EP1595079A1 - Accurate fluid operated cylinder positioning system - Google Patents
Accurate fluid operated cylinder positioning systemInfo
- Publication number
- EP1595079A1 EP1595079A1 EP04704847A EP04704847A EP1595079A1 EP 1595079 A1 EP1595079 A1 EP 1595079A1 EP 04704847 A EP04704847 A EP 04704847A EP 04704847 A EP04704847 A EP 04704847A EP 1595079 A1 EP1595079 A1 EP 1595079A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- piston
- housing
- fluid
- position sensor
- chamber
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
- F15B11/006—Hydraulic "Wheatstone bridge" circuits, i.e. with four nodes, P-A-T-B, and on-off or proportional valves in each link
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
- F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
- F15B11/04—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed
- F15B11/046—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed depending on the position of the working member
- F15B11/048—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed depending on the position of the working member with deceleration control
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B9/00—Servomotors with follow-up action, e.g. obtained by feed-back control, i.e. in which the position of the actuated member conforms with that of the controlling member
- F15B9/02—Servomotors with follow-up action, e.g. obtained by feed-back control, i.e. in which the position of the actuated member conforms with that of the controlling member with servomotors of the reciprocatable or oscillatable type
- F15B9/08—Servomotors with follow-up action, e.g. obtained by feed-back control, i.e. in which the position of the actuated member conforms with that of the controlling member with servomotors of the reciprocatable or oscillatable type controlled by valves affecting the fluid feed or the fluid outlet of the servomotor
- F15B9/09—Servomotors with follow-up action, e.g. obtained by feed-back control, i.e. in which the position of the actuated member conforms with that of the controlling member with servomotors of the reciprocatable or oscillatable type controlled by valves affecting the fluid feed or the fluid outlet of the servomotor with electrical control means
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/43—Programme-control systems fluidic
- G05B19/44—Programme-control systems fluidic pneumatic
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/30—Directional control
- F15B2211/305—Directional control characterised by the type of valves
- F15B2211/3056—Assemblies of multiple valves
- F15B2211/30565—Assemblies of multiple valves having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve
- F15B2211/30575—Assemblies of multiple valves having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve in a Wheatstone Bridge arrangement (also half bridges)
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/30—Directional control
- F15B2211/31—Directional control characterised by the positions of the valve element
- F15B2211/3105—Neutral or centre positions
- F15B2211/3111—Neutral or centre positions the pump port being closed in the centre position, e.g. so-called closed centre
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/30—Directional control
- F15B2211/31—Directional control characterised by the positions of the valve element
- F15B2211/3144—Directional control characterised by the positions of the valve element the positions being continuously variable, e.g. as realised by proportional valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/30—Directional control
- F15B2211/315—Directional control characterised by the connections of the valve or valves in the circuit
- F15B2211/3157—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line
- F15B2211/31576—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line having a single pressure source and a single output member
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/30—Directional control
- F15B2211/32—Directional control characterised by the type of actuation
- F15B2211/327—Directional control characterised by the type of actuation electrically or electronically
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/60—Circuit components or control therefor
- F15B2211/63—Electronic controllers
- F15B2211/6303—Electronic controllers using input signals
- F15B2211/6306—Electronic controllers using input signals representing a pressure
- F15B2211/6309—Electronic controllers using input signals representing a pressure the pressure being a pressure source supply pressure
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/60—Circuit components or control therefor
- F15B2211/63—Electronic controllers
- F15B2211/6303—Electronic controllers using input signals
- F15B2211/6306—Electronic controllers using input signals representing a pressure
- F15B2211/6313—Electronic controllers using input signals representing a pressure the pressure being a load pressure
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/60—Circuit components or control therefor
- F15B2211/63—Electronic controllers
- F15B2211/6303—Electronic controllers using input signals
- F15B2211/6336—Electronic controllers using input signals representing a state of the output member, e.g. position, speed or acceleration
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
- F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
- F15B2211/7051—Linear output members
- F15B2211/7053—Double-acting output members
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
- F15B2211/765—Control of position or angle of the output member
- F15B2211/7656—Control of position or angle of the output member with continuous position control
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B2219/00—Program-control systems
- G05B2219/30—Nc systems
- G05B2219/41—Servomotor, servo controller till figures
- G05B2219/41304—Pneumatic
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B2219/00—Program-control systems
- G05B2219/30—Nc systems
- G05B2219/41—Servomotor, servo controller till figures
- G05B2219/41309—Hydraulic or pneumatic drive
Definitions
- the present invention relates to an accurate positioning system for a fluid operated cylinder having at least one expandible chamber defined by a housing and a movable piston.
