Apparatus and method for controlling steering of electric power steering system

Abstract

An electric power steering system steering control device and method are disclosed. The electric power steering system steering control device of the present invention comprises a processor; and a memory for storing instructions executed by the processor, wherein the processor generates a compensation current for generating a reaction torque opposing the steering direction according to at least one of the kinetic energy stored by the mass component of the electric power steering system and the potential energy stored by the rotational elastic component due to tire twisting, using a steering angle and a previously learned end angle.

Description

Technology Field

[0001] The present invention relates to an electric steering system steering control device and method. Background Technology

[0003] In an electric power steering system, when the driver rotates the steering wheel to the right or left end, a mechanical collision occurs between the rack bar stopper and the gearbox housing. To prevent this, the electric power steering system detects the end angle of the rack bar and reduces the driving output of the motor as it reaches the end angle.

[0004] Methods for reducing the driving output of a motor are classified into direct and indirect methods.

[0005] The direct method reduces the output of the steering logic based on the steering angle position, utilizing a motor output damping table to immediately reduce the motor output as it approaches the end point. While the direct method offers fast responsiveness and can achieve optimal performance under specific load conditions, it has drawbacks, such as significant variation in deceleration performance during vehicle load fluctuations (changes in road surface or vehicle speed) and difficulty in maintaining a constant steering angle when holding at the end point.

[0006] The indirect method sets an angular velocity limit and controls the speed to prevent it from being exceeded. It determines the limit using an angular velocity limit table and controls the angular velocity to prevent the driver from steering above that limit. While the indirect method has the advantage of allowing intuitive tuning based on angular velocity, it has the disadvantage of making it difficult to optimize the speed controller. In the indirect method, high control gain improves deceleration performance but causes noise and an unnatural steering feel, whereas low control gain carries the risk of component burnout due to impact on the end of the gear before deceleration is achieved.

[0007] The background technology of the present invention is disclosed in the ‘steering device and control method thereof’ of Korean Published Patent Application No. 10-2019-0034950 (April 3, 2019). The problem to be solved

[0009] The present invention was devised to improve upon the aforementioned problems, and an objective according to one aspect of the present invention is to provide an electric power steering system steering control device and method that improves deceleration performance and minimizes deviations in deceleration performance according to vehicle load by generating a reaction torque that opposes the driver's steering direction based on the kinetic energy stored by the mass component of the electric power steering system and the potential energy stored by the rotational elastic component due to tire torsion. means of solving the problem

[0011] An electric power steering system steering control device according to one aspect of the present invention comprises a processor; and a memory for storing instructions executed by the processor, wherein the processor generates a compensation current for generating a reaction torque that opposes the steering direction according to at least one of the kinetic energy stored by the mass component of the electric power steering system and the potential energy stored by the rotational elastic component due to tire twisting, using a steering angle and a previously learned end angle.

[0012] The processor of the present invention is characterized by storing the current steering angle as the learning end angle when a preset learning condition is satisfied.

[0013] The processor of the present invention is characterized by storing a preset hardware design value as the learning end angle when a preset learning initialization condition is satisfied.

[0014] The processor of the present invention is characterized by damping the motor current applied to the motor according to an output damping ratio preset for the steering angle.

[0015] The processor of the present invention is characterized by limiting the motor current when the steering angle reaches the learning end angle.

[0016] The processor of the present invention is characterized by generating a kinetic energy compensation current proportional to the magnitude of the kinetic energy stored by the mass component of the electric steering system.

[0017] The processor of the present invention is characterized by adjusting the kinetic energy compensation current according to the vehicle speed.

[0018] The processor of the present invention is characterized by generating a potential energy compensation current proportional to the magnitude of the potential energy stored by the rotational elastic component due to tire twisting, and applying it to the motor current applied to the motor.

[0019] The processor of the present invention is characterized by adjusting the potential energy compensation current according to the vehicle speed.

[0020] A steering control method for an electric steering system according to one aspect of the present invention is characterized by comprising: a step in which a processor learns a learning end angle; and a step in which the processor generates a compensation current to generate a reaction torque opposing the steering direction according to at least one of the kinetic energy stored by the mass component of the electric steering system and the potential energy stored by the rotational elastic component due to tire twisting, using the steering angle and the previously learned learning end angle.

