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Prepared by: Brad Neumann Dept. of Electrical and Computer Engineering Utah State University

ECE5320 Mechatronics Assignment #1: Literature Survey on Sensors and Actuators Topic: Servo Hydraulic Actuator. Prepared by: Brad Neumann Dept. of Electrical and Computer Engineering Utah State University E: b.neumann@aggiemail.usu.edu; T: ( 435) 890-0038; F: (435)797-3054 (ECE Dept.).

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Prepared by: Brad Neumann Dept. of Electrical and Computer Engineering Utah State University

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  1. ECE5320 MechatronicsAssignment #1: Literature Survey on Sensors and Actuators Topic: Servo Hydraulic Actuator Prepared by: Brad Neumann Dept. of Electrical and Computer Engineering Utah State University E: b.neumann@aggiemail.usu.edu; T: (435) 890-0038; F: (435)797-3054 (ECE Dept.) 3/7/2008

  2. Outline • Reference list • To explore further • Major applications • Major components • Basic working principle illustrated • A typical sample configuration in application • Components in greater detail • Major specifications • Limitations • And many more relevant issues in applications (such as, how to choose, cost information, where to buy etc.) ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  3. Reference list • Fig. 1 from “Concrete Solutions” http://www.isa.org/InTechTemplate.cfm?Section=Article_Index1&template=/ContentManagement/ContentDisplay.cfm&ContentID=65607 • “Hydraulic Controllers” by Raymond G. Reip in Process/Industrial Instruments and Controls Handbook: Pg. 3.57-3.70 http://www.accessengineeringlibrary.com/mghpdf/0071449191_ar003.pdf • “Design and Control of a High Performance SCARA Type Robotic Arm with Rotary Hydraulic Actuators” http://ieeexplore.ieee.org.dist.lib.usu.edu/stamp/stamp.jsp?tp=&arnumber=5090244 • “Process/Industrial Instruments and Controls Handbook,” Fifth EditionAuthor: Gregory K. McMillan http://www.accessengineeringlibrary.com/mghpdf/0071449191_ar003.pdf • “Electro Hydraulics Goes Wet ‘n’ Wild” by Dennis Ritolahttp://hydraulicspneumatics.com/200/IndZone/Entertainment/Article/False/84552/IndZone-Entertainment • E ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  4. Reference List Continued • “Hydraulics Powers Great Wheel of Beijing” Bosch Rexroth Group http://hydraulicspneumatics.com/200/IndZone/Entertainment/Article/False/81645/IndZone-Entertainment • “Rotary Actuator Designs” http://www.hydraulicspneumatics.com/200/FPE/MotorsActuators/Article/True/6426/MotorsActuators • Picture of excavator http://advancedcsi.com/main/images/Design/580%20loader%20backhoe%20(boom%20hydraulics).jpg • “How Hydraulic Machines Work” by Marshall Brian http://science.howstuffworks.com/hydraulic4.htm ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  5. To explore further (Survival pointers of web references etc) • http://science.howstuffworks.com/hydraulic4.htm • “Hydraulic Controllers” by Raymond G. Reip in Process/Industrial Instruments and Controls Handbook: Pg. 3.57-3.70 http://www.accessengineeringlibrary.com/mghpdf/0071449191_ar003.pdf • www.hydraulicspneumatics.com ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  6. Major Applications • Hydraulic control is a suitable method of actuation when handling large loads with a need for high precision. Hydraulics are forgiving when the possibility for overload is high as well. • There are many instances where hydraulic systems were more favorable as opposed to electric motors. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  7. Applications • Examples include: • A backhoe or excavator • Robotic arm in an assembly line • Apparatus used to pour concrete into molds • The largest ferris wheel in the world • Mining machinery • A prototype waterslide simulator ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  8. Major Components of the System • Hydraulic Actuator • Control Valve • Hydraulic Power Unit (HPU) or pump • Position Sensor • Various Pressure Sensors • Controller (Usually a PID) • Reservoir • Acculmulator • Connecting Fluid Lines/Tubing ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  9. A Typical Hydraulic System Fig. 1 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  10. Basic Working Principles • The pump supplies pressure to the supply port of the control valve • The valve controls whether the actuator extends or retracts • Sensors provide feedback for the movement • Fluid exits the decreasing chamber and returns to the reservoir • The accumulator ensures smooth operation by averaging out the pressure changes ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  11. Two Types of Hydraulic Actuation • Piston • Most commonly seen in industry • Relatively easier