- Sales of cylinder positioning systems have generally fallen into one of two categories, simple and complex.
- a simple system is inexpensive, and typically uses timing or limit switches to achieve control. Although this type of system has significant cost advantages, it has some performance disadvantages.
- Limit switch systems lack the ability to dynamically change the point or points at which the cylinder stops, and timing controlled systems require constant pressure, load, and wear.
- Complex systems are more tolerant of pressure, load, and wear changes but have disadvantages in cost and complexity. Complex systems can cost between 10 and 20 times more than the simple system. The complex systems typically use fragile or expensive sensor technology, and require a trained, experienced person for installation.
- the present invention discloses an accurate and inexpensive fluid operated cylinder positioning system and method. Positioning a cylinder or valve mainstage based on differential pressure according to the present invention can be a viable method of control that is more cost effective and completely different from current offerings by industry leaders.
- the present invention uses standard, inexpensive components and techniques to achieve control with accuracy approaching that of an expensive system, but with a cost comparable to a simple system.
- a position control system is used for controlling a fluid operated cylinder having at least one fluid chamber defined by a piston located within a housing for movement between first and second end limits of travel.
- the system includes at least two electrically actuated proportional flow valves connected to each port of the fluid operated cylinder to be controlled for selectively and proportionally controlling fluid flow into and out of the at least one fluid chamber of the fluid operated cylinder to be controlled.
- At least one pressure sensor is provided for measuring fluid pressure with respect to each chamber of the fluid operated cylinder to be controlled.
- At least one discreet position sensor is located adjacent a midpoint of the fluid operated cylinder to be controlled for sensing a discreet centered position of the piston within the cylinder.
- a control program according to the present invention is operably connected to the at least two valves, the at least one pressure sensor, and the at least one position sensor for controlling actuation of the at least two valves in response to pressure measured by the at least one pressure sensor and location measured by the at least one position sensor.
- Figure 1 is a simplified schematic diagram of a multiple valve configuration for controlling fluid flow with respect to at least one expandible chamber of a fluid operated cylinder in accordance with a control program stored in memory; and [0009] Figure 2 is a simplified schematic view of a flow diagram for the control program according to the present invention.
- the present invention implements a pneumatic cylinder control scheme with a cost comparable to a simple system, but with performance approaching that of a complex system.
- the control scheme according to the present invention is a combination of hardware and software.
- the hardware is supportive of the required functions.
- actual operation is determined by the software.
- the software is constructed in such a fashion that variables determine the actual final operation.
- This approach allows for example, a variety of motion profiles, i.e. control of acceleration/deceleration profiles, velocity, timing, force, repetition, etc.
- this control scheme allows operation of either dual acting cylinders or single acting cylinders.
- the present invention can operate cylinders with fluid control on both sides, or cylinders with fluid on one side and a mechanism such as a spring to cause return on the other side.
- the control scheme according to the present invention described also applies to other fluids such as hydraulics or other liquids.
- the cylinder can be replaced by a main stage valve. These are typically very large valves.
- the control scheme acts as a proportional pilot for the mainstage, allowing proportional positioning of the mainstage valve.
- the valve industry has used complex methods such as torque motors or proportional valves with precision fee back for controlling such mainstage valves.
- valve positioner control The device used for this application is referred to as a valve positioner control.
- the control scheme described herein according to the present invention can therefore be used to replace the existing positioner control.
- the mainstage valve can be operated with various fluids and can operate as a dual acting or as a single acting mainstage positioner.
- a method of controlling a standard pneumatic cylinder can be developed with reasonable accuracy by monitoring and changing the pressure on one or both sides of the piston.
- the basic theory behind this type of cylinder control is that if a known volume, i.e. a cylinder chamber, has a given amount of air pressure within that known volume, it will exert a known force on the chamber. This is demonstrated by the basic formula:
- F, P, and A represent Force, Pressure, and Area, respectively.
- D is the inner diameter of the cylinder and A-, is the area of the cap-end of the cylinder. [0018] The area for the load end of the piston is simply the equation above minus the area of the rod:
- V C A.-L C (7)
- L c is the length from the inside end of the cap end to the surface of the piston.
- L j is the length from the inside end of the cap end to the surface of the piston. Therefore, the volume of air in the cap end of the cylinder is:
- implementation of the control method according to the present invention can be performed with a multi-valve configuration, such as a four-valve pack, coupled with two pressure transducers; i.e. one transducer for each port of the fluid operated cylinder.
- the transducers can be off-the-shelf parts, which are commercially available from vendors such as DigiKey.
