Speed control of hydraulic actuator of dynamic test system

Abstract

In a method of controlling a hydraulic actuator of a test station, a differential signal is generated using an actuator controller based on a difference between a reference signal and a feedback signal. The flow control circuit is set in one of a first state and a second state based on the flow attenuation signal. When the flow control circuit is in the first state, the differential signal is delivered as an actuator command signal to the control valve. When the flow control circuit is in the second state, the attenuation differential signal is delivered as an actuator command signal to the control valve. The flow and direction of the hydraulic fluid flow are controlled based on the actuator command signal. The flow rate corresponding to the attenuated differential signal is less than the flow rate corresponding to the differential signal.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based upon and claims the benefit of U.S. Provisional Application Serial No. 63 / 535910, filed on August 31, 2023, the contents of which are hereby incorporated by reference in their entirety. Technical Field

[0003] Embodiments of the present disclosure relate generally to a test station for a dynamic test system and, more particularly, to speed control of a hydraulic actuator of the test station. Background Art

[0004] Dynamic testing systems, such as those developed by MTS Systems, include test stations that perform various tests by applying loads and displacements to a test object using hydraulic actuators. Test stations may include, for example, a vehicle test station that applies simulated driving conditions to a moving vehicle, or a building test station that applies simulated seismic activity to a building.

[0005] The actuators of the test station are driven by a flow of hydraulic fluid. The actuation performed by each actuator is controlled using a control valve (eg, a proportional control valve) that regulates the flow and direction of the hydraulic fluid flowing through the actuator.

[0006] For safety reasons, workers are usually prohibited from entering the test station during the execution of the test. The input safety valve that controls the high-pressure flow of hydraulic fluid to the test station can be placed in a low-flow state, thereby limiting the flow of hydraulic fluid to the test station and its actuators. Thus, when the safety valve is in the low-flow state, the movement speed of the actuator is greatly reduced and, for example, it is possible for a worker to safely enter the test station and check the test actuation performed by the actuator.

[0007] Such input safety valves inherently cause system pressure drops. These pressure drops must be overcome by a higher pressure of the hydraulic fluid during normal operation, which results in reduced energy efficiency. Furthermore, such input safety valves typically only provide a single layer of safety to prevent the actuator from being driven at a speed higher than the desired speed. Summary of the invention

[0008] Embodiments of the present disclosure relate to methods for controlling a hydraulic actuator of a test station of a dynamic test system and a test station configured to perform these methods. The method is implemented in a test station, which includes: a hydraulic actuator configured to drive actuation of a test object using a hydraulic fluid flow; a control valve; an actuation sensor; a test controller; an actuator controller; and a flow control circuit. In the method, a feedback signal indicating an actuation parameter is generated using an actuation sensor. A reference signal indicating a desired actuation is generated based on a test program using a test controller. A differential signal is generated based on a difference between the reference signal and the feedback signal using an actuator controller. A flow control circuit is set to one of a first state and a second state based on a flow attenuation signal. When the flow control circuit is in the first state, the differential signal is delivered to the control valve as an actuator command signal. When the flow control circuit is in the second state, the attenuated differential signal is delivered to the control valve as an actuator command signal. The flow and direction of the hydraulic fluid flow are controlled based on the actuator command signal. The flow corresponding to the attenuated differential signal is less than the flow corresponding to the differential signal.

[0009] In some embodiments of the method, the flow rate corresponding to the attenuated differential signal is a non-zero flow rate.

[0010] In some embodiments of the method, the non-zero flow rate is less than about 20% of the flow rate corresponding to the differential signal.

[0011] In some embodiments of the method, the non-zero flow rate limits movement of an actuator rod of a hydraulic actuator that causes the actuation to less than about 15 mm / sec.

[0012] In some embodiments of the method, the flow corresponding to the decaying differential signal is substantially zero and is substantially clamped at a position of the actuator stem that induces the actuation.

[0013] In some embodiments of the method, the hydraulic actuator includes a cylinder and an actuator rod including a piston contained within the cylinder, wherein movement of the piston and the actuator rod relative to the cylinder causes the actuation.

[0014] In some embodiments, the control valve includes a valve housing, the valve housing including: an inlet port coupled to a supply of high-pressure hydraulic fluid; an outlet port coupled to a low-pressure return reservoir; a first port coupled to a first working volume formed by an inner cavity of a cylinder and a piston; and a second port coupled to a second working volume formed by an inner cavity of the cylinder and a piston. The control valve may also include: a valve body contained in the housing, the valve body having a position for directing a flow of hydraulic fluid received at the inlet port to one of the first port and the second port or not to any of the first port and the second port and controlling a flow rate of the hydraulic fluid flow; and a valve body driver configured to adjust a position of the valve body based on an actuator command signal.

