Electricity: motive power systems – Positional servo systems – With particular 'error-detecting' means
Patent
1996-06-14
1999-07-06
Ro, Bentsu
Electricity: motive power systems
Positional servo systems
With particular 'error-detecting' means
318432, 318489, B62D 504
Patent
active
059201746
DESCRIPTION:
BRIEF SUMMARY
RELATED APPLICATION
This application is a National Stage of International Application No. PCT/JP95/02098 under 35 U.S.C. .sctn.371, filed Oct. 13, 1995.
TECHNICAL FIELD
The present invention relates to a control apparatus of an electric power steering apparatus equipped with an apparatus capable of detecting abnormality of a torque detection value.
BACKGROUND ART
In general, in a control apparatus of an electric power steering apparatus, a detection is made by a torque sensor constructed by a steering torque potentiometer of a steering system, and an electric motor for producing steering auxiliary force to the above-described steering system is controlled by a control means in response to a torque detection value of the torque sensor.
As described above, in the control apparatus of the electric power steering apparatus, since the steering auxiliary force produced by the electric motor is controlled based on the torque detection value of the torque sensor, when the torque detection value detected by the torque sensor is brought into the abnormality condition, the correct control can be no longer performed. Therefore, it is required to detect the abnormality of the torque sensor.
Here, as the abnormality of the torque sensor, there are two types of abnormality. That is, the torque detection value is drifted due to variations in power supply voltages and the aging change in contact resistance values of a connector connected to the torque sensor. Also, the torque detection value becomes abnormal, because of abnormality in the torque sensor caused by variations in the torque detection value by the aging change in the contact resistance values of the connector, and also loose contacts of the sliding contactor of the potentiometer.
Conventionally, as the drift detecting circuit for detecting drift abnormality of the torque sensor, for instance, one drift detecting circuit as shown in FIG. 20 has been proposed.
In this prior art, a torque sensor 101 is so arranged that applied steering torque is converted into torsion angle displacement of a torsion bar, and this torsion angle displacement is detected by a main potentiometer 102 and a sub-potentiometer 103 series-connected to the main potentiometer 102. Both end portions of the series circuit constructed of the series-connected potentiometers 102 and 103 are commonly connected to a power supply E, and the connection portion of the serial circuit is grounded. Torque voltages are derived from sliding contactors 102a and 103a of the respective potentiometers 102 and 103 by supplying the current of the power supply thereto, and these torque voltages are inputted to an electronic control circuit 104 employed in a power steering apparatus. Then, each of torque voltages Vm and Vs appearing at each of input resistors Rm and Rs provided at the input terminal of this electric control circuit 104 is entered via A/D converters 105 and 106 to a microcomputer 107. In the microcomputer 107, a calculation is made of a motor current instruction value based upon the torque voltage value Vm of the main potentiometer 102, and a drift is detected based upon the torque voltage values Vm and Vs of both of the main potentiometer 102 and the sub-potentiometer 103.
As indicated by a solid line in FIG. 21, torque voltages representative of a mutual reverse phase characteristic (cross characteristic) are produced from the respective potentiometers 102 and 103 constructed in the above manner. The torque voltage Vm of the sliding contactor 102a and the torque voltage Vs of the sliding contactor 103a become the same value as the voltage value Vo when the input torque is zero. For instance, assuming now that the respective sliding contactors 102a and 103a are moved together toward the lower side in the circuit diagram of FIG. 20 by applying right steering torque thereto, the torque voltage Vm is decreased in a substantially linear form, whereas the torque voltage Vs is increased in a substantially linear form. On the other hand, assuming now that the respective sliding contactors 102a and
REFERENCES:
patent: 5097420 (1992-03-01), Morishita
patent: 5699874 (1997-12-01), Miyaura
Endo Syuji
Kanoh Hiroyuki
Kawada Hideaki
Koiwai Hisayoshi
Kouzaki Yuji
NSK Ltd.
Ro Bentsu
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