- OpAmps can be used for signal conditioning in a standard circuit configuration, and feed into analog inputs of the valve pack.
- a position control system 10 according to the present invention is illustrated in Figure 1 for controlling a fluid operated cylinder 12 having at least one fluid chamber 14, 16 defined by a piston 18 located within a housing 20 for movement between first and second end limits of travel 22, 24.
- the system 10 can include at least two electrically actuated proportional flow valves 26, 28, 30, 32 connected to each port 34, 36 of the fluid operated cylinder 12 to be controlled.
- the valves 26, 28, 30, 32 selectively and proportionally control fluid flow into and out of the at least one fluid chamber 14, 16 of the fluid operated cylinder 12 to be controlled.
- At least one pressure sensor 38, 40 is provided for measuring fluid pressure with respect to each chamber 14, 16 of the fluid operated cylinder 12 to be controlled.
- At least one discreet position sensor 42 is located adjacent a midpoint of the fluid operated cylinder 12 to be controlled for sensing a discreet centered position of the piston 18 within the housing 20.
- a central processing unit 44 includes a control program and is operably connected to the at least two valves 26, 28, 30, 32, the at least one pressure sensor 38, 40, and the at least one position sensor 42 for controlling actuation of the at least two valves 26, 28, 30, 32 in response to pressure measured by the at least one pressure sensor, 38, 40 and location measured by the at least one position sensor 42.
- the at least one discreet position sensor 42 can include a first position sensor 42 located adjacent a midpoint of the fluid operated cylinder, and a second position sensor 46 or 48 located adjacent one end of travel of the piston 18 in the housing 20 for providing soft stop deceleration of the piston 18 prior to contact with an end wall of the housing 20 defining the at least one chamber 14, 16.
- the at least one chamber 14, 16 can include a first expandable fluid chamber 14 adjacent one end of travel of the piston 18 in the housing 20 and a second expandable fluid chamber 16 adjacent another end of travel of the piston 18 in the housing 20.
- the at least two electrically actuated proportional flow valves 26, 28, 30, 32 can include a first valve 26 associated with the first expandable fluid chamber 14 for selectively and proportionally controlling fluid flow into the first expandable fluid chamber 14 and a second valve 28 associated with the first expandable fluid chamber 14 for selectively and proportionally controlling fluid flow out of the first expandable fluid chamber 14.
- the at least one pressure sensor 38, 40 can include a first pressure sensor 38 associated with the first expandable fluid chamber 14 and a second pressure sensor 40 associated with the second expandable fluid chamber 16.
- a third pressure sensor 50 can be provided for monitoring the pressure of the pressurized fluid source.
- the at least one discreet position sensor 42 can include a first position sensor 42 located adjacent a midpoint of the fluid operated cylinder 12, a second position sensor 46 located adjacent one end of travel of the piston 18 in the housing 20 for providing soft stop deceleration of the piston 18 prior to contact with an end wall of the housing 20 defining the first chamber 14, and a third position sensor 48 located adjacent an opposite end of travel of the piston 18 in the housing 20 for providing soft stop deceleration of the piston prior to contact with an end wall of the housing 20 defining the second fluid chamber 16.
- the control program according to the present invention can initialize a home position corresponding to the centered position of the piston 18 within the housing 20, when the piston 18 is sensed by the at least one discreet position sensor 42 located adjacent the midway position with respect to the housing 20.
- the control program according to the present invention can also calculate a value corresponding to an amount of pressure required in the at least one expandable fluid chamber 14, 16 for moving the piston 18 a desired distance within in the housing 20 from the discreet centered position located midway with respect to the housing 20.
- the control program can control the at least two electrically actuated proportional flow control valves 26, 28, and/or 30, 32 to obtain the calculated pressure within the at least one expandable fluid chamber 14, 16 corresponding to the desired distance of movement for the piston 18 within the housing 20.
- biasing means can include any suitable mechanical device, by way of example and not limitation, a return spring force. If two expandable fluid chambers 14, 16 are provided to be controlled by the system 10 according to the present invention, the biasing means corresponds to the second expandable fluid chamber. It should be recognized that the pressure calculations described in greater detail above can be modified to correspond to pressure acting against a mechanical spring force when determining the appropriate amount of pressure to provide in a single expandable fluid chamber, and that modifications to the pressure calculations could also be made to accommodate a dual piston rod configuration rather than the single rod piston configuration described in detail here.
- the cylinder 12 preferably has two active expandable fluid chambers 14,
- Two proportional control valves 26, 28 or 30, 32 are connected to each chamber 14, 16. One valve removes fluid, by way of example and not limitation, a fluid such as compressed air or hydraulic fluid, from the connected chamber, while the other valve supplies pressurized fluid to the connected chamber.