[0015] In some embodiments of the method, the valve body actuator includes a servo or a solenoid.

[0016] In some embodiments of the method, the valve body includes a spool or a piston.

[0017] In some embodiments of the method, the actuation comprises movement of the test object; the actuation sensor comprises a displacement sensor; and the feedback signal indicates the displacement or movement of the test object.

[0018] In some embodiments of the method, the actuation comprises a force acting on the test object; the actuation sensor comprises a force gauge; and the feedback signal is indicative of the force applied to the test object.

[0019] In some embodiments, the method includes generating a flow decay signal using a test controller.

[0020] In some embodiments, the method includes attenuating the differential signal using the flow control circuit to form an attenuated differential signal.

[0021] One embodiment of a test station includes: a hydraulic actuator configured to induce actuation of a test object using a hydraulic fluid flow; a control valve configured to control the flow and direction of the hydraulic fluid flow and the actuation in response to an actuator command signal; an actuation sensor configured to generate a feedback signal indicative of a parameter of the actuation; a test controller configured to generate a reference signal corresponding to a desired actuation based on a test program; an actuator controller configured to generate a differential signal based on a difference between the reference signal and the feedback signal; and a flow control circuit. The flow control circuit includes a first state and a second state, in which the flow control circuit is configured to deliver the differential signal as the actuator command signal to the control valve, and in which the flow control circuit is configured to deliver an attenuated differential signal as the actuator command signal to the control valve. The flow control circuit switches from the first state to the second state in response to a flow attenuation signal. The flow corresponding to the attenuated differential signal is less than the flow corresponding to the differential signal.

[0022] In some embodiments of the test station, the flow rate corresponding to the attenuated differential signal is a non-zero flow rate.

[0023] In some embodiments of the test station, the non-zero flow rate is less than about 20% of the flow rate corresponding to the differential signal.

[0024] In some embodiments of the test station, the non-zero flow rate limits movement of an actuator rod of a hydraulic actuator that causes the actuation to less than about 15 mm / sec.

[0025] In some embodiments of the test station, the flow corresponding to the attenuated differential signal is substantially zero and clamped at a position of the actuator stem that induces the actuation.

[0026] In some embodiments of the test station, the hydraulic actuator includes a cylinder and an actuator rod including a piston contained within the cylinder, wherein movement of the piston and the actuator rod causes the actuation.

[0027] In some embodiments, the control valve includes a valve housing, the valve housing including: an inlet port coupled to a supply of high-pressure hydraulic fluid; an outlet port coupled to a low-pressure return reservoir; a first port coupled to a first working volume formed by an inner cavity of a cylinder and a piston; and a second port coupled to a second working volume formed by an inner cavity of the cylinder and a piston. The control valve may also include: a valve body contained in the housing, the valve body having: a position for directing a flow of hydraulic fluid received at the inlet port to one of the first port and the second port or not to any of the first port and the second port and controlling a flow rate of the hydraulic fluid flow; and a valve body driver configured to adjust a position of the valve body based on an actuator command signal.

[0028] In some embodiments of the test station, the valve body actuator includes a servo or a solenoid.

[0029] In some embodiments of the testing station, the valve body includes a spool valve or a piston.

[0030] In some embodiments of the test station, the actuation comprises movement of the test object; the actuation sensor comprises a displacement sensor; and the feedback signal indicates the displacement or movement of the test object.

[0031] In some embodiments of the test station, the actuation comprises a force acting on the test object; the actuation sensor comprises a force gauge; and the feedback signal is indicative of the force applied to the test object.

[0032] This summary is intended to introduce a selection of inventive concepts in a simplified form, which are further described in the detailed description below. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to help determine the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all of the disadvantages noted in the background technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a simplified diagram of an example of a dynamic testing system according to an embodiment of the present disclosure.

[0034] Figure 2 and Figure 3 is a schematic diagram of an example of a test station according to an embodiment of the present disclosure.

[0035] Figure 4 is a diagram of an example of a flow control circuit according to an embodiment of the present disclosure.

[0036] Figure 5 is a simplified diagram of an example of a differential signal according to an embodiment of the present disclosure.

[0037] Figure 6 and Figure 7 is a simplified graphical example of an attenuated differential signal according to an embodiment of the present disclosure.

[0038] Figure 8 is a flow chart illustrating a method of controlling a hydraulic actuator of a test station according to an embodiment of the present disclosure.

[0039] Fig. 9 is a simplified diagram of an example of a controller according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0040] Embodiments of the present disclosure will be described more fully below with reference to the accompanying drawings. Elements identified with the same or similar reference numerals refer to the same or similar elements. However, different embodiments of the present disclosure can be implemented in many different forms, and should not be interpreted as being limited to the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure will be thorough and complete, and the scope of the present disclosure will be fully conveyed to those skilled in the art.