[0021] In the step of generating a compensation current according to the present invention, the processor is characterized by storing the current steering angle as the learning end angle when a preset learning condition is satisfied.

[0022] In the step of generating a compensation current according to the present invention, the processor is characterized by storing a preset hardware design value as the learning end angle when a preset learning initialization condition is satisfied.

[0023] In the step of generating the compensation current of the present invention, the processor is characterized by attenuating the motor current applied to the motor according to an output damping ratio preset for the steering angle.

[0024] In the step of generating a compensation current according to the present invention, the processor limits the motor current when the steering angle reaches the learning end angle.

[0025] In the step of generating a compensation current according to the present invention, the processor is characterized by generating a kinetic energy compensation current that is proportional to the magnitude of the kinetic energy stored by the mass component of the electric steering system.

[0026] In the step of generating a compensation current according to the present invention, the processor is characterized by adjusting the kinetic energy compensation current according to the vehicle speed.

[0027] In the step of generating a compensation current according to the present invention, the processor generates a potential energy compensation current proportional to the magnitude of the potential energy stored by the rotational elastic component due to tire twisting and applies it to the motor current applied to the motor.

[0028] In the step of generating a compensation current according to the present invention, the processor is characterized by adjusting the potential energy compensation current according to the vehicle speed. Effects of the invention

[0030] An electric power steering system steering control device and method according to one aspect of the present invention can improve deceleration performance and minimize deviations in deceleration performance according to vehicle load by generating a reaction torque that opposes the driver's steering direction based on the kinetic energy stored by the mass component of the electric power steering system and the potential energy stored by the rotational elastic component due to tire torsion.

[0031] An electric steering system steering control device and method according to another aspect of the present invention enables the maintenance of a constant steering angle by minimizing performance variations even when the vehicle load fluctuates due to changes in road surface speed. Brief explanation of the drawing

[0033] FIG. 1 is a block diagram of a steering control device for an electric steering system according to one embodiment of the present invention. FIG. 2 is a conceptual diagram of a motor output limiting process according to one embodiment of the present invention. FIG. 3 is a block diagram of a motor output limiting unit according to one embodiment of the present invention. FIG. 4 is a flowchart illustrating a rack bar end learning process according to one embodiment of the present invention. FIG. 5 is a flowchart illustrating a motor output limiting process according to one embodiment of the present invention. Specific details for implementing the invention

[0034] Hereinafter, an embodiment of an electric power steering system steering control device and method according to an embodiment of the present invention is described. In this process, the thickness of lines or the size of components shown in the drawings may be exaggerated for clarity and convenience of explanation. Furthermore, the terms described below are defined considering their functions in the present invention, and these may vary depending on the intention or convention of the user or operator. Therefore, the definitions of these terms should be based on the content throughout this specification.

[0035] The present invention may be implemented in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly explain the invention in the drawings, parts unrelated to the description have been omitted, and similar parts throughout the specification have been given similar reference numerals.

[0036] Throughout the specification, when a part is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0037] The implementations described herein may be implemented, for example, as methods or processes, devices, software programs, data streams, or signals. Even if discussed only in the context of a single form of implementation (e.g., discussed only as a method), the implementation of the discussed features may also be implemented in other forms (e.g., devices or programs). Devices may be implemented in appropriate hardware, software, and firmware, etc. Methods may be implemented in devices such as processors, which generally refer to processing devices including, for example, computers, microprocessors, integrated circuits, or programmable logic devices.

[0039] FIG. 1 is a block diagram of a steering control device for an electric steering system according to one embodiment of the present invention, and FIG. 2 is a conceptual diagram of a motor output limiting process according to one embodiment of the present invention.

[0040] Referring to FIG. 1, an electric steering system steering control device according to one embodiment of the present invention may include a steering angle sensor (100), a steering angle velocity sensor (200), a current sensor (300), a torque sensor (400), a vehicle speed sensor (500), a memory (600), and a processor (700).