- the system includes control electronics 44, and preferably three pressure transducers, 40, 42, 48. The control electronics 44, along with the onboard software, control the four proportional control valves 26, 28, 30, 32 in response to commands from an external source, by way of example and not limitation, such as commands from a network or computer workstation.
- the pressure transducers 38, 40, 50 monitor the pressure of the pressurized fluid supply, and both expandable fluid chambers 14, 16 in an effort to control the dispensing of pressurized fluid to and from the expandable chambers 14, 16 to provide accurate positioning control of the piston 18 and connected rod output force.
- the proportional control valves 26, 28, 30, 32 can be piezo-electric actuated control valves of a type similar to those described in U.S. Pat. No. 6,548,938 issued on April 15, 2003, or a piezo-electric actuator of the type similar to that disclosed in U.S. Design Pat. No. D483,335 issued on December 9, 2003, or PCT Published Application No. WO 04/006,349 published on July 3, 2003, or PCT Published Application No.
- the piezo-electric actuator is controlled for proportional valve operation by direct control of the voltage applied to the piezo, or by monitoring the amount of energy in the piezo-electric actuator and using a current charge control, which is different than pulse width modulation as used for proportional control of solenoid operated valves.
- the control program can begin by initializing the system in step 100.
- the control program locates a home or piston-centered position as indicated by a hall-effect sensor, and brings pressure on both sides of the piston 18 to be equal to one another so that there is no movement of the piston 18 within the housing.
- the control system can bring the pressure on both sides of the cylinder to 50 psi while at the centered position which can be verified by the signals received from the at least one position sensor 42 and the at least one pressure sensor 38, 40.
- step 100 the control program continues to query 102 to determine if a change in position is desired. If a change in position is not desired, the control program returns to the beginning of query 102. If a change in position is desired, the control program continues to step 104 where the necessary pressure is calculated based on the desired movement. The control program then continues to query 106 where it is determined if the desired position is toward the cap end of the cylinder 12. If the desired position is toward the cap end, the program branches to step 108 where pressure is raised in the load end expandable fluid chamber of the cylinder 20. If the desired position is not toward the cap end in response to query 106, the control program branches to step 110 where pressure is raised in the cap end expandable fluid chamber of the cylinder 20.
- step 108 or step 110 the program continues to query 112 where it is determined if the pressures on either side of the piston 18 are equal. If the pressures are not equal, the program branches to step 114 to monitor the at least one position sensor 42 and to reset the home centered position of the piston 18. After performing step 114, the control program returns to the beginning of query 112. If the pressures are equal in query 112, the control program continues to query 116 where it is determined if the desired position is toward the load end of the cylinder 20. If the desired position is toward the load end in response to query 116, the control program continues to step 118 where pressure is lowered in the load end expandable fluid chamber of the cylinder 20. If the desired position is not toward the load end in response to query 116, the control program continues to step 120 where the pressure is lowered in the cap end expandable fluid chamber of the cylinder 20.
- step 118 or step 120 the program continues to query 122, where it is determined if the pressures on both sides of the piston 18 are equal. If the pressures on both sides of the piston 20 are not equal in response to query 122, the control program branches to step 124 to monitor the at least one position sensor 42 and to reset the home centered position of the piston 18 in the housing 20. After performing step 124, the control program returns to the beginning of query 122 to determine if the pressures on both sides of the piston 18 are equal. If the pressures on both sides of the piston 18 are equal in response to query 122, the control program continues to step 126 indicating that the piston 18 is done moving, since the piston has reached the desired position, and the current position is saved by the control program. After performing step 126, the control program returns to the beginning of query 102.
- control program described in Figure 2 corresponds to a cylinder 12 having first and second expandable fluid chambers 14, 16 defined by a piston 18 located within a housing 20 for movement between first and second end limits of travel. If only a single expandable fluid chamber is provided, the control program illustrated in Figure 2 can be modified by eliminating query 116, steps 118, 120, query 122 and step 124. In this configuration, if the answer to query 112 is yes, the control program can continue directly to step 126 and continue as previously described. As previously described in greater detail above, this configuration can include mechanical means for biasing the piston 18 toward the home centered position with respect to the housing 20, by way of example and not limitation, such as a mechanical spring force.
