The work leading to the present invention has benefited from financial support from the coal and steel research funds of the European Community by virtue of grant agreement No. 607957.

The invention relates in a general manner to a device for real-time control of vehicle trajectory. The invention relates more precisely to a lateral control device for generating in real time a vehicle turning command, in particular for an autonomous automotive vehicle or a vehicle for which driving is partially delegated, that is to say a vehicle able to move totally or partially with no human driver.

Devices or systems for real-time control of trajectory, in particular on the basis of states relating to the vehicle, are already known in numerous technical fields, including in the automotive field.

For example, patent EP1074903B1 discloses a system for following a lane with detection of marking of the lane. A direct-chain action module produces a steering driving term based on a target line position with the help of a graphics processor. The elements disclosed allow an application of this system to a rectilinear lane, or indeed one with low-curvature bends with no noticeable influence on the vehicle's dynamics, to be envisioned. An application to a lane with high-curvature bends, as might be encountered for example on mountain roads, can pose a problem of dynamic reactivity of the vehicle in order to maintain itself flexibly in the lane.

Again for example, patent U.S. Pat. No. 8,751,089B2 discloses a trajectory following control system for mobile unit. The system controls a mobile unit so as to follow a target path described by free-form curves. Though this type of system may be appropriate for piloting a robot in a space with no constraint of such a nature as to prevent the freedom of form of the curves that are appropriate for a target path, it may pose problems for an autonomous vehicle whose piloting does not consist in making it follow a target path but in maintaining it in a traffic lane, irrespective of the form of the curves that are imposed by the geometry of the lane.

The objective of the invention is to address the problems posed by the prior art, in particular in terms of effectiveness, reactivity and ease of implementation.

To attain this objective, the subject of the invention is a device for real-time control of trajectory of an autonomous vehicle comprising a control module which produces in real time on the basis of a real or estimated vector of states at each instant of following of a lane by the vehicle moving at a current speed, a first turning command to stabilize the trajectory of the vehicle with respect to the lane. The device is noteworthy in that it comprises an anticipator module which generates a quantity representative of a meta-vector of disturbances for each predicted position of the vehicle at instants succeeding in given amount the current instant and of the vector of states at the current instant, and in that the control module produces the first turning command by quadratic optimization of a relation between said representative quantity generated and a meta-vector of successive turning commands for each predicted position of the vehicle at said instants succeeding in given amount the current instant.

Particularly, said disturbances are curvatures of the lane for each predicted position of the vehicle.

Particularly also, said representative quantity comprises, for each predicted position of the vehicle at said instants succeeding in given amount the current instant, at least one product of the vector of states at the current instant by a numerical matrix modeling a dynamic relation of the vehicle and raised to a power equal to a succession rank of said predicted position.

Advantageously, said representative quantity comprises, for each predicted position of the vehicle at said instants succeeding in given amount the current instant, at least one product of factors comprising on the one hand a disturbance on the lane at the predicted position, and on the other hand a numerical matrix modeling a dynamic relation of the vehicle and raised to a power equal to a succession rank of said predicted position.

Again particularly, the device comprises an apparatus combining the properties of an optical camera and of a radar so as to provide at least one director line geometry of the lane in the form of a polynomial.

More particularly, the anticipator module comprises a sub-module for calculating curvature on the basis of the median director line geometry of the lane by means of the formula:

γk+i=y″⁡(x)(1+[y′⁡(x)]2)32.

Preferably, the relation between said representative quantity generated and the meta-vector of successive turning commands lo comprises, for each quadratic product of an anticipated state, an elementary states weighting matrix and an elementary command weighting matrix.

In particular, the elementary states weighting matrix for the last anticipated state comprises coefficients which are particular in that they are associated with a decreasing positive function of the Lyapunov type, so as to favor a convergence of the optimization.

Independently of the particular coefficients of the elementary states weighting matrix, the device comprises a module compelling all or some of the elementary commands of the meta-vector of successive turning commands to comply with constraints of type comprising at least one upper bound on the states, on the commands and/or on the measurements and/or comprising at least one lower bound on the states, on the commands and/or on the measurements.

Again advantageously, the control device comprises a module imposing constraints on all or some of the elementary commands of the meta-vector of successive turning commands, of type comprising an upper bound and a lower bound on the states, on the commands and/or on the measurements.

Particularly, the module moreover imposes constraints on the elementary commands of the meta-vector of successive turning commands, so that the last predicted state vector is in a polytope which ensures asymptotic convergence beyond the prediction horizon.

