A full-redundancy power-assisted system for a vehicle steering engine

Abstract

The present application relates to the technical field of steering system, in particular to a full-redundancy power-assisted system of automobile steering machine.A full-redundancy power-assisted system of automobile steering machine, comprising a main control system and an auxiliary control system, characterized in that: the main control system and the auxiliary control system are consistent in structure, the main control system comprises a main chip power supply, a main inductor, a main power supply chip, a main control unit, a main pre-drive chip, a main capacitor, a main three-phase bridge and a main phase separator, the main control unit is powered by a 12V DC power supply after a filter circuit composed of the main chip power supply, the main inductor and the main capacitor, the main power supply chip is responsible for distributing and managing the voltage input of each component of the main control system, the main control unit is responsible for coordinating the power-assisted output of the main road of the steering system after comprehensively receiving signals, and the motor is driven by the main three-phase bridge through the main phase separator after power amplification by the main pre-drive chip.Compared with the prior art, the automobile steering system can meet the highest functional safety level.

Description

Technical Field

[0001] This invention relates to the field of steering system technology, specifically to a fully redundant power steering system for automobiles. Background Technology

[0002] Autonomous vehicles can effectively reduce driver workload, improve vehicle safety, and lower the incidence of traffic accidents. Simultaneously, they can significantly increase the capacity of existing roads, effectively alleviating traffic congestion, mitigating environmental pollution, and addressing various social and environmental problems caused by the rapid increase in car ownership. Currently, one of the core issues in autonomous driving technology research is how to achieve stable and reliable lateral control of the vehicle during autonomous driving. Lateral motion control refers to the control of the vehicle's direction of travel, aiming to guide the vehicle along a pre-set path. Lateral motion control is achieved through active front-wheel steering technology, enabling the vehicle to steer more quickly and responsively during driving. The steering system is one of the key technologies for achieving autonomous driving functions and a crucial foundation for stable and safe vehicle operation.

[0003] Traditional automotive steering systems can only support low levels of autonomous or assisted driving, primarily because their electronic and electrical architecture is non-redundant. When a single point of failure occurs, the steering system loses power steering, leaving the car in a "lost control" state and unable to support "autonomous driving," threatening the safety of the driver or pedestrians. Therefore, to meet the increasingly demanding requirements of autonomous driving technology, developing a fully redundant automotive steering system that supports advanced autonomous driving is imperative. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, this invention provides a fully redundant power steering system for automobiles, ensuring that the automobile steering system meets the highest functional safety level.

[0005] To achieve the above objectives, a fully redundant power steering system for automobiles is designed, comprising a main control system and an auxiliary control system. The main control system and the auxiliary control system have identical structures. The main control system includes a main chip power supply, a main inductor, a main power chip, a main control unit, a main pre-drive chip, a main capacitor, a main three-phase bridge, and a main phase separator. The main control unit is powered by a 12V DC power supply from the main chip power supply through a filter circuit composed of the main inductor and the main capacitor. The main power chip is responsible for distributing and managing the voltage input of each component in the main control system. The main control unit, by integrating the received signals, coordinates the power assist output of the main steering path and performs power adjustments through the main pre-drive chip. After power amplification, the main three-phase bridge drives the motor through the main phase separator; the auxiliary control system includes an auxiliary chip power supply, an auxiliary inductor, an auxiliary power chip, an auxiliary control unit, an auxiliary pre-drive chip, an auxiliary capacitor, an auxiliary three-phase bridge, and an auxiliary phase separator. The auxiliary control unit is powered by the auxiliary chip power supply through a filter circuit composed of an auxiliary inductor and an auxiliary capacitor, and then powered by a 12V DC power supply to the entire auxiliary control system. The auxiliary power chip is responsible for distributing and managing the voltage input of each component of the auxiliary control system. The auxiliary control unit is responsible for coordinating the power assist output of the steering system auxiliary circuit by integrating the received signals. After power amplification by the auxiliary pre-drive chip, the auxiliary three-phase bridge drives the motor through the auxiliary phase separator; the main control unit and the auxiliary control unit are connected by communication.

[0006] The motor is a six-phase motor.

[0007] The main control system and auxiliary control system use communication methods including UART, SPI, CAN, and PWM.

