ECE5320 Mechatronics Assignment#01: Literature Survey on Sensors and Actuators Topic: Piezoelectric Actuators

1. ECE5320 MechatronicsAssignment#01: Literature Survey on Sensors and Actuators Topic: Piezoelectric Actuators Prepared by: Saurabh Bhalerao Dept. of Electrical and Computer Engineering Utah State University E: s.bhalerao@aggiemail.usu.edu 3/1/2009

2. Slide-2 Outline • Reference list • Overview • Major applications • Basic working principle illustrated • Major specifications • Limitations 03/06/09 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

3. Slide-3 Reference list • http://www.cedrat.com/en/mechatronic-products/actuators.htmlFor the applications and manufacturing details • http://www.trstechnologies.com/Products/actuators.php Further reading • http://optics.nasa.gov/tech_days/tech_days_2005/docs/33%20JPL%20MEMS%20Actuators.pdf • http://motion-controls.globalspec.com/Industrial-Directory/piezoelectric_actuator • http://www.morganelectroceramics.com/tutorials/piezoguide1.html 03/06/09 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

4. Slide-4 To explore further (survival pointers of web references etc) • http://www.draper.com/digest2000/paper7.pdf • http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=1627332 • http://www.physikinstrumente.com/tutorial/index.htm 03/06/09 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

5. Slide-5 Overview • The three simplest piezoelectric actuator designs are :- a.)the cylindrical actuator b.) the bimorph (and unimorph) actuator c.) multilayer actuator 03/06/09 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

6. Slide-6 Overview – Piezoelectric Actuators Groups of unit cells with the same orientation are called Weiss domains. Because of the random distribution of the domain orientations in the ceramic material no macroscopic piezoelectric behavior is observable. Diagram from: http://www.physikinstrumente.com/en/products/prdetail.php?sortnr=400600.00 03/06/09 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

7. Slide-7 Overview Contd Due to the ferroelectric nature of the material, it is possible to force permanent alignment of the different domains using a strong electric field. This process is called poling (see Fig). Some PZT ceramics must be poled at an elevated temperature. Diagram from: http://www.physikinstrumente.com/en/products/primages.php?sortnr=400600.00&picview=2#gallery 03/06/09 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

8. Slide-8 Major Applications • Optics & Vision: Positioning of mirrors or lenses, micro-scanning, Astronomy, Focusing, Laser cavity tuning, Alignment or deformation of fibers, Deformation of FBG, Scanners, Choppers, Interferomoters, PDP glass cutting, Modulators,. • Mechanics: Positioning of tools, Pick & Place, Diamond turning, Oval piston machining, Damping, Active control, Generation of ultrasonic or sonic vibrations, NDT, Health monitoring. • Fluidics: Proportional valves, Pumps, Measuring, Injections, Ink jet, Droplet generators, Flow mass meter. • Electronics: Positioning of masks, wafers or magnetic heads, Non-magnetic actuation, Circuit breakers, Chip testing. • Air & space: Active flaps, Shape control, Active wing. • Electrical energy: Piezoelectric generator, Energy harvesting, Electric switch. 03/06/09 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

9. Slide-9 Major Advantages • Small • Lightweight • Passive • Low power • Wide bandwidth • Rugged • Resistant to EM interference • High sensitivity 03/06/09 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

10. Slide-10 Principle of Operation When operated well below the resonant frequency, a piezo actuator behaves as a capacitor: The actuator displacement is proportional to stored charge (first order estimate). The capacitance of the actuator depends on the area and thickness of the ceramic, as well as on its material properties Diagram from: http://www.physikinstrumente.com/en/products/prdetail.php?sortnr=400600.75 03/06/09 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

11. Slide-11 Principles #2 • Maximum Applicable Forces (Compressive Load Limit, Tensile Load Limit) :- The mechanical strength values of PZT ceramic material (given in the literature) are often confused with the practical long-term load capacity of a piezo actuator. PZT ceramic material can withstand pressures up to 250 MPa (250 x 106 N/m2) without breaking Diagram from: http://www.physikinstrumente.com/en/products/prdetail.php?sortnr=400600.40 03/06/09 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

12. Slide-12 Principles #3 Diagram from: http://www.physikinstrumente.com/en/products/primages.php?sortnr=400600.60&picview=3#gallery Every time the piezo drive voltage changes, the piezo element changes its dimensions. Due to the inertia of the piezo actuator mass (plus any additional load), a rapid move will generate a force acting on (pushing or pulling) the piezo. 03/06/09 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

13. Slide-13 Control of Piezo Actuators Position Servo-Control Position servo-control eliminates nonlinear behavior of piezoceramics such as hysteresis and creep and is the key to highly repeatable nanometric motion. Diagram from: Fiber Optic Sensor Workbook, Eric Udd Courtesy: Andrew Moss optic fiber sensors 03/06/09 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

14. Slide-14 Controls= #2 Position servo-controlled piezo drives offer linearity and repeatability many times better than that of open-loop systems. The resolution (minimum incremental motion) of piezo actuators is actually better for open-loop than for closed-loop systems. Diagram from: http://www.physikinstrumente.com/en/products/primages.php?sortnr=400600.95&picview=3#gallery 03/06/09 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

15. Slide-15 Controls #3 Diagram from: http://www.physikinstrumente.com/en/products/prdetail.php?sortnr=400600.95 In open-loop, there is no sensor or servo-electronics to put additional noise on the control signal. In a servo-controlled piezo system, the sensor and control electronics are thus of considerable importance. With appropriate, high-quality systems, subnanometer resolution is also possible in closed-loop mode. Capacitive sensors attain the highest resolution, linearity and stability. 03/06/09 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

16. Slide-16 Major Specifications • Accuracy • Designed measurement parameters • Dynamic range • External sensors required (if any)‏ • Operating wavelengths • Response time 03/06/09 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

17. Slide-17 Limitations • Generally have to be tuned to a specific wavelength to function properly. • This can be used to limit noise susceptibility but limits the general application of any given actuator. 03/06/09 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

18. Slide-18 Advantages The advantages of position servo-control are: * High linearity, stability, repeatability and accuracy * Automatic compensation for varying loads or forces * Virtually infinite stiffness (within load limits)‏ * Elimination of hysteresis and creep effects 03/06/09 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

19. Slide-19 Comparison b/w PMN and PZT • The quadratic relationship between drive voltage and displacement means that PMN actuator are intrinsically nonlinear, in contrast to PZT actuators. PMN actuators have an electrical capacitance several times as high as piezo actuators and hence require higher drive currents for dynamic applications. 03/06/09 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

20. Slide-20 Other Considerations • Generally Optical fiber sensors are found at most major suppliers of electronic sensors. • They are classified specifically by the parameter they are designed to sense and not as Optical fi 03/06/09 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators