Degradation processing system for interaction of steer-by-wire system and whole vehicle

Abstract

The invention discloses a degradation processing system for interaction of a steer-by-wire system and a whole vehicle, and the system comprises an input signal processing module which processes a vehicle speed signal, a degradation state signal of an upper steering system, a degradation state signal of a lower steering system, and a degradation state signal of the whole vehicle; the degradation state management module is used for managing the action, the jump and the power-on state of the degradation state of the steering system; and the output state processing module is used for processing the effectiveness of the degradation state and the sending and alarming mode of the degradation state. By managing the degradation state of the steer-by-wire system, the reliability of the steering system is improved. When the system fails, the failure is managed in a classified mode, the optimal degradation state is determined by combining the current whole vehicle state to be given to the whole vehicle, and therefore it is guaranteed that the whole vehicle runs in the corresponding degradation state, and the vehicle speed and performance of the vehicle are limited according to the degradation state.

Description

Technical Field

[0001] This invention relates to the field of automotive steer-by-wire, and more particularly to safety downgrade technology for steer-by-wire, belonging to the field of functional safety technology. Background Technology

[0002] Traditional car steering systems achieve steering through the mechanical connection between the steering wheel and the front wheels. With the rapid development of autonomous driving and automotive intelligence, higher requirements are placed on the vehicle chassis, and traditional steering systems can no longer meet the diverse needs of advanced autonomous driving and intelligent cockpits.

[0003] Steer-by-Wire (SbW) systems eliminate the mechanical connection between the steering wheel and the steering actuator, thus decoupling the upper and lower steering structures. While this facilitates vehicle space layout, it also presents new challenges for functional safety. In traditional steering systems, even if power steering is lost, the driver can still control the vehicle's steering through the mechanical connection, preventing a complete loss of steering ability. Due to the unique structure of steer-by-wire systems (eliminating the mechanical connection), situations such as loss of communication between the upper and lower steering systems, loss of control of the upper steering system, or failure of the lower steering system to execute steering commands can lead to a loss of steering ability. Therefore, it is essential to implement methods to prevent failures or to handle safety issues in case of failure. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a degradation processing system for the interaction between the steer-by-wire system and the whole vehicle, which can solve the problem of the steering system losing steering ability due to malfunction of the steer-by-wire system.

[0005] To address the aforementioned problems, the present invention provides a steer-by-wire system and a degraded processing system for vehicle interaction, comprising:

[0006] The input signal processing module processes the vehicle speed signal, the degraded status signal of the upper steering system, the degraded status signal of the lower steering system, and the degraded status signal of the whole vehicle.

[0007] The degraded state management module manages the actions, jumps, and power-on status of the steering system in the degraded state.

[0008] The output status processing module handles the validity of the degraded status, the external transmission of the degraded status, and the alarm method.

[0009] Furthermore, the input signal processing module includes a vehicle speed signal processing unit, an upper steering system degraded state signal processing unit, a lower steering system degraded state signal processing unit, and a whole vehicle degraded state signal processing unit. The vehicle speed signal processing unit performs filtering and validity verification on the vehicle speed signal. The upper steering system degraded state signal processing unit verifies the validity of the upper steering system degraded state signal. The lower steering system degraded state signal processing unit verifies the validity of the lower steering system degraded state signal. The whole vehicle degraded state signal processing unit verifies the validity of the whole vehicle degraded state signal.

[0010] Furthermore, the vehicle speed signal processing unit first uses a low-pass filtering algorithm to process the vehicle speed signal, and then verifies the validity of the processed vehicle speed signal.

[0011] Furthermore, when the degraded status signal of the upper steering system, the degraded status signal of the lower steering system, and the degraded status signal of the whole vehicle are invalid, the upper steering system degraded status signal processing unit, the lower steering system degraded status signal processing unit, and the whole vehicle degraded status signal processing unit use default signal values.

