Suspension of load controlled in actuator system

Abstract

To provide a load removal method for removing a load of a test object in a test system, an interlock load removal method of the test object, a test system for monitoring and removing the load of the test object, and a hydraulic assembly.SOLUTION: A load removal method for removing a load of a test object in a test system includes determining a load difference in at least one of a calculated load of a valve for an actuator in the test system and a calculated load of a load cell connected to the actuator. The controlled load removal of the load of the test object is initiated via a system controller when the determined load difference reaches a first level. An interlock load removal of the load of the test object is performed via the valve when the determined load difference reaches a second level higher than the first level.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority from U.S. Provisional Patent Application No. 63 / 581,465, filed September 8, 2023, entitled "CONTROLLED LOAD ABORT IN AN ACTUATOR SYSTEM," the contents of which are incorporated herein by reference in their entirety. [Background technology]

[0002] The following discussion is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.

[0003] In a test system, the test objects are very expensive and it is necessary to quickly and effectively reduce the loading on the test objects under certain conditions to prevent damage to the test objects. Summary of the Invention

[0004] This Summary and Abstract herein are provided to introduce selected concepts in a simplified form that are further described below in the Detailed Description. This Summary and Abstract are not intended to identify key features or essential features of the claimed subject matter, nor are they intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all of the shortcomings discussed in the Background.

[0005] In one aspect, a method of unloading a load on a test object in a test system includes determining a load differential between at least one of a calculated load on a valve for an actuator of the test system and a calculated load on a load cell coupled to the actuator. A controlled unloading of the load on the test object is initiated via a system controller when the determined load differential reaches a first level. An interlock unloading of the load on the test object is performed via the valve when the determined load differential reaches a second level that is higher than the first level.

[0006] In some embodiments, commands to the valves are issued via a system controller.

[0007] Determining the load difference can be performed in a number of ways and can include comparing a calculated load at the valve to a calculated load at the load cell, or determining the load difference can include determining load values ​​for the two outputs of the load cell and specifying the load difference as the difference between the load values ​​for the two outputs of the load cell, or determining the load difference can include comparing a calculated load at the valve to a commanded load at the valve, or determining the load difference can include comparing a load value output of the load cell to a commanded load at the valve. In some embodiments, determining the load difference is performed continuously during a flow mode of the test system.

[0008] In some embodiments, initiating controlled unloading via the system controller may include unloading during a flow mode of the test system to unload the load difference to a harmless load difference.

[0009] Performing interlock load removal may include isolating a valve from a hydraulic pressure source of the test system, taking pressure measurements at a piston of the actuator, determining a load differential on either side of a piston of a hydraulic actuator coupled to the valve, and using the valve to ramp the load differential to a harmless load difference.

[0010] Taking a measurement of the pressure at the piston can occur at a predetermined delay time after isolating the valve.

[0011] If desired, the ramping of the load difference can be performed over a predetermined period of time, and if desired, the ramping of the load difference can be performed linearly over a predetermined period of time.

[0012] In another aspect, a method of interlock unloading a test specimen in a test system having a valve controlling an actuator includes isolating the valve from a hydraulic source of the test system and determining a load differential on either side of a piston of a hydraulic actuator coupled to the valve. The load differential is then ramped to a harmless load differential using the valve.

[0013] In some embodiments, the method may include delaying a predetermined amount of time between isolating and determining the load difference. Optionally, the ramping of the load difference may be performed over a predetermined period of time, and, optionally, the ramping of the load difference may be performed linearly over the predetermined period of time. Determining the load difference may be performed using any of the methods described above.

[0014] In yet another aspect, a test system for monitoring and unloading a load on a test object includes a hydraulic assembly and a controller. The hydraulic assembly includes a control valve configured to control a load on a hydraulic actuator coupled to the test object, a pair of pressure transducers configured to detect and transmit pressure on the hydraulic actuator, and an isolation valve isolating the control valve from the hydraulic pressure. The controller is configured to determine a load difference in at least one of a calculated load on the valve for the actuator of the test system and a calculated load on a load cell coupled to the actuator. The controlled unloading of the load on the test object is initiated via the system controller when the determined load difference reaches a first level. An interlocked unloading of the load on the test object is performed via the valve when the determined load difference reaches a second level that is higher than the first level.

