Abstract: The present invention involves a system and method of controlling a vehicle steer-by-wire system to provide the variable and adjustable steering feel for the driver utilizing expert-type fuzzy logic technology. The steering wheel fuzzy logic controller controls the steering wheel torque to produce the variable and adjustable steering feel continuously based on changes in steering wheel angle, road wheel torque and vehicle speed.

Abstract: The present invention involves a method and system of initial aligning wheels of vehicle steer-by-wire systems with two independent front road wheels in the real time. The method comprises providing a steering wheel control sub-system and a road wheel control sub-system. The method further includes providing an initial alignment unit and procedure to align the road wheels and steering wheel. Moreover, the method includes receiving the relative and absolute steering wheel angle road wheel angles. The method further includes generating the wheel aligning reference angles based on the relative and absolute wheel angle, generating the switch control signal based wheel aligning reference angles using the logic operation with the threshold, and determining the steer-by-wire systems in the control state or in the initial alignment state.

Abstract: The present invention provides systems and methods of friction compensation in a steer-by-wire system or in a general electric steering system using control, estimation and modeling methodologies. A friction compensator in the steer-by-wire control system produces a friction compensating torque value equal and opposite in sign to the instantaneous friction torque. This compensating friction torque is added to the steering system control signal to eliminate the effects of friction present in the system such that the system performances are improved. The friction compensator produces the compensating friction torque according to one of two schemes: model-based or non-model based. The model-based scheme encompasses a number of different methods including a standard model-based scheme, a disturbance torque observer-based scheme, an adaptive friction compensation scheme, or a model reference adaptive control scheme. The non-model based scheme includes a fuzzy logic scheme.

Abstract: The present invention involves a method of controlling a vehicle steer-by-wire system having two independent road wheels. In one embodiment, the method comprises providing a steering wheel control sub-system to generate road wheel reference angles and to produce steering feel for a vehicle driver. The method further includes providing a road wheel control sub-system with servo control structure having road wheel angles and angular rates feedbacks including a road wheel controlled plant and a road wheel controller for controlling actual road wheel angles to track to road wheel reference angles. Moreover, a robust control is implemented in the road wheel controller to overcome affects of uncertainties and disturbances from the steer-by-wire system, vehicle, and external environment.

Abstract: One aspect of the present invention regards an automotive steering wheel control system having a steering wheel, a magnetorheological damper in communication with the steering wheel and a road wheel control system operably connected to the magnetorheological damper where the magnetorheological damper controls the steering wheel in response to a torque signal from the road wheel control system.

Abstract: The present invention involves a method of controlling a vehicle steer-by-wire system having two independent road wheels. In one embodiment, the method comprises providing a steering wheel control sub-system to generate road wheel reference angles and to produce steering feel for a vehicle driver. The method further includes providing a road wheel control sub-system with a servo control system structure including a multivariable road wheel controlled plant and a multivariable road wheel controller for controlling actual road wheel angles to track to road wheel reference angles. The method further includes generating left and right road wheel reference angles from the steering wheel angle with a road wheel reference angle generator using variable left and right steering ratios and calibration processes based on calibration variables, wherein the road wheel reference angle generator has first and second stages to produce left and right road wheel reference angle outputs.

Abstract: The present invention involves a system and method of controlling a steering wheel for simulated steering feel on a steering wheel of a vehicle with front road wheels in a steer-by-wire system. The method includes sensing actual torsion on the steering wheel, comparing the actual torsion to a threshold torque value, sensing actual angular velocity of the steering wheel, and comparing the actual angular velocity to a threshold angular velocity. The method further includes generating a simulated steering feel torque on the steering wheel, if the actual torsion is greater than the threshold torque value and the actual angular velocity is less than the threshold angular velocity. The method further comprises returning the steering wheel to the center position at a specified angular velocity, if the actual torsion is less than the threshold torque value and the actual angular velocity is greater than the threshold angular velocity.