[0012] Furthermore, the degraded states are classified according to the severity of the fault, from low to high: normal state, first degraded state, intermediate degraded state, second degraded state, and third degraded state. The normal state is when the steer-by-wire system has no faults and operates normally. The first degraded state is when the steer-by-wire system has a malfunction that does not affect the functional safety of the steering system, and the steer-by-wire system prohibits the operation of the malfunction. The second degraded state is when the steer-by-wire system is in a semi-assisted output state or the current request signal input only supports low-speed driving of the vehicle. The third degraded state is when the steer-by-wire system loses its steering function, making it impossible for the vehicle to perform steering operations.

[0013] Furthermore, the jump management of the degradation state management module includes jumping from the initial state to the normal state, jumping from the normal state to the first degradation state, jumping from the intermediate degradation state to the normal state, jumping from the first degradation state to the normal state, jumping from the normal state to the intermediate degradation state, jumping from the first degradation state to the intermediate degradation state, jumping from the intermediate degradation state to the first degradation state, jumping from the intermediate degradation state to the second degradation state, jumping from the intermediate degradation state to the third degradation state, and jumping from the second degradation state to the third degradation state.

[0014] Furthermore, the degradation state management module manages the degradation state where the fault that caused the system to enter a degradation state after power-on has been recovered, and the degradation state where the fault that caused the system to enter a degradation state after power-on has not been recovered.

[0015] Furthermore, after power is restored, if the fault that caused the system to enter a degraded state has been recovered, the steer-by-wire system will jump from the initialization state to a higher degraded state that is better than the degraded state of the system in the previous power-on cycle; if the fault that caused the system to enter a degraded state has not been recovered after power is restored, the steer-by-wire system will maintain the degraded state of the previous power-on cycle.

[0016] Furthermore, the output status processing module includes a degraded status validity verification unit, a degraded status external transmission processing unit, and an alarm information processing unit. The degraded status validity verification unit detects whether the current degraded status is the degraded status output by the degraded status management module. The degraded status external transmission processing unit matches the degraded status of the steer-by-wire system with the degraded status required by the vehicle and then transmits it externally. The alarm information processing unit transmits corresponding alarm prompt information according to different degraded statuses.

[0017] Furthermore, if the degradation status validity verification unit detects that the current degradation status is inconsistent with the degradation status output by the degradation status management module, then the previous valid degradation status will be retained.

[0018] This invention improves the reliability of the steer-by-wire system by managing its degraded states. When a system failure occurs, this invention categorizes and manages the failure, determining the optimal degraded state for the vehicle based on its current state. This ensures the vehicle operates in the corresponding degraded state and limits its speed and performance accordingly. Simultaneously, this invention receives the vehicle's degraded state, providing the driver with more operational flexibility. Even without a serious fault (such as unilateral failure), the steer-by-wire system can still provide steering capability. Even in the event of a severe failure, the vehicle coordinates with other systems to bring the steering system into a safe state, collectively ensuring driving safety after a failure and reducing the risk of accidents caused by steer-by-wire system failure. Furthermore, this invention, through degraded state management, records the type and severity of the fault, facilitating initial assessment by maintenance personnel and enabling faster fault location. Attached Figure Description

[0019] Figure 1 This is an architecture diagram of the degradation processing system of the present invention;

[0020] Figure 2 This is a schematic diagram illustrating the data flow direction in this invention;

[0021] Figure 3 This is a schematic diagram of the transition between each degradation state in this invention. Detailed Implementation

[0022] The embodiments of the present invention are described below with reference to the accompanying drawings and specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Specific details are set forth in the following description to provide a thorough understanding of the present invention; however, the present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be based on different viewpoints and applications. Those skilled in the art can make various similar extensions and substitutions without departing from the spirit of the present invention.

[0023] The steer-by-wire system and the degraded processing system for vehicle interaction in this embodiment, such as Figure 1 As shown, it includes:

[0024] The input signal processing module processes the vehicle speed signal, the degraded status signal of the upper steering system, the degraded status signal of the lower steering system, and the degraded status signal of the whole vehicle.

[0025] The degraded state management module manages the actions, jumps, and power-on status of the steering system in the degraded state.

[0026] The output status processing module handles the validity of the degraded status, the external transmission of the degraded status, and the alarm method.

