Rack force observer vehicle diagnostics of an electronic power steering system

Abstract

Electronic power steering system (10) comprising an electronic road wheel actuator (12) and a motion control system (14), wherein the motion control system (14) and / or the electronic power steering system (12) comprises / comprising at least one computing unit, a memory storing computer-executable components, and a processor executing the computer-executable components stored in the memory, wherein the electronic road wheel actuator (12) comprises a position control module (16), a movement position sensor (18), and an electronic steering rack force observer (20), wherein the motion control system (14) comprises a rack force observer vehicle diagnostic (22) and a motion control (24), wherein the movement position sensor (18) is configured to communicate the steering angle of the vehicle to the position control module (16) and the rack force observer (20) of the electronic steering system, wherein the movement position sensor (18) is arranged to communicate a steering speed to the rack force observer (20) of the electronic steering system, wherein the position control module (16) is configured to communicate the instructions of the electronic steering system motor to the rack force observer (20) of the electric steering system, wherein the position control module (16) comprises a position control, a torque control, or a torque superposition architecture, wherein the rack force observer (20) of the electronic steering system is configured to measure or estimate rack force data and communicate the rack force data to the rack force observer vehicle diagnostics (22) within the motion control system (14), wherein, within the motion control system (14), the rack force observer vehicle diagnostics (22) are configured to receive rack force data from the rack force observer (20) of the electronic steering system, vehicle speed data from the wheel speed sensor module (26), vehicle condition data from an inertial measurement unit module (28), vehicle network data from a braking system module (30), and position data from a GPS module (32), wherein the rack force observer vehicle diagnostics (22) are configured to analyze rack force data from the rack force observer (20) of the electronic steering system, vehicle speed data from the wheel speed sensor module (26), vehicle condition data from an inertial measurement unit module (28), vehicle network data from a braking system module (30), and position data from a GPS module (32) to calculate steering offset diagnostic data, which is subsequently communicated to the motion control module (24), and wherein the motion control module (24) is configured to receive the steering offset diagnostic data from the rack force observer vehicle diagnostic module (22) and also to receive position data from the GPS module (32) to calculate a compensated target steering angle (34) which is communicated to the position control module (16) within the road wheel actuator (12) of the electronic steering system.

Description

Technical area

[0001] The field to which the disclosure generally relates includes vehicle steering systems and, more particularly, methods for rack force observer vehicle diagnostics of an electronic power steering system. background

[0002] Vehicles may have steering systems. Autonomous driving and steering systems, typically associated with "self-driving vehicles," may have electronic steering systems that rely primarily on steering angle for autonomous control of a vehicle and for maintaining or changing the direction a vehicle is following.

[0003] DE 10 2007 000 995 A1 discloses a method for influencing the driving dynamics of a motor vehicle with a power steering system, comprising a servo assistance unit, a superposition gear and an actuator for correcting a driver's steering angle by introducing an additional angle, wherein a total steering angle for adjusting the wheel steering angle of steered wheels is formed by means of the superposition gear and wherein a control and regulating unit assigned to the actuator determines a target specification for the additional angle, wherein upon detection of an understeering condition, the target specification of the additional angle is changed such that the wheel lateral force is maintained in a range of a maximum achievable wheel lateral force maximum value dependent on environmental influences for the duration of the understeering condition.

[0004] DE 10 2011 055 339 A1 discloses a method for determining a rack force for a steering device of a vehicle, in which the rack force is determined as a function of a steering angle variable that characterizes an actual wheel steering angle or a target value of the wheel steering angle. In order to specify a method for determining a rack force with which a target steering torque can be generated in such a way that the driver is provided with a comfortable steering feel and the steering device nevertheless provides the driver with the most realistic feedback possible about a state of motion of the vehicle, the method comprises: determining a variable that characterizes a lateral force on an axle of the steering device, and determining the rack force as a function of the lateral force, wherein the determination of the rack force comprises filtering by means of a signal processing element with proportional-differential transmission behavior.

