Electric power-assisted steering system

Abstract

The invention discloses an electric power-assisted steering system which comprises a relay, a main MCU (Microprogrammed Control Unit) and an auxiliary MCU, wherein a normally-open contact of the relay is connected in a power-assisted motor driving loop in series; the main MCU and the auxiliary MCU carry out data transmission in a serial communication mode; the relay is jointly controlled by the main MCU and the auxiliary MCU; in the electrified initial operation period, the switching logic of the relay is diagnosed, and whether the relay can be controlled by the two MCUs to actuate according to correct logic is judged; in the program polling operation period, the two MCUs mutually monitor the operating states, when any one of the two MCUs breaks down, the relay is switched off through the other normally-operating MCU, a power supply of the motor-assisted motor driving loop is cut off, and the electric power-assisted steering system is enabled to be switched to the mechanical steering mode. With the adoption of the electric power-assisted steering system, the potential safety hazards in a hardware watchdog or a software watchdog can be solved, and the system security is guaranteed.

Description

technical field [0001] The invention relates to the technical field of automotive electronics, in particular to an electric power steering system with dual MCU (micro control unit) redundant monitoring functions. Background technique [0002] The electric power steering system is an automobile safety-related component, which has extremely high requirements on safety performance. It is required that when the electric power steering system breaks down or fails, the system / ECU (Electronic Control Unit) can cut off the power, so that the electric power steering system is in the mechanical steering mode to ensure driving safety. This puts forward safety requirements for each key sub-component of the electric power steering system, among which, the safety design of ECU software and hardware is particularly critical. [0003] At present, the safety design of the electric power steering system is mainly reflected in setting a hardware watchdog or a software watchdog, but this metho...

AI Technical Summary

Problems solved by technology

[0003] At present, the safety design of electric power steering system is mainly reflected in the setting of hardware watchdog or software watchdog, but this method has certain defects.

For example, although the hardware watchdog has the function of restarting the MCU, the general hardware watchdog device takes too long to feed the dog and cannot meet the action time specified by the safety performance requirements. The hardware watchdog cannot directly cut off the electric power steering system. If the power of the MCU needs to be increased, an additional auxiliary circuit needs to be added; the use of the software watchdog may cause the system to restart frequently, which will bring other safety hazards during the driving process; if the cause of the failure is that the crystal oscillator of the MCU stops Neither the watchdog nor the software watchdog can achieve the purpose of directly cutting off the power of the electric power steering system; the MCU cannot detect whether the hardware watchdog itself is faulty

Images