[0015] In some embodiments, in the test system, the valve can further include a controller receiving the pressure and valve firmware configured to reduce a differential load on a piston of a hydraulic actuator. The valve firmware can be configured to perform an interlock load removal of the load on the test article by isolating the valve from a hydraulic source of the test system, determining a load differential on a piston of an actuator coupled to the valve, and using the valve to ramp the load differential to a harmless load differential. Determining the load differential can be performed using any of the methods set forth above.

[0016] The valve firmware can be further configured to delay a predetermined amount of time between isolating and determining the load difference. Optionally, the valve firmware is further configured to ramp the load difference over a predetermined period of time. Further optionally, the valve firmware is configured to linearly ramp the load difference over a predetermined period of time.

[0017] In some embodiments, the test system may further include a power controller coupled between the controller and the hydraulic assembly to control power supplied to the valves and the hydraulic assembly, to receive and send signals indicative of loads on the hydraulic actuators and valves, and to receive and send commands from the controller.

[0018] In yet another aspect, a hydraulic assembly includes a proportional valve configured to control a hydraulic actuator, the proportional valve having a controller that receives a pressure indicative of a load on a test object, the proportional valve operating valve firmware configured to reduce a differential load on a piston of the hydraulic actuator.

[0019] In some embodiments, the hydraulic assembly can include a pair of pressure transducers configured to sense pressure in the hydraulic actuator and transmit the pressure to the proportional valve.

[0020] The valve firmware can be configured to perform interlock load removal of the differential load by isolating the proportional valve from the hydraulic pressure source to the hydraulic assembly, taking pressure measurements at the actuator pistons, determining a load differential at the hydraulic actuator pistons, and using the valve to ramp the load differential to a harmless load differential. Determining the load differential can be performed using any of the methods set forth above.

[0021] In some embodiments, the valve firmware is further configured to obtain a pressure measurement at the piston at a predetermined delay time after isolating the valve. Optionally, the valve firmware is further configured to ramp the load difference over a predetermined period of time. Further optionally, the valve firmware is configured to linearly ramp the load difference over a predetermined period of time.

[0022] The hydraulic assembly may include an isolation valve that isolates the proportional valve from a hydraulic power source.

[0023] This summary is not intended to describe each disclosed embodiment or every implementation of controlled load interruption as described herein. Many other novel advantages, features, and relationships will become apparent as this description proceeds. The drawings and description that follow more particularly exemplify illustrative embodiments. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 is a block diagram of a test system according to one embodiment of the present disclosure.

[0025] [Diagram 2] FIG. 1 is a block diagram of a hydraulic assembly according to one embodiment of the present disclosure.

[0026] [Diagram 3] FIG. 1 is a diagram of a test specimen according to one embodiment of the present disclosure.

[0027] [Figure 4A] FIG. 1 is a perspective view of a typical hydraulic assembly. [Figure 4B] FIG. 1 is a perspective view of a typical hydraulic assembly.

[0028] [Diagram 5] FIG. 2 is a hydraulic circuit diagram of one embodiment of the present disclosure.

[0029] [Figure 6] FIG. 2 is a flow chart diagram of a method according to one embodiment of the present disclosure.

[0030] [Figure 7] FIG. 4 is a flow chart diagram of a method according to another embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] FIG. 1 illustrates a system 100 for monitoring and unloading a load on a test object. The system 100 includes, in one embodiment, a hydraulic assembly 110 and a system controller 130. The hydraulic assembly 110 includes, in one embodiment, a control valve 112 configured to control a load on a hydraulic actuator 120 coupled to the test object. The hydraulic assembly 110 further includes a pair of pressure transducers 114 configured to detect and transmit pressure on the hydraulic actuator 120. An isolation valve 116 is provided to selectively isolate the control valve 112 from a hydraulic source 140 of hydraulic pressure. In such a case, the control valve 112 can locally unload the actuator 120 on the test object according to instructions executed by a local processor within the control valve without further instructions from the system controller 130.

