Abstract: A method for controlling a limited by-wire active front steering system includes measuring an input steering angle, determining a tire saturation limit, and comparing the saturation limit to the input angle. A target actuator angle from a steering actuator is limited when the input angle is greater than the saturation limit. A constant value provides a fixed steering gear ratio when the input angle is less than the saturation limit. A limited by-wire steering system for a vehicle includes a steering device, a sensor for measuring an input steering angle, a controller for calculating a first target actuator angle when the input angle is less than a threshold, and a second target actuator angle when the input angle is greater than the threshold. The threshold is a calibrated saturation limit of a road wheel of the vehicle.

Abstract: A vehicle parametric active front steering (AFS) system remedial action is described herein. AFS system modules inter-communicate via messages containing parameters. The AFS system detects a message error, determines an invalid parameter, and takes appropriate remedial action. An error is detected if an error condition is satisfied or if occurrence of incorrect messages reaches or exceeds a certain predetermined frequency. The AFS system takes the remedial action by setting default values of valid parameters corresponding to the invalid parameter.

Abstract: A method is provided for limiting a steering angle overlay applied by a steering actuator in a limited by-wire active front steering (AFS) system. The method includes determining a maximum rate limit for the steering angle overlay in order to minimize an undesired disturbance to the driver in the form of a torque and/or angle feedback while maximizing the rate of steering overlay allowed for a given set of vehicle operating conditions. The maximum rate limit is determined by a function of the input steering rate and braking level. A limited AFS system includes both steering and braking input devices, a steering actuator, and a controller having an algorithm. The controller uses the algorithm to calculate the maximum overlay rate limit and limits the steering actuator to the maximum overlay rate limit.

Abstract: A method for controlling steering in a vehicle includes the steps of obtaining a vehicle steering communication, controlling an actuator coupled to a hand wheel, a road wheel, or both using a primary active steering functionality, if the vehicle steering communication reflects one or more of a plurality of types of specified errors, and controlling the actuator using the primary active steering functionality and a supplemental active steering functionality, if the vehicle steering communication does not reflect one or more of the plurality of types of specified errors.

Abstract: A system as described herein relates generally to automotive active front steering control systems having a main processor and a redundant sub-processor. The system provides a way of controlling the electrical and mechanical locking of an actuator motor in a variable gear ratio active front steering system. The method enables the sub-processor to electrically lock the active front steer actuator motor via the main processor to reduce mechanical wear or damage to the variable gear ratio system if the main processor is unable to electrically lock the actuator motor before it mechanically locks the actuator motor. The system also provides an error detecting technique that is robust to false failures and allows the active front steering system to safely transition into a fail safe mode if an error occurs.

Abstract: A motor control strategy for a motor in a front steering system for a vehicle that reduces vibrations from the motor being transferred to a vehicle hand-wheel. The control strategy also includes operating the electric motor in a commutation freeze mode if a position error signal is less than a first predetermined threshold by sending signals to coils of the motor to prevent to the motor from rotating, operating the electric motor in a commutation normal mode if the position error signal is greater than a second predetermined threshold that is greater than the first predetermined threshold, and operating the electric motor in an angle step mode if the position error signal is between an intermediate threshold and the second threshold where the angle step mode provides a signal to the motor to move the motor forward or backward a predetermined number of motor steps, one step at a time.

Abstract: A system and method for secure and restricted transitions between steering control modes for a vehicle with active front steering is disclosed. Possible operating control modes include precision, electric phase locking, and proportional integral derivative (PID) modes. Each operating control mode is monitored and the operational status of the modes are checked before transitioning. For security, the system can prevent transitions from PID to precision control mode and restrict electric phase locking mode to transition only to a mechanical locking mode.

Abstract: A method is provided for limiting a steering angle overlay applied by a steering actuator in a limited by-wire active front steering (AFS) system. The method includes determining a maximum rate limit for the steering angle overlay in order to minimize an undesired disturbance to the driver in the form of a torque and/or angle feedback while maximizing the rate of steering overlay allowed for a given set of vehicle operating conditions. The maximum rate limit is determined by a function of the input steering rate and braking level. A limited AFS system includes both steering and braking input devices, a steering actuator, and a controller having an algorithm. The controller uses the algorithm to calculate the maximum overlay rate limit and limits the steering actuator to the maximum overlay rate limit.

Abstract: A motor control strategy for a motor in a front steering system for a vehicle that reduces vibrations from the motor being transferred to a vehicle hand-wheel. The control strategy also includes operating the electric motor in a commutation freeze mode if a position error signal is less than a first predetermined threshold by sending signals to coils of the motor to prevent to the motor from rotating, operating the electric motor in a commutation normal mode if the position error signal is greater than a second predetermined threshold that is greater than the first predetermined threshold, and operating the electric motor in an angle step mode if the position error signal is between an intermediate threshold and the second threshold where the angle step mode provides a signal to the motor to move the motor forward or backward a predetermined number of motor steps, one step at a time.