[0041] The functions described herein may be performed by a single controller, multiple controllers, or at least one controller. As used herein, when one or more functions are described as being performed by a "controller", such as a specific controller, one or more controllers, or at least one controller, embodiments include performing the (these) functions by a single controller or processor or multiple controllers or processors, unless otherwise specified. In addition, as used herein, when multiple functions are performed by at least one controller, all functions may be performed by a single controller, or some functions may be performed by one controller and other functions may be performed by another controller. Therefore, the execution of one or more functions by at least one controller does not require that all functions can be performed by each controller.

[0042] Figure 1 is a simplified diagram of an example of a dynamic test system 100 according to an embodiment of the present disclosure. The test system 100 may include one or more test stations 102, each of which may be configured to perform a test or condition simulation by applying forces and / or displacements to a test object 103 (e.g., a car, a building, etc.) using a hydraulic actuator 104 driven by a flow of hydraulic fluid 106.

[0043] The flow 106 may be provided based on a hydraulic fluid flow 108 generated by one or more hydraulic power units (HPUs) 110. The system 100 may include a reservoir 116 that stores pressurized hydraulic fluid received from the HPU 110 and discharges a hydraulic fluid flow 118 that may be used to form the flow 106 supplied to the test station 102. The system 100 may include a distributor 120 that receives the hydraulic fluid flow from the HPU 110 and / or the reservoir 116 and distributes the hydraulic fluid flow 106 to the test station 102. Other configurations of the system 100 may be used to supply the desired hydraulic fluid flow 106 to the test station 102.

[0044] The system 100 may be a closed loop system in which a low pressure hydraulic fluid flow 106 ′ exhausted from the test station 102 , such as via a combined return flow 124 , is returned back to the HPU 110 via the hydraulic distribution system 120 , for example.

[0045] The system controller 126 may be operable to control various aspects of the system 100 , including the functioning of the HPU 110 , valves (eg, accumulator and / or distributor valves), and / or other aspects of the system 100 to supply the desired flow of hydraulic fluid 106 to the test station 102 .

[0046] Figure 2 1 is a schematic diagram of an example of a test station 102 according to an embodiment of the present disclosure. As described above, the test station 102 includes a plurality of hydraulic actuators 104, such as hydraulic actuators 104A-D, which are configured to apply forces to a test object 103 and / or induce motion of the test object. Each of the hydraulic actuators 104A-D is driven by a corresponding flow portion 106A-D of a hydraulic fluid flow 106, which is driven by one or more hydraulic power units 110 ( Figure 1 )generate.

[0047] Each test station 102 may include a test station controller 130 that is generally configured to perform tests on the test object 103 based on the execution of a test program stored, for example, in a non-transitory computer readable medium. In response to the execution of the test program, the test station controller 130 controls the hydraulic fluid flows 106A-D using corresponding control valves 132 to control the actuators 104 to apply force and / or motion to the test object 103 in a conventional manner.

[0048] Computing device 134 may be configured to generate a graphical user interface through which a user may interact with and / or control test station 102 , execute test programs, view data, and / or perform other tasks, such as through a series of communications with test station controller 130 .

[0049] One or more safety input valves 136 (e.g., solenoid valves) may control the flow of high pressure hydraulic fluid 106 to the test station 102, such as in response to a control signal from the test station controller 130, the system controller 126, or another suitable device (e.g., an emergency stop device). Each safety input valve 136 has a fully open state that provides a substantially unrestricted path for the flow of hydraulic fluid 106 to the test station 102. The valves 136 also have a closed or substantially closed state in which the valves 136 block or substantially block the flow of hydraulic fluid 106 to the test station 102. The solenoids of the valves 136 may have a default or de-energized state corresponding to the closed or substantially closed state.

[0050] When the safety input valve 136 is in a substantially closed state, the opening in the valve 136 allows the hydraulic fluid flow 106 to flow to the test station 102. However, the flow rate of the flow 106 is significantly restricted. Regardless of the setting of the control valve 132, this limits the flow rate of the hydraulic fluid 106 to the test station 102 and the actuator 104, thereby limiting the movement speed of the actuator 104.

[0051] For example, in response to detecting a fault, or before an operator enters the test area where the actuator 104 and the test object 103 are located, the safety input valve 136 can be set to a substantially closed state by the test station controller 130, the system controller 126, or another controller of the system 100. Thus, one or more safety input valves 136 provide a certain level of safety for the test station 102.