[0032] The system controller 130, in one embodiment, is configured to determine a load difference between at least one of a calculated load at the control valve 112 for the hydraulic actuator 120 of the test system 100 and a calculated load at the load cell 122 coupled to the hydraulic actuator. In a first method of unloading a load at the test object by each actuator connected to the test object, the system controller 130 is further configured to initiate a controlled unloading of the load at the test object via the system controller 130 when the determined load difference reaches a first level. This controlled unloading occurs during a flow mode of the system, i.e., when the hydraulic source 140 is coupled to the system 100 and the valve operation of each control valve 112 is controlled by the system controller 130. This first level may be referred to as a stop level. If controlled load removal at the stop level does not work, the controller 130 is further configured to perform interlock load removal of the load at the test object via commands sent to each control valve 112 of each actuator 120 required to unload the load at the test object when the determined differential load reaches a second level higher than the first level, at which point valve controlled load removal, i.e., interlock load removal, is used to unload the load at the test object.

[0033] In one embodiment, the control valve 112 further includes a local valve controller 113 that receives pressure from a pressure transducer 114, and valve firmware 115 operable by the local controller 113 and configured to reduce differential loading on a piston of a hydraulic actuator 120. The unloading of an actuator by execution of firmware 115 by the local valve controller 113, which controls the operation of its associated actuator 120, is performed, in one embodiment, without further input from the system controller 130. The control valve 112 is shown in more detail in FIG.

[0034] The firmware 115, in one embodiment, is configured to perform an interlock load removal of the load on the test article. Generally, this is accomplished in one embodiment by isolating the control valve 112 from the hydraulic source 140 via operation of the isolation valve 116 (which can be initiated by the system controller 130 or, alternatively, from the local controller 113 executing the firmware 115). The local controller 113 determines the load difference on the piston 124 of the hydraulic actuator 120 coupled to the control valve 112 and operates the control valve 112 to ramp the load difference to a harmless load difference using the control valve 112. This is done solely by the control valve 112 operating the firmware 115 upon receiving an interlock load removal command issued by the system controller 130 in an interlock state.

[0035] The system controller 130, in one embodiment, is an external controller that executes software to operate the test system 100 based on test procedures in a system computer 131 that provides a user interface to a user for configuration, operation, and monitoring of testing of test objects.

[0036] The firmware 115 of the control valve 112 is designed to operate the control valve 112 independently of the system controller 130 to appropriately and safely ramp the load difference on the test object to a harmless load difference. The test object may be a very expensive piece of equipment worth millions of dollars. As used herein, a "harmless load difference" is a load difference on the test object from one or more actuators connected to the test object that a test engineer considers safe from any damage to the test object. Thus, in a "harmless load difference" state from one or more actuators, there may be some load application on the test object, but damage to the test object is unlikely. A "harmless load difference" can also be a load difference that does not result in a load application that is not typical of the test object in the test system.

[0037] In the test system 100, multiple control valves 112 can be connected to multiple hydraulic actuators 120 that apply loads to various locations or portions of the test object. In the exemplary embodiment shown in FIG. 3, a series of eight hydraulic actuators 1201, 1202, ..., 1208 are shown, each controlled by a hydraulic assembly 1101, 1102, ..., 1108. The load cell 122 of each hydraulic actuator 120 is configured to provide a load signal to the system controller 130. The pressure sensor 114 and the control valve 112 are also configured to provide a load signal to the system controller 130. Typically, one isolation valve 116 is provided for each control valve 120. The system controller 130 controls the operation of each isolation valve 116 and control valve 112 in a "flow mode" in which the test object is tested according to a desired test procedure.