[0041] The electric power steering system may include a steering system (not shown) extending from a steering wheel (not shown) to both wheels (not shown) and an auxiliary power mechanism that provides steering assistance power to the steering system.

[0042] The steering system may largely include a steering wheel (not shown), a steering shaft (not shown), a pinion shaft (not shown), a rack bar (not shown), and both wheels (not shown).

[0043] The steering wheel is connected to the steering shaft and can transmit the driver torque generated by the driver to the steering shaft.

[0044] The steering shaft is connected to the pinion shaft via a pair of universal joints, allowing it to transmit driver torque to the pinion shaft. The pinion shaft can be connected to the rack bar through a rack-pinion mechanism. Both ends of the rack bar are connected to both wheels via tie rods and knuckle arms, respectively. Additionally, conventional steering systems incorporate a torsion bar.

[0045] The driver steers the vehicle by controlling the direction of both wheels using the steering system; when the driver operates the steering wheel, driver torque is generated in the steering system, and both wheels are steered through the rack-pinion mechanism and tie rods by this driver torque.

[0046] The steering angle sensor (100) is installed on the steering shaft that transmits the operating force in conjunction with the steering wheel operated by the driver, and can detect the rotation angle of the steering wheel, i.e., the steering angle.

[0047] The steering angle velocity sensor (200) can detect the steering angle velocity of the steering wheel. Meanwhile, although the present embodiment describes the steering angle velocity being detected by separately providing a steering angle velocity sensor (200), the steering angle velocity may also be obtained by differentiating the steering angle.

[0048] The current sensor (300) can detect the current of the motor that provides auxiliary rotational force and is connected to the rotation axis of the steering wheel.

[0049] The torque sensor (400) can detect driver torque when the driver operates the steering wheel.

[0050] The vehicle speed sensor (500) can detect the vehicle speed.

[0051] The memory (600) can store various data used by the processor (700). The data may include instructions for performing operations or steps according to embodiments of the present invention. That is, the memory (600) can store instructions for improving deceleration performance by generating a reaction torque that opposes the driver's steering direction according to the kinetic energy stored by the mass component of the electric steering system and the potential energy stored by the rotational elastic component due to tire twisting.

[0052] The memory (600) may include at least one storage medium among a flash memory type, a hard disk type, a multimedia card micro type, a card type memory, RAM (Random Access Memory), SRAM (Static Random Access Memory), ROM (Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable Programmable Read-Only Memory), and EEPROM (Electrically Erasable Programmable Read-Only Memory).

[0053] The processor (700) can be connected to memory (600) and can execute instructions stored in memory (600). By executing instructions stored in memory (600), the processor (700) can control at least one other component (e.g., hardware or software component) connected to the processor (700) and can perform various data processing or operations.

[0054] Additionally, the processor (700) may be configured to perform each function separately at the hardware, software, or logic level. In this case, dedicated hardware may be used to perform each function. To this end, the processor (700) may be implemented as or include at least one of an Application Specific Integrated Circuit (ASIC), a Digital Signal Processor (DSP), a Programmable Logic Device (PLD), Field Programmable Gate Arrays (FPGAs), a Central Processing Unit (CPU), microcontrollers, and / or microprocessors.

[0055] The processor (700) may be implemented as a Central Processing Unit (CPU) or a System on Chip (SoC), and may control multiple hardware or software components connected to the processor (700) by running an operating system or application, and may perform various data processing and operations. The processor (700) may be configured to execute at least one instruction stored in memory (600) and store the execution result data in memory (600).

[0056] The processor (700) can generate a reaction torque that opposes the steering direction of the driver. To this end, the processor (700) can generate a compensation current according to at least one of the kinetic energy stored by the mass component of the electric steering system and the potential energy stored by the rotational elastic component due to tire twisting according to the steering angle, and apply it to the motor.

[0057] To explain more specifically, the processor (700) can generate kinetic energy compensation current and potential energy compensation current of the electric steering system to improve deceleration performance and minimize deviation in deceleration performance according to vehicle load.

