FAULT DIAGNOSIS

• US 20080189076A1
• Filed: 06/19/2007
• Published: 08/07/2008
• Est. Priority Date: 06/22/2006
• Status: Active Grant

• Current Assignee: Scania CV AB (Volkswagen AG)
• Original Assignee: Scania CV AB (Volkswagen AG)
• Inventors: Nyberg, Mattias
• Granted Patent: US 7,529,643 B2
• Time in Patent Office: Days
• US Class Current: 702/185
• CPC Class Codes: G06F 11/2257 using expert systems

Abstract

Status estimation i s determined for an entity having a plurality of components. An original disjunction of diagnostic expressions indicating at least one of a fault-free or at least one fault mode for at least one of the components is determined, which is then investigated against a set of diagnostic test results, and expressions that do not imply the test result are discarded. Further, for each statement in the test result, a joint diagnostic expression is generated representing a conjunction of the statement and the currently investigated diagnostic expression. Joint diagnostic expressions that imply one of the original diagnosis expressions are discarded. Otherwise, they are added to an updated disjunction of diagnostic expressions. All remaining diagnostic expressions in the temporary disjunction of diagnostic expressions are then added to the updated disjunction of diagnostic expressions, and a status report is produced.

Claims

1. A diagnosis engine (100) for estimating a status of an entity (150, 200) with a plurality of components (c₁, . . . , c_n) which each is assumed to be in a fault-free mode or be in exactly one of at least one fault mode, the diagnosis engine (100) comprising:

a processing unit (110) adapted to analyze test results (P¹, P^R); and

at least one storage area (120, 130, 140) adapted to store diagnostic data in respect of the entity (150, 200), wherein said processing unit (110) is adapted to;

receive an original disjunction of diagnostic expressions (D) indicating at least one of said modes for at least one of said components (c₁, . . . , c_n),

receive test results (P) of a set of diagnostic tests (T) in respect of the entity (150, 200), the result of each test (t₁, . . . , t_x) being a disjunction of statements (P¹₁ . . . P¹_x;

. . . ;

P^R₁ . . . P^R_z) wherein each statement (P^J_j) indicates at least one of said modes for one of said components (c₁, . . . , c_n),

store the expressions in the original disjunction of diagnostic expressions (D) to a temporary disjunction of diagnostic expressions (D_old) in a first storage area (120),

investigate, for each diagnostic expression in the temporary disjunction of diagnostic expressions (D_old), whether or not a currently investigated diagnostic expression (D₁) implies the test result (P^J);

if not so, remove the expression (D₁) from the temporary disjunction of diagnostic expressions (D_old); and

, for each statement (P^J_j) in the test result,

generate a joint diagnostic expression (D_new) representing a conjunction of the statement (P^J_j) and the currently investigated diagnostic expression (D₁),

compare the joint diagnostic expression (D_new) with each diagnostic expression in the original disjunction of diagnostic expressions (D) except for the currently investigated diagnostic expression (D₁), and if an original diagnostic expression (D_k) is found, where the joint diagnostic expression (D_new) implies the original diagnosis expression (D_k),

discard the joint diagnostic expression (D_new), and otherwise,

add the joint diagnostic expression (D_new) to an updated disjunction of diagnostic expressions (Q) in a second storage area (130), the updated disjunction of diagnostic expressions (Q) representing an estimated status of the entity (150, 200), thereafter

add all remaining diagnostic expressions in the temporary disjunction of diagnostic expressions (D_old) to the updated disjunction of diagnostic expressions (Q), and

produce a status report (R[Q]) based on the updated disjunction of diagnostic expressions (Q).

2. The diagnosis engine (100) according to claim 1, wherein after having processed a result of a first test (t₁) of the tests (T), the processing unit (110) is adapted to, for each result of at least one second test (t_x) of the tests (T):

investigate, for each diagnostic expression in the temporary disjunction of diagnostic expressions (D_old), whether or not a currently investigated diagnostic expression (D_i) implies the result of the second test (t_x);

if not so, remove the expression (D_i) from the temporary disjunction of diagnostic expressions (D_old); and

, for each statement (P^J_j) in the result of the second test (t_x),

generate a joint diagnostic expression (D_new) representing a conjunction of the statement (P^J_j) and the currently investigated diagnostic expression (D_i),

compare the joint diagnostic expression (D_new) with each diagnostic expression in the original disjunction of diagnostic expressions (D) except for the currently investigated diagnostic expression (D₁), and if an original diagnostic expression (D_k) is found, where the joint diagnostic expression (D_new) implies the original diagnosis expression (D_k),

discard the joint diagnostic expression (D_new), and otherwise,

add the joint diagnostic expression (D_new) to the updated dated disjunction of diagnostic expressions (Q) in the second storage area (130), thereafter

add all remaining diagnostic expressions in the temporary disjunction of diagnostic expressions (D_old) to the updated disjunction of diagnostic expressions (Q), and

produce an updated status report (R[Q]) based on the updated disjunction of diagnostic expressions (Q).

