Assignment#01: Literature Survey on Sensors and Actuators ECE5320 Mechatronics Assignment#01: Literature Survey on Sensors and Actuators Topic: Pneumatic Actuator Prepared by: Anthony Meeks Dept. of Electrical and Computer Engineering Utah State University E: ; T: (435)797-; F: (435) (ECE Dept.) W: 3/11/2010

5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-2 Outline –Reference list –To probe further –Major applications –Basic working principle illustrated –Types of linear actuators –Types of rotary actuators –Control Valves –A typical sample configuration in application –Major specifications –Limitations and comparison –How to choose

5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-3 Reference list Andrew Parr: Hydraulics and Pneumatics A technician’s and engineer’s guide (1991) Clarence W. de Silva: Mechatronics An integrated Approach (2005)

5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-4 To probe further For more information on how pneumatic actuators work, refer to Hydraulics and Pneumatics (1991) by Andrew Parr.

5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-5 Major applications Rotary motion for air tools Pneumatic Sander in the USU Technology building Pneumatic Drill in the USU Technology building

Major applications 5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-6 Linear actuator for all types of linear motion m_detail.cfm?tree_id=113

Major applications 5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-7 Artificial Muscles

Basic working principle illustrated 5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-8 Pressurized gas pushes a piston with a rod to create linear motion Hydraulics and Pneumatics (Parr 1991) Air is compressed and stored in a tank Valves Control direction of air flow, thus controlling extension or retraction of piston

5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-9 Basic working principle illustrated Mathematical Analysis: If the system doesn’t require extreme precision, then the mathematical analysis can be really simple The force that can be delivered by a pneumatic system is only dependent on two factors, the surface area of the piston, and the pressure inside the cylinder The pressure is assumed to be constant since the gas tank is so much larger than the pneumatic system. (For most practical applications) P1 P2 Extending Retracting The pressure on the other side of the piston is assumed to be ambient since it is venting to the room. Remember to subtract the area of the rod from the area of the piston when retracting Hydraulics and Pneumatics (Parr 1991)

5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-10 Basic working principle illustrated If the system needs to be extremely accurate, and precise, particularly when speed is involved, the analysis becomes much more difficult to do because of the nonlinearities with compressible gas. Points to consider The venting gas will be a little higher than ambient, its actual value is dependent on the size of the venting port, valve constrictions The pressure in the lines will be a little lower than in the reservoir tank due to losses in valves and joints If precise movement is needed with high loads, consider using hydraulics instead of pneumatics

Types of Linear Actuators 5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-11 Double Acting Fluid Enters the extend port to extend the piston, and enters the retract port to retract the piston. Hydraulics and Pneumatics (Parr 1991)

Types of Linear Actuators 5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-12 Single Acting Fluid pressure is used to extend the piston, a spring is used to retract the piston This type of actuator is used when strong extensional forces, and light retraction forces are needed Hydraulics and Pneumatics (Parr 1991)

Types of Linear Actuators 5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-13 Telescopic Cylinder Two pistons slide in and out together This system is used when the rod is subject to bending loads. The extra piston adds rigidity to the actuator. Hydraulics and Pneumatics (Parr 1991)

Types of Linear Actuators 5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-14 Impact Cylinders Both ends of the piston are pressurized. The extensional side is then depressurized causing a pressure difference, thus accelerating the piston. This type of piston is used when an instant, high force application is needed. (metal stamping) Hydraulics and Pneumatics (Parr 1991)

Types of Linear Actuators 5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-15 Rodless Cylinders Rodless Cylinders have pistons, but no piston rod. The three most common types are: band cylinder cable cylinder magnetic cylinder em_detail.cfm?tree_id=124 cts/item_detail.cfm?tree_id=118 cts/item_detail.cfm?tree_id=113

Types of Linear Actuators 5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-16 Rodless Cylinders: Band Cylinder The slot on the top of the cylinder is sealed off everywhere except the location of the actuator. It is sealed by two flexible layers of metal that open up for the actuator as it slides. Actuator is connected straight to the piston Two flexible Metals that seal come apart in the actuator Tolomatic_s_BC2_rodless_Pneumatic_cylinder_offers _equal_piston_areas_in_both_directions_eliminating_ load_variations_while_also.jpg

5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-17 Types of Linear Actuators Rodless Cylinders: Cable Cylinder A cable is connected to both sides of the piston in the cylinder, that wrap around the cylinder to the actuator cts/item_detail.cfm?tree_id=118

5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-18 Types of Linear Actuators Rodless Cylinders: Magnetic Cylinder There is a magnet attached to the piston inside the cylinder, that is magnetically coupled to the moving actuator outside the cylinder. em_detail.cfm?tree_id=124 s/item_detail.cfm?tree_id=123

