Abstract: A method for reshaping an electric drive signal of a real-time damper in a sprung mass system includes detecting a periodic frequency and magnitude of a target periodic vibration of a sprung mass. The periodic vibration has velocity and elasticity components that are 90 degrees out-of-phase. An electric drive signal to the real-time damper is reshaped by a controller depending on polarity of the velocity component to thereby generate a composite drive signal. The damper is energized using the composite drive signal to modify a damper force. Reshaping the electric drive signal includes injecting a force and/or an intermittent drive suppression component onto the electric drive signal based on the frequency and magnitude. The sprung mass system may have a frame and body, motion and wheel speed sensors, the real-time dampers, road wheels, and a controller programmed to perform the method.

Abstract: Systems and methods are provided for limit cycle detection and cessation. A control system generates a drive signal with at least one drive component. An actuator effects a response to the drive signal and a sensor measures the response. Characteristics of the drive signal and of the drive components are accessed by a controller. The characteristics are compared to a predetermined set of characteristics. When the characteristics fall within the predetermined set of characteristics, a magnitude of at least one of the characteristics is evaluated. When the magnitude exceeds a predetermined value indicative of the limit cycle, an action is undertaken to stop the limit cycle.

Abstract: A method for reshaping an electric drive signal of a real-time damper in a sprung mass system includes detecting a periodic frequency and magnitude of a target periodic vibration of a sprung mass. The periodic vibration has velocity and elasticity components that are 90 degrees out-of-phase. An electric drive signal to the real-time damper is reshaped by a controller depending on polarity of the velocity component to thereby generate a composite drive signal. The damper is energized using the composite drive signal to modify a damper force. Reshaping the electric drive signal includes injecting a force and/or an intermittent drive suppression component onto the electric drive signal based on the frequency and magnitude. The sprung mass system may have a frame and body, motion and wheel speed sensors, the real-time dampers, road wheels, and a controller programmed to perform the method.

Abstract: Systems and methods are provided for limit cycle detection and cessation. A control system generates a drive signal with at least one drive component. An actuator effects a response to the drive signal and a sensor measures the response. Characteristics of the drive signal and of the drive components are accessed by a controller. The characteristics are compared to a predetermined set of characteristics. When the characteristics fall within the predetermined set of characteristics, a magnitude of at least one of the characteristics is evaluated. When the magnitude exceeds a predetermined value indicative of the limit cycle, an action is undertaken to stop the limit cycle.

Abstract: An electric power steering (EPS) system and methods to attenuate disturbances at the steering wheel by providing a feed forward motor drive input. The EPS includes an electric motor configured to provide a motor drive output responsive to a motor drive input, and an electronic control unit (ECU) being configured to provide the motor drive input, with at least one motor drive component of the motor drive input including compensatory periodic disturbance data. The ECU is further configured to provide disturbance attenuation with the at least one motor drive component from a road wheel signal and vibratory characteristics of a disturbance signal affecting the steering system.

Abstract: A method of controlling a assembly includes measuring a first amplitude of a selected harmonic order of the radial force variation of the assembly, and locating a first angular location of the selected order of the radial force variation of the assembly. A second angular location of a tire is located, which indicates a phase of the selected order of a radial force variation of the tire, having a second amplitude. A third angular location of a wheel is located, which indicates a phase of the selected order of a runout value of the wheel, and has a third amplitude. A remaining force metric may be calculated using the pairs of the first amplitude and the first angular location, the second amplitude and the second angular location, and the third amplitude and the third angular location.

Abstract: An electric power steering (EPS) system and methods to attenuate disturbances at the steering wheel by providing a feed forward motor drive input. The EPS includes an electric motor configured to provide a motor drive output responsive to a motor drive input, and an electronic control unit (ECU) being configured to provide the motor drive input, with at least one motor drive component of the motor drive input including compensatory periodic disturbance data. The ECU is further configured to provide disturbance attenuation with the at least one motor drive component from a road wheel signal and vibratory characteristics of a disturbance signal affecting the steering system.

Abstract: Methods and systems are provided for controlling a steering system of a vehicle is provided. A detection unit is configured to obtain a compass heading, a global positioning system (GPS) heading, or both. A processor is coupled to the detection unit, and is configured to determine whether a vehicle is on a straight line path using the compass heading, the GPS heading, or both, and to selectively implement a feature of the steering system based on whether it is determined that the vehicle is not on a straight line path.

Abstract: A method of controlling a tire/wheel assembly includes measuring a first amplitude of a selected harmonic order of the radial force variation of the assembly, and locating a first angular location of the selected order of the radial force variation of the assembly. A second angular location of a tire is located, which indicates a phase of the selected order of a radial force variation of the tire, having a second amplitude. A third angular location of a wheel is located, which indicates a phase of the selected order of a runout value of the wheel, and has a third amplitude. A remaining force metric may be calculated using the pairs of the first amplitude and the first angular location, the second amplitude and the second angular location, and the third amplitude and the third angular location.