[0005] DE 10 2012 107 597 A1 discloses a method for determining a target preset value for a motor torque of an electric servomotor in a power steering system for a motor vehicle, wherein the target preset value is determined using a motor torque pre-control component, which forms a controlled portion, and a motor torque controller component, which forms a controlled portion, wherein the controlled variable is a torsion bar torque, and wherein both motor torque components are functionally offset against one another in order to determine the target preset value for the motor torque of the servomotor.

[0006] DE 10 2007 000 995 A1 and DE 10 2011 055 339 A1 teach, in an electronic steering system, determining and setting a compensated target steering angle using an estimated rack force.

[0007] DE 10 2012 107 597 A1 discloses an electronic steering system which takes into account an estimated rack force during autonomous steering interventions. Summary of illustrative variations

[0008] The object of the invention is to provide an improved rack force observer vehicle diagnosis of an electronic power steering system.

[0009] The above-mentioned object is achieved by a method having the features of claim 1.

[0010] A method for use in a vehicle having an electronic steering system, a position control module, a rack force observer of the electronic steering system, and a rack force observer vehicle diagnostic, comprising: measuring a steering angle and a steering speed of the vehicle; communicating a steering angle of the vehicle to the position control module and the rack force observer of the electronic steering system; communicating a steering speed of the vehicle to the rack force observer of the electronic steering system; communicating instructions from the electronic steering system motor to the rack force observer of the electronic steering system; and calculating rack force data and communicating the rack force data to the rack force observer vehicle diagnostic; and determining a compensated target steering angle.

[0011] Another method for use in a vehicle having an electronic steering system, a position control module, a rack force observer of the electronic steering system, and rack force observer vehicle diagnostics, comprises: receiving rack force data from a rack force observer of the electronic steering system; receiving data from a wheel speed sensor module; vehicle condition data from an inertial measurement unit module; vehicle network data from a braking system module; and position data from a GPS module; analyzing rack force data from the rack force observer of the electronic steering system; vehicle speed data from the wheel speed sensor modules; vehicle condition data from an inertial measurement unit module; vehicle network data from a braking system module; and position data from the GPS module; calculating steering offset diagnostic data;Communicating the calculated steering offset diagnostic data to a motion control module; receiving the steering offset diagnostic data from a rack force observer vehicle diagnostic module; and calculating a compensated target steering angle.;

[0012] Another method comprises the steps of providing an electronic power steering system having a steering rack; at least one wheel; a braking system module; a wheel speed sensor module; an inertial measurement unit module; a position control module; a motion control module; a GPS module; a rack force observer of the electronic steering system; a rack force observer vehicle diagnostic; at least one computing unit; a memory storing computer-executable components; a processor capable of executing the computer-executable components stored in the memory.The computer-executable components, when executed by the processor, may perform a method comprising: receiving and analyzing rack force data from the rack force observer of the electronic steering system; vehicle speed data from the wheel speed sensor module; vehicle state data from the inertial measurement unit module; vehicle network data from the braking system module; and position data from the GPS module; calculating steering offset diagnostic data; communicating the steering offset diagnostic data to the motion control module; calculating a compensated target steering angle; communicating the compensated target steering angle to the position control module; and adjusting the steering angle of the at least one wheel.

[0013] Further illustrative variations within the scope of the invention will become more apparent from the detailed description provided below. It should be understood that the detailed description and specific examples, while disclosing variations of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. Short description of the characters

[0014] Selected examples of variations within the scope of the invention will become more apparent from the detailed description and the accompanying figures, in which: Fig. 1 shows an illustrative variation of a product having an electronic steering system equipped with hardware sufficient to perform at least some of the methods described herein; Fig. 2 illustrates a flowchart illustrating an example process of a system that enables calculating a compensated target steering angle and adjusting the vehicle steering angle; and Fig. 3 illustrates a flowchart illustrating an electronic steering system that enables the calculation of a compensated target steering angle and the adjustment of the vehicle steering angle. Detailed description of illustrative variations

[0015] The following description of the variations is merely illustrative in nature and is in no way intended to limit the scope of the invention, its application, or uses.

