# US 2025/0146516 A1 · Methods for fault diagnosis of pressure sensor of electro-hydraulic system with explicit controller and implicit controller in parallel

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- Number: US 2025/0146516 A1
- Document ID: US20250146516A1
- Status: Published application
- Kind: A1
- Application number: 18/914,117
- Filed: 2024-10-12
- Published: 2025-05-08
- Earliest claimed: 2023-11-07
- Assignees: East China Jiaotong University; Chongqing University
- Applicants: East China Jiaotong University; Chongqing University
- Inventors: Gang LI; Diancheng CHEN; Ruqi DING; Min CHENG; Liqiu LIAO; Zhanchao HE; Guoliang HU; Qianjie LIU; Liping ZENG
- Web page: https://patentgrep.com/patent/US20250146516A1

## CPC

- F15B 19/005: {Fault detection or monitoring}
- F15B 13/086: {Sensing means, e.g. pressure sensors}
- F15B 21/087: {Control strategy, e.g. with block diagram}
- F15B 2211/3057: having two valves, one for each port of a double-acting output member
- F15B 2211/30575: in a Wheatstone Bridge arrangement (also half bridges)
- F15B 2211/327: electrically or electronically
- F15B 2211/6306: representing a pressure
- F15B 2211/6309: the pressure being a pressure source supply pressure
- F15B 2211/6313: the pressure being a load pressure
- F15B 2211/6336: representing a state of the output member, e.g. position, speed or acceleration
- F15B 2211/6653: Pressure control
- F15B 2211/6654: Flow rate control
- F15B 2211/6656: Closed loop control, i.e. control using feedback
- F15B 2211/7053: Double-acting output members
- F15B 2211/8636: Circuit failure, e.g. valve or hose failure
- F15B 2211/87: Detection of failures
- F15B: SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR

## Abstract

A method for fault diagnosis of a pressure sensor of an electro-hydraulic system with an explicit controller and an implicit controller in parallel is provided. The method may include receiving parameter information of the electro-hydraulic system; estimating a first chamber pressure of the hydraulic actuator online by utilizing a second chamber pressure of the hydraulic actuator; obtaining valve opening signals of the explicit controller and the implicit controller in a valve controller; converting the valve opening signals are difference-calculated to obtain two residual signals; and the residuals of an independent metering valve 1 and an independent metering valve 2 are compared with a preset threshold, respectively, to identify whether the independent metering valve 1 and the independent metering valve 2 are faulty or not. The method is simple to operate, has a fast response time and low cost for troubleshooting, and improves the diagnostic accuracy and coverage of the electro-hydraulic system.