to model • Because of it’s wide use there is a large selection to buy from • Rotory Vane • Simplest form of hydraulic rotary actuation • Allows for direct drive in robotic arms • 5 to 20 times more efficient than similar electric motors in regards to power to weight ratios ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  12. Two Kinds of Rotary Vane Actuators • Single Vane Rotary • Uses one vane with a partition that separates it into two chambers. Varying the pressure in either causes the movement. • Rotation can be up to 280 degrees • Double Vane Rotary • Uses two partitions limiting rotation to 100 degrees • Has twice the torque capability as the single vane for the same space ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  13. Double Vane Rotary Actuator • Diametrically opposite chamber are of the same pressure. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  14. Linear/Piston Actuation • Hydraulic cylinders come in many shapes and sizes for all sorts of applications. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  15. Typical Sensors Used • Pressure sensors • Flow Sensors • Linear Displacement Transducer • Hall Effect Sensor on the external casing • In-cylinder transducer • Optical Encoder for rotary actuator ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  16. Valves There are a couple different ways to drive the spool valve: • Direct Drive valve • Uses proportional solenoids or linear force motors to drive the position of the main spool • Can be used in manual operations or controlled feedback systems • Can handle frequencies between 2 and 10 Hz • Servo valve • Flapper valve and Jet pipe valve ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  17. The Spool Valve • Found in most hydraulic actuating systems. • As the spool (center) slides left or right, input flow, Ps, can be channeled to the desired side of the piston. Example: When spool moves to let flow into A, pressure in B is allowed to release and flow back to the pump through the other valve on the spool ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  18. Large Hydraulic Machines • A classic example of a hydraulic machine, an excavator, uses more than 4 hydraulic actuators. • All connected to a central control valve block that receives electrical signals from the operator ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  19. Flapper Valves • Flapper valves use a pivoting mechanism to change the pressure between inputs to the drive cylinder by pressing against a nozzle or moving away. This allows fluid to flow back to the reserve, causing a drop in pressure on that side. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  20. Jet Pipe Valves • Uses a jet of hydraulic fluid that can be vectored into either input to the hydraulic cylinder while the other flows back to the reserve. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  21. Two-Stage valves • For applications that require operating at high pressures or high flow rates a combination of valves if very efficient. • In most instance the second stage valve is a spool valve and is coupled with either another spool, a jet pipe or a flapper valve as the first stage. • Complex servo valves can usually handle frequencies between 10 and 300 Hz ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  22. Pumps • Two common types of pumps used in a hydraulic actuating system are vane pumps and gear pumps. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  23. Major Specifications • Work cylinder/rod diameter and chamber length • Valve inlet and outlet diameters • Hydraulic fluid type (Usually oil) • Pump rated flow rate and pressure (Determines the speed at which the piston can extend and the force it can exert) • Horsepower required to maintain that pressure/flow rate • Required operable bandwidth ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  24. Cost • The cost of a hydraulic system or actuator relies heavily on the application • There are many different online companies that offer a wide variety of actuators for every application. Prices can be obtained for a specific actuator with defined parameters • The bigger the force/power requirements of the system, the more expensive the actuator will be ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  25. Limitations • Hydraulic systems require clean working conditions. Filters are required to keep the maximum size of contaminants to 3 microns for servo valve systems and 40 microns as a general rule for most industrial applications • System is subject to leakage • Proportional valve controllers using solenoids can be unstable in the event there is a power outage ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

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