[0052] A test station requires a higher degree of safety, such as a safety measure that ensures that the maximum movement speed of the actuator is below a desired threshold limit when a fault is detected or an operator enters the test area. However, it is generally undesirable to include too many safety input valves 136 in the system 100 because they cause a pressure drop in the flow 106 that must be overcome by a higher hydraulic fluid pressurization than would be required if the valves 136 were not present, which can adversely affect the efficiency with which the hydraulic fluid flow 106 can be generated. It is generally desirable for the safety measure not to have such adverse effects.

[0053] Figure 3 1 is a simplified diagram of an example of a test station 102 according to an embodiment of the present disclosure. As discussed above, the test station 102 includes a test station controller 130 and at least one hydraulic actuator 104 and its corresponding control valve 132. Figure 3 Only one pair of hydraulic actuators 104 and control valves 132 are shown in the figure to simplify the description, but it should be understood that the test station 102 may include two or more actuators 104 and corresponding control valves 132, such as Figure 2 shown.

[0054] The control valve 132 of each hydraulic actuator 104 operates to control the flow rate (e.g., gallons per minute) of hydraulic fluid flow 106 received from a high pressure source (e.g., HPU 110) 137 to the actuator 104, and the discharge of flow 106' to a low pressure reservoir 138 (e.g., a reservoir returning to the HPU 110). In addition, the control valve 132 controls the direction of flow through the hydraulic actuator 104 to control the actuation applied to the test object 130.

[0055] In one example, the hydraulic actuator 104 includes a cylinder 140 and an actuator rod 142 having a piston 144 contained within the cylinder 140. The cylinder 140 includes a first port 146 and a second port 148 through which the hydraulic fluid stream 106 flows. The valve 132 controls the direction of the hydraulic fluid stream 106 flowing through the first port 146 and the second port 148 to control the movement direction of the actuator rod 142 and the movement speed of the actuator rod 142 relative to the cylinder 140 based on the flow rate of the hydraulic fluid stream 106.

[0056] The control valve 132 may take any suitable form. Examples of the control valve 132 include a servo valve or a solenoid valve configured to provide the variable flow and direction control described above. Figure 3 As shown, the control valve 103 generally includes an electronic device 150, a valve body 152, and a valve body actuator 154. The valve body 152 has an adjustable position to control the direction and flow of the hydraulic fluid flow 106. The electronic device 150 is configured to control the valve body actuator 154 in response to an actuator command signal 156 to adjust the position of the valve body 152. For example, the valve body 152 can take the form of a spool valve, and the valve body actuator 154 can take the form of a servo. An example of this type of control valve 132 is described in U.S. Publication No. 2016 / 0123355.

[0057] In some embodiments, control valve 132 includes a position sensor 158 configured to detect a position of valve body 152, such as relative to housing 160 of valve 132. Electronics 150 are configured to output a position signal 162 indicative of the detected position of valve body 152.

[0058] During execution of a test procedure, the test station controller 130 issues a reference signal 164 related to a desired actuation to be performed by the hydraulic actuator 104 on the test object 103. Each actuator 104 includes an actuation sensor 166 configured to sense a parameter (e.g., displacement and / or force) of the actuation performed by the actuator 104 and to issue a feedback signal 168 indicative of the sensed parameter. The actuation sensor 166 may include, for example: a displacement sensor 166A, such as a linear variable differential transformer, configured to detect displacement and / or movement of the actuator rod 142 relative to the cylinder 140 and generate a feedback signal 168A indicative of the detected displacement and / or movement; and / or a force gauge 166B, configured to detect a force applied by the actuator 104 (e.g., a force applied to the test object 103) and generate a feedback signal 168B indicative of the detected force, such as a linear variable differential transformer. Figure 3 Conventional regulator circuits may be used to process signals 168A and / or 168B (eg, amplify, filter, etc.) to generate final feedback signal 168 .

[0059] The actuator controller 170 is configured to compare the reference signal 164 with the feedback signal 168 corresponding to each actuator 104 and generate a differential signal 172 for the corresponding control valve 132. Figure 3 1 as receiving a single reference signal 164 and issuing a single differential signal 172 corresponding to the depicted actuator 104, the actuator controller 170 may be configured to receive multiple reference signals 164 and corresponding feedback signals 168 for each hydraulic actuator 104 of the test station 102 from the test station controller 130 and issue a differential signal 172 to control the corresponding valve 132. In a conventional test station 102, the differential signal 172 operates as the illustrated actuator command signal 156 to the control valve 132, thereby regulating the flow rate and / or flow direction of the fluid flow 106 to produce the desired actuation.

[0060] Embodiments of the present disclosure include a flow control circuit (FRCC) 180 for each valve 132 that receives the differential signal 172 from the actuator controller 170 and outputs the actuator command signal 156 to the control valve 132. Alternatively, a single flow control circuit may be adapted to receive multiple differential signals 172 corresponding to multiple actuators 104 of the test station 102 and output the actuator command signal 156 to the corresponding control valve 132. To simplify the discussion, the flow control circuit will be described with respect to the operation of the flow control circuit 180 with a single hydraulic actuator 104 and valve 132.

