Control system and electric power steering control device

• US 8,825,299 B2
• Filed: 09/30/2010
• Issued: 09/02/2014
• Est. Priority Date: 09/30/2010
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Takatsuka, Yuji, Iwamoto, Keisuke
• Primary Examiner(s): Tarcza, Thomas
• Assistant Examiner(s): PIPALA, EDWARD J
• Application Number:
  US13/699,192
• Publication Number:
  US 20130066523A1
• Time in Patent Office: 1,433 Days
• Field of Search: 701/1, 701/36, 701/41, 701/43, 701/48, 701/70, 701/71, 701/72, 701/76, 701/78, 701/79, 701/82, 701/83, 701/91, 701/92, 701/93, 701/96, 701/97, 701/29.1, 701/29.2, 701/29.7, 701/30.3, 701/30.5, 701/30.7, 701/30.9, 701/31.1, 701/32.7, 701/32.8, 701/33.6, 701/33.7, 701/33.8, 701/33.9, 701/34.1, 701/34.3, 701/34.4, 340/901, 340/903, 340/425.5, 340/435, 340/436, 340/438, 340/439, 340/444, 340/932.2
• US Class Current: 701/41
• CPC Class Codes: B62D 15/027 Parking aids, e.g. instruction means
• CPC Class Codes: B62D 5/0493 detecting processor errors, e.g. plausibility of steering direction
• CPC Class Codes: B62D 6/08 responsive only to driver input torque
• CPC Class Codes: G05B 11/01 electric

Abstract

A main control device generates a first signal and a second signal, which is substantially equivalent to the first signal, in accordance with the input signal, a sub-control device includes a comparison-judgment-processing unit that compares the first signal with the second signal, and judges that an abnormality occurs when a state, in which a deviation between the both signals is greater than equal to a predetermined value, is continued in a time being equal to a first predetermined time, and a limitation unit is configured in such a way that the limitation unit adds a predetermined limitation to the output of the main control device in accordance with a result for which the comparison-judgment-processing unit judges that the abnormality occurs.

Claims

1. A control system comprising:

a main control device that generates output for controlling a controlled object in accordance with an input signal;

a sub-control device for monitoring an operating state of the main control device;

a communication-processing unit for communicating between the main control device and the sub-control device;

a limitation unit for limiting the output of the main control device in accordance with the monitoring by the sub-control device;

wherein

the main control device includes a first signal-processing unit that generates a first signal, which is used for generating the output, in accordance with the input signal, a second signal-processing unit that generates a second signal, which is substantially equivalent to the first signal, in accordance with the input signal, and an initialization-processing unit that periodically initializes the second signal,

the communication-processing unit has a function of transmitting the first signal and the second signal from the main control device to the sub-control device,

the sub-control device includes a comparison-judgment-processing unit that compares the first signal with the second signal, which are transmitted from the main control device via the communication-processing unit, and judges that an abnormality occurs when a state, in which a deviation between the both signals is greater than equal to a predetermined value, is continued in a time being longer than or equal to a first predetermined time, an initialization-judgment-processing unit that judges that an abnormality occurs when a state, in which the second signal is not initialized by the initialization-processing unit, is continued in a time being longer than or equal to a second predetermined time, and an abnormality-judging unit that judges that an abnormality occurs when at least one of the comparison-judgment-processing unit and the initialization-judgment-processing unit judges that the abnormality occurs,

and the limitation unit is configured in such a way that the limitation unit adds a predetermined limitation to the output of the main control device, when the abnormality-judging unit judges that the abnormality occurs;

wherein

the initialization-processing unit is configured in such a way that the initialization-processing unit initializes the second signal, after the communication-processing unit performs the transmission, and

a process cycle of the second signal-processing unit is defined to be longer than an initialization cycle of the initialization-processing unit.

2. An electric power steering control device comprising:

a main control device that generates output for controlling a motor that generates a steering auxiliary torque corresponding to a steering torque applied by a driver;

a sub-control device for monitoring an operating state of the main control device;

a communication-processing unit for communicating between the main control device and the sub-control device;

a limitation unit for limiting the output of the main control device in accordance with the monitoring by the sub-control device;

a torque-detecting unit for detecting the steering torque applied by the driver; and

a motor-current-detecting unit for detecting a motor current passed through the motor;

wherein

the main control device includes a first car-speed-signal-processing unit that generates a first car-speed signal in accordance with a car-speed signal inputted from a car-speed sensor (4), a second car-speed-signal-processing unit that generates a second car-speed signal, which is substantially equivalent to the first car-speed signal, in accordance with the car-speed signal, a target-current-determination unit that determines a target current of the motor in accordance with at least the detected steering torque and the first car-speed-signal, and a motor-current-control unit that generates output for controlling the motor current in accordance with the determined target current,