Types of Rotary Actuator 5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-19 Pressurized gas passes through a rotary device such as a vane motor to generate rotary motion Vain actuator High Pressure Low Pressure Vanes are spring loaded to adjust for different radii in rotation Hydraulics and Pneumatics (Parr 1991) Pneumatic Sander in the USU Technology building

Types of Rotary Actuator 5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-20 Gear Actuator High Pressure Low Pressure Two teeth faces with high pressure on one side, and low pressure on the other. One tooth face with high pressure on one side, and low pressure on the other. The resulting torque causes the left gear to rotate counter clockwise, the right gear to rotates clockwise as shown. Hydraulics and Pneumatics (Parr 1991)

Control Valves 5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-21 Purpose: Controls the direction of gas flow for retracting and extending the piston Compressed Air Extension Line Retraction Line Extend ModeRetract Mode Poppet Valve: Solenoid Spool Valve Hydraulics and Pneumatics (Parr 1991) /products/valves/NafSolpilot.aspx om/en/product.aspx?id=185

Types of Valves 5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-22 The Poppet valve Poppet valves operate with ball or disk seals to close a hole, and open a hole when actuated to let fluid through. These type of valves are also used for the gas inlet, and the exhaust outlet for the internal combustion engine. This illustration of a 3/2 valve has fluid flows from A to R when the button is depressed. It travels from P to A with pressed. Hydraulics and Pneumatics (Parr 1991)

Types of Valves 5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-23 Spool Valves Spool valves operate by sliding a horizontal spool left or right. In the figure to the right, Fluid flows from P to A in the left position, and P to B in the right position. Because the moving piece is cylindrical, this is ideal for a solenoid actuating valve. Hydraulics and Pneumatics (Parr 1991) eindia.com/fp/t humb/1/390/2 83.jpg

Types of Valves 5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-24 Rotary valves operate by turning a valve with channels to direct the air in the direction of the desired flow. In the figure to the right, fluid can have P-A/R-B flow, P-B/R-A flow, and an off setting. Rotary Valves Hydraulics and Pneumatics (Parr 1991)

Types of Valves 5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-25 Solenoids are used to control valves. Using an electrical current, solenoids can control how much a valve should be opened to control the fluid flow in a pneumatic and hydraulic system. Solenoid Spool Valve Electrical current in the solenoid coils will displace the spool rod to the desired position Solenoid Controller Valves om/en/product.aspx?id=185 m/images/figures/web_coil_a nd_solenoid_schematic.jpg

5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-26 The most common type of compressor used in industry for pneumatics is the piston compressor. The compressed air is stored in a tank that’s connected to a series of pipes (usually copper) that carry the compressed air to every pneumatic system in a plant/shop Tank Piston Compressor inc.com/images/airCompressor.jpg

Application 5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-27 Metal Foil Cutter at the Space Dynamics Laboratory

5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-28 Small piston cylinder grips the metal foil Magnetic rodless cylinder pulls the foil to the desired length Scissors ride a rodded cylinder to cutting position A vertical rodded cylinder actuates the cut for the scissors. Position sensors are used to control position Application Metal Foil Cutter at the Space Dynamics Laboratory Magnetic rodless cylinder Pneumatic clamp grabs the foil Sensor to detect stopping point

Specifications Pay attention to maximum pressure a cylinder is able to hold. Actuator travel distance and length of cylinder. Area of piston head. This along with the applied pressure determines the max load the actuator can move. Max load the actuator can hold. For rodded cylinders, pay attention to possible bending loads on being applied to the rod. If high, then consider a telescopic cylinder. 5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-29

Limitations Shouldn’t use in high pressure situations, use hydraulics instead. Air is compressible, which makes for tougher analysis because of the nonlinearities with compressible fluids. The flow rate is difficult to control due to the compressibility of air. 5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-30

Pneumatic vs. Hydraulic Comparison 5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-31 TopicHydraulicPneumatic Energy SourceElectric motor/Diesel Energy Storagelimited (accumulatorGood (reservoir) Distribution systemLimited (local)Good (plant wide) Energy costLowHigh Rotary actuatorsLow SpeedWide speed range Rotary actuatorsGood ControlDifficult to control Linear actuatorCylinders, High forceCylinders Medium force Controllable forceControllable high forceControllable medium force Points to noteLeakage dangerous, fire hazardNoise Better for pneumatic Better for Hydraulic Depends on Requirements

How to choose 5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-32 If linear space is limited, a rodless cylinder is the best choice. Cylinders with rods require twice the length of a rodded cylinder since it comes out of the cylinder. Rodless Cylinder’s cost more, so if space is available, should use one with a rod. Should use a telescopic cylinder if bending loads are high on the rod.

Where to buy Best place via internet to buy components of a pneumatic system is and 5/12/2015 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-33