[0061] In one example, the flow control circuit 180 has a first state in which the actuator command signal 156 is in the form of the differential signal 172, such as by passing the differential signal 172 as the actuator command signal 156, and a second state in which the actuator command signal 156 is in the form of an attenuated differential signal 182. The flow control circuit 180 may switch between the first state and the second state in response to a flow attenuation signal 184, which may be issued by the test station controller 130, the system controller 126, or another device of the system 100, such as a user-activated switch.

[0062] The flow rate of the hydraulic fluid 106 flowing through the control valve 152 corresponding to the attenuated differential signal 182 form of the actuator command signal 156 is less than the flow rate of the hydraulic fluid 106 corresponding to the differential signal 172 form of the actuator command signal 156. Therefore, when the flow control circuit 180 is in the first state, the control valve 152 is substantially controlled by the differential signal 172 in a conventional manner.

[0063] When the flow control circuit 180 is in the second position, the control valve 132 is controlled to reduce the flow of the hydraulic fluid flow 106 and the speed of the actuation performed by the actuator 104 by an amount specified by the differential signal 172. As a result, the flow control circuit 180 operates to limit the speed of the actuation performed by the actuator 104, but does not impart an additional pressure drop along the path of the hydraulic fluid flow 106, such as would be the case if an additional relief input valve 136 were added.

[0064] In some embodiments, the decaying differential signal 182 indicates a flow rate corresponding to about 50-95% decay (e.g., about 75-90% decay) of the flow rate of the differential signal 172, thereby causing the decaying differential signal 182 to control the valve 132 to provide the flow 106 with a reduced non-zero flow rate. For example, when the differential signal 172 is configured to drive the valve body 152 to a position corresponding to a flow rate of 20 gallons per minute, the corresponding decaying differential signal 182 can be configured to drive the valve body 152 to a position corresponding to a reduced non-zero flow rate, such as 2 gallons per minute (e.g., decayed by 90%). In one embodiment, the non-zero flow rate corresponding to the decaying differential signal 182 is less than about 20% of the flow rate corresponding to the differential signal 172. In one embodiment, the decaying differential signal 182 limits the maximum velocity of the actuator rod 142 relative to the cylinder 140 to less than 15 mm / sec, such as less than 10 mm / sec.

[0065] In one embodiment, the flow control circuit 180 can be configured to provide approximately 100% attenuation of the differential signal 172 when in the second state, thereby causing the control valve 132 to substantially stop the flow of hydraulic fluid 106 (e.g., + / - 0.05 gallons per minute) and actuate. Thus, when the flow control circuit 180 is in the second state and provides 100% attenuation of the differential signal 172, the attenuated differential signal 182 drives the valve body 152 to a position that stops the flow 106, thereby clamping the position of the actuator rod 142 relative to the cylinder 140 at a certain position.

[0066] Flow control circuit 180 may take any suitable form. Figure 4 1 is a simplified diagram of an example of a flow control circuit 180 according to an embodiment of the present disclosure. In some embodiments, the circuit 180 includes an attenuation circuit 186 configured to generate an attenuated differential signal 182. The circuit 180 may include a switch circuit 187 for selectively outputting the differential signal 172 or the attenuated differential signal 182 as the actuator command signal 156 based on the attenuation control signal 184.

[0067] The switch circuit 187 can take any suitable form, such as a conventional switch circuit. In one example, the switch circuit 187 includes a pair of switches 188A and 188B (or equivalent circuits) that operate to pass the differential signal 172 or the attenuated differential signal 182 as the command signal 156. The one or more attenuation control signals 184 can include a signal 184A that is used to enable or disable the switches 188A and 188B, such as by inverting the signal 184A to the switch 188B using an inverter 190. Thus, for example, one signal 184A (e.g., a logical 1) can enable the switch 188A and disable the switch 188B, thereby outputting the differential signal 172 as the command signal 156, while another signal 184A (e.g., a logical 0) can disable the switch 188A and enable the switch 188B, thereby outputting the attenuated differential signal 182 as the command signal 156 (dashed line).

[0068] The actuator command signal 156, the differential signal 172, and the attenuated differential signal 182 may take various forms. In one example, each signal may take the form of a sinusoidal signal whose average value causes the actuator 154 to adjust the position of the valve body 152, thereby controlling the direction and amount of hydraulic fluid flow 106 through the control valve 132. The direction of the flow 106 and the direction of the actuator stem 142 are controlled based on whether the average value is positive or negative, and the amount of flow 106 is controlled based on the magnitude of the average value.