[0027] Specifically, the input signal processing module includes a vehicle speed signal processing unit, an upper steering system degraded status signal processing unit, a lower steering system degraded status signal processing unit, and a whole vehicle degraded status signal processing unit. The degraded status management module includes a degraded status action management unit, a degraded status jump management unit, and a degraded status power-on management unit. The output status processing module includes a degraded status validity verification unit, a degraded status external transmission processing unit, and an alarm information processing unit.

[0028] In the entire degradation processing system, such as Figure 2 The data flow diagram shown indicates that the signal is input to the input signal processing module for processing, then passed to the degradation state management module for degradation state management, and finally passed to the output state processing module for processing and output of the final state.

[0029] In the input signal processing module, the vehicle speed signal processing unit performs filtering and validity verification on the vehicle speed signal. This mainly involves first using a low-pass filtering algorithm to process the vehicle speed signal to ensure that the vehicle speed signal does not change abruptly, and then verifying the validity of the processed vehicle speed signal to ensure that the received vehicle speed signal is usable.

[0030] In the input signal processing module, the upper steering system degraded status signal processing unit verifies the validity of the upper steering system degraded status signal, the lower steering system degraded status signal processing unit verifies the validity of the lower steering system degraded status signal, and the vehicle degraded status signal processing unit verifies the validity of the vehicle degraded status signal. Only when each signal is valid is it transmitted to the subsequent degraded status management module; when a signal is invalid, its default signal value is used for processing.

[0031] In the degradation state management module, the degradation state action management unit divides the degradation state into normal state, first degradation state, intermediate degradation state, second degradation state, and third degradation state according to the severity of the fault from low to high. The degradation state action management unit determines the current degradation state of the system based on the signal output by the input signal processing module and stores the degradation state.

[0032] The fault conditions corresponding to each degraded state and the corresponding actions of the steering system in each degraded state are described below:

[0033] In the normal state (NORMAL STATE), the steer-by-wire system is functioning normally without any malfunctions.

[0034] In the first degraded state (DEGRADATION 1STATE), the steer-by-wire system experiences a failure function that does not affect the functional safety of the steering system. In this state, the steer-by-wire system is prohibited from operating the failure function.

[0035] Intermediate state is an intermediate state before the system jumps to the second or third degraded state, and an intermediate state before jumping to the first degraded state or the normal state.

[0036] The second degraded state (DEGRADATION 2STATE) is when the steer-by-wire system is in a semi-assisted output state or the current request signal input only supports low-speed driving of the whole vehicle, such as when there is only one request signal input;

[0037] In the third degraded state (DEGRADATION 3STATE), the steer-by-wire system loses its steering function, making the vehicle unable to perform steering operations.

[0038] In current steer-by-wire systems, the functional failures that cause the system to enter the first degraded state include, but are not limited to, the following:

[0039] 1) Single-channel communication failure, including bus shutdown or timeout for all signals on the bus, and hardware failure that only affects single-channel communication, such as CAN transceiver failure;

[0040] 2) Key signals in the steer-by-wire system are lost, such as signals that affect steering capability or performance (e.g., vehicle speed signal, wheel speed signal);

[0041] 3) The soft limit function is malfunctioning;

[0042] 4) The alignment function is not working;

[0043] 5) Certain functions or signals that affect functional safety, such as when three or more redundancies are implemented in the system but one fails, leaving only two redundancies in the system (e.g., angle signals, if three inputs are redundant and one input is lost, leaving only two usable).

[0044] When the steer-by-wire system experiences a severe failure and enters a degraded intermediate state, the degraded state action management unit records the duration of this state. If the duration of the degraded intermediate state exceeds a set threshold, the degraded state jump management unit will degrade the steer-by-wire system. However, during the degrade process, the vehicle must still maintain a certain level of steering capability at high speeds. When the steer-by-wire system experiences a very severe failure and enters a degraded intermediate state, the recording of duration stops, and the system directly jumps to the second or third degraded state.

[0045] Of course, the intermediate state of degradation can be recovered. If the serious fault that has occurred in the steer-by-wire system can be cleared (i.e. the fault type supports recovery and it is determined that the fault has been recovered), then the intermediate state of degradation can jump to the normal state or the first degradation state.