[0058] The kinetic energy compensation current is proportional to the magnitude of the kinetic energy stored by the mass component of the steering system and can generate a reaction torque that opposes the driver's steering direction.

[0059] Kinetic energy compensation current can rapidly decelerate angular velocity by generating high reaction torque under conditions where the magnitude of kinetic energy is large, such as low-friction surfaces in parking lots or sudden U-turn steering conditions.

[0060] The potential energy compensation current is proportional to the magnitude of the stored potential energy due to the rotational elastic component caused by tire twisting, and can generate a reaction torque that opposes the driver's steering direction. Generally, since the reaction torque increases sharply as it approaches the end point, the potential energy compensation current serves to decelerate the angular velocity. By minimizing performance fluctuations even when the vehicle load changes due to road surface conditions or vehicle speed, it ensures that a constant steering angle is maintained. In other words, the potential energy compensation current prevents the steering wheel from turning further toward the end point when the load decreases, and prevents the steering wheel from returning in the opposite direction of the end point when the load increases.

[0061] The processor (700) may include a motor current generation unit (710), an end angle learning unit (720), and a motor output limiting unit (730).

[0062] The motor current generation unit (710) determines the driving conditions of the vehicle based on the steering angle, steering angle velocity, driver torque, and vehicle speed, and generates motor current of the motor according to these driving conditions to generate steering assist power, thereby improving the driver's steering feel and enabling stable steering.

[0063] The end angle learning unit (720) can learn the end angle. The learned end angle may be a learned angle obtained through end angle learning.

[0064] The end angle learning unit (720) can learn the end angle depending on whether the pre-set learning conditions are satisfied when the end learning is not completed.

[0065] The end angle learning unit (720) can store the end angle when the learning condition is satisfied and learn the end angle using the stored end angle. Here, the learning condition may be an OLP condition for performing an OLP (Over Load Protection) function based on the steering angle, angular velocity, and motor current. The end angle learning unit (720) can determine that the OLP condition, i.e., the learning condition, is satisfied if the steering angle exceeds a preset first steering angle reference value, the angular velocity exceeds a preset first angular velocity reference value, and the motor current exceeds a preset motor current reference value.

[0066] OLP limits motor output under specific conditions to prevent the continuous flow of maximum current at the wheel tip during steering.

[0067] Typically, when an electric power steering system rotates the steering wheel to its maximum extent, a large current is applied to generate high output; however, components such as the motor, ECU (Engine Control Unit), or MCU (Motor Control Unit) may fail or be damaged due to heat. Accordingly, OLP prevents the motor or ECU (MCU) from failing or being damaged due to heat generated by the high current application in the electric power steering system. Specifically, when the driver rotates the steering wheel to its maximum, OLP determines that the maximum current is in a state based on the steering wheel's load information and steering angle information, and by limiting the current, reduces the heat generated in the electric power steering system.

[0068] The end angle learning unit (720) can store the current steering angle as the learned end angle when the above-mentioned OLP condition is satisfied. That is, when the OLP condition is satisfied, the end angle learning unit (720) stores the end angle and learns the learned end angle based on the stored end angle. Typically, when the driver steers the steering wheel to the end, the OLP operation condition is satisfied, so the learned end angle may be the steering angle at the point in time when the OLP operation condition is satisfied.

[0069] Meanwhile, as described above, even after learning is completed, the learning initialization condition may be satisfied due to factors such as curb impact, stored value error, or hardware failure. In this case, the end angle learning unit (720) can determine whether the learning initialization condition is satisfied based on the steering angle, angular velocity, and driver torque. The end angle learning unit (720) can determine that the learning initialization condition is satisfied if the steering angle is less than a preset second steering angle reference value, the angular velocity is less than a second angular velocity reference value, and the driver torque exceeds a torque reference value.

[0070] When the learning initialization condition is satisfied, the end angle learning unit (720) may learn the end angle based on the hardware design value. That is, the end angle learning unit (720) may set the hardware design value, which is mechanically structured, as the end angle to be learned.

[0071] The motor output limiting unit (730) can generate a compensation current according to at least one of the kinetic energy stored by the mass component of the electric steering system and the potential energy stored by the rotational elastic component due to tire twisting, depending on the steering angle and the end learning angle, and apply it to the motor.