[0069] Figure 51 is a simplified diagram of an example of a sinusoidal differential signal 172 having a positive average value 191 relative to a zero axis 192. The positive average value 191 drives the position of the valve body 152 to a position where the hydraulic fluid flow 106 travels in a first direction, such as into port 146 and out of port 148 ( Figure 3 ), and the negative average value 191 drives the position of the valve body 152 to a position where the hydraulic fluid flow 106 travels in a second direction, such as out of the port 146 and into the port 148. Based on the amplitude 193 of the average value 191, the position of the valve body 152 is further adjusted so that the flow 106 has a higher flow when the amplitude 193 is high and a lower flow when the amplitude 193 is low.

[0070] Attenuation circuit 186 may provide attenuated differential signal 182 using any suitable technique. Figure 6 An example of the attenuated differential signal 182 is shown. In some embodiments, the generated attenuated differential signal 182 may be based on the attenuation control signal 184B, such as Figure 4 shown.

[0071] In one example, the damping circuit 186 outputs a predefined damped differential signal 182A in response to the damping control signal 184, regardless of the differential signal 172. The predefined damped differential signal 182A may have a predefined average value 191' (positive or negative) and an amplitude 193' that instructs the valve body actuator 154 to move the position of the valve body 152 to a predefined position, thereby generating a predefined hydraulic fluid flow 106 direction and flow rate. In some embodiments, the directional flow rate of the flow 106 based on the signal 182A is non-zero, and the actuation speed in response to the flow 106 is limited to less than about 15 mm / sec, such as described above. In other embodiments, the flow rate of the flow 106 based on the signal 182A is substantially zero.

[0072] In another example, the attenuation circuit 186 outputs an attenuated differential signal 182B corresponding to a fixed attenuation of the differential signal 172. Thus, the attenuation circuit 186 receives the differential signal 172 and uses a conventional attenuation circuit to attenuate the differential signal 172 by a fixed percentage to form the attenuated differential signal 182B. Thus, the attenuated differential signal 182B is substantially a mirror image of the differential signal 172, but has a smaller average value 191' and amplitude 193', such as Figure 6 , as indicated by the example signal 182 shown in . The fixed attenuation may be selected based on the size of the hydraulic actuator 104 to ensure that the flow rate and corresponding actuation speed of the flow 106 do not exceed a desired maximum value, as discussed above. The fixed percentage may correspond to a value within the range discussed above to produce a non-zero or substantially zero flow rate of the flow 106.

[0073] In another example, the attenuation circuit 186 outputs an attenuated differential signal 182C corresponding to the variable attenuation of the differential signal 172. Thus, the attenuation circuit 186 receives the differential signal 172 and uses conventional attenuation circuits to attenuate the differential signal 172 by a variable percentage based on the attenuation control signal 184B to form the attenuated differential signal 182C, which can be used. Figure 6 182 '. Thus, the attenuated differential signal 182C is substantially a mirror image of the differential signal 172, but has a smaller average value 191 'and amplitude 193 '. The variable percentage indicated by the signal 184B can be selected based on the size of the hydraulic actuator 104 to ensure that the flow rate of the flow 106 and the corresponding actuation speed do not exceed the desired maximum value, as discussed above. The variable attenuation can correspond to a value within the range discussed above to produce a non-zero or substantially zero flow rate of the flow 106.

[0074] In yet another example, the attenuation circuit 186 outputs the attenuated differential signal 182D corresponding to a predefined maximum flow rate of the flow 106 . Figure 7 1 is a simplified diagram of an example of an attenuated differential signal 182D according to an embodiment of the present disclosure. Here, the attenuation circuit 186 receives the differential signal 172 and truncates the differential signal 172 at a predefined amplitude 196 using conventional attenuation circuitry to form the signal 182D. Therefore, the average value 191' and the amplitude 193' of the signal 182D are reduced from the average value 191 and the amplitude 193 of the differential signal 172. The predefined amplitude 196 can be selected based on the size of the hydraulic actuator 104 to ensure that the flow rate and corresponding actuation speed of the flow 106 do not exceed the desired maximum value, as discussed above. The predefined amplitude 196 can correspond to an attenuation value within the range discussed above to produce a non-zero flow rate of the flow 106.

[0075] Figure 8 1 is a flow chart illustrating a method of controlling a hydraulic actuator 104 of a test station 102 according to an embodiment of the present disclosure. The test station may be formed according to one or more embodiments described above. Although the method is described with respect to a single hydraulic actuator 104 and its control valve 132, it should be understood that the method may be applied to multiple hydraulic actuators 104 of a test station 102, such as Figure 2 Actuators 104A-D of the test station shown in FIG.