[0038] The local firmware 115 of each control valve 112, in one embodiment, is further configured to delay a predetermined period of time between isolating the hydraulic assembly 110 from the hydraulic source 140 and determining the load difference. This is done to allow for the pressure to set after isolation. The local firmware 115, in one embodiment, is further configured to ramp the load difference over a predetermined period of time. The predetermined period of time can be programmed into the firmware 115 of the control valve 112, such as during setup. The ramp time can be adjusted by reprogramming the local firmware 115. The ramping of the load difference over a predetermined period of time is, in one embodiment, performed linearly over the predetermined period of time. However, this should not be considered a limitation. Rather, load removal via a linear ramp is only one embodiment in that operation of each valve 112 by the local processor 113 in accordance with the valve's local firmware 115 can perform load removal according to a non-linear ramp using measured pressure from a pressure transducer 114 measuring cylinder pressure on either side of the actuator piston. The control valve 112, in one embodiment, is a proportional valve.

[0039] The system 100 further includes, in one embodiment, a power controller 150 coupled between the system controller 130 and the hydraulic assembly 110. The power controller 150 is operable to control power supplied to each control valve 112 and each isolation valve 116 of each hydraulic assembly 110 which controls each actuator 120, receive and transmit signals indicative of the load at each hydraulic actuator 120 and each control valve 112, and receive and transmit commands from the system controller 130 regarding the application of a load to the test object and / or the removal of the load to the test object as either a controlled stall load removal (under the control of the system controller 130 using command signals sent to each valve control 112) or an interlock load removal at each actuator 120 (under the control of the local processor 113 executing local firmware 115 at the control valve 112). Signals exchanged between the power controller 150 and the system controller 130 are carried on communication lines 152 which can be wired, wireless, or a combination thereof.

[0040] It should be noted that the same reference numbers are used for the same or similar elements in different drawings. It should also be understood that the terminology used herein is for the purpose of describing the embodiments, and the terminology is not intended to be limiting. Unless otherwise indicated, ordinal numbers (e.g., first, second, third, etc.) are used to distinguish or identify different elements or steps within a group of elements or steps, and do not impose sequential or numerical limitations on the elements or steps of the embodiment. For example, the "first", "second", and "third" elements or steps do not necessarily have to appear in that order, and do not necessarily limit the embodiment to three elements or steps. It should also be understood that unless otherwise indicated, any designations such as "left," "right," "front," "rear," "top," "bottom," "forward," "reverse," "clockwise," "counterclockwise," "up," "down," or other similar terms such as "upper," "lower," "rear," "forward," "vertical," "horizontal," "proximal," "distal," "middle," etc., are used for convenience and are not intended to imply, for example, any particular fixed location, orientation, or direction. Instead, such designations are used, for example, to reflect relative locations, orientations, or directions. It should also be understood that the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise.

[0041] 2, a hydraulic assembly 110 is shown diagrammatically including a control valve 112 configured to control a hydraulic actuator, e.g., 120. The control valve 112, in one embodiment, is a proportional valve having its own local controller 113 and local firmware 115 mounted therein to control operation of the control valve 112 during interlock load removal operations.

[0042] The hydraulic assembly 110, in one embodiment, further includes a pair of pressure transducers 114 (one for each port of the actuator 120) configured to detect pressure on either side of the piston in each actuator and transmit a signal indicative of the measured pressure at the hydraulic actuator 120. A controller 113 for the control valve 112 is configured to receive the measured pressure indicative of the load on the test article. The control valve 112, in one embodiment, operates local valve firmware 115 as described above, which is configured to remove differential loads on the pistons of the hydraulic actuators in an interlock load removal state, typically to a harmless load difference for each associated actuator 120.

