Path-controlling module, associated path-controlling device and associated method
A motor-vehicle path-controlling module is arranged to model the path of the vehicle during a change in traffic lane by a Bezier curve relating a value of a parameter to a value of a lateral deviation of the vehicle from the center of a traffic lane and to a value of a time-dependent variable representative of the variation in the change of path; determine a setpoint state vector of a closed feedback loop of a path-controlling device, the loop being designed to control the motor vehicle so that it follows the path modelled by the Bezier curve, the vector being determined on the basis of the lateral deviation, of the time-dependent variable and of the parameter, and transmit the setpoint state vector to the input of the loop.
1. A path-control method for a vehicle, comprising:
modeling a path of the vehicle during a lane change using a Bézier curve linking a value of a parameter to a value of a lateral deviation of the vehicle with respect to a center of a lane on an ordinate axis and to a value of a time-dependent variable representative of a variation in a change in the path on an abscissa axis;
determining a setpoint state vector of a path-control device based on the lateral deviation, the time-dependent variable and the parameter; and
steering the vehicle using the path-control device based on a state variable so that the vehicle follows the modeled path.
2. The method as claimed in claim 1 , wherein the determining of the setpoint state vector comprises:
a) determining a value of the parameter so that each increment of a time counter of the path-control device is comprised between two consecutive time-dependent variables;
b) determining two consecutive lateral deviations based on the value of the parameter;
c) determining an intermediate lateral deviation by interpolating between the two consecutive lateral deviations; and
d) determining setpoint values comprising a setpoint lateral deviation, a setpoint yaw velocity, a setpoint heading angle, and a setpoint lateral velocity, the setpoint values being determined based on the intermediate lateral deviation, of the two consecutive time-dependent variables and of the two consecutive lateral deviations,
wherein the setpoint state vector comprises the setpoint lateral deviation and the setpoint values.
3. The method as claimed in claim 2 , further comprising determining a corrective radius of curvature based on the two consecutive time-dependent variables, the two consecutive lateral deviations and a longitudinal velocity of the vehicle, and transmitting the corrective radius of curvature to the path-control device.
4. The method as claimed in claim 3 , wherein when the change in the path is triggered, the time counter is started, and when the value reached by the counter is greater than or equal to the value of a time-dependent variable associated with a control point of the Bézier curve comprising a time-dependent variable of greatest value, the counter is stopped to indicate an end of the change in the path.
5. The method as claimed in claim 4 , further comprising repeating iterations of a), b), c), d) and repeating iterations of the determining of the corrective radius of curvature for each increment of the counter, two consecutive increments being separated by a constant duration.
6. A path-control module for a vehicle, the module comprising:
processing circuitry configured to:
model a path of the vehicle during a lane change using a Bézier curve linking a value of a parameter to a value of a lateral deviation of the vehicle with respect to a center of a lane on an ordinate axis and to a value of a time-dependent variable representative of a variation in a change in the path on an abscissa axis,
determine a setpoint state vector of a closed control loop of a path-control device, the closed control loop being configured to steer the vehicle so that the vehicle follows the path modeled by the Bézier curve, the vector being determined based on the lateral deviation, the time-dependent variable and the parameter, and
transmit the setpoint state vector as input to the closed control loop.
7. The module as claimed in claim 6 , wherein the processing circuitry is configured to:
e) determine a value of the parameter so that each increment instant of a time counter of the path-control device is comprised between two consecutive time-dependent variables;
f) determine two consecutive lateral deviations based on the value of the parameter;
g) determine an intermediate lateral deviation by interpolating between the two consecutive lateral deviations; and
h) determine setpoint values comprising a setpoint lateral deviation, a setpoint yaw velocity, a setpoint heading angle, and a setpoint lateral velocity, the setpoint values being determined based on the intermediate lateral deviation, of the two consecutive time-dependent variables and of the two consecutive lateral deviations,
wherein the setpoint state vector comprises the setpoint lateral deviation and the setpoint values.
8. The module as claimed in claim 7 , wherein the processing circuitry is configured to determine a corrective radius of curvature based on the two consecutive time-dependent variables, the two consecutive lateral deviations and a longitudinal velocity of the vehicle, and to transmit the corrective radius of curvature to the path-control device.
9. The module as claimed in claim 8 , wherein the processing circuitry is configured to start the time counter when a change in path is triggered and to stop the counter to indicate an end of the change in path when the value reached by the counter is greater than or equal to the value of a time-dependent variable associated with a control point of the Bézier curve comprising a time-dependent variable of greatest value.
10. A path-control device comprising:
processing circuitry configured to
model a path of a vehicle during a lane change using a Bézier curve linking a value of a parameter to a value of a lateral deviation of the vehicle with respect to a center of a lane on an ordinate axis and to a value of a time-dependent variable representative of a variation in a change in the path on an abscissa axis,
determine a setpoint state vector of a closed control loop of a path-control device, the closed control loop being configured to steer the vehicle so that the vehicle follows the path modeled by the Bézier curve, the vector being determined based on the lateral deviation, the time-dependent variable and the parameter,
transmit the setpoint state vector as an input to the closed control loop, and
steer the vehicle via the closed control loop so that the vehicle follows the path modeled by the Bézier curve.