[0008] The communication between the main control unit and the auxiliary control unit includes vehicle CAN signals, torque angle signals, system operating status signals, power assist request signals, motor power assist distribution signals, and motor PWM wave signals.

[0009] The aforementioned fully redundant power steering system can be used in one of the following systems: upper column steering system, dual pinion steering system, and parallel shaft steering system.

[0010] The control methods for a fully redundant power assist system include normal operating mode, main road vehicle signal failure mode, main road control unit failure mode, auxiliary road ADC failure mode, and auxiliary road power signal failure mode.

[0011] The normal working mode is as follows:

[0012] S11 When the auxiliary control system fails, the main control system will receive the relevant fault signal from the auxiliary control system, and then implement the corresponding degradation strategy and calculate and allocate the system's auxiliary output.

[0013] S12, when the main control system fails, the auxiliary control system will receive relevant fault signals from the main control system and determine whether the fault type will cause the system to switch between main and auxiliary control.

[0014] The failure modes of the main road vehicle signal are as follows:

[0015] S21. When the vehicle CAN signal of the main control system fails or is lost, the main control unit of the main control system cannot perform system assist calculation and allocation based on the real-time vehicle operating status.

[0016] S22, the main control system will send a signal indicating the failure of its own vehicle CAN signal to the auxiliary control system through inter-chip communication. After receiving the signal from the main control system, the vehicle system will transmit the vehicle signal received by the auxiliary control system to the main control system for steering assist calculation and distribution; the vehicle system can output 100% assist.

[0017] The failure mode of the main control unit is as follows:

[0018] S31, When the main control unit of the main control system fails, the main control system completely loses its working capability;

[0019] S32, when the vehicle system detects a failure in the main control system, the vehicle system will set the auxiliary control system as the main information path and use it for steering assist calculation and distribution; the vehicle system will output a maximum of 50% assist.

[0020] The failure modes of the auxiliary ADC are as follows:

[0021] S41, when the ADC of the auxiliary control system fails, the motor will not be able to be driven;

[0022] S42, at this time, the main control system and the auxiliary control system still complete information interaction. In the ADC failure mode of the auxiliary control system, the main and auxiliary control systems do not switch, and the vehicle system outputs a maximum of 50% assistance.

[0023] The failure mode of the auxiliary power supply signal is as follows:

[0024] S51, when the power supply to the auxiliary control system fails, the entire auxiliary control system is in a power-off state and cannot work.

[0025] In the S52, the main and auxiliary controls do not switch during the power failure mode of the auxiliary control system, and the two ends of the system cannot complete inter-chip communication. The system can output a maximum of 50% assist.

[0026] Compared with the prior art, the present invention provides a fully redundant power steering system for automobiles, ensuring that the automobile steering system meets the highest functional safety level.

[0027] Under normal circumstances, the fully redundant power steering system proposed in this invention keeps the two ends of the motor working simultaneously. Therefore, the fully redundant power steering system architecture can make full use of the vehicle's dual power output and has good compatibility with the vehicle's power system.

[0028] Furthermore, the fully redundant power steering system architecture only requires a maximum of 50% steering assistance per side channel, significantly reducing the performance requirements for various hardware components. This helps improve the lifespan of electronic devices and effectively increases the lifespan and safety of the vehicle's steering system. Therefore, through evaluation from multiple aspects such as vehicle matching, hardware requirements, and degradation strategies, the fully redundant power steering system architecture demonstrates excellent overall performance. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the system architecture of the present invention.

[0030] Figure 2 This is a schematic diagram showing the communication between the main control unit and the auxiliary control unit.

[0031] Figure 3 This is a schematic diagram of a fully redundant system in normal operating mode.

[0032] Figure 4 This is a diagram of the vector control structure for a six-phase permanent magnet motor.

[0033] Figure 5 A graph showing the relationship between the percentage of assistance provided and ambient temperature.

[0034] Figure 6 This is a schematic diagram showing the state switching of the main road vehicle signal failure mode.

[0035] Figure 7 This is a diagram illustrating the failure mode state switching of the main circuit control unit.

[0036] Figure 8 This is a schematic diagram showing the state switching of the auxiliary ADC failure mode.

[0037] Figure 9 This is a schematic diagram showing the state switching of the auxiliary power supply signal failure mode. Detailed Implementation

[0038] The present invention will now be further described with reference to the accompanying drawings.