Abstract: A method for controlling a limited by-wire active front steering system includes measuring an input steering angle, determining a tire saturation limit, and comparing the saturation limit to the input angle. A target actuator angle from a steering actuator is limited when the input angle is greater than the saturation limit. A constant value provides a fixed steering gear ratio when the input angle is less than the saturation limit. A limited by-wire steering system for a vehicle includes a steering device, a sensor for measuring an input steering angle, a controller for calculating a first target actuator angle when the input angle is less than a threshold, and a second target actuator angle when the input angle is greater than the threshold. The threshold is a calibrated saturation limit of a road wheel of the vehicle.

Abstract: An active front steering (AFS) system that provides hand-wheel damping. The AFS system includes a damping control sub-system that determines a hand-wheel angular velocity based on the rate of change of a hand-wheel angle signal. The damping control sub-system determines the damping control signal by multiplying the angular velocity of the hand-wheel angle signal with a control gain. The damping control signal is added to a steering signal from a variable gear ratio control sub-system to generate a steering command signal. The damping control sub-system sets to the damping control signal to zero if a signal from a vehicle stability enhancement sub-system is activated.

Abstract: A method for controlling steering in a vehicle includes the steps of obtaining a vehicle steering communication, controlling an actuator coupled to a hand wheel, a road wheel, or both using a primary active steering functionality, if the vehicle steering communication reflects one or more of a plurality of types of specified errors, and controlling the actuator using the primary active steering functionality and a supplemental active steering functionality, if the vehicle steering communication does not reflect one or more of the plurality of types of specified errors.

Abstract: An active front wheel steering control system for a vehicle that includes a first control sub-system that provides AFS oversteer control to control the angle of the front wheels during an oversteer condition, and a second control sub-system that provides AFS understeer control to control the angle of the front wheels during an understeer condition. A controller monitors a first parameter as an oversteer flag associated with the first control sub-system and a second parameter as an understeer flag associated with the second control sub-system.

Abstract: A vehicle comprises a semi-active suspension including controllably adjustable suspension dampers. Open loop and closed loop damper commands are determined for each damper and, depending upon turning direction and damper motion, each damper is controlled with one of the open loop and closed loop damper commands.

Abstract: A vehicle parametric active front steering (AFS) system remedial action is described herein. AFS system modules inter-communicate via messages containing parameters. The AFS system detects a message error, determines an invalid parameter, and takes appropriate remedial action. An error is detected if an error condition is satisfied or if occurrence of incorrect messages reaches or exceeds a certain predetermined frequency. The AFS system takes the remedial action by setting default values of valid parameters corresponding to the invalid parameter.

Abstract: An active front steering system includes a motor controller configured to compute a position error from a commanded position value and an actual position value, and then enter one of two modes—a commutation enable mode and a commutation freeze mode—depending upon the value of this position error. The commutation freeze mode applies when the absolute value of the position error is less than a predetermined threshold, and involves sending a set of signals to the motor's phase inputs such that commutation of the motor is prevented and a substantially constant motor hold torque is produced. The commutation enable mode applies when the absolute value of the position error is greater than or equal to the predetermined threshold, and corresponds to normal commutating operating mode.

Abstract: A system and method for secure and restricted transitions between steering control modes for a vehicle with active front steering is disclosed. Possible operating control modes include precision, electric phase locking, and proportional integral derivative (PID) modes. Each operating control mode is monitored and the operational status of the modes are checked before transitioning. For security, the system can prevent transitions from PID to precision control mode and restrict electric phase locking mode to transition only to a mechanical locking mode.

Abstract: An active front steering system includes a motor controller configured to compute a position error from a commanded position value and an actual position value, and then enter one of two modes—a commutation enable mode and a commutation freeze mode—depending upon the value of this position error. The commutation freeze mode applies when the absolute value of the position error is less than a predetermined threshold, and involves sending a set of signals to the motor's phase inputs such that commutation of the motor is prevented and a substantially constant motor hold torque is produced. The commutation enable mode applies when the absolute value of the position error is greater than or equal to the predetermined threshold, and corresponds to normal commutating operating mode.

Abstract: A vehicle active front steering (AFS) control system is described herein. The AFS system utilizes variable gear ratio and lead steer control methodologies. The AFS system utilizes independent and supervisory control systems to control the AFS system parameters in accordance with designated security metrics, to lower the time to lock the AFS system angle actuator in the event the security metrics are not met, and to lower likelihood of fault detection errors by checking a difference between a target road wheel angle and an actual road wheel angle obtained from a first control path and, for added security, by checking a difference between the target road wheel angle and the actual road wheel angle from a second control path, as a function of the vehicle velocity. The techniques described herein may check a value of an AFS control parameter from the first control path to the value of the same AFS control parameter from the second control path.

Abstract: A system as described herein relates generally to automotive active front steering control systems having a main processor and a redundant sub-processor. The system provides a way of controlling the electrical and mechanical locking of an actuator motor in a variable gear ratio active front steering system. The method enables the sub-processor to electrically lock the active front steer actuator motor via the main processor to reduce mechanical wear or damage to the variable gear ratio system if the main processor is unable to electrically lock the actuator motor before it mechanically locks the actuator motor. The system also provides an error detecting technique that is robust to false failures and allows the active front steering system to safely transition into a fail safe mode if an error occurs.