[0046] It should be noted that the aforementioned severe failure and very severe failure are merely ways of describing faults. Those skilled in the art can analyze the impact of a failure on the system during architecture design, such as whether the failure affects motor control and steering capability, whether a unilateral failure is still considered reliable, or whether it affects functional safety, and record the occurrence of the fault. For example, if a fault results in a lack of power steering on one side, but the redundant system can still output the requested torque, then the current fault is considered a severe fault, entering a degraded intermediate state. In this state, the steering system can continue to output torque, and then a state transition is performed based on the occurrence of the failure.

[0047] A critical failure refers to jumping to the second or third degraded state, such as when steering up or down, or when redundant systems need to exchange information about the current fault to determine whether the entire system has the ability to perform steering.

[0048] The jump mechanism used by the degraded status jump management unit, such as... Figure 3As shown, the transitions include: from the initial state to the normal state, from the normal state to the first degraded state, from the degraded intermediate state to the normal state, from the first degraded state to the normal state, from the normal state to the degraded intermediate state, from the first degraded state to the degraded intermediate state, from the degraded intermediate state to the first degraded state, from the degraded intermediate state to the second degraded state, from the degraded intermediate state to the third degraded state, and from the second degraded state to the third degraded state.

[0049] Specifically, the transition mechanism between each downgraded state is triggered according to the following conditions:

[0050] After initialization is complete and no faults occur, the system transitions from the initialization state to the normal state, i.e., INIT→NORMAL STATE.

[0051] When the integrity of the up / down steering system is limited, that is, some system functions are lost but safety is not affected, the system jumps from the normal state to the first degraded state, i.e., NORMAL STATE→DEGRADATION 1STATE;

[0052] When the upper / lower steering system is only half-capable or has no execution capability, or when only one steering angle request is available, the system jumps from the current normal state or the first degraded state to the intermediate degraded state, i.e., NORMAL STATE / DEGRADATION 1STATE→INTERMEDIATE STATE. Specifically, the upper / lower steering system being only half-capable or having no execution capability includes situations where the upper steering system can only output half the power assist due to failure or environmental factors (e.g., power assist degraded resulting in insufficient current output capability), a single point failure affecting functional safety resulting in a lack of redundant computing capability, or a failure of the motor control of a single-sided system resulting in a lack of single-sided execution capability.

[0053] When the failure of the upper steering system and the lower steering system is recovered, the system can jump from the current degraded intermediate state or the first degraded state to the normal state, that is, INTERMEDIATE STATE / DEGRADATION 1STATE→NORMALSTATE.

[0054] When a system failure results in a lack of power steering on one side, the up / down steering system has reliable redundancy. This means that the software calculation and execution, as well as the hardware capabilities, are designed with multiple redundancies to ensure that the steering system can output the requested torque. The system is in a degraded intermediate state. After the fault is recovered, or if the steering system loses some functions but the failure does not affect functional safety, the system jumps from the degraded intermediate state to the first degraded state, i.e., INTERMEDIATE STATE → DEGRADATION1STATE.

[0055] When the steer-by-wire system remains in a degraded intermediate state for an extended period exceeding a set time threshold, or when the upper steering system loses its ability to execute commands, or when coordination between the upper and lower steering systems fails, the system transitions from the degraded intermediate state to the second degraded state: INTERMEDIATE STATE → DEGRADATION 2STATE. The upper and lower steering systems communicate via CAN signals. The upper steering system sends signals such as requested angles to the lower steering system, while the lower steering system sends signals such as road feel signals to the upper steering system. Simultaneously, the upper and lower steering systems exchange degraded status messages. When effective communication between the upper and lower steering systems fails, it is assumed that the upper steering system cannot provide feedback based on the lower steering system's status, and the lower steering system cannot execute steering commands based on the upper system's requests. In this case, coordination between the upper and lower steering systems is considered impossible.

[0056] When the steer-by-wire system loses the angle request signal or the steering system loses its steering execution capability, the system jumps from the intermediate state or the second degraded state to the third degraded state, i.e., INTERMEDIATE STATE / DEGRADATION2STATE → DEGRADATION 3STATE.