[0016] As used herein, “vehicle” may refer generally to cargo or passenger vehicles, automobiles, and both manned and unmanned variations thereof.

[0017] As used herein, "operating environment" may generally refer to driveways, highways, streets, trails, parking lots, parking structures, tunnels, bridges, traffic intersections, residential garages, or commercial garages. The operating environment is intended to include any location or space accessible by a vehicle.

[0018] In some illustrative variations, a vehicle may include an electronic steering system. In such cases, the steering system may be manually operable by a driver via a steering interface, autonomously operable by an autonomous steering system, or operable in a combination of autonomous and manual steering, with the steering system configured to receive and interpret steering inputs from a driver, the autonomous steering system, or both at the same time.

[0019] In some illustrative variations, a steering interface may include a handwheel, a joystick, a trackball, a slider, a throttle, a push button, a toggle switch, a lever, a touchscreen, a mouse, or any other means of user input.

[0020] In some illustrative variations, a vehicle may have a steering system that includes a steering interface and a steerable drive system, such as, but not limited to, a steering wheel, a steering rack, and road wheels. The steering system may be of the electric power steering type, in which physical connections mechanically communicate actuation of the steering interface to the steerable drive system. The steering system may be of the steer-by-wire type, in which physical mechanisms non-mechanically communicate actuation of the steering interface to the steerable drive system, and in which actuation of the steering interface influences associated actuation of the steerable drive system via communication of electronic devices, such as, but not limited to, sensors, transceivers, and electronically excitable actuators.

[0021] In some illustrative variations, an electronic steering system in an autonomously driving vehicle may influence the vehicle's trajectory via a motion control system having a plurality of sensors. The plurality of sensors may measure and / or observe a variety of road-driving factors, such as vehicle speed, wheel speed, wheel angle, yaw rate, acceleration, roll angle, pitch angle, braking system activity, global positioning system (GPS) data, and other measurable variables related to vehicle motion. The electronic steering system in an autonomously driving vehicle may measure a steering angle position to determine a trajectory. As one example, an autonomously driving vehicle may determine that a vehicle executing a turn needs to adjust the steering angle by "X" degrees to complete the autonomous turn.The electronic steering system in an autonomously driving vehicle can measure forces on a vehicle's steering rack or calculate calculated forces on the steering rack using a rack force observer. The rack force observer can monitor an electrical current within the electronic steering system relative to a position of the electric motor to calculate forces on the steering rack. In this way, sudden changes in the rack force due to external influences originating in the operating environment can be observed and measured, and subsequently compensated for.

[0022] In some illustrative variations, a vehicle having an electronic steering system may measure, observe, sense, or calculate forces on a vehicle's steering rack, in addition to factors such as vehicle speed, wheel speed, wheel angle, yaw rate, acceleration, roll angle, pitch angle, braking system activity, global positioning system (GPS) data, and other factors. A motion control system, in combination with modules such as position controllers, steering rack observers, motion controllers, motion position sensors, braking sensors, inertial measurement unit(s) (IMU), GPS, and various other systems, may measure or calculate disturbances affecting steering angle and rack force that originate in the vehicle's operating environment.For example, a motion control system that measures a vehicle wheel angle approximately parallel to the vehicle trajectory, but also measures or calculates greater-than-expected rack forces, can detect dynamic situations such as adverse driving conditions, a component failure within the electronic steering system, or other conditions. A disturbance in the steering rack forces can be detected by monitoring a steering angle position and steering angle compensation relative to a straight-ahead position, which can be confirmed by secondary vehicle sensors such as wheel speed sensors, heading sensors, yaw rate sensors, and lateral acceleration sensors.