[0039] like Figure 1As shown, a fully redundant power steering system for automobiles includes a main control system and an auxiliary control system. The main control system and the auxiliary control system have the same structure. The main control system includes a main chip power supply, a main inductor, a main power supply chip, a main control unit, a main pre-drive chip, a main capacitor, a main three-phase bridge, and a main phase separator. The main control unit 13a is powered by the main chip power supply 20a through a filter circuit composed of the main inductor 11a and the main capacitor 16a, and then supplies power to the entire main control system through a 12V DC power supply. The main power supply chip 12a is responsible for distributing and managing the voltage input of each component of the main control system. The main control unit 13a integrates the received signals and is responsible for coordinating the power assist output of the main steering system. After power amplification by the main pre-drive chip 15a, the power is delivered through the main three-phase bridge 17a and the main phase separator. The main control unit 18a drives the motor 19; the auxiliary control system includes an auxiliary chip power supply, an auxiliary inductor, an auxiliary power supply chip, an auxiliary control unit, an auxiliary pre-drive chip, an auxiliary capacitor, an auxiliary three-phase bridge, and an auxiliary phase separator. The auxiliary control unit 13b is powered by the auxiliary chip power supply 20b through a filter circuit composed of auxiliary inductor 11b and auxiliary capacitor 16b, and then powered by a 12V DC power supply to the entire auxiliary control system. The auxiliary power supply chip 12b is responsible for distributing and managing the voltage input of each component of the auxiliary control system. The auxiliary control unit 13b is responsible for coordinating the power assist output of the steering system auxiliary circuit by integrating the received signals. After power amplification by the auxiliary pre-drive chip 15b, the auxiliary three-phase bridge 17b drives the motor 19 through the auxiliary phase separator 18b. The main control unit 13a and the auxiliary control unit 13b are connected by communication.

[0040] Motor 19 is a six-phase motor.

[0041] The communication methods for the main control system and the auxiliary control system include UART, SPI, CAN, and PWM communication.

[0042] The communication between the main control unit 13a and the auxiliary control unit 13b includes vehicle CAN signals, torque angle signals, system operating status signals, power assist request signals, motor power assist distribution signals, and motor PWM wave signals.

[0043] A fully redundant power steering system can be used in one of the following systems: upper column steering system, dual pinion steering system, and parallel shaft steering system.

[0044] A control method for a fully redundant power steering system for automobiles includes a normal operating mode, a main road vehicle signal failure mode, a main road control unit failure mode, an auxiliary road ADC failure mode, and an auxiliary road power supply signal failure mode.

[0045] This fully redundant power steering system architecture consists of a main control system and an auxiliary control system that are completely symmetrical on both sides. The two systems can operate independently to complete the calculation and transmission of steering assist. Furthermore, both systems can share a common grounding protection or each path can have independent grounding protection to ensure the system's electrical safety. Under normal operating conditions, the main control system is the primary control path, and the auxiliary control system is the secondary control path. The two systems exchange information in real time to ensure the system operates in a redundant state.

[0046] The fully redundant power steering system architecture for automobiles mainly consists of electronic and electrical components including at least one motor (six-phase motor), two control units (one main control unit 13a and one auxiliary control unit 13b), two power chips (one main power chip 12a and one auxiliary power chip 12b), two pre-drive chips (one main pre-drive chip 15a and one auxiliary pre-drive chip 15b), two CAN transceivers, two three-phase bridges (one main three-phase bridge 17a and one auxiliary three-phase bridge 17b), two reverse polarity protectors (one main MOSFET 14a and one auxiliary MOSFET 14b), six phase separators grouped into two main and auxiliary paths, used to control the protection of the two motors respectively, two vehicle power supplies (one main chip power supply 20a and one auxiliary chip power supply 20b), several filter inductors (main inductor 11a and auxiliary inductor 11b) and capacitors (main capacitor 16a and auxiliary capacitor 16b), and a rotor position chip, etc.

