ECE5320 Mechatronics Assignment#01: Literature Survey on Sensors and Actuators Topic: Servo Pneumatic ActuatorOutlineBrief/OriginsAdvantagesAdvantages (Contd.)DisadvantagesElements of a pneumatic servo actuator system:The components of a pneumatic actuation system are:Pneumatic CompressorsSingle ActionDouble ActionHow It Works?!Major Operating SpecificationsOther SpecificationsLimitationsHow to Choose?Overcoming control problems associated with pneumatics:Slide 18Computer control of pneumatic actuators:Some commercially available actuator systems:Application Areas:Sample ImagesFutureReference ListECE5320 MechatronicsAssignment#01: Literature Survey on Sensors and Actuators Assignment#01: Literature Survey on Sensors and Actuators Topic: Servo Pneumatic ActuatorPrepared by:VIJAY C. [email protected]/06/200901/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-2Outline –Brief/Origin–Advantages and Disadvantages–Elements of a Servo Pneumatic system–Pneumatic Compressors–How it works?–Major specifications–How to choose?–Limitations–Overcoming problems with Pneumatics–Computer control–Reference List01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-3Brief/Origins•The term ‘pneumatic’ originates from the Greek word ‘pneumos’, namely to breathe.•Conventional pneumatic actuation is a long established means of providing power in industrial processes.•A variant on the conventional cylinder actuator was developed to provide a positioning capability based the input of a pressure signal.01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-4Advantages•Systems are simple and easily maintained.•The components are relatively low in cost.•Widely sourced.•Control is easily achieved in conventional forms.•Generally safe in operation.•Self cooling properties.•Clean in nature.01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-5Advantages (Contd.)•Good power density. •Compliant due to the compressibility of air.•Actuators can stall over prolonged periods with no adverse effects.•Relatively temperature insensitive. •Fast acting with high accelerations / deceleration’s.•Servo technology can be coupled with low cost computing to exploit the capabilities of advanced control techniques to overcome severe control issues normally associated with regular pneumatic actuation.01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-6Disadvantages•Compressed air is an expensive and inefficient power source due to the compression process and distribution losses.•Losses through leakage are likely.•Can be potentially dangerous when operated at elevated pressures.• Water vapor can accrue. •Compressibility is inherent.01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-7Elements of a pneumatic servo actuator system:01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-8The components of a pneumatic actuation system are:•The compressed air generation system, consisting of the compressor, the cooler, possibly a dryer.•The storage tank, the intake and output filters.•The compressed air treatment unit, usually consisting of the FRL assembly (filter, pressure regulator, and possibly a lubrifier), which permits filtration and local regulation of the supply pressure to the actuator valve.•The valve, that is, the regulator of the pneumatic power.•The actuator, which converts the pneumatic power into mechanical power.•The piping.•Sensors and transducers.•User Interface.01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-9Pneumatic Compressors•Single Action.•Double Action.01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-10Single Action•Pneumatic porting only in one direction•Usually have a return spring to return the system to the stable position01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-11Double Action•The two sides of the piston are pressurized •This enables two-way motion•The forces can be different in opposing directions if desired01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-12How It Works?!•Pressure can be placed on one side of a piston which causes it to extend •It can be detracted using an opposing force or a spring when the original force is removed01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-13Major Operating Specifications•Cylinder stroke – “distance between fully extended and fully retracted rod positions”•Operating pressure range – “specifies the full-required range of operating pressure”•Globalspec.com01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-14Other Specifications•Bore size•Mounting options•Connectors or port size•Body material•Features01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-15Limitations•Length of rod stroke is limited•Wide range of pressures•Operating temperature01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-16How to Choose?•Cylinder style•Bore size and length•Material / robustness•Cost•Pressure ratings•Application01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-17Overcoming control problems associated with pneumatics:•Pneumatic servo actuators operating at the relatively low pressures pertinent to industrial usage are characterized by highly non-linear system behavior due to factors such as the compressibility of air, low inherent damping, time lags, dead zone, position dependent stiffness, time-dependent frictional effects in the actuator and non-linear control components with discontinuities, which leads to undesirable operational characteristics such as instability, inconsistent transient response, large static positioning errors and limit cycling.01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-18•The stability of pneumatic actuators can be improved with the use of either pressure feedback or ‘minor loop’ compensation in the form of velocity and acceleration feedback.•The transient response can be enhanced with ‘gain scheduling’ techniques implemented in the form of look-up tables. •The static
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