Predictive energy and motion management for multitrailer heavy-duty vehicles
A method is disclosed for controlling motion of a heavy-duty vehicle. Information is obtained related to an upcoming vehicle path and vehicle maneuver along the path; and related to a road friction coefficient along the path. Lateral and longitudinal wheel slip limits are configured for at least two wheels of an axle or lumped group-axle on the vehicle. The lateral and longitudinal wheel slip values are related to respective lateral and longitudinal tyre force values via a pre-determined combined tyre slip model. A vehicle motion profile is determined for performing the vehicle maneuver as a solution to a non-linear optimal control problem (NOCP). The NOCP is constrained by the lateral and longitudinal wheel slip limits and formulated to account for the road friction coefficient and/or curvature along the upcoming vehicle path. Motion of the vehicle is controlled along the path based on the determined target vehicle motion profile.
1 . A method for controlling motion of a heavy-duty vehicle, comprising obtaining information related to an upcoming vehicle path and vehicle maneuver along the path, configuring lateral and longitudinal wheel slip limits for at least two wheels of an axle or lumped group-axle on the heavy-duty vehicle, wherein lateral and longitudinal wheel slip values are related to respective lateral and longitudinal tire force values via a pre-determined combined tire slip model,
determining a vehicle motion profile for performing the vehicle maneuver along the path as a solution to a non-linear optimal control problem (NOCP),
wherein the NOCP is constrained by the lateral and longitudinal wheel slip limits, and
controlling the motion of the heavy-duty vehicle along the path based on the determined target vehicle motion profile.
2 . The method according to claim 1 , comprising obtaining information related to a road friction coefficient and/or curvature along the upcoming vehicle path, wherein the NOCP is formulated to account for the road friction coefficient and/or curvature along the upcoming vehicle path.
3 . The method according to claim 1 , wherein the vehicle motion profile comprises a target tire force trajectory and/or a target wheel slip trajectory for at least two wheels to be followed along the upcoming vehicle path.
4 . The method according to claim 1 , wherein the vehicle motion profile comprises a target vehicle unit acceleration and/or a target vehicle speed to be followed along the upcoming vehicle path.
5 . The method according to claim 1 , wherein the heavy-duty vehicle comprises a propulsion actuator with regenerative braking capability on more than one driven axle.
6 . The method according to claim 1 , wherein the heavy-duty vehicle is a multitrailer vehicle comprising a self-powered dolly vehicle unit.
7 . The method according to claim 1 , comprising determining the vehicle motion profile for performing the vehicle maneuver along the path as a solution to a non-linear optimal control problem (NOCP), wherein the NOCP is configured to minimize an energy consumption by the vehicle along the path.
8 . The method according to claim 1 , comprising converting the NOCP to a sequential program and determining the vehicle motion profile as a solution to the sequential program.
9 . The method according to claim 1 , comprising configuring a nonlinear single-track vehicle model of the heavy-duty vehicle with lumped group-axles.
10 . The method according to claim 1 , comprising reducing a number of states in one or more longitudinal dynamic equations of the NOCP.
11 . The method according to claim 1 , comprising configuring two different levels of discretization for longitudinal and lateral dynamic equations of the NOCP, wherein the two different levels of discretization comprise a first discretization for the longitudinal dynamic equations of the NOCP and a second discretization for the lateral dynamic equations of the NOCP, wherein the first discretization is more coarse than the second discretization.
12 . The method according to claim 1 , comprising configuring a linear time-varying (LTV) version of the lateral dynamic equations of the NOCP and/or the combined tire slip model, where the LTV is linearized around an initial reference vehicle motion profile along the path.
13 . The method according to claim 1 , comprising solving a differential-algebraic system of equations (DAE) comprising algebraic equations of the combined tire slip model of each of a set of lumped axles of the heavy-duty vehicle to find wheel speed reference trajectories for each axle on the heavy-duty vehicle linearizing longitudinal algebraic equations F x =ƒ x (v x , v y , ω) of each of the lumped axles around the corresponding wheel speed reference trajectory, and solving the resulting linearized equations for wheel speed symbolically, such that ω=ƒ x,lin −1 (v x , v y , F x ) for each wheel, and substituting the wheel speed expressions w into respective expressions for lateral tyre force F y =ƒ y (v x , v y , ω),
wherein F x represents longitudinal tyre force, F y represents lateral tyre force, v x represents longitudinal tyre velocity, v y represents lateral tyre velocity, ω represents wheel speed, ƒ x (⋅) is a function for representing tyre longitudinal force, ƒ y (⋅) is a function for representing tyre lateral force, and ƒ x,lin −1 (⋅) represents a solution for a linearized version of ƒ x (⋅).
14 . The method according to claim 1 , wherein a distance of the path is between 5-1000 m.
15 . The method according to claim 1 , wherein the vehicle maneuver comprises a road speed limit to be adhered to.
16 . The method according to claim 1 , comprising controlling the motion of the heavy-duty vehicle by issuing any of: an acceleration request, a wheel torque request, and/or a wheel slip request, in dependence of the vehicle motion profile to one or more actuator control units of the heavy-duty vehicle.
17 . A control unit comprising processing circuitry configured to perform the method according to claim 1 .
18 . A heavy-duty vehicle comprising the control unit according to claim 17 .