[0047] like Figure 1 , Figure 2 As shown, in normal operating mode, the main and auxiliary paths of this fully redundant steering system are simultaneously operational. The main control system is powered by a 12V DC supply from the main chip power supply 20a through a filter circuit (main inductor 11a and main capacitor 16a). The main power chip 12a distributes and manages the voltage input to each component of the main control system. The main control unit 13a integrates the signals received by the main control system and coordinates the power assist output of the main steering path. After power amplification by the main pre-drive chip 15a, it drives the six-phase motor 19 to provide 50% power assist to the system. To reduce the failure rate of the steering system in the event of power assist loss, a main phase separator 18a is added to ensure that the six-phase motor 19 can still operate independently even if any phase fails. Furthermore, to prevent the steering system components from failing due to reverse connection of the vehicle power supply at the main control system end, a reverse polarity protector main MOSFET 14a is introduced to increase the robustness of the main control system.

[0048] The auxiliary control system is identical to the main control system, providing 50% assistance. Under normal operating conditions, both the main and auxiliary systems each provide 50% assistance. When combined, this fully redundant steering system can provide 100% steering assistance to meet the needs of high-level autonomous driving in various scenarios, ensuring the intelligent and safe driving of the entire vehicle.

[0049] The overall control strategy of the fully redundant power assist system of this invention is as follows: the upper-level system uses a master-slave control mode to ensure reasonable calculation and allocation of the requested torque of the active unit, while the lower-level system responds independently to ensure accurate motor assist output. The main control unit 13a and the auxiliary control unit 13b communicate with each other, supporting real-time data transmission and synchronization between the two control units. Master-slave switching and signal transmission can ensure maximum system availability in the event of a fault.

[0050] like Figure 3 The diagram shows a fully redundant system under normal operating conditions. The main control system and auxiliary control system receive two independent vehicle power signals, torque input signals, and vehicle CAN signals, respectively. When either of these pathways is affected by external environmental or signal interference, the individual system (the two systems do not interfere with each other) will compensate for the interference it receives. When the ambient temperature is too high or too low, the temperature sensor in the ECU will calculate the temperature change of the individual system in real time and adjust and compensate for the motor assist output according to the temperature change range. For example, if the temperature decreases, the system will actively increase the motor assist to compensate for insufficient steering assist caused by low ambient temperature. If the temperature increases, the system will actively reduce the motor assist output to avoid damage to the steering system's electronic components due to high ambient temperature. Similarly, when either system senses power fluctuations, it will also compensate for the steering assist based on the amplitude of the power change to overcome damage to the steering system's electronic components or unstable steering assist control caused by power system instability. When the steering system senses different road surface stimuli, it predicts the road conditions in the next period based on real-time road feedback and adjusts the power assist output in a timely manner to adapt to different road surface conditions, thereby improving vehicle handling stability and driver comfort.

[0051] like Figure 4 , Figure 5 As shown, taking the example of protecting the system by reducing the output of the motor assistance when the ambient temperature rises to a certain range, the process of automatic protection of the system is described. The mathematical model of the permanent magnet synchronous motor is the foundation for realizing vector control. In the dq coordinate system, the mathematical model of the permanent magnet motor can be expressed by the following formula: The flux linkage equation is... The voltage equation is: ; The torque equation is: ;in , , and Ld and Lq represent the dq-axis components of stator voltage, current, and flux linkage, respectively; Ld and Lq are the dq-axis inductances of the stator windings, and R1 is the stator resistance. For rotor permanent magnet flux linkage; This refers to the electromagnetic torque of the motor. This represents the number of pole pairs of the motor. Let be the rotor's electric angular velocity. As can be seen from Equation 3, It mainly consists of two parts: excitation torque and reluctance torque. The essence of vector control is the control of the amplitude and phase of the stator current vector of the motor.

[0052] like Figure 4 The diagram shows the vector control structure of a six-phase permanent magnet motor for a steering gear, which mainly employs a dual closed-loop structure for speed and current. In this motor control system, the rotor position sensor (RPS) detects the position of the rotor magnetic poles in real time, obtaining the absolute position of the rotor and the actual speed of the motor. The difference between the speed reference and the speed feedback is adjusted by the ASR to obtain the dq-axis current command of the current loop; the phase current detected by the current sampling resistor is transformed by Clarke and Park to obtain the feedback stator current. and The current loop reference and feedback difference are used to obtain the voltage reference in the α-β coordinate system through ACR and Park inverse transformation, and then the desired gate PWM signal is generated and sent to the inverter through SVPWM technology. As shown in Equation 3, once the motor parameters are determined, the electromagnetic torque depends only on the current. and Related, through the and Independent control allows for precise control of the torque of the permanent magnet motor.

