SYSTEM AND METHOD FOR CONTROLLING DAMPERS OF AN ACTIVE SUSPENSION SYSTEM
A control system and method is disclosed for controlling an active suspension and a leveling system for a motor vehicle. The control system may use estimator, controller and management modules. The estimator module processes measured signals obtained from various components and sensors of the vehicle relating to modal displacements, velocities and accelerations, and calculates derived signals which are used as inputs to the controller module. The controller module calculates the desired damper force for each active damper based on motions of the vehicle body and wheels. The management module translates the desired active damper force into an appropriate set of control signals to control each active damper. These operations are performed for each active damper of the vehicle to control each damper in real time.
1 . An active suspension system for a vehicle, wherein the vehicle has a plurality of active dampers and a plurality of sensors for providing information on operating states of the vehicle, comprising:
an estimator module configured to receive inputs from the plurality of sensors and to generate a plurality of first outputs including differing body accelerations during operation of the vehicle;
a controller module in communication with the estimator module and configured to receive the plurality of first outputs from the estimator module and to generate a plurality of second output signals for controlling the active dampers; and
a management module configured to receive the second output signals and to calculate actuator signals to be applied to each of the plurality of active dampers to implement a user selected ride condition.
2 . The active suspension system of claim 1 , wherein the first plurality of output signals generated by the estimator module includes at least two or more of the following:
signals relating to damper forces;
hydraulic power consumption;
wheel displacements, velocities and accelerations of a plurality of wheels of the vehicle;
damper displacements, velocities and accelerations;
pressures associated with a pump of the system and pressures associated with compression and rebound conditions of each of the active dampers;
body displacements, velocities and accelerations;
modal displacements, velocities and accelerations associated with heave, pitch and roll movements of the vehicle; and
vehicle and power pack signals.
3 . The active suspension system of claim 1 , wherein the inputs to the estimator module from the plurality of sensors comprises at least two or more of the following:
lateral acceleration of the vehicle;
brake pressure;
individual wheel speeds;
vehicle speed;
throttle pedal position;
steering wheel angle;
steering wheel angle rate;
brake torque (request);
engine torque (request) and
engine revolutions per minute (RPM).
4 . The active suspension system of claim 1 , wherein the second plurality of outputs include, for each said active damper:
a damper force;
a control current offset for a compression phase of operation of the active damper;
a control current offset for a rebound phase of operation of the active damper.
5 . The active suspension system of claim 1 , wherein the actuator signals generated by the management module comprise at least one or more of the following:
switch valve control current signals;
power pack pump speed signals; and
valve control currents for rebound and compression phases of operation of each said active damper.
6 . The active suspension system of claim 1 , wherein the controller module includes a skyhook control module including:
a first non-linear look-up table having as its input a modal heave velocity and as an output a gain factor multiplied by a linear gain to enable a sensitivity of a modal heave force to be adjusted over a range of a modal heave velocity.
7 . The active suspension system of claim 6 , wherein the controller module includes a skyhook control module including:
a second non-linear look-up table having as an input vehicle velocity, and as an output a gain factor multiplied with an output from the first non-linear look-up table, to enable the modal heave force to be a function of a velocity of the vehicle.
8 . The active suspension system of claim 7 , wherein the skyhook control module further includes a plurality of additional look-up tables pertaining to a subplurality of:
roll displacements;
pitch displacements;
heave displacements;
heave velocities;
heave accelerations;
roll velocities;
roll acceleration;
pitch velocities; and
pitch accelerations.
9 . The active suspension system of claim 1 , wherein the controller module further includes at least a subplurality of:
a feed-forward module for calculating a desired pitch moment based on sensed brake pressure and vehicle velocity;
a modal based feed forward control module for calculating actuator forces at each wheel of the vehicle necessary to achieve a target pitch angle with respect to longitudinal acceleration and a target roll angle with respect to lateral acceleration;
a road preview module for calculating desired actuator forces for controlling each said active damper based on road preview information, wherein the road preview information involves characteristics pertaining to a road profile in front of the vehicle while the vehicle is moving;
a force stabilization control module configured to reduce a transmission of force spikes into a body of the vehicle from a road surface during cornering maneuvers of the vehicle;
a wheel damping control module for reducing high frequency wheel shake of a wheel of the vehicle; and
an end stop damping control module configured to counteract a motion of one of the active dampers if the one said active damper moves toward its travel limits.