Abstract: A steer-by-wire control system that includes a road wheel actuation control system controlling road wheel angles to track a road wheel reference angle and a steering wheel control system producing a steering wheel angle to the road wheel actuation control system, steering feel for the vehicle driver and active steering wheel return. The steering wheel control system further including a steering wheel model matching controller that receives an input signal from the steering wheel control system and an input signal from the road wheel control system and generates a control output signal based on a model-matching control law, wherein the control output signal controls a reaction torque of the steering wheel control system to produce the steering feel for the driver and control the return rate of a steering wheel or a joystick.

Abstract: The present invention involves a system and method of controlling a vehicle steer-by-wire system to provide the variable and adjustable steering feel for the driver utilizing expert-type fuzzy logic technology. The steering wheel fuzzy logic controller controls the steering wheel torque to produce the variable and adjustable steering feel continuously based on changes in steering wheel angle, road wheel torque and vehicle speed. The method comprises receiving an actual steering wheel angle, an actual road wheel angle, an actual road wheel torque, and an actual vehicle speed. The method includes converting the actual input variables into values in fuzzy sets based on their membership functions with linguistic term labels. The method further includes inferring a reaction torque control variable using fuzzy logic inference rules. The method includes converting a fuzzy reaction torque control variable into an actual reaction torque control variable.

Abstract: The present invention involves a system and method of re-configurable control for a vehicle steer-by-wire system. A steer-by-wire control system includes a steering wheel control system and a road wheel control system for a vehicle. Each control system is provided with a respective controlled plant and a re-configurable controller. The controllers receive output measurement signals from the respective controlled plants and produce control command signals for the controlled plants for re-configurable control of the steer-by-wire system. An adaptive re-configurable control is provided with fault detection and isolation, fault decision, parameter identification for the steer-by-wire controlled plant, and the re-configurable controllers with automatic adjustable structure and/or parameters. The re-configurable controllers automatically adjust their structure and parameters to maintain stability and certain performance requirements despite faults that occur in the steer-by-wire system.

Abstract: The present invention involves a system and method of controlling a steer-by-wire system to produce adjustable steering feel for A vehicle driver by providing control of reaction torque on a steering wheel of a vehicle. The method includes a quantitative description for the steering feel which is obtained by establishing a relationship of steering wheel reaction torque and steering wheel angle, road wheel torque, and vehicle speed. The system and method include steer-by wire system closed-loop feedback controls with inner torque loop, steering wheel rate feedback loop, and steering wheel angular position feedback loop to implement providing the steering feel, active steering wheel return with the different rotation rate, steering wheel stop according to the road wheel angular position in a parking state, and directional angle reference generation to road wheels.

Abstract: The present invention involves a method of controlling a vehicle steer-by-wire system having two independent road wheels. In one embodiment, the method comprises providing a steering wheel control sub-system to generate road wheel reference angles and to produce steering feel for a vehicle driver. The method further includes providing a road wheel control sub-system including a road wheel controlled plant and a road wheel controller for controlling actual road wheel angles to track to road wheel reference angles. Moreover, the method includes applying road wheel angles and angular rates as feedback signals to implement the left and right road wheel angles tracking for left and right road wheel reference angles in the road wheel control system with servo control system structure.

Abstract: The present invention involves a system and method of controlling a variable steering ratio of a vehicle steer-by-wire system. The variable steering ratio control varies the steering ratio continuously according to steering angle and vehicle speed. The method comprises sensing an actual steering wheel angle and an actual speed of the vehicle and converting the actual steering wheel angle and vehicle speed into values in fuzzy sets based on a steering wheel angle and vehicle speed membership functions with linguistic term labels. The method further includes determining a corresponding degree of membership of the steering wheel angle and vehicle speed. The method further includes inferring a fuzzy road wheel reference angle output value by determining the degree of membership function for the road wheel reference angle using fuzzy rules based on the degrees of steering angle and the vehicle speed. The method further includes converting a fuzzy road wheel angle into an actual road wheel angle.

Abstract: This invention describes a bi-directional smooth transition switch with bumpless transfer. It is composed of two feedback loops. Each loop has feedback and forward-loop compensators. During loop operation, one feedback loop is active, while the other is inactive. The smooth transition switch operates in the following manner. The switch output is measured. Next, an error signal is formed as the difference between the forward-loop compensator output and the switch output. This error signal is fed to the input of a high gain feedback compensator. The output of the feedback compensator is a feedback signal. When no switching occurs, the feedback signal remains zero in the active loop, and the output signal of the inactive loop will track the output signal of the active loop. When the switchover occurs, the inactive loop will replace the original active loop and provide smooth transition switch's output.