[0043] As noted above, the local firmware 115 is configured, in one embodiment, to perform interlock load removal of differential loads present across a piston of an associated actuator. This is performed, in one embodiment, by isolating the control valve 112 from the hydraulic source 140 of hydraulic power to the hydraulic assembly 110. After isolation, a measurement of pressure at a piston, such as piston 124 of an actuator, such as hydraulic actuator 120, is made, such as from pressure transducer 114. The load differential at piston 124 of hydraulic actuator 120 is determined, and the load differential is ramped to a harmless load differential using the control valve 112. As noted above, operation of the control valve 112 is independent and not under the supervision or control of the system controller 130, other than to initiate interlock load removal, and is dependent on the local controller 113 and firmware 115 of the control valve 112 in ramping the load differential to a harmless load difference.

[0044] As noted above, the local firmware 115, in one embodiment, is further configured to obtain multiple measurements of hydraulic pressure on either side of the piston at a predetermined delay time after isolating the control valve 112. The local firmware 115 is further configured to ramp, e.g., linearly ramp, the load differential present on each associated actuator 120 over a predetermined time period. In one embodiment, the hydraulic assembly 110 further includes an isolation valve 116 that is used to isolate the control valve 112 from the hydraulic power source 140. In one embodiment, the isolation valve 116 is a solenoid valve.

[0045] Under normal operating conditions, the test system 100 has hydraulic pressure supplied to the actuators 120 by a hydraulic source 140. The test system 100 can have many hydraulic actuators 120, each coupled to the hydraulic source 140 via a manifold or other hydraulic distribution system. In one embodiment, the test system 100 includes multiple test subsystems, each including multiple hydraulic actuators. In one embodiment, each subsystem includes eight hydraulic actuators 120, each with an associated control valve 112 and isolation valve 116, and associated connections through a power controller 150 that includes power sources for the subsystems and the ability to relay valve and actuator information to a system controller 130. In one embodiment, the system controller 130 is a test system controller, such as a FlexTest 200 controller manufactured by MTS Systems Corporation, Eden Prairie, Minnesota, USA.

[0046] The test system 100 mitigates the risk of non-representative load application, i.e., load application that may damage the test article being tested by the test system 100, in several ways. There is a calculated load provided from the control valves 112 of the subsystems to the system controller 130 via the power controller 150. The system controller 130 determines possible load differentials from one or more actuators 120 that may not be operating correctly in various ways as described further herein. If there is a possible load differential of the test article, the system controller 130 can initiate a controlled load removal, referred to above as a stop level or simply a "stop state". In the stop state, the system controller 130 is in control and uses the normal operation of the hydraulics of the test system to reduce the load differential while hydraulic power is still being provided. The failure of certain components in the test system 100 can trigger a stop, or a controlled load removal, as known in the art. However, monitoring of the calculated and commanded loads on the pressure transducers and components of the test system 100 and / or the measured loads from the associated load cells 122 may also lead to the issuance of a stop command from the system controller 130.

[0047] If the stop command fails, i.e., the load difference on the test object is not reduced or alleviated, this indicates a possible problem related to the integrity of the control loop of the system controller 130 or the test system 100 implementing the stop command. In this situation, or if the load difference continues to increase beyond the stop level to a second, higher level, an interlock is commanded by the system controller 130 for one or more actuators 120, but typically the command is initiated for all actuators 120. A traditional interlock may result in an unrepresentative or uneven unloading of the load on the test object, potentially resulting in damage to the test object. In an embodiment of the present disclosure, the interlock leads to a controlled, e.g. linear, unloading of the load difference on the test object through the use of the control valve 112 as controlled by each local processor 113, which operates completely independently after receiving an interlock command in an interlock condition. Local firmware 115 executed by each local processor 113 controls the unloading of load differences up to harmless load differences, typically without using the system controller 130, other than initiating an interlock command to each control valve 112.