[0072] In addition, the motor output limiting unit (730) can immediately attenuate the motor current when the steering angle reaches the end learning value by applying an output attenuation ratio to the motor current generated by the motor current generation unit (710) according to a preset output attenuation ratio table.

[0073] FIG. 3 is a block diagram of a motor output limiting unit according to one embodiment of the present invention.

[0074] Referring to FIG. 3, the motor output limiting unit (730) receives an end learning angle from the end angle learning unit (720) and receives the steering angle, vehicle speed steering angle velocity, and driver torque, respectively, from the steering angle sensor (100), vehicle speed sensor (500), steering angle velocity sensor (200), and torque sensor (400).

[0075] The motor output limiting unit (730) can receive motor current from the motor current generating unit (710). The motor output limiting unit (730) can extract the output damping ratio set for the steering angle from the output damping ratio table for the motor current.

[0076] The output damping ratio table may be a table in which the output damping ratio of the motor current for each steering angle is stored.

[0077] In the output damping ratio table, the output damping ratio decreases as the steering angle increases, and can become '0' at the learning end angle.

[0078] As the output damping ratio decreases as the steering angle and the learning end angle approach, the motor output limiting unit (730) can reduce the motor current as the steering angle and the learning end angle approach, thereby reducing the steering assist power provided to the steering system. Subsequently, when the steering angle and the learning end angle match, the motor output limiting unit (730) can make the motor current '0' by applying an output damping ratio of '0' to the motor current. Therefore, in the state where the steering angle and the learning end angle match, the motor current applied to the motor is immediately damped to '0', so no steering assist power is provided to the steering system.

[0079] The motor output limiting unit (730) can generate a compensation current proportional to the magnitude of the kinetic energy stored in the mass component of the steering system, thereby generating a reaction torque that opposes the driver's steering direction. Through this, the angular velocity can be rapidly reduced under high-speed steering conditions where the kinetic energy is large.

[0080] To explain in more detail, the motor output limiting unit (730) has a learning end angle and a mass component of the steering system and a steering angle velocity. It can be applied to generate kinetic energy compensation current.

[0081] Here, m is the mass component of the steering system and v can be the steering angular velocity.

[0082] Additionally, the motor output limiting unit (730) can adjust the kinetic energy compensation current according to the vehicle speed. That is, the motor output limiting unit (730) can increase or decrease the kinetic energy compensation current according to the vehicle speed. The motor output limiting unit (730) can increase the kinetic energy compensation current as the vehicle speed decreases.

[0083] The motor output limiting unit (730) can correct the kinetic energy compensation current with a steering angle decoupling gain set according to the steering angle and the learning end angle.

[0084] The motor output limiting unit (730) can compare the steering angle and the learning end angle to calculate the difference between the steering angle and the learning end angle, and extract the steering angle decoupling gain according to the calculated difference value and apply it to the kinetic energy compensation current.

[0085] The steering angle decoupling gain increases as the difference between the steering angle and the learning end angle decreases, and can reach a maximum when the steering angle and the learning end angle match.

[0086] The motor output limiting unit (730) can maximize the steering angle decoupling gain value when the difference between the steering angle and the learning end angle decreases so that the steering angle and the learning end angle match, that is, when the difference between the steering angle and the learning end angle is '0'. Accordingly, the kinetic energy compensation current increases as the difference between the steering angle and the learning end angle decreases, and when the difference between the steering angle and the learning end angle becomes '0', the kinetic energy compensation current can be maximized.

[0087] The motor output limiting unit (730) can generate a potential energy compensation current proportional to the magnitude of the potential energy stored by the rotational elastic component due to tire twisting, thereby generating a reaction torque that opposes the driver's steering direction. Through this, the angular velocity can be rapidly reduced as the steering angle reaches the end. Additionally, while the steering wheel is in a held state, even if the vehicle load changes due to vehicle load fluctuation conditions, such as changes in road surface or vehicle speed, the steering angle is maintained constant so that the steering wheel does not turn further toward the end when the load decreases, or return to the opposite direction of the end when the load increases.