## Claims

### Claim 1

A method for fault diagnosis of a pressure sensor of an electro-hydraulic system with an explicit controller and an implicit controller in parallel implemented by a processor, comprising:
receiving parameter information of the electro-hydraulic system, the parameter information including a first chamber pressure of a hydraulic actuator and a second chamber pressure of the hydraulic actuator;
obtaining, based on the first chamber pressure, an opening signal of an independent metering valve 1 controlled by the explicit controller; and obtaining, based on an online estimate value of the first chamber pressure, an opening signal of the independent metering valve 1 controlled by the implicit controller;
obtaining, based on the second chamber pressure, an opening signal of an independent metering valve 2 controlled by the explicit controller using a pressure control loop; and obtaining, based on a reference velocity of the hydraulic actuator, an opening signal of the independent metering valve 2 controlled by the implicit controller using a flow control loop;
determining a first residual of the independent metering valve 1 by performing subtraction on the opening signal of the independent metering valve 1 calculated by both the implicit controller and the explicit controller at the same time. and determining a second residual of the independent metering valve 2 by performing subtraction on the opening signal of the independent metering valve 2 calculated by both the implicit controller and the explicit controller at the same time; and the opening signal of the independent metering valve 2 controlled by the explicit controller;
identifying whether the independent metering valve 1 and the independent metering valve 2 are faulty by comparing the first residual and the second residual respectively with preset thresholds corresponding to the first residual and the second residual, wherein
the obtaining an online estimate value of the first chamber pressure by estimating in the initial state, based on the pressure of two chambers of a hydraulic actuator which different weights are assigned, the first chamber pressure includes:
designing a tracking controller GTr of the first chamber pressure:
G
Tr
=
2
⁢
ζω
n
⁢
s
+
ω
n
2
K
p
⁢
s
2
+
K
i
⁢
s
where s denotes a transfer function after a Laplace transform of a first differential link, Kp denotes a proportional adjustment coefficient, Ki denotes an integral adjustment coefficient, and ωn and ξ denote a closed-loop intrinsic frequency and damping of the tracking controller; and
determining the online estimate value according to a following equation:
p
ˆ
1
=
G
Tr
⁢
G
PI
1
+
G
Tr
⁢
G
PI
⁢
p
1
+
G
PI
1
+
G
Tr
⁢
G
PI
⁢
(
p
2
,
ref
-
p
2
)
,
where GPI=Kp+Ki1/s, {circumflex over (p)}1 denotes the online estimate value, p1 denotes the first chamber pressure, p2 denotes the second chamber pressure, p2,ref denotes a preset target reference pressure, and GPI denotes a proportional integral controller,
G
Tr
⁢
G
PI
1
+
G
Tr
⁢
G
PI
as a weight coefficient responding directly to changes in p1, and
G
PI
1
+
G
Tr
⁢
G
PI
as a weight coefficient responding directly to changes in (p2,ref−p2);
the obtaining, based on the first chamber pressure, an opening signal of an independent metering valve 1 controlled by the explicit controller includes:
adopting the flow control loop for the independent metering valve 1 controlled by the explicit controller and determining the opening signal of the independent metering valve 1 controlled by the explicit controller according to a following equation:
u
1
=
u
-
1
(
ν
ref
·
A
1
,
p
s
-
p
1
)
,
where u1 denotes the opening signal, vref denotes the reference velocity of the hydraulic actuator, A1 denotes an area of a rodless chamber of the hydraulic actuator, ps denotes a pressure of the electro-hydraulic system, p1 denotes the first chamber pressure, u−1(qref,Δp1) denotes a valve opening calibrated in advance using a reference flow and a differential pressure, qref denotes a product of the reference velocity vref and the area A1 of the rodless chamber, and Δp1 denotes a difference between the pressure ps of the electro-hydraulic system and the first chamber pressure p1;
the obtaining, based on the online estimate value of the first chamber pressure, an opening signal of the independent metering valve 1 controlled by the implicit controller includes:
adopting the flow control loop for the independent metering valve 1 controlled by the implicit controller and determining the opening signal u of the independent metering valve 1 controlled by the implicit controller according to a following equation:
u
1
′
=
u
-
1
(
ν
ref
·
A
1
,
p
s
-
p
ˆ
1
)
,
where {circumflex over (p)}1 denotes the online estimate value of the first chamber pressure, u−1(qref,Δp1′) denotes a valve opening calibrated in advance using a reference flow and a differential pressure, and Δp1′ denotes a difference between the pressure ps of the electro-hydraulic system and the online estimate value {circumflex over (p)}1;
the obtaining, based on the second chamber pressure, an opening signal of an independent metering valve 2 controlled by the explicit controller using a pressure control loop includes:
adopting the pressure control loop for the independent metering valve 2 controlled by the explicit controller and determining the opening signal of the independent metering valve 2 controlled by the explicit controller according to a following equation:
u
2
=
K
p
·
(
p
2
-
p
2
,
ref
)
+
K
i
⁢
∫
t
t
i
(
p
2
-
p
2
,
ref
)
⁢
dt
,
where u2 denotes the opening signal, p2 denotes the second chamber pressure, p2,ref denotes the preset target reference pressure, t denotes an integration starting time, and ti denotes an integration termination time; and
the obtaining, based on a reference velocity of the hydraulic actuator, an opening signal of the independent metering valve 2 controlled by the implicit controller using a flow control loop includes:
adopting the flow control loop for the independent metering valve 2 controlled by the implicit controller and determining the opening signal u′2 of the independent metering valve 2 controlled by the implicit controller according to a following equation:
u
2
′
=
u
-
1
(
v
ref
·
A
2
,
p
2
-
p
r
)
,
where A2 denotes an area of a rod chamber of the hydraulic actuator, pr denotes a return oil pressure, u−1(qref′,Δp2) denotes a valve opening calibrated in advance using a reference flow and a differential pressure, qref′ denotes a product of the reference velocity vref and the area A2 of the rod chamber, and Δp2 denotes a difference between the second chamber pressure p2 and the return oil pressure pr;
determining a flow adjustment amount based on a relationship between the first residual and the preset threshold corresponding to the first residual and a relationship between the second residual and the preset threshold corresponding to the second residual, including:
in response to a determination that the first residual exceeds the preset threshold corresponding to the first residual and the second residual exceeds the preset threshold corresponding to the second residual,
updating, based on a second preset rule, the flow adjustment amount,
generating, based on an updated flow adjustment amount, at least one of a power source adjustment instruction and an opening adjustment instruction; and
adjusting, based on the power source adjustment instruction, a power source flow by adjusting a working volume of a piston within a power source;
adjusting, based on the opening adjustment instruction, a degree of valve spool opening, by the explicit controller.