[0053] To ensure maximum availability of the steering system while also ensuring its self-protection safety, the steering system architecture implements a power assist reduction protection mechanism when the ambient temperature exceeds 110°C. This prevents damage from continuous operation at high temperatures. The system utilizes real-time ambient temperature monitoring and a software module to implement power assist reduction protection at corresponding temperatures. The relationship between the percentage power assist reduction above 110°C and the ambient temperature is as follows: Figure 8 As shown, when the temperature exceeds 125℃, the system will reduce the power assist to 0, meaning the motor will stop providing steering assistance to the outside world, in order to protect the system from high temperatures.

[0054] When a fault occurs, the fully redundant power steering system architecture implements appropriate degradation strategies and necessary master-slave switching based on the form and severity of the fault, thereby ensuring system safety and availability. Major faults include, but are not limited to, failure of electronic and electrical components, loss or error of signals, software vulnerabilities, and vehicle power supply failure. Generally, when signals such as the main road torque signal, angle signal, and CAN signal fail or are lost, the system does not switch, because the other path can obtain the corresponding information through IPC for control and torque distribution. However, when signals or electronic components such as the main road RPS signal, current signal, phase separation, and pre-drive chip fail, master-slave switching is required, mainly because the main road actuator has failed, and the upper-level control cannot control it.

[0055] In summary, when the upper-level control terminal of the main circuit fails, master-slave switching is generally not performed; however, when the lower-level execution terminal of the main circuit fails, master-slave switching is required to ensure the reliability and security of the system. The following analysis of several typical failure modes further explains the master-slave switching and fault degradation modes of this fully redundant auxiliary system.

[0056] like Figure 6 The diagram illustrates the state switching of the main road vehicle signal failure mode. When the vehicle CAN signal of the main control system fails or is lost, the main control unit of the main control system cannot perform system power assist calculation and allocation based on the real-time vehicle operating status, resulting in the "paralysis" of the main control system. In this case, the main control system will send a signal indicating its own vehicle CAN signal failure to the auxiliary control system via inter-chip communication. Upon receiving the signal from the main control system, the system will transmit the vehicle signal received by the auxiliary control system to the main control system for power assist calculation and allocation. Because the auxiliary control system can still receive the complete vehicle CAN signal in this failure mode and can synchronize the vehicle CAN signal to the main control system via inter-chip communication, no master-slave switching occurs in this fault mode, and the system can still output 100% power assist.

[0057] like Figure 7 The diagram illustrates the state switching of the main control unit failure mode. When the main control system completely loses its operational capability, the auxiliary control system, unable to receive relevant signals from the main control system for an extended period, will be set as the primary information path for steering assist calculation and distribution. Because the failure of the main control unit also causes the main control system of the six-phase motor it controls to malfunction, the vehicle system can only output a maximum of 50% steering assist after the master-slave switch occurs in this fault mode.

[0058] like Figure 8The diagram shows the state switching of the auxiliary circuit ADC failure mode. When the ADC of the auxiliary control system fails, the six-phase motor cannot be driven. Although information exchange between the two systems can still be completed, the main and auxiliary controls do not switch in this fault mode, and the vehicle system can only output a maximum of 50% assistance.

[0059] like Figure 9 The diagram shows the state switching of the auxiliary power supply signal failure mode. When the power supply of the auxiliary control system fails, the entire auxiliary control system is in a power-off state and cannot work. Therefore, in this fault mode, the main and auxiliary controls do not switch, and the two ends of the system cannot complete inter-chip communication. The system can output a maximum of 50% assistance.

