Controller Area Network Condition Monitoring and Bus Health on In-Vehicle Communications Networks

• US 20080186870A1
• Filed: 01/29/2008
• Published: 08/07/2008
• Est. Priority Date: 02/01/2007
• Status: Active Grant

• Current Assignee: Deere & Company
• Original Assignee: Deere & Company
• Inventors: Anderson, Noel Wayne, Butts, Nicholas Lloyd
• Granted Patent: US 8,213,321 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04L 2012/40215 Controller Area Network CAN
• CPC Class Codes: H04L 2012/40273 the transportation system being a vehicle
• CPC Class Codes: H04L 41/0659 by isolating or reconfiguring faulty entities
• CPC Class Codes: H04L 43/045 for graphical visualisation of monitoring data
• CPC Class Codes: H04L 43/0847 Transmission error

Abstract

A method and system monitor a communications network, e.g., a controller area network (CAN), and more specifically, an in-vehicle communications network, by maintaining a count of each type of error code and a histogram of all network messages seen by each of the controllers during a measurement period; and by determining a bus health index of the communication bus based upon a percentage of a given type of error to the total count of all errors during a measurement period. An individual controller or controller area network bus segment can be indicated as having a communications problem as a result of the health index.

Claims

1. A method for monitoring a condition of a communications network having a plurality of controllers communicatively coupled over the network by a communication bus, the method comprising:

maintaining a count of each type of error code and a histogram of all network messages seen by each of the controllers within a separate communication bus segment during a measurement period; and

determining a bus health index of each segment of the communication bus based upon a percentage of a given type of error to the total count of all errors during a measurement period.

2. The method of claim 1 wherein the bus health index is further based on pre-defined weights given to the percentage of each of the given type of errors to the total count of errors, and the number of messages lost during the measurement period.

3. The method of claim 1 further comprising determining a potential future failure of a component before the component fails by determining a change in the health index as a result of changes, over a time period of a plurality of measurement periods, in the percentages of at least one of the given type of errors to the total count of all errors determined during each of the plurality of measurement periods.

4. The method of claim 1 further comprising determining a given controller to fail at some future point in time based on trends of the health index.

5. The method of claim 1 further comprising generating web pages with the status and results of the monitoring by displaying graphs of network errors, network bus loading, and error counts.

6. The method of claim 1 further comprising detecting and isolating an individual controller that is having a communications problem by determining that the isolated individual controller having the communication problem has an elevated health indicator when compared to other controllers on the network bus whereby an indication is given to a user that the individual controller or network bus segment should be replaced or repaired.

7. A system comprising:

a communications network having a plurality of controllers communicatively coupled over the network by a communication bus, the system comprising;

program code associated with each controller for maintaining a count of each type of error code and a histogram of all network messages seen by each of the controllers during a measurement period; and

a central controller having means for determining a bus health index of the communication bus based upon a percentage of a given type of error to the total count of all errors during a measurement period.

8. The system of claim 7 wherein the counts from each controller are synchronized across all controllers through a start and stop message to all controllers.

9. A system for monitoring an in-vehicle communications network having a plurality of separate controllers for each one of a plurality of sensors and devices, the controllers communicatively coupled over the network, comprising:

means for receiving data from each controller of a count of each type of error code and a histogram of all network messages seen by each of the controllers during a measurement period; and

a central controller having means for determining a network health index for each controller comprising a first part based upon a total error count for the controller and individual error counts multiplied by a user-defined configurable weight and a second part based upon a number of messages a controller transmits versus the number of messages another controller receives.

10. The system of claim 9 further comprising means for determining, based on trends in the data, if a given controller is going to fail by setting the desired weights for the various errors based on previously running the program code for determining and receiving data from the in-vehicle controllers over time and recording the results and adjusting the desired weights based on the results.

11. The system of claim 9 wherein the type of error codes comprise at least one of a stuff error that indicates six or more consecutive bits of the same state;

a form error that indicates that a fixed format part of a controller are network frame was received with an incorrect state, and ACK error that indicates when no other controllers on the bus acknowledge the transmitted controller area network message;

a bit 1 error that indicates when a transmitting unit wanted to transmit a recessive bit (a logic

     1) but the monitoring value on the bus was a dominant (a logic

     0) bit;

a bit 0 error that indicates when a transmitting unit wanted to transmit a dominant bit (a logic

     0) but the monitoring value on the bus was a recessive bit (a logic

     1);

a CRC error that indicates when the calculated CRC of the data that was received and the CRC within the frame do not match, typically caused by a corrupt bit in the frame;

an error warning indicating that the controller area network controller has gone from the Error Active state to the Error Passive State; and

bus off error that indicates that the controller area network controller has shut itself off from transmitting or receiving data.