[0088] To explain in more detail, the motor output limiting part (730) has a rotational elastic component due to tire twisting and a steering angle. It can be applied to generate potential energy compensation current.

[0089] Here, k is the rotational elastic component due to tire twist, and x can be the steering angle.

[0090] Additionally, the motor output limiting unit (730) can adjust the potential energy compensation current according to the vehicle speed. That is, the motor output limiting unit (730) can increase or decrease the potential energy compensation current according to the vehicle speed. The motor output limiting unit (730) can increase the potential energy compensation current as the vehicle speed decreases.

[0091] The motor output limiting unit (730) can output to the motor current to which the output damping ratio is applied, by summing the kinetic energy compensation current and the potential energy compensation current, thereby causing a reaction torque that opposes the steering direction of the steering wheel to act.

[0092] Hereinafter, a steering control method for an electric steering system according to one embodiment of the present invention will be described in detail with reference to FIGS. 4 and 5.

[0093] FIG. 4 is a flowchart illustrating a rack bar end learning process according to one embodiment of the present invention.

[0094] Referring to FIG. 4, the end angle learning unit (720) can determine whether end learning is completed (S110).

[0095] If the end learning is not completed as a result of the judgment in step S110, the end angle learning unit (720) can determine whether the pre-set learning conditions are satisfied (S120). The end angle learning unit (720) can determine that the OLP condition is satisfied if the steering angle exceeds the pre-set first steering angle reference value, the angular velocity exceeds the pre-set first angular velocity reference value, and the motor current exceeds the pre-set motor current reference value.

[0096] If the learning condition of the judgment result in step S120 is satisfied, the end angle learning unit (720) can store the current steering angle as the learned end angle (S130).

[0097] Meanwhile, if the learning is not completed as a result of the judgment in step S110, the end angle learning unit (720) can determine whether the learning initialization condition is satisfied based on the steering angle, angular velocity, and driver torque (S140). The end angle learning unit (720) can determine that the learning initialization condition is satisfied if the steering angle is less than a preset second steering angle reference value, the angular velocity is less than a second angular velocity reference value, and the driver torque exceeds a torque reference value.

[0098] If the learning initialization condition of the judgment result in step S140 is satisfied, the end angle learning unit (720) can set a mechanically structured hardware design value as the learning end angle (S150).

[0099] Next, the motor output limiting unit (730) can limit the motor output based on the learning end angle and steering angle.

[0100] FIG. 5 is a flowchart illustrating a motor output limiting process according to one embodiment of the present invention.

[0101] Referring to FIG. 5, the motor output limiting unit (730) receives an end learning angle from the end angle learning unit (720) and receives the steering angle, vehicle speed steering angle velocity, and driver torque, respectively, from the steering angle sensor (100), vehicle speed sensor (500), steering angle velocity sensor (200), and torque sensor (400).

[0102] The motor output limiting unit (730) receives the motor current from the motor current generation unit (710) and can apply the output damping ratio set for the steering angle to the motor current by extracting the output damping ratio from the output damping ratio table (S210). In this case, the motor output limiting unit (730) can reduce the motor current by decreasing the output damping ratio as the steering angle and the learning end angle approach each other, thereby reducing the steering assist power provided to the steering system. Subsequently, when the steering angle and the learning end angle match, the motor current can be made to '0' by applying an output damping ratio of '0' to the motor current.

[0103] Meanwhile, the motor output limiting unit (730) can generate a compensation current proportional to the magnitude of the kinetic energy stored by the mass component of the steering system (S220). That is, the motor output limiting unit (730) can generate a kinetic energy compensation current using the learning end angle, the mass component of the steering system, and the angular velocity. In this case, the motor output limiting unit (730) can correct the kinetic energy compensation current according to the vehicle speed. Additionally, the motor output limiting unit (730) can compare the steering angle and the learning end angle to calculate the difference between the steering angle and the learning end angle, extract a steering angle decoupling gain based on the calculated difference value, and then apply this steering angle decoupling gain to the kinetic energy compensation current. Accordingly, the kinetic energy compensation current increases as the difference between the steering angle and the learning end angle decreases, and can reach a maximum when the difference between the steering angle and the learning end angle is '0'.