[0023] The measured steering rack force, combined with the measured steering position, can provide the vehicle with a wealth of information that cannot otherwise be measured or observed. The system can provide situational awareness and diagnostics to assist when vehicle maintenance is required. Dynamic situations can be detected, such as braking on surfaces with varying friction coefficients, steering torque during acceleration, a lifted wheel under high lateral acceleration, a flat tire, and rising / falling road cambers and crowned roads. Suspension and tire diagnostics can also be detected through deteriorating ball joints, tie rod ends, shock absorbers, brake disc problems, tire imbalance, and tire pressure.The cause of a fault can be detected using information about the steering angle position (including compensation), the rack load forces, and with the aid of other vehicle sensors such as wheel speed sensors and lateral acceleration sensors. Situational awareness can then be communicated to and used by systems throughout the vehicle, including signaling that maintenance is required, adjusting an autonomous driving trajectory or vehicle speed, or indicating that a driver needs to adjust a trajectory or vehicle speed when a motion control system cannot.

[0024] Referring to Fig. 1, an illustrative variation of a product may include an electronic power steering system 10 including an electronic road wheel actuator 12 and a motion control system 14. The motion control system 14 and / or the electronic power steering system may include at least one computing unit; a memory storing computer-executable components; and a processor executing the computer-executable components stored in the memory. The electronic road wheel actuator 12 may include a position control module 16, a motion position sensor 18, and a rack force observer 20 of the electric steering system. The motion control system 14 may include a rack force observer vehicle diagnostics 22 and a motion control module 24.

[0025] The motion position sensor 18 can communicate the vehicle's steering angle to the position control module 16 and the rack force observer 20 of the electronic steering system. The motion position sensor 18 can communicate a steering speed to the rack force observer 20 of the electronic steering system. The position control module 16 can communicate the electronic steering system motor commands to the rack force observer 20 of the electric steering system. The position control module 16 can include a position controller, a torque controller, or a torque overlay architecture. The electronic steering system's rack force observer 20 can measure or calculate rack force data and communicate the rack force data to the rack force observer vehicle diagnostics 22 within the motion control system 14.

[0026] Within the motion control system 14, the rack force observer vehicle diagnostics 22 may receive rack force data from the electronic steering system's rack force observer 20; vehicle speed data from the wheel speed sensor module 26; vehicle condition data from an inertial measurement unit module 28; vehicle network data from a braking system module 30; and position data from a GPS module 32. The rack force observer vehicle diagnostics 22 may analyze rack force data from the electronic steering system's rack force observer 20; vehicle speed data from the wheel speed sensor module 26; vehicle condition data from an inertial measurement unit module 28; vehicle network data from a braking system module 30; and position data from a GPS module 32 to calculate or compute steering offset diagnostic data, which may subsequently be communicated to the motion control module 24.The motion control module 24 may receive the steering offset diagnostic data from the rack force observer vehicle diagnostic 22 and may also receive position data from the GPS module 32 to calculate or compute a compensated target steering angle 34, which may be communicated to the position control module 16 within the road wheel actuator 12 of the electronic steering system.

[0027] Compensated target steering angle data 34 received by the position control module 16 may be used to adjust a steering angle, vehicle speed, or other variables to increase safety of the autonomous driving system, to signal maintenance when needed, to adjust an autonomous driving trajectory or vehicle speed, or to indicate that a driver needs to adjust a trajectory or vehicle speed if a motion control system cannot do so.

[0028] Fig. 2 is a flowchart illustrating an example process of a motion control system including an electronic steering system that enables calculating a compensated target steering angle and adjusting a vehicle steering angle. The motion control system and / or the electronic power steering system may include at least one computing unit; a memory storing computer-executable components; and a processor executing the computer-executable components stored in the memory, wherein the computer-executable components may include steps. Step 40 may include measuring and communicating a steering angle of a vehicle to a position control module and to a rack force observer of the electronic steering system. Step 42 may include measuring and communicating a steering speed to the rack force observer of the electronic steering system.Step 44 may include communicating instructions from the electronic steering system motor to the rack force observer of the electronic steering system. Step 46 may include calculating rack force data and communicating the rack force data to the rack force observer vehicle diagnostics. Step 48 may include adjusting the steering angle, vehicle speed, or other variables to increase the safety of an autonomously driving vehicle. Step 48 may further include signaling to a user that vehicle maintenance is required, adjusting an autonomous driving trajectory or vehicle speed, or indicating that a driver needs to adjust a trajectory or vehicle speed.