### Claim 2 (depends on 1)

The method of claim 1, wherein the identifying whether the independent metering valve 1 and the independent metering valve 2 are faulty by comparing the first residual and the second residual respectively with preset thresholds corresponding to the first residual and the second residual includes:
determining whether the first residual exceeds the preset threshold corresponding to the first residual;
in response to a determination that the first residual does not exceed the preset threshold corresponding to the first residual, determining whether the second residual exceeds the preset threshold corresponding to the second residual;
in response to a determination that the second residual exceeds the preset threshold corresponding to the second residual, determining that a signal is abnormal; or
in response to a determination that the second residual does not exceed the preset threshold corresponding to the second residual, determining that a first chamber pressure sensor of the hydraulic actuator and a second chamber pressure sensor of the hydraulic actuator are fault free.

### Claim 3 (depends on 2)

The method of claim 2, wherein the determining whether the first residual exceeds the preset threshold corresponding to the first residual further includes:
in response to a determination that the first residual exceeds the preset threshold corresponding to the first residual, determining whether the second residual exceeds the preset threshold corresponding to the second residual;
in response to a determination that the second residual exceeds the preset threshold corresponding to the second residual, determining that at least the second chamber pressure sensor of the hydraulic actuator is faulty; or
in response to a determination that the second residual does not exceed the preset threshold corresponding to the second residual, determining that the first chamber pressure sensor of the hydraulic actuator is faulty.

### Claim 4 (depends on 1)

A device for fault diagnosis of a pressure sensor of an electro-hydraulic system with an explicit controller and an implicit controller in parallel, comprising at least one processor and a storage medium, wherein
the storage medium is configured to store instructions; and
the processor is configured to operate according to the instructions to perform the method for fault diagnosis of a pressure sensor of an electro-hydraulic system with an explicit controller and an implicit controller in parallel according to claim 1.

### Claim 5 (depends on 1)

A non-transitory computer-readable storage medium storing a computer program, wherein when executed by a processor, the computer program may perform the method for fault diagnosis of a pressure sensor of an electro-hydraulic system with an explicit controller and an implicit controller in parallel according to claim 1.

### Claim 6 (depends on 1)

The method of claim 1, wherein the identifying whether the independent metering valve 1 and the independent metering valve 2 are faulty by comparing the first residual and the second residual respectively with preset thresholds corresponding to the first residual and the second residual includes:
determining, based on vibration data and electrical interference data, a sequence of interference time points through an interference model, wherein the interference model is a recurrent neural network model;
filtering, based on the sequence of interference time points, pressure data at a plurality of consecutive time points acquired by the pressure sensor; and
determining, based on filtered pressure data, the first residual and the second residual.

### Claim 7 (depends on 6)

The method of claim 6, wherein a training process of the interference model includes:
obtaining, by performing statistics on a large amount of historical vibration data and historical electrical interference data, a statistical result;
determining, based on the statistical result, different sets of training samples; and
training the different sets of training samples alternately according to scale sizes, wherein the different sets of training samples have different learning rates during the training process.