Abstract: A method for testing a vehicle includes designing a tire that has a runout as a function of an angular position of the tire that induces a desired vibration in a vehicle when the tire operates on the vehicle. The method also includes performing a test on the vehicle while operating the vehicle with the tire having the design that induces a desired vibration in a vehicle.

Abstract: Methods and apparatus are provided for determining steering performance. The method includes coupling at least one load source to the steering system, and coupling a portion of the steering system to an angle input source. The method also includes outputting one or more control signals by a processor to the at least one load source to apply a load to the steering system and outputting one or more control signals by the processor to the angle input source to apply an input to the steering system. The method includes receiving torque data indicating a performance of the steering system based on the load applied to the steering system by the at least one load source and the input applied by the angle input source.

Abstract: Methods and systems are provided for evaluating a steering system of a vehicle, in which the steering system includes a steering column, steering rack, and pinion. The rack is manipulated as the steering system is mounted to a testing system. The steering column is also manipulated as the steering system is mounted to the testing system. Data is collected from the manipulating of the rack and the dithering of the steering column for use in evaluating the steering system.

Abstract: Methods and apparatus are provided for determining steering performance. The method includes coupling at least one load source to the steering system, and coupling a portion of the steering system to an angle input source. The method also includes outputting one or more control signals by a processor to the at least one load source to apply a load to the steering system and outputting one or more control signals by the processor to the angle input source to apply an input to the steering system. The method includes receiving torque data indicating a performance of the steering system based on the load applied to the steering system by the at least one load source and the input applied by the angle input source.

Abstract: Methods, system and apparatus are provided for reducing steering wheel vibrations (SWVs). At least one heterodyning operation is performed during the generation of a gain-and-phase-compensated motor drive command signal. The gain-and-phase-compensated motor drive command signal is generated at a particular angular frequency, based on an angular velocity and an angular position of a wheel. The gain-and-phase-compensated motor drive command signal is communicated to an electric power steering system to control motor torque to reduce periodic content in a periodic electrical torque signal at the particular angular frequency.

Abstract: Methods and systems are provided for determining frequencies associated with tire crown bending. The system includes a vibration generating device configured to excite vibrations through a tire. The system further includes a vibration sensing arrangement configured to sense vibrations at a plurality of sensing points on the tire. A computer is in communication with the vibration sensing arrangement and configured to determine a first frequency associated with bending of the crown of the tire based at least partially on phase differences between the sensed vibrations at the plurality of points on the tire.

Abstract: A method is provided for controlling a motor drive torque in an EPS system having a motor and a steering assembly. The method includes receiving a torque signal from the steering assembly; processing the torque signal in accordance with a steering perception program to produce a motor control signal; and controlling the motor drive torque based on the motor control signal.

Abstract: A system for characterizing a vehicle tire is provided. The system includes a testing assembly configured to support the vehicle tire. The assembly includes a force-moment transducer configured to gather force information from the vehicle tire in response to a stimulus on the vehicle tire. The system further includes an accelerometer coupled to the vehicle tire and configured to gather vibration information from the vehicle tire in response to the stimulus on the vehicle tire. The system further includes a post-processing system configured to receive the vibration information from the accelerometer and the force information from the force-moment transducer. The post-processing system is further configured to extract resonant frequencies from the vibration information and the force information.

Abstract: Methods and systems are provided for suppression of steering wheel vibrations generated by periodic disturbances in a vehicle steering system. An exemplary method reducing steering wheel vibrations caused by periodic disturbances involves determining a gross torque attributable to the periodic disturbances in the steering system, identifying a desired amount of suppression of the vibrations at the steering wheel, determining an offset torque based on the gross torque and the desired amount of suppression, and generating a motor command signal in a manner that is influenced by the offset torque. The motor drive command signal is provided to an electric motor coupled the steering wheel and/or the vehicle tires, and the motor drive command signal influences the torque applied by the motor to assist steering of the vehicle tires by the steering wheel in a manner that attenuates the vibrations communicated to the steering wheel by the desired amount.

Abstract: Methods and systems are provided for controlling a steering system of a vehicle is provided. A detection unit is configured to obtain a compass heading, a global positioning system (GPS) heading, or both. A processor is coupled to the detection unit, and is configured to determine whether a vehicle is on a straight line path using the compass heading, the GPS heading, or both, and to selectively implement a feature of the steering system based on whether it is determined that the vehicle is not on a straight line path.

Abstract: Methods and systems are provided for controlling an electric power steering system. In one embodiment, a method includes: storing a compensation table having compensation values that are associated with motor torque drive values; receiving a current motor torque drive signal; determining a compensation action the current motor torque drive signal; determining a compensation value based on the compensation action and the table; and generating a motor torque drive signal based on the compensation value.