[0104] The motor output limiting unit (730) can generate a potential energy compensation current proportional to the magnitude of the potential energy stored by the rotational elastic component due to tire twisting (S230). That is, the motor output limiting unit (730) can generate a potential energy compensation current using the rotational elastic component due to tire twisting and the angular velocity. In addition, the motor output limiting unit (730) can adjust the potential energy compensation current according to the vehicle speed. That is, the motor output limiting unit (730) can increase or decrease the potential energy compensation current according to the vehicle speed.

[0105] Next, the motor output limiting unit (730) can output to the motor current to which the output damping ratio is applied, by adding the kinetic energy compensation current and the potential energy compensation current, thereby causing a reaction torque that opposes the steering direction of the steering wheel to be applied (S240).

[0106] In this embodiment, to aid in understanding the embodiment, the motor current generation unit (710), the end angle learning unit (720), and the motor output limiting unit (730) are described as separate components within the processor (700); however, depending on the embodiment, the processor (700) may be implemented as a configuration in which each sub-component is integratedly performed.

[0107] As used herein, the term “part” may include a unit implemented in hardware, software, or firmware, and may be used interchangeably with terms such as logic, logic block, component, or circuit. The “part” may be a component formed integrally, or a minimum unit of said component or a part thereof that performs one or more functions. For example, according to one embodiment, the “part” may be implemented in the form of an Application-Specific Integrated Circuit (ASIC).

[0108] Although the present invention has been described with reference to the embodiments illustrated in the drawings, this is merely illustrative and those skilled in the art will understand that various modifications and equivalent alternative embodiments are possible therefrom. Accordingly, the true technical scope of protection of the present invention should be determined by the claims below. Explanation of the symbols

[0110] 100: Steering angle sensor 200: Steering angle velocity sensor 300: Current sensor 400: Torque sensor 500: Vehicle speed sensor 600: Memory 700: Processor 710: Motor current generation unit 720: End angle learning section 730: Motor output limiter

Claims

Claim 1 An electric power steering system steering control device comprising: a processor; and a memory for storing instructions executed by the processor, wherein the processor generates a compensation current to generate a reaction torque opposite to the steering direction according to at least one of the kinetic energy stored by the mass component of the electric power steering system and the potential energy stored by the rotational elastic component due to tire twisting, using a steering angle and a previously learned end angle. Claim 2 In claim 1, the electric steering system steering control device, wherein the processor stores the current steering angle as the learning end angle when a preset learning condition is satisfied. Claim 3 In claim 1, the electric steering system steering control device, wherein the processor stores a preset hardware design value as the preset learning end angle when a preset learning initialization condition is satisfied. Claim 4 In claim 1, the above processor is an electric steering system steering control device that dampens the motor current applied to the motor according to an output damping ratio preset for the steering angle. Claim 5 In paragraph 4, the processor is an electric steering system steering control device that limits the motor current when the steering angle reaches the learning end angle. Claim 6 In claim 1, the processor is an electric steering system steering control device that generates a kinetic energy compensation current proportional to the magnitude of the kinetic energy stored by the mass component of the electric steering system. Claim 7 In claim 6, the processor is an electric power steering system steering control device that adjusts the kinetic energy compensation current according to the vehicle speed. Claim 8 In claim 1, the processor is an electric steering system steering control device that generates a potential energy compensation current proportional to the magnitude of the potential energy stored by the rotational elastic component due to tire twisting and applies it to the motor current applied to the motor. Claim 9 In claim 8, the processor is an electric power steering system steering control device that adjusts the potential energy compensation current according to the vehicle speed. Claim 10 A steering control method for an electric steering system comprising: a step in which a processor learns a learning end angle; and a step in which the processor generates a compensation current to generate a reaction torque opposing the steering direction according to at least one of the kinetic energy stored by the mass component of the electric steering system and the potential energy stored by the rotational elastic component due to tire twisting, using the steering angle and the previously learned learning end angle.

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