the communication-processing unit has a function of transmitting the first signal and the second signal from the main control device to the sub-control device,

the sub-control device includes a comparison-judgment-processing unit that compares the first signal with the second signal, which are transmitted from the main control device via the communication-processing unit, and judges that an abnormality occurs when a state, in which these signals are not equal to each other, is continued in a time being longer than or equal to a first predetermined time, a car-speed-judgment unit that judges that an abnormality occurs when the comparison-judgment-processing unit judges that the abnormality occurs, and a motor-current-abnormality-judging unit that judges that an abnormality occurs when a state, in which a current threshold is defined based on at least the detected steering torque, the first car-speed-signal, and a judgment result of the car-speed-judgment unit, and the detected motor-current value is greater than the current threshold, is continued in a time being longer than or equal to a third predetermined time,

and the limitation unit is configured in such a way that the limitation unit adds a predetermined limitation to the output of the motor-current-control unit, when the motor-current-abnormality-judging unit judges that the abnormality occurs.

3. An electric power steering control device according to claim 2, wherein the current threshold is determined based on the detected steering torque, the first car-speed-signal, and a judgment result of the car-speed-judgment unit, and the current threshold is defined as a first current threshold when a judgment result by the car-speed-judgment unit is normal state, and the first car-speed signal is lower than a predetermined value, and defined as a second current threshold when the judgment result by the car-speed-judgment unit is abnormal state, or the first car-speed signal is greater than or equal to the predetermined value, and moreover, the second current threshold is lower than the first current threshold.

4. An electric power steering control device according to claim 2, further comprising:

an automatic parking-control unit that outputs an automatic parking-control current for performing automatic parking control and an automatic parking control-command flag, which is turned on when the automatic parking control is executed and turned off when the automatic parking control is stopped; and

an current-addition unit that adds the automatic parking-control current to the motor-target current so as to generate a new target current;

characterized in that

the current threshold is determined based on the detected steering torque, the first car-speed signal, a judgment result by the car-speed-judgment unit, and the automatic parking control-command flag, and the current threshold is defined as a first current threshold when a judgment result by the car-speed-judgment unit is normal state, and the first car-speed signal is lower than a predetermined value, and moreover, the automatic parking control-command flag is turned on, and defined as a second current threshold when the judgment result by the car-speed-judgment unit is abnormal state, or the first car-speed signal is greater than or equal to the predetermined value, or the automatic parking control-command flag is turned off, and moreover, the second current threshold is lower than the first current threshold.

5. An electric power steering control device comprising:

a main control device that generates output for controlling a motor that generates a steering auxiliary torque corresponding to a steering torque applied by a driver;

a sub-control device for monitoring an operating state of the main control device;

a communication-processing unit for communicating between the main control device and the sub-control device;

a limitation unit for limiting the output of the main control device in accordance with the monitoring by the sub-control device;

a torque-detecting unit for detecting the steering torque applied by the driver; and

a motor-current-detecting unit for detecting a motor current passed through the motor;

wherein

the main control device includes a first car-speed-signal-processing unit that generates a first car-speed signal in accordance with a car-speed signal inputted from a car-speed sensor, a second car-speed-signal-processing unit that generates a second car-speed signal, which is substantially equivalent to the first car-speed signal, in accordance with the car-speed signal, a target-current-determination unit that determines a target current of the motor in accordance with at least the detected steering torque and the first car-speed-signal, a motor-current-control unit that generates output for controlling the motor current in accordance with the determined target current, and an initialization-processing unit that periodically initializes the second signal,

the communication-processing unit has a function of transmitting the first signal and the second signal from the main control device to the sub-control device,

the sub-control device includes a comparison-judgment-processing unit that compares the first signal with the second signal, which are transmitted from the main control device (503) via the communication-processing unit, and judges that an abnormality occurs when a state, in which these signals are not equal to each other, is continued in a time being longer than or equal to a first predetermined time, an initialization-judgment-processing unit that judges that an abnormality occurs when a state, in which the second signal is not initialized by the initialization-processing unit, is continued in a time being longer than or equal to a second predetermined time, a car-speed-judgment unit that judges that an abnormality occurs when at least one of the comparison-judgment-processing unit and the initialization-judgment-processing unit judges that the abnormality occurs, and a motor-current-abnormality-judging unit that judges that an abnormality occurs when a state, in which a current threshold is defined based on at least the detected steering torque, the first car-speed-signal, and a judgment result of the car-speed-judgment unit, and the detected motor-current value is greater than the current threshold, is continued in a time being longer than or equal to a third predetermined time,

and the limitation unit is configured in such a way that the limitation unit adds a predetermined limitation to the output of the motor-current-control unit, when the motor-current-abnormality-judging unit judges that the abnormality occurs.