[0076] The method is performed using at least one controller of the system 100 (e.g., the system controller 126, the test station controller 130, etc.), such as based on executing program instructions using one or more processors of the controller to perform the method. This means that a single controller can be used to perform the steps of the method, or multiple controllers can be used to perform the steps of the method. When multiple controllers are used to perform the steps of the method, different controllers can be used to perform different steps of the method. Therefore, as used herein, the phrase "at least one controller" does not require that each controller performs all method steps or causes all method steps to be performed.

[0077] In step 200 of the method, a feedback signal 168 is generated using an actuation sensor 166 (e.g., a displacement sensor 166A and / or a dynamometer 166B) that indicates an actuation parameter of the hydraulic actuator 104. This may occur during the execution of a test defined by a test procedure on the test object 103. As discussed above, the parameter may be a displacement, movement, or load corresponding to the actuation.

[0078] In step 202 of the method, a reference signal 164 indicative of a desired actuation is generated based on a test procedure using the test controller 130 , and in step 204 a differential signal 172 is generated based on a difference between the reference signal 164 and the feedback signal 168 using the actuator controller 170 .

[0079] The flow control circuit 180 is set to a first state or a second state based on the flow attenuation signal 184. When in the first state, the flow control circuit 180 delivers the differential signal 172 as the actuator command signal 156 to the control valve 132, as shown in step 206 of the method. When in the second state, the flow control circuit 180 delivers the attenuated differential signal 182 as the actuator command signal 156 to the control valve 132, as shown in step 208 of the method.

[0080] In step 210 of the method, the flow rate and direction of the hydraulic fluid flow 106 is controlled by the control valve 132 based on the actuator command signal 156. The flow rate corresponding to the attenuated differential signal 182 is less than the flow rate corresponding to the differential signal 172.

[0081] The degree of damping performed by the flow control circuit 180 can be in accordance with the above-described embodiments, resulting in the damped differential signal 182 indicating a non-zero flow rate, such as less than about 20% of the flow rate indicated by the corresponding differential signal 172, or 100% damping to clamp the actuator rod 142 to a certain position. The non-zero flow rate indicated by the damped differential signal 182 can set the maximum speed at which the actuator rod 142 moves relative to the cylinder 140 to less than 15 mm / sec, such as less than 10 mm / sec.

[0082] The controller of the system 100 (eg, the system controller 126, the test station controller 130, the actuator controller 170, the valve electronics 150, etc.) may be implemented in any suitable manner to control the various functions described herein, such as Fig. 9 The example controller 220 is shown in the form of an example controller 220. The controller 220 may include one or more processors 222 and a memory 224. The one or more processors 222 are configured to implement various functions described herein in response to executing instructions (such as a test program) contained in the memory 224.

[0083] The one or more processors 222 may be components of one or more computer-based systems and may include one or more control circuits, a microprocessor-based engine control system, and / or one or more programmable hardware components, such as a field programmable gate array (FPGA). The memory 224 represents a local and / or remote memory or computer-readable medium. Such a memory 224 includes any suitable computer-readable medium that complies with the patent subject matter and does not include transient waves or signals. Examples of the memory 224 include conventional data storage devices, such as hard disks, CD-ROMs, optical storage devices, magnetic storage devices, and / or other suitable data storage devices. The controller 220 may include a circuit 226 that is used by the one or more processors 222 to receive input signals 228 (e.g., sensor signals), issue control signals 230 (e.g., signals 164, 172, etc.), and / or transmit data 232, such as in response to the execution of instructions stored in the memory 224 by the one or more processors 222.

[0084] Although embodiments of the present disclosure have been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the present disclosure.

Claims

1. A method for controlling a hydraulic actuator of a test station of a dynamic test system, the test station comprising: a hydraulic actuator configured to induce actuation of a test object using a flow of hydraulic fluid; Control valves; Actuation sensor; Test the controller; Actuator controller; as well as Flow control circuit, The method comprises: generating, using the actuation sensor, a feedback signal indicative of a parameter of the actuation; generating, using the test controller, a reference signal indicative of a desired actuation based on a test procedure; generating, using the actuator controller, a differential signal based on a difference between the reference signal and the feedback signal; placing the flow control circuit in one of a first state and a second state based on a flow decay signal; Delivering an actuator command signal to the control valve using the flow control circuit includes: delivering the differential signal as the actuator command signal to the control valve when the flow control circuit is in the first state; and delivering the attenuated differential signal as the actuator command signal to the control valve when the flow control circuit is in the second state; and controlling the amount and direction of the hydraulic fluid flow based on the actuator command signal, The flow rate corresponding to the attenuated differential signal is smaller than the flow rate corresponding to the differential signal.

2. The method according to claim 1, wherein: The flow rate corresponding to the attenuated differential signal is a non-zero flow rate.

3. The method according to claim 2, wherein: The non-zero flow rate is less than about 20% of the flow rate corresponding to the differential signal.