[0057] In this degradation processing system, the transition from the normal state or the first degradation state to the second degradation state or the third degradation state involves passing through intermediate degradation states. This design approach is mainly based on the following three considerations:

[0058] First, from a time perspective, failures usually do not occur directly, but rather develop and appear sequentially.

[0059] Second, in terms of the causes of failure, we can eliminate common causes between subsystems and redundant subsystems;

[0060] Third, from the perspective of vehicle processing, each state transition of the vehicle requires processing time. This system's setting of a downgraded intermediate state can provide sufficient time for the vehicle to confirm faults and take corresponding measures.

[0061] Of course, if a fault occurs and it is indeed necessary to immediately switch to the third or second degraded state, the overall switching time can be designed and defined according to safety requirements and customer requirements to ensure that the vehicle can respond quickly.

[0062] The degraded state power-on management unit is mainly used to perform state transitions based on the degraded state of the previous power-on cycle after power-on. It is mainly divided into the following two types:

[0063] One scenario is that after power is restored, the fault that caused the system to enter a degraded state has been recovered. In this case, the steering-by-wire system jumps from the initialization state to a higher-level degraded state that is better than the degraded state in the previous power-on cycle, as shown in Table 1.

[0064] Table 1 shows the status transitions after power-on and fault recovery.

[0065]

[0066]

[0067] In another scenario, if the fault that caused the system to enter a degraded state is not resolved after power is restored, the steering-by-wire system will remain in the degraded state of the previous power-on cycle.

[0068] The degradation status validity verification unit checks whether the current degradation status is the same as the degradation status output by the degradation status management module. If the current degradation status is found to be inconsistent with the degradation status output by the degradation status management module (i.e., there is a problem with the degradation status transition), then the previous valid degradation status will be used. If the degradation status verification is correct, then the current degradation status will be used for external processing.

[0069] The degraded state external processing unit matches the degraded state of the steer-by-wire system with the degraded state required by the vehicle and then sends it to the vehicle. The vehicle limits the vehicle speed and performance according to the degraded state.

[0070] The alarm information processing unit sends out corresponding alarm prompts based on different degradation states. If it is in the first degradation state, a yellow warning light will be sent out; if it is in an intermediate degradation state, the second degradation state, or the third degradation state, a red warning light will be sent out.

[0071] This invention designs a degradation processing method that meets the functional safety requirements of the entire vehicle. It primarily manages failures in the steer-by-wire system, selecting an appropriate degradation state based on the current vehicle status and sending it to the vehicle to notify it to degrade to the corresponding degradation state. Then, based on the degradation state, the vehicle's speed and performance are limited, thereby improving system reliability. When a system failure is detected, this invention can guarantee the reliability of the entire vehicle system through joint processing with other redundant systems. Degradation to a specific state is only implemented when the vehicle's state meets specific driving scenarios. Simultaneously, it provides the driver with more operational flexibility. Even in the event of a single point of failure, the system can still provide steering capability. Even in the event of a very severe failure, the vehicle will coordinate with other systems to bring the steering system into a safe state, reducing the risk of accidents caused by steering system failure. Ultimately, driving safety is ensured after a failure through the joint efforts of the steering system, vehicle pre-control, and braking system. Furthermore, the degradation state management of this invention can also record the type and severity of the fault, facilitating preliminary judgment by maintenance personnel and enabling faster fault location.

[0072] The present invention has been described in detail above through specific embodiments. These embodiments are merely preferred embodiments of the present invention, and the present invention is not limited to the above-described implementation methods. Equivalent substitutions and improvements made by those skilled in the art without departing from the principles of the present invention should be considered within the scope of the technology protected by the present invention.

Claims

1. A degradation processing system for interaction between a steer-by-wire system and the entire vehicle, characterized in that, include: The input signal processing module processes the vehicle speed signal, the degraded status signal of the upper steering system, the degraded status signal of the lower steering system, and the degraded status signal of the whole vehicle. The degraded state management module manages the actions, jumps, and power-on status of the steering system in the degraded state. The output status processing module handles the validity of the degraded status, the external transmission of the degraded status, and the alarm method.