[0048] 3, one subsystem is shown with eight hydraulic assemblies 1101, 1102, ..., 1108. Each hydraulic assembly 1101, 1102, ..., 1108 is coupled to a manifold or the like of the hydraulic source 140, to its own hydraulic actuator 1201, 1202, ..., 1208, and to the power controller 150 via communication lines 152. Load cells 1221, 1222, ..., 1228 are coupled to each associated actuator 1201, 1202, ..., 1208 and to the test object 300 to transmit the load from each actuator 120. It should be noted that each load cell 1221, 1222, ..., 1228 can provide one or more, e.g., two, signals to the system controller 130 indicative of the measured load thereon. The control valves 112 of the hydraulic assemblies 1101, 1102, ..., 1108 are coupled to the hydraulic source 140 and to the power controller 150 and in normal operation receive instructions from the system controller 130 via the power controller 150 to effect a desired load application to the test object 300, to effect a stop condition as described above, or to initiate an interlock load removal on each actuator 1201, 1202, ..., 1208 via its associated control valve 112. Upon interlock, each valve of the hydraulic assemblies 1101, 1102, ..., 1108 is isolated from the hydraulic source 140 and operates independently according to its local firmware 115 to ramp the load difference on its respective load cell / actuator to a harmless load difference.

[0049] An exemplary design of one hydraulic assembly 110 configuration is shown in Figures 4A and 4B. The hydraulic assembly 110 is configured with a manifold 118 to which hydraulic lines can be connected. The control valve 112, pressure transducer 114, and isolation valve 116, in one embodiment, are mounted on the manifold 118. The isolation valve 116, in one embodiment, is enabled by a solenoid.

[0050] 5 illustrates a hydraulic circuit 500 used to supply hydraulic pressure to the control valves 112 and hydraulic actuators 120. The hydraulic source 140 has pressure and return lines 142 and 144 that supply hydraulic fluid to and from each control valve 112. An isolation valve 116 isolates the pressure lines 142, and therefore the hydraulic source 140, from the control valves 112, pressure transducers 114, and hydraulic actuators 120 upon initiation of an interlock load removal. In one embodiment, the isolation valve is enabled by a solenoid. Once the isolation valve 116 isolates the control valves 112, transducers 114, and hydraulic actuators 120, local firmware 115 executing in a local processor 113 in the control valve 112 determines the load differential that exists at the associated actuator 120 and operates to ramp the load differential to a harmless load differential for that actuator 120 without further input from the system controller 130. Check valves 502 , 504 , and 506 help regulate or control the pressure in hydraulic system 500 .

[0051] A method 600 for unloading a load on a test object in a test system is shown in flow chart 600 of FIG. 6. Method 600 includes determining, at block 602, the possible presence of a load difference on the test object in at least one of a calculated load on a valve for an actuator of the test system and a calculated load on a load cell coupled to the actuator, or other condition requiring a stop condition to be implemented by system controller 130. With respect to undesirable loading on the test object, method 600 further includes initiating, at block 604, a controlled unloading of the load on the test object via the system controller when the determined load difference reaches a first level. This first level may be referred to as a stop level or a stop condition. The stop condition initiates a controlled unloading of the load on the test object using the system controller. However, if the controlled unloading via the system controller 130 performed at standstill is deemed insufficient, then in block 606, an interlock unloading of the load on the test specimen via each valve of each actuator is performed when the determined load difference reaches a second level higher than the first level, after which valve controlled unloading, i.e., interlock unloading, is used to unload the load on the test specimen. Commands to each valve are issued via the system controller 130, in one embodiment.

[0052] There are numerous possible load difference determinations that can be used to determine the first and correction first levels for the stop and the second load difference level for the interlock. The presence of a potential undesirable load difference in the test article can be determined or confirmed using one or more different criteria. In one embodiment, determining includes comparing a commanded load (desired from the actuator) as controlled by the associated valve to a measured load from the associated load cell. In another embodiment, determining the load difference includes determining whether the load values ​​for the two outputs of the load cell as described above are different and assigning the determined load difference as the difference between the load values ​​for the two outputs of the load cell. In another embodiment, determining that a load difference exists includes comparing a calculated load at the valve to a commanded load at the valve. And in yet another embodiment, determining the load difference includes comparing a load value output of the load cell to a commanded load at the valve.