10 . The active suspension system of claim 1 , wherein the management module includes a separate management module subsystem for each one of four active dampers.
11 . The active suspension system of claim 10 , wherein each one of the management module subsystems includes a look-up table for implementing a sport mode of tuning its associated said active damper.
12 . The active suspension system of claim 10 , wherein each one of the management module subsystems includes a look-up table for implementing a touring mode of tuning its associated said active damper.
13 . The active suspension system of claim 11 , wherein the lookup table of the management module subsystem includes separate look-up tables for valves associated with the plurality of active dampers, and wherein the look-up tables are directed to valve values for compression or rebound phases of operation of the active dampers to implement the sport mode of tuning.
14 . The active suspension system of claim 12 , wherein the lookup table of the management module subsystem includes separate look-up tables for valves associated with the plurality of active dampers, and wherein the look-up tables are directed to valve values for compression or rebound phases of operation of the active dampers to implement the touring mode of tuning.
15 . An active suspension system for a vehicle having four active dampers and a plurality of sensors for providing information on a plurality of states of the vehicle, comprising:
an estimator module configured to receive inputs from the plurality of sensors and to generate a plurality of first outputs relating to accelerations associated with operation of the vehicle;
a controller module in communication with the estimator module and configured to receive the plurality of first outputs from the estimator module and to generate a plurality of second output signals for controlling the active dampers; and
a management module configured to receive the second outputs and to calculate actuator signals to be applied to each one of the plurality of active dampers, the management module including:
a separate management module subsystem for each said active damper, each said management module subsystem including:
a first look-up table for valve control values for controlling at least one valve associated with each of the active dampers to implement a sport mode of operation for the active dampers; and
a second look-up table for valve control values for controlling at least one valve associated with each of the active dampers to implement a touring mode of operation for the active dampers.
16 . The active suspension system of claim 15 , wherein the controller modules includes:
a first non-linear look-up table having as its input a modal heave velocity and as an output a gain factor multiplied by a linear gain to enable a sensitivity of a modal heave force to be adjusted over a range of a modal heave velocity; and
a second non-linear look-up table having as an input vehicle velocity, and as an output a gain factor multiplied with an output from the first non-linear look-up table, to enable the modal heave force to be a function of a velocity of the vehicle.
17 . The active suspension system of claim 15 , wherein the controller module further includes at least a subplurality of:
a feed-forward module for calculating a desired pitch moment based on sensed brake pressure and vehicle velocity;
a modal based feed forward control module for calculating actuator forces at each wheel of the vehicle necessary to achieve a target pitch angle with respect to longitudinal acceleration and a target roll angle with respect to lateral acceleration;
a road preview module for calculating desired actuator forces for controlling each said active damper based on road preview information, wherein the road preview information involves characteristics pertaining to a road profile in front of the vehicle while the vehicle is moving;
a force stabilization control module configured to reduce a transmission of force spikes into a body of the vehicle from a road surface during cornering maneuvers of the vehicle;
a wheel damping control module for reducing high frequency wheel shake of a wheel of the vehicle; and
an end stop damping control module configured to counteract a motion of the active damper if the active damper moves toward its travel limits.
18 . A method for forming an active suspension system for a vehicle, wherein the vehicle has a plurality of active dampers and a plurality of sensors for providing information on operating states of the vehicle, comprising:
using an estimator module configured to receive inputs from the plurality of sensors and to generate a plurality of first outputs including differing body accelerations during operation of the vehicle;
using a controller module in communication with the estimator module and configured to receive the plurality of first outputs from the estimator module and to generate a plurality of second output signals for controlling the active dampers; and
using a management module configured to receive the second outputs and to calculate actuator signals to be applied to each of the plurality of active dampers.