2. The downgraded processing system for the steer-by-wire system and vehicle interaction according to claim 1, characterized in that, The input signal processing module includes a vehicle speed signal processing unit, an upper steering system degraded state signal processing unit, a lower steering system degraded state signal processing unit, and a whole vehicle degraded state signal processing unit. The vehicle speed signal processing unit filters and verifies the validity of the vehicle speed signal. The upper steering system degraded state signal processing unit verifies the validity of the upper steering system degraded state signal. The lower steering system degraded state signal processing unit verifies the validity of the lower steering system degraded state signal. The whole vehicle degraded state signal processing unit verifies the validity of the whole vehicle degraded state signal.

3. The downgraded processing system for the steer-by-wire system and vehicle interaction according to claim 2, characterized in that, The vehicle speed signal processing unit first processes the vehicle speed signal using a low-pass filtering algorithm, and then verifies the validity of the processed vehicle speed signal.

4. The steer-by-wire system and the degraded processing system for vehicle interaction according to claim 2, characterized in that, When the degraded status signal of the upper steering system, the degraded status signal of the lower steering system, and the degraded status signal of the whole vehicle are invalid, the upper steering system degraded status signal processing unit, the lower steering system degraded status signal processing unit, and the whole vehicle degraded status signal processing unit use the default signal values.

5. The downgraded processing system for the steer-by-wire system and vehicle interaction according to claim 1, characterized in that, The degraded states, ranked from lowest to highest severity of the fault, include: normal state, first degraded state, intermediate degraded state, second degraded state, and third degraded state. The normal state is when the steer-by-wire system has no faults and operates normally. The first degraded state is when the steer-by-wire system experiences a malfunction that does not affect the functional safety of the steering system, and the steer-by-wire system prohibits the operation of the malfunction. The second degraded state is when the steer-by-wire system is in a semi-assisted output state or the current request signal input only supports low-speed driving of the vehicle. The third degraded state is when the steer-by-wire system loses its steering function, making it impossible for the vehicle to perform steering operations.

6. The steer-by-wire system and the degraded processing system for vehicle interaction according to claim 1, characterized in that, The jump management of the degradation state management module includes jumping from the initial state to the normal state, jumping from the normal state to the first degradation state, jumping from the intermediate degradation state to the normal state, jumping from the first degradation state to the normal state, jumping from the normal state to the intermediate degradation state, jumping from the first degradation state to the intermediate degradation state, jumping from the intermediate degradation state to the first degradation state, jumping from the intermediate degradation state to the second degradation state, jumping from the intermediate degradation state to the third degradation state, and jumping from the second degradation state to the third degradation state.

7. The steer-by-wire system and the degraded processing system for vehicle interaction according to claim 1, characterized in that, The degradation state management module manages the degradation state where the fault that caused the system to enter a degradation state after power-on has been recovered, and the degradation state where the fault that caused the system to enter a degradation state after power-on has not been recovered.

8. The steer-by-wire system and the degraded processing system for vehicle interaction according to claim 7, characterized in that, After power is restored, if the fault that caused the system to enter a degraded state has been recovered, the steer-by-wire system will jump from the initialization state to a higher degraded state that is better than the degraded state in the previous power-on cycle. If the fault that caused the system to enter a degraded state is not resolved after power is restored, the steering-by-wire system will maintain the degraded state of the previous power-on cycle.

9. The steer-by-wire system and the degraded processing system for vehicle interaction according to claim 1, characterized in that, The output status processing module includes a degraded status validity verification unit, a degraded status external transmission processing unit, and an alarm information processing unit. The degraded status validity verification unit detects whether the current degraded status is the degraded status output by the degraded status management module. The degraded status external transmission processing unit matches the degraded status of the steer-by-wire system with the degraded status required by the vehicle and then transmits it externally. The alarm information processing unit transmits corresponding alarm prompt information according to different degraded statuses.

10. The steer-by-wire system and the degraded processing system for vehicle interaction according to claim 9, characterized in that, If the degradation status validity verification unit detects that the current degradation status is inconsistent with the degradation status output by the degradation status management module, then the previous valid degradation status will be used.

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