Abstract: A steer-by-wire control system that includes a road wheel actuation control system controlling road wheel angles to track a road wheel reference angle and a steering wheel control system producing a steering wheel angle to the road wheel actuation control system, steering feel for the vehicle driver and active steering wheel return. The steering wheel control system further including a steering wheel model matching controller that receives an input signal from the steering wheel control system and an input signal from the road wheel control system and generates a control output signal based on a model-matching control law, wherein the control output signal controls a reaction torque of the steering wheel control system to produce the steering feel for the driver and control the return rate of a steering wheel or a joystick.

Abstract: The present invention involves a method of controlling a vehicle steer-by-wire system having two independent road wheels. In one embodiment, the method comprises providing a steering wheel control sub-system to generate road wheel reference angles and to produce steering feel for a vehicle driver. The method further includes providing a road wheel control sub-system including a multivariable road wheel controlled plant and a multivariable road wheel controller for controlling actual road wheel angles to track to road wheel reference angles within a servo control system structure having road wheel angular position feedback and road wheel angular rate feedback loops. The method includes modeling the multivariable road wheel controlled plant and implementing the multivariable road wheel controller.

Abstract: The present invention involves a system and method of controlling a steering wheel for simulated steering feel on a steering wheel of a vehicle with front road wheels in a steer-by-wire system. The method includes sensing actual torsion on the steering wheel, comparing the actual torsion to a threshold torque value, sensing actual angular velocity of the steering wheel, and comparing the actual angular velocity to a threshold angular velocity. The method further includes generating a simulated steering feel torque on the steering wheel, if the actual torsion is greater than the threshold torque value and the actual angular velocity is less than the threshold angular velocity. The method further comprises returning the steering wheel to the center position at a specified angular velocity, if the actual torsion is less than the threshold torque value and the actual angular velocity is greater than the threshold angular velocity.

Abstract: The present invention involves a method of controlling a vehicle steer-by-wire system having two independent road wheels. In one embodiment, the method comprises providing a steering wheel control sub-system to generate road wheel reference angles and to produce steering feel for a vehicle driver. The method further includes providing a road wheel control sub-system including a multivariable road wheel controlled plant and a multivariable-road wheel controller for controlling actual road wheel angles to track to road wheel reference angles within a servo control system structure having road wheel angular position feedback and road wheel angular rate feedback loops. Moreover, the method includes implementing the multivariable road wheel controller to control tracking of the actual left and right wheel angles with the left and right road wheel reference angles, respectively.

Abstract: A steer-by-wire system of the preferred embodiment of the invention includes a steering sensor, a turning subsystem, a vehicle sensor, and a controller subsystem. The turning subsystem further includes a first turning actuator to adjust a turning angle of a first road wheel, a first turning sensor to sense first turning factors of the first turning actuator, a second turning actuator to adjust a turning angle of a second road wheel, and a second turning sensor to sense second turning factors of the second turning actuator. The controller subsystem is connected to the steering sensor, to the first turning sensor, to the second turning sensor, and to the vehicle sensor. The control subsystem independently controls the first turning actuator and the second turning actuator.

Abstract: The present invention involves a system and method of controlling a steering wheel for simulated steering feel on a steering wheel of a vehicle with front road wheels in a steer-by-wire system. The method includes sensing actual torsion on the steering wheel, comparing the actual torsion to a threshold torque value, sensing actual angular velocity of the steering wheel, and comparing the actual angular velocity to a threshold angular velocity. The method further includes generating a simulated steering feel torque on the steering wheel, if the actual torsion is greater than the threshold torque value and the actual angular velocity is less than the threshold angular velocity. The method further comprises returning the steering wheel to the center position at a specified angular velocity, if the actual torsion is less than the threshold torque value and the actual angular velocity is greater than the threshold angular velocity.