lined sheet of substance and photo emitter detector pair.
Servos are the better choice in vertical applications in which the motor must hold a load still and for smooth operations.
A servo motor in robotic is at every "joint" of a robot which is used to actuate movements, giving the robot arm its precise angles.
Robotic Vehicle: Commonly used in military applications and bomb detonation, servo motors control the wheels of the robotic vehicle, generating enough torque to move, stop, and start the vehicle smoothly as well as control its speed.
Servo motor in industries (william, 2014)
Some Industrial Applications for Servo Motors.
Conveyor Belts: Servo motors move, stop, and start conveyor belts carrying product along to various stages, for example, in product packaging/bottling, and labelling.
Metal Cutting & Metal Forming Machines: Servo motors provide precise motion control for milling machines, lathes, grinding, centring, punching, pressing, and bending in metal fabrication for such items as jar lids to automotive wheels.
Solar Tracking System: Servo motors adjust the angle of solar panels throughout the day so that each panel continues to face the sun, harnessing maximum energy from sunup to sundown.
Woodworking/CNC: Servo motors control woodturning mechanisms (lathes) that shape table legs and stair spindles, for example, as well as portending and drilling the holes necessary for assembling those products later in the process.
Textiles: Servo motors control industrial spinning and weaving machines, looms, and knitting machines that produce textiles such as carpeting and fabrics as well as wearable items such as socks, caps, gloves, and mittens.
Printing Presses/Printers: Servo motors stop and start the print heads precisely on the page as well as move paper along to print multiple rows of text or graphics in exact lines, whether it's a newspaper, a magazine, or an annual report.
Automatic Door Openers: Supermarkets and hospital entrances are prime examples of automated door openers controlled by servo motors, whether the signal to open is via push plate beside the door for handicapped access or by radio transmitter positioned overhead.
The industrial application of servomotors has grown significantly for the following reasons:
• Reduction of price of power conversion products.
• Establishment of advanced control of PWM inverters.
• Development of new, more powerful and easier to use permanent magnet materials.
• The developing need for highly accurate position control.
• The manufacture of all these components in a very compact form.