[0053] Determining the load difference, in one embodiment, is performed continuously during the flow mode of the test system, i.e., during normal operation of the test system 100 to perform the desired test on the test article. Each possible load difference can be monitored, and a load difference that is either on the way to a first, stop level, triggers a controlled load removal stop condition via a command issued by the system controller 130 in response to the determined load difference. When the stop, i.e., controlled load removal, does not reduce the load difference and the load difference rises to a second level higher than the first level, an interlock load removal is commanded by the system controller 130. Performing interlock load removal in each of one or more actuators 120 (generally all actuators), in one embodiment, includes isolating each control valve 112 from the hydraulic pressure source 140 of the test system and obtaining pressure measurements on either side of the piston of one actuator 120, e.g., via a pressure transducer 114 coupled to each port of that actuator 120. The load difference across the pistons is determined and ramped to a harmless load difference using control valve 112 under the control of local processor 113 executing local firmware 115. Taking a measurement of the pressure at the pistons, in one embodiment, occurs after a predetermined delay time after valve isolation so that the load application at the test object 120 can be properly verified. Ramping the load difference, in one embodiment, is performed over a predetermined period of time, and in one embodiment, is performed linearly over the predetermined period of time.

[0054] Interlock load removal of a test article in a test system is performed according to a method 700 shown in FIG. 7. The method 700 relates to operation of each hydraulic circuit 500 upon receiving an interlock command from the system controller 130. The method includes isolating the control valve 112 from the hydraulic source 140 of the test system, in block 702, by operation of the isolation valve 116 in one embodiment, and determining a load difference on both sides of a piston of an actuator coupled to the valve, in block 704. The load difference is ramped to a harmless load difference using the valve, in block 706. The method 700 may further include delaying a predetermined period of time between isolating and determining the load difference. It should also be noted that typically an initial load difference present for each actuator, as measured by the pressure transducer 114, is stored in memory in the control valve 112 and used by the local processor 113 executing the local firmware 115. The initial pressure is used to verify the desired load difference during the ramping to the harmless load difference. The measured pressure from the pressure transducer 114 is continuously received by the local processor such that the control valve 112 is controlled to achieve a desired reduction in the load difference during load removal. As noted above, the ramping of the load difference can be done over a predetermined time, e.g., can be performed linearly over a predetermined time period. It should be noted that in one embodiment, the predetermined delay and the predetermined time period are substantially identical for all actuators 120 coupled to the test object. This can be advantageous because even if each control valve 112 were operating independently, the load from the actuators 120 would begin substantially simultaneously and be reduced at a certain percentage rate according to the stored load removal instructions in the local firmware 115. Thus, the load removal across the test object is performed in a somewhat balanced manner across the test object to reduce the possibility of damage to the test object during load removal.

[0055] Thus, embodiments of the present disclosure provide methods and systems for controlled load removal of a test object in a test system when the load difference reaches a first, stop level, and safe linear interlock load removal when the load difference reaches a second, higher interlock level.

[0056] The above disclosed subject matter is to be regarded as illustrative and not limiting, and the appended claims are intended to cover all such modifications, improvements and other embodiments that fall within the true scope of the present disclosure. Thus, to the maximum extent permitted by law, the scope of the present disclosure should be determined by the broadest permissible interpretation of the appended claims and their equivalents, and should not be limited or restricted by the foregoing detailed description.

Claims

1. 1. A method for unloading a load on a test object in a testing system, comprising: determining a load difference between at least one of a calculated load on a valve for an actuator of the test system and a calculated load on a load cell coupled to the actuator; initiating, via a system controller, a controlled unloading of the load on the test object when the determined load difference reaches a first level; performing an interlock load removal of the load on the test object via the valve when the determined load difference reaches a second level higher than the first level; A method comprising:

2. Determining the load differential comprises: Comparing the calculated load on the valve to the calculated load on the load cell; or determining load values ​​for two outputs of the load cell and specifying the load difference as the difference between the load values ​​for the two outputs of the load cell; or Comparing the calculated load on the valve with the commanded load on the valve; or comparing the load value output of said load cell to a commanded load on said valve; The method of claim 1 , comprising:

3. The method of claim 1 or 2, wherein determining the load difference is performed continuously during a flow mode of the test system.