3. A motor vehicle (200) consisting of a plurality of components (c₁, . . . , c_n, . . . , c_s) and a diagnosis system adapted to estimate a status of at least a sub-group (c₁, . . . , c_n) of said components, wherein the diagnosis system comprises the diagnosis engine (100) of claim 1.

4. A method of diagnosing an entity with a plurality of components (C₁, . . . , c_n) which each is assumed to be in a fault-free mode or be in exactly one of at least one fault mode, said method comprising:

receiving an original disjunction of diagnostic expressions (D) indicating at least one of said modes for at least one of said components (c₁, . . . , c_n),

receiving a test result (P) of a set of diagnostic tests (T) in respect of the entity (150, 200), the result of each test (t₁, . . . , t_x) being a disjunction of statements (P¹₁ . . . P¹x;

. . . ;

P^R₁ . . . P^R_z) wherein each statement (P^J_j) indicates at least one of said modes for one of said components (c₁, . . . , c_n),

storing the expressions in the original disjunction of diagnostic expressions (D) to a temporary disjunction of diagnostic expressions (D_old) in a first storage area (120),

investigating, for each diagnostic expression in the temporary disjunction of diagnostic expressions (D_old), whether or not a currently investigated diagnostic expression (D_i) implies the test result (P^J);

if not so, remove the expression (D₁) from the temporary disjunction of diagnostic expressions (D_old); and

, for each statement (P^J_j) in the test result,

generating a joint diagnostic expression (D_new) representing a conjunction of the statement (P^J_j) and the currently investigated diagnostic expression (D_i),

comparing the joint diagnostic expression (D_new) with each diagnostic expression in the original disjunction of diagnostic expressions (D) except for the currently investigated diagnostic expression (D_i), and if an original diagnostic expression (D_k) is found, where the joint diagnostic expression (D_new) implies the original diagnosis expression (D_k),

discarding the joint diagnostic expression (D_new), and otherwise,

adding the joint diagnostic expression (D_new) to an updated disjunction of diagnostic expressions (Q) in a second storage area (130), the updated disjunction of diagnostic expressions (Q) representing an estimated status of the entity (150, 200), thereafter

adding all remaining diagnostic expressions in the temporary disjunction of diagnostic expressions (D_old) to the updated disjunction of diagnostic expressions (Q), and

producing a status report (R[Q]) based on the updated disjunction of diagnostic expressions (Q).

5. The method according to claim 4, wherein the receiving an original disjunction of diagnostic expressions (D) step receives an original disjunction of diagnostic expressions (D) that is empty prior to receiving a first test result (P) of a first set of diagnostic tests (T) of the entity.

6. The method according to claim 4, wherein after having processed a result of a first test (t₁) in the test result (P), the method comprises, for each result of at least one second test (t_x) in the test result (P):

investigating, for each diagnostic expression in the temporary disjunction of diagnostic expressions (D_old), whether or not a currently investigated diagnostic expression (D₁) implies the result of the second test (t_x);

if not so, remove the expression (D₁) from the temporary disjunction of diagnostic expressions (D_old); and

, for each statement (P^J_j) in the result of the second test (t_x),

generating a joint diagnostic expression (D_new) representing a conjunction of the statement (P^J_j) and the currently investigated diagnostic expression (D_i),

comparing the joint diagnostic expression (D_new) with each diagnostic expression in the original disjunction of diagnostic expressions (D) except for the currently investigated diagnostic expression (D_i), and if an original diagnostic expression (D_k) is found, where the joint diagnostic expression (D_new) implies the original diagnosis expression (D_k),

discarding the joint diagnostic expression (D_new), and otherwise,

adding the joint diagnostic expression (D_new) to the updated disjunction of diagnostic expressions (Q) in a second storage area (130), thereafter

adding all remaining diagnostic expressions in the temporary disjunction of diagnostic expressions (D_old) to the disjunction of diagnostic expressions (Q), and

producing an updated status report (R[Q]) based on the updated disjunction of diagnostic expressions (Q).

7. A computer program product directly loadable into the internal memory of a computer, comprising software for controlling the steps of claim 4 when said program is run on the computer.

8. The computer program product according to claim 7 further comprising software for controlling the steps of claim 5 when said program is run on the computer.

9. The computer program product according to claim 7 further comprising software for controlling the steps of claim 6 when said program is run on the computer.

10. A computer readable medium (160), having a program recorded thereon, where the program is to make a computer control the steps of claim 4.

11. The computer readable medium according to claim 10, wherein said program recorded thereon is further capable of making a computer control the steps of claim 5.

12. The computer readable medium according to claim 10, wherein said program recorded thereon is further capable of making a computer control the steps of claim 6.