[0029] Fig.3 is a flowchart illustrating an example process of a motion control system including an electronic steering system that enables calculating a compensated target steering angle and adjusting a vehicle steering angle. The motion control system and / or the electronic power steering system may include at least one computing unit; a memory storing computer-executable components; and a processor executing the computer-executable components stored in the memory, wherein the computer-executable components may include steps of: Step 50 may include receiving rack force data from a rack force observer of the electronic steering system.Step 50 may also include receiving vehicle speed data from a wheel speed sensor module; vehicle condition data from an inertial measurement unit module; vehicle network data from a braking system module; and position data from a GPS module. Step 52 may include analyzing rack force data from the electronic steering system's rack force observer; vehicle speed data from vehicle speed sensor modules; vehicle condition data from an inertial measurement unit module; vehicle network data from a braking system module; and position data from the GPS module. Step 54 may include calculating steering offset diagnostic data based on data received during step 50 and step 52. Step 56 may include communicating the calculated steering offset diagnostic data to a motion control module.Step 58 may include receiving the steering offset diagnostic data from a rack force observer vehicle diagnostic module. Step 60 may optionally include receiving position data from a GPS module and communicating the position data to the motion control module. Step 62 may include calculating a compensated target steering angle, vehicle speed, and other variables. Step 64 may include communicating the compensated target steering angle to the position control module within the electronic steering system. Step 66 may include adjusting the steering angle, vehicle speed, or other variables to increase safety of the autonomous vehicle having an electronic steering system.Step 66 may additionally include, if necessary, signaling maintenance, adjusting an autonomous driving trajectory or vehicle speed, or indicating that a user needs to adjust a trajectory or vehicle speed.

[0030] The following description of variations is merely illustrative of components, elements, acts, products, and methods that are considered to be within the scope of the invention and is in no way intended to limit such scope by what is specifically disclosed or not expressly set forth. The components, elements, acts, products, and methods described herein may be combined, combined, and rearranged otherwise than as expressly described herein and still be considered to be within the scope of the invention.

[0031] According to Variation 1, a method for use in a vehicle having an electronic steering system, a position control module, a rack force observer of the electronic steering system, and a rack force observer vehicle diagnostic may include: measuring the steering angle and steering speed of the vehicle; communicating a steering angle of the vehicle to the position control module and the rack force observer of the electronic steering system; communicating a steering speed of the vehicle to the rack force observer of the electronic steering system; communicating instructions from an electronic steering system motor to the rack force observer of the electronic steering system; and calculating rack force data and communicating the rack force data to the rack force observer vehicle diagnostic; and determining a compensated target steering angle.

[0032] Variation 2 may include a method according to Variation 1 and may further include adjusting the steering angle of the vehicle.

[0033] Variation 3 may include a method according to any one of Variations 1 to 2 and may further include signaling to a user that vehicle maintenance is required.

[0034] Variation 4 may include a method according to any one of Variations 1 to 3 and may further include signaling to a user that an adjustment of a travel trajectory or a vehicle speed is required.

[0035] Variation 5 may include a method for use in a vehicle including an electronic steering system, a position control module, a rack force observer of the electronic steering system, and rack force observer vehicle diagnostics, the method comprising: receiving rack force data from a rack force observer of the electronic steering system; receiving vehicle speed data from a wheel speed sensor module; vehicle condition data from an inertial measurement unit module; vehicle network data from a braking system module; and position data from a GPS module; analyzing rack force data from the rack force observer of the electronic steering system; vehicle speed data from the wheel speed sensor modules; vehicle condition data from an inertial measurement unit module; vehicle network data from a braking system module; and position data from the GPS module;Calculating steering offset diagnostic data; communicating the calculated steering offset diagnostic data to a motion control module; receiving the steering offset diagnostic data from a rack force observer vehicle diagnostic module; and calculating a compensated target steering angle.;

[0036] Variation 6 may include a method according to Variation 5 and may further include receiving position data from a GPS module and communicating the position data to the motion control module prior to calculating a compensated target steering angle, vehicle speed, or other variables.