4. 4. The method of claim 1, wherein initiating the controlled unloading via the system controller comprises unloading during a flow mode of the test system to unload the load difference to a harmless load difference.

5. performing the interlock load removal comprises: isolating the valve from a hydraulic power source of the test system; obtaining a measurement of pressure at a piston of the actuator; determining a load differential across a piston of the actuator coupled to the valve; ramping said load difference to a harmless load difference using said valve; The method according to any one of claims 1 to 4, comprising:

6. The method of claim 5 , wherein taking a measurement of pressure at the piston occurs at a predetermined delay time after isolating the valve.

7. 6. The method of claim 5, wherein the ramping of the load difference is performed over a predetermined period of time, and in one embodiment the ramping of the load difference is performed linearly over the predetermined period of time.

8. 1. A method for interlock unloading a test specimen in a test system having a valve controlling an actuator, comprising: isolating the valve from a hydraulic source of the test system; determining a load differential across a piston of the actuator coupled to the valve; ramping said load difference to a harmless load difference using said valve; A method comprising:

9. 9. The method of claim 8, further comprising delaying a predetermined amount of time between isolating and determining the load difference, and / or wherein ramping the load difference occurs over a predetermined period of time, and in one embodiment ramping the load difference is performed linearly over the predetermined period of time.

10. 1. A test system for monitoring and unloading a load on a test object, comprising:

1. A hydraulic assembly comprising: a control valve configured to control a load on a hydraulic actuator coupled to the test object; a pair of pressure transducers configured to detect and transmit pressure in the hydraulic actuator; an isolation valve isolating the control valve from hydraulic pressure; a hydraulic assembly comprising: A controller, determining a load difference between at least one of a calculated load on a valve for an actuator of the test system and a calculated load on a load cell coupled to the actuator; initiating, via a system controller, a controlled unloading of the load on the test object when the determined load difference reaches a first level; performing an interlock load removal of the load on the test object via the valve when the determined load difference reaches a second level higher than the first level; A controller configured to: A test system comprising:

11. The valve further includes a controller receiving the pressure and valve firmware configured to reduce a differential load on a piston of the hydraulic pressure, and in one embodiment, the valve firmware comprises: isolating the valve from a hydraulic source of the test system; determining a load differential on a piston of the actuator coupled to the valve; ramping said load difference to a harmless load difference using said valve; and performing an interlock load removal of the load on the test object by The test system of claim 10.

12. 1. A hydraulic assembly comprising: a proportional valve configured to control a hydraulic actuator, the proportional valve having a controller that receives a pressure indicative of a load on a test object, the proportional valve operating valve firmware configured to reduce a differential load on a piston of the hydraulic actuator; Hydraulic assembly.

13. The hydraulic assembly of claim 12 , further comprising a pair of pressure transducers configured to sense pressure in the hydraulic actuator and transmit the pressure to the proportional valve.

14. The valve firmware comprises: isolating the proportional valve from a source of hydraulic power to the hydraulic assembly; obtaining a measurement of pressure at a piston of the actuator; determining a load differential on the piston of the hydraulic actuator; ramping said load difference to a harmless load difference using said valve; and performing an interlock load removal of the differential load by A hydraulic assembly according to claim 12 or 13.

15. 15. A hydraulic assembly as claimed in any one of claims 12 to 14, wherein the valve firmware is further configured to obtain a pressure measurement at the piston at a predetermined delay time after isolating the valve, and / or the valve firmware is further configured to ramp the load difference over a predetermined period of time, in one embodiment the valve firmware is further configured to linearly ramp the load difference over the predetermined period of time.

Images