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Automation & Control Theory (AREA)
- Fluid-Pressure Circuits (AREA)
- Actuator (AREA)
- Servomotors (AREA)
Abstract
Description
Claims
Applications Claiming Priority (7)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US44219103P | 2003-01-24 | 2003-01-24 | |
US442191P | 2003-01-24 | ||
US46054903P | 2003-04-04 | 2003-04-04 | |
US460549P | 2003-04-04 | ||
US47103103P | 2003-05-16 | 2003-05-16 | |
US471031P | 2003-05-16 | ||
PCT/US2004/001853 WO2004065798A1 (en) | 2003-01-24 | 2004-01-23 | Accurate fluid operated cylinder positioning system |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1595079A1 true EP1595079A1 (en) | 2005-11-16 |
Family
ID=32777022
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP04704847A Withdrawn EP1595079A1 (en) | 2003-01-24 | 2004-01-23 | Accurate fluid operated cylinder positioning system |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP1595079A1 (en) |
JP (1) | JP4690309B2 (en) |
CA (1) | CA2513707C (en) |
WO (1) | WO2004065798A1 (en) |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN100462883C (en) * | 2006-02-23 | 2009-02-18 | 上海交通大学 | Mesa ball X-Y trace pneumatic controller |
US9128008B2 (en) | 2012-04-20 | 2015-09-08 | Kent Tabor | Actuator predictive system |
DE102016206822A1 (en) | 2016-04-21 | 2017-10-26 | Festo Ag & Co. Kg | Method for supplying compressed air to a compressed air consumer, valve device and data carrier with a computer program |
CA3024749A1 (en) | 2016-05-20 | 2017-11-23 | Nasarc Technologies Inc. | Motion control method and system for servicing of welding torch |
CN110914554B (en) * | 2017-02-15 | 2022-07-19 | 株式会社尼康 | Dual valve fluid actuator assembly |
JP6962944B2 (en) * | 2019-01-08 | 2021-11-05 | Ckd株式会社 | Fluid pressure actuator movement amount detection device |
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JPS4925362A (en) * | 1972-06-30 | 1974-03-06 | ||
US4628499A (en) * | 1984-06-01 | 1986-12-09 | Scientific-Atlanta, Inc. | Linear servoactuator with integrated transformer position sensor |
JPS63176801A (en) * | 1987-01-13 | 1988-07-21 | Kashio Denki Kk | Control method for positioning of air cylinder |
DE3708989C2 (en) * | 1987-03-19 | 1993-10-14 | Festo Kg | Control device for a piston displaceable in a double-acting cylinder |
JPH0442561Y2 (en) * | 1987-05-26 | 1992-10-08 | ||
JPH02229902A (en) * | 1989-03-01 | 1990-09-12 | Matsushita Electric Ind Co Ltd | Pneumatic driving unit |
JPH044301A (en) * | 1990-04-18 | 1992-01-08 | Matsushita Electric Ind Co Ltd | Air pressure driving device |
US5424941A (en) * | 1991-08-02 | 1995-06-13 | Mosier Industries, Inc. | Apparatus and method for positioning a pneumatic actuator |
JP2884545B2 (en) * | 1992-11-25 | 1999-04-19 | キヤノン株式会社 | Control method of cylinder device |
JPH07317701A (en) * | 1994-05-24 | 1995-12-08 | Sugimoto Seiki Kk | Electromagnetic controller for cylinder and its controlling method |
DE19801338C1 (en) * | 1998-01-16 | 1999-06-02 | Festo Ag & Co | Damped piston positioning device with electronic regulator |
US6289259B1 (en) * | 1998-10-16 | 2001-09-11 | Husky Injection Molding Systems Ltd. | Intelligent hydraulic manifold used in an injection molding machine |
DE10122297C1 (en) * | 2001-05-08 | 2002-06-27 | Festo Ag & Co | Hydraulic circuit and control system for moving piston and locking it in position has proximity switches measuring cylinder position and sending signals to control circuit |
-
2004
- 2004-01-23 WO PCT/US2004/001853 patent/WO2004065798A1/en active Application Filing
- 2004-01-23 CA CA2513707A patent/CA2513707C/en not_active Expired - Fee Related
- 2004-01-23 JP JP2006501113A patent/JP4690309B2/en not_active Expired - Fee Related
- 2004-01-23 EP EP04704847A patent/EP1595079A1/en not_active Withdrawn
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See references of WO2004065798A1 * |
Also Published As
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JP2006515409A (en) | 2006-05-25 |
CA2513707C (en) | 2011-10-11 |
WO2004065798A1 (en) | 2004-08-05 |
JP4690309B2 (en) | 2011-06-01 |
WO2004065798A8 (en) | 2004-11-11 |
CA2513707A1 (en) | 2004-08-05 |
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