[0037] Variation 7 may include a method according to any of Variations 5 to 6 and may further include communicating the compensated target steering angle to the position control module.

[0038] Variation 8 may include a method according to any one of variations 5 to 7 and may further include adjusting the steering angle of the vehicle.

[0039] Variation 9 may include a method according to any one of variations 5 to 8 and may further include signaling to a user that vehicle maintenance is required.

[0040] Variation 10 may include a method according to any one of Variations 5 to 9 and may further include signaling to a user that an adjustment of a travel trajectory or a vehicle speed is required.

[0041] Variation 11 may include an electronic power steering system including a steering rack; at least one wheel; a braking system module; a wheel speed sensor module; an inertial measurement unit module; a position control module; a motion control module; a GPS module; an electronic steering system rack force observer; rack force observer vehicle diagnostics; at least one computing unit; a memory storing computer-executable components; and a processor executing the computer-executable components stored in the memory.The computer-executable components, when executed by the processor, are operable to: receive and analyze rack force data from the rack force observer of the electronic steering system; vehicle speed data from the wheel speed sensor module; vehicle condition data from the inertial measurement unit module; vehicle network data from the braking system module; and position data from the GPS module; calculate steering offset diagnostic data; communicate the steering offset diagnostic data to the motion control module; calculate a compensated target steering angle; communicate the compensated target steering angle to the position control module; and adjust the steering angle of the at least one wheel. List of reference symbols 10 electronic power steering system 12 Road wheel actuator 14 Motion control system 16 Position control module 18 Motion position sensor 20 rack force observers of the electronic steering system 22 Rack force observer vehicle diagnostics 24 Motion control module 26 Wheel speed sensor module 28 inertial measuring unit module 30 Brake system module 32 GPS module 40 - 66 process steps

Claims

[1] Electronic power steering system (10) comprising an electronic road wheel actuator (12) and a motion control system (14), wherein the motion control system (14) and / or the electronic power steering system (12) comprises / comprising at least one computing unit, a memory storing computer-executable components, and a processor executing the computer-executable components stored in the memory, wherein the electronic road wheel actuator (12) comprises a position control module (16), a movement position sensor (18), and an electronic steering rack force observer (20), wherein the motion control system (14) comprises a rack force observer vehicle diagnostic (22) and a motion control (24), wherein the movement position sensor (18) is configured to communicate the steering angle of the vehicle to the position control module (16) and the rack force observer (20) of the electronic steering system, wherein the movement position sensor (18) is arranged to communicate a steering speed to the rack force observer (20) of the electronic steering system, wherein the position control module (16) is configured to communicate the instructions of the electronic steering system motor to the rack force observer (20) of the electric steering system, wherein the position control module (16) comprises a position control, a torque control, or a torque superposition architecture, wherein the rack force observer (20) of the electronic steering system is configured to measure or estimate rack force data and communicate the rack force data to the rack force observer vehicle diagnostics (22) within the motion control system (14), wherein, within the motion control system (14), the rack force observer vehicle diagnostics (22) are configured to receive rack force data from the rack force observer (20) of the electronic steering system, vehicle speed data from the wheel speed sensor module (26), vehicle condition data from an inertial measurement unit module (28), vehicle network data from a braking system module (30), and position data from a GPS module (32), wherein the rack force observer vehicle diagnostics (22) are configured to analyze rack force data from the rack force observer (20) of the electronic steering system, vehicle speed data from the wheel speed sensor module (26), vehicle condition data from an inertial measurement unit module (28), vehicle network data from a braking system module (30), and position data from a GPS module (32) to calculate steering offset diagnostic data, which is subsequently communicated to the motion control module (24), and wherein the motion control module (24) is configured to receive the steering offset diagnostic data from the rack force observer vehicle diagnostic module (22) and also to receive position data from the GPS module (32) to calculate a compensated target steering angle (34) which is communicated to the position control module (16) within the road wheel actuator (12) of the electronic steering system.

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