4. The method according to claim 3, wherein: The non-zero flow rate limits movement of an actuator rod of the hydraulic actuator that causes the actuation to less than about 15 mm / sec.

5. The method according to claim 1, wherein: A flow rate corresponding to the attenuated differential signal is substantially zero and substantially clamps an actuator stem causing the actuation.

6. The method according to any one of claims 1 to 5, wherein: The hydraulic actuator comprises: cylinder; and an actuator rod comprising a piston contained within the cylinder, wherein movement of the piston and the actuator rod relative to the cylinder causes the actuation; and The control valve comprises: A housing, the housing comprising: an inlet port coupled to a supply of high pressure hydraulic fluid; an outlet port coupled to a low pressure reflux reservoir; a first port coupled to a first working volume formed by an inner cavity of the cylinder and the piston; and a second port coupled to a second working volume formed by the inner cavity of the cylinder and the piston; a valve body contained in the housing, the valve body having a position for directing the flow of the hydraulic fluid received at the inlet port to one of the first port and the second port or not to any of the first port and the second port and controlling a flow rate of the flow of the hydraulic fluid; and A valve body driver is configured to adjust a position of the valve body based on the actuator command signal.

7. The method according to claim 6, wherein: The valve body actuator includes a servo or a solenoid; and The valve body includes a sliding valve or a piston.

8. The method according to any one of claims 1 to 7, wherein: The actuation comprises movement of the test object; The actuation sensor comprises a displacement sensor; and The feedback signal is indicative of a displacement or movement of the test object.

9. The method according to any one of claims 1 to 8, wherein: The actuation comprises a force acting on the test object; The actuation sensor comprises a force gauge; and The feedback signal is indicative of a force applied to the test object.

10. The method of any one of claims 1 to 9, comprising generating the flow decay signal using the test controller.

11. The method of any one of claims 1 to 10, comprising attenuating the differential signal using the flow control circuit to form the attenuated differential signal.

12. A test station of a dynamic test system, the test station comprising: a hydraulic actuator configured to induce actuation of a test object using a flow of hydraulic fluid; a control valve configured to control the flow and direction of the hydraulic fluid and the actuation in response to an actuator command signal; an actuation sensor configured to generate a feedback signal indicative of a parameter of the actuation; a test controller configured to generate a reference signal corresponding to a desired actuation based on a test program; an actuator controller configured to generate a differential signal based on a difference between the reference signal and the feedback signal; as well as a flow control circuit having a first state in which the flow control circuit is configured to deliver the differential signal as the actuator command signal to the control valve and a second state in which the flow control circuit is configured to deliver the attenuated differential signal as the actuator command signal to the control valve, in: The flow control circuit switches from the first state to the second state in response to the flow decay signal; and The flow rate corresponding to the attenuated differential signal is less than the flow rate corresponding to the differential signal.

13. The test station according to claim 12, wherein: The flow rate corresponding to the attenuated differential signal is a non-zero flow rate.

14. The test station according to claim 13, wherein: The non-zero flow rate is less than about 20% of the flow rate corresponding to the differential signal.

15. The test station according to claim 14, wherein: The non-zero flow rate limits movement of an actuator rod of the hydraulic actuator that causes the actuation to less than about 15 mm / sec.

16. The test station of claim 12, wherein: The flow corresponding to the attenuated differential signal is substantially zero and clamps the actuator stem causing the actuation.

17. A test station according to any one of claims 12 to 16, wherein: The hydraulic actuator comprises: cylinder; and an actuator rod comprising a piston contained within the cylinder, wherein movement of the piston and the actuator rod causes the actuation; and The control valve comprises: A valve housing, the valve housing comprising: an inlet port coupled to a supply of high pressure hydraulic fluid; an outlet port coupled to a low pressure reflux reservoir; a first port coupled to a first working volume formed by an inner cavity of the cylinder and the piston; and a second port coupled to a second working volume formed by the inner cavity of the cylinder and the piston; a valve body contained in the valve housing, the valve body having a position for directing the flow of the hydraulic fluid received at the inlet port to one of the first port and the second port or not to any of the first port and the second port and controlling a flow rate of the flow of the hydraulic fluid; and A valve body driver is configured to adjust a position of the valve body based on the actuator command signal.

18. The test station of claim 17, wherein: The valve body actuator includes a servo or a solenoid; and The valve body includes a sliding valve or a piston.

19. A test station according to any one of claims 12 to 18, wherein: The actuation comprises movement of the test object; The actuation sensor comprises a displacement sensor; and The feedback signal is indicative of a displacement or movement of the test object.

20. A test station according to any one of claims 12 to 19, wherein: The actuation comprises a force acting on the test object; The actuation sensor comprises a force gauge; and The feedback signal is indicative of a force applied to the test object.

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