Claims

1. A fully redundant power steering system for automobiles, comprising a main control system and an auxiliary control system, characterized in that: The main control system and the auxiliary control system have the same structure. The main control system includes a main chip power supply, a main inductor, a main power supply chip, a main control unit, a main pre-drive chip, a main capacitor, a main three-phase bridge, and a main phase separator. The main control unit (13a) is powered by the main chip power supply (20a) through a filter circuit composed of the main inductor (11a) and the main capacitor (16a), and then by a 12V DC power supply to the entire main control system. The main power supply chip (12a) is responsible for distributing and managing the voltage input of each component of the main control system. The main control unit (13a) is responsible for coordinating the power assist output of the steering system main road by integrating the received signals. After power amplification by the main pre-drive chip (15a), the motor (19) is driven by the main three-phase bridge (17a) through the main phase separator (18a). The auxiliary control system includes... The system includes an auxiliary chip power supply, an auxiliary inductor, an auxiliary power chip, an auxiliary control unit, an auxiliary pre-drive chip, an auxiliary capacitor, an auxiliary three-phase bridge, and an auxiliary phase separator. The auxiliary control unit (13b) is powered by the auxiliary chip power supply (20b) through a filter circuit composed of an auxiliary inductor (11b) and an auxiliary capacitor (16b), and then supplies power to the entire auxiliary control system through a 12V DC power supply. The auxiliary power chip (12b) is responsible for distributing and managing the voltage input of each component of the auxiliary control system. The auxiliary control unit (13b) is responsible for coordinating the power assist output of the steering system auxiliary circuit by integrating the received signals. After power amplification by the auxiliary pre-drive chip (15b), the auxiliary three-phase bridge (17b) drives the motor (19) through the auxiliary phase separator (18b). The main control unit (13a) and the auxiliary control unit (13b) are connected by communication. The communication between the main control unit (13a) and the auxiliary control unit (13b) includes vehicle CAN signal, torque angle signal, system operating status signal, power assist request signal, motor power assist distribution signal, and motor PWM wave signal.

2. The fully redundant power steering system for automobiles according to claim 1, characterized in that: The motor (19) is a six-phase motor.

3. The fully redundant power steering system for automobiles according to claim 1, characterized in that: The main control system and auxiliary control system use communication methods including UART, SPI, CAN, and PWM.

4. The fully redundant power steering system for automobiles according to claim 1, characterized in that: The aforementioned fully redundant power steering system can be used in one of the following systems: upper column steering system, dual pinion steering system, and parallel shaft steering system.

5. The fully redundant power steering system for automobiles according to claim 1, characterized in that: The control methods for a fully redundant power assist system include normal operating mode, main road vehicle signal failure mode, main road control unit failure mode, auxiliary road ADC failure mode, and auxiliary road power signal failure mode.

6. The fully redundant power steering system for automobiles according to claim 5, characterized in that: The normal working mode is as follows: S11 When the auxiliary control system fails, the main control system will receive the relevant fault signal from the auxiliary control system, and then implement the corresponding degradation strategy and calculate and allocate the system's auxiliary output. S12, when the main control system fails, the auxiliary control system will receive relevant fault signals from the main control system and determine whether the fault type will cause the system to switch between main and auxiliary control.

7. A fully redundant power steering system for automobiles according to claim 5, characterized in that: The failure modes of the main road vehicle signal are as follows: S21. When the vehicle CAN signal of the main control system fails or is lost, the main control unit of the main control system cannot perform system assist calculation and allocation based on the real-time vehicle operating status. S22, the main control system will send a signal indicating the failure of its own vehicle CAN signal to the auxiliary control system through inter-chip communication. After receiving the signal from the main control system, the vehicle system will transmit the vehicle signal received by the auxiliary control system to the main control system for steering assist calculation and distribution; the vehicle system can output 100% assist.

8. A fully redundant power steering system for automobiles according to claim 5, characterized in that: The failure mode of the main control unit is as follows: S31, When the main control unit of the main control system fails, the main control system completely loses its working capability; S32, when the vehicle system detects a failure in the main control system, the vehicle system will set the auxiliary control system as the main information path and use it for steering assist calculation and distribution; the vehicle system will output a maximum of 50% assist.

9. A fully redundant power steering system for automobiles according to claim 5, characterized in that: The failure modes of the auxiliary ADC are as follows: S41, when the ADC of the auxiliary control system fails, the motor will not be able to be driven; S42, at this time, the main control system and the auxiliary control system still complete information interaction. In the ADC failure mode of the auxiliary control system, the main and auxiliary control systems do not switch, and the vehicle system outputs a maximum of 50% assistance.

10. A fully redundant power steering system for automobiles according to claim 5, characterized in that: The failure mode of the auxiliary power supply signal is as follows: S51, when the power supply to the auxiliary control system fails, the entire auxiliary control system is in a power-off state and cannot work. In the S52, the main and auxiliary controls do not switch during the power failure mode of the auxiliary control system, and the two ends of the system cannot complete inter-chip communication. The system can output a maximum of 50% assist.

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