Method and module for determining of reference values for a vehicle control system
Reference speed values for a vehicle's control system are determined by: determining, using map and location data, route segments, each with route characteristics; performing, simulation cycles, each comprising simulation steps of: predicting the speed when the set speed is imparted as the reference speed; comparing with first lower and upper limit values, which define an engine torque, for use in the next simulation cycle; making a second prediction of the speed when the engine torque is a value that depends on the result of said first comparison in the immediately preceding simulation cycle; comparing the second predicted vehicle speed with second lower and upper limit values, which delineate a range within which the speed is maintained, with an offset added if the vehicle is in a route segment with a steep hill; and determining the reference value based on the second comparison and/or the second predicted vehicle speed.
1. A method for determination of at least one reference value for a control system of a vehicle, the method comprising:
acquiring a set speed v set for the vehicle;
determining a horizon for the itinerary by reference to map data and location data, which horizon comprises one or more route segments, each route segment having at least one route characteristic;
performing, by a module including an automated processor, a number of simulation cycles, wherein each simulation cycle s j includes a number N of simulation steps conducted at a predetermined rate f, the simulation steps comprising:
making a first prediction of the speed v pred — cc of the vehicle along the horizon according to a conventional cruise control when the set speed v set is imparted as a reference speed v ref , wherein the first prediction depends on the route characteristic of said route segment;
comparing, as a first comparison, the first predicted vehicle speed v pred — cc with at least one of first lower and upper limit values v lim1 and v lim2 , wherein the first lower and upper limit values v lim1 and v lim2 define an engine torque T for use in an immediately following simulation cycle s j+1 ;
making a second prediction of the speed v pred — Tnew of the vehicle along the horizon when the engine torque T is a value which depends on the result of said first comparison in an immediately preceding simulation cycle s j−1 ;
comparing, as a second comparison, the second predicted vehicle speed v pred — Tnew with at least one of second lower and upper limit values v min and v max , wherein the second lower and upper limit values v min and v max delineate a range within which the speed of the vehicle is maintained, and adding an offset v offset to at least one of said second lower and upper limit values v min and v max when the at least one route characteristic of the route segment in which the vehicle is located indicates a steep hill;
determining the at least one reference value along the horizon based on the said second comparison and/or the second predicted vehicle speed v pred — Tnew in this simulation cycle s j ; and
controlling, by the control system of the vehicle, the speed of the vehicle according to the at least one reference value.
2. A method according to claim 1 , wherein said offset v offset is positive when the vehicle is in a route segment with a route characteristic indicating a steep upgrade.
3. A method according to claim 1 , wherein said offset v offset is negative when the vehicle is in a route segment with a route characteristic indicating a steep downgrade.
4. A method according to claim 1 , wherein the value of said offset v offset varies over time.
5. A method according to claim 1 , wherein the value of said offset v aset is at least partly based on a driving mode applied by the vehicle.
6. A method according to claim 5 , wherein said driving mode is chosen by a driver of the vehicle.
7. A method according to claim 1 , wherein only one out of acceleration and retardation is allowed within a section L where a steep upgrade is followed by a steep downgrade within the length of section L from said steep upgrade.
8. A method according to claim 1 , wherein only one out of acceleration and retardation is allowed within a section L where a steep downgrade is followed by a steep upgrade within the length of section L from said steep downgrade.
9. A method according to claim 7 , wherein the length of section L depends on
the speed of the vehicle, and/or
a driving mode applied.
10. A method according to claim 1 , wherein an offset on the respective second lower and upper limit values v min and v max is allowed when the current speed of the vehicle is outside the range bounded by the second lower and upper limit values v min and v max and when the second prediction v pred — Tnew of the speed of the vehicle indicates that the set speed v set will be reached by imparting the reference value which resulted in the second prediction v pred — Tnew of the speed of the vehicle.
11. A non-transitory computer-readable medium product incorporating instructions for enabling a computer of a vehicle to perform steps according to the method of claim 1 when the instructions are run on said computer.
12. A module configured to control a speed of a vehicle, the module comprising:
an input unit configured to receive a set speed v set for the vehicle;
a horizon unit configured to determine a horizon for an itinerary of the vehicle, by reference to map data and location data which comprise route segments, each route segment having at least one route characteristic;
a calculation unit configured to perform a number of simulation cycles, wherein each simulation cycle s j comprises a number N of simulation steps conducted at a predetermined rate f, the simulation steps comprising:
making a first prediction of the speed v pred — cc of the vehicle along the horizon according to a conventional cruise control when the set speed v set is imparted as a reference speed v ref , which first prediction depends on the at least one route characteristic of said route segment;
comparing, as a first comparison, the first predicted vehicle speed v pred — cc with at least one of first lower and upper limit values v lim1 and v lim2 , wherein the first lower and upper limit values v lin1 and v lin2 define an engine torque T for use in an immediately following simulation cycle s j+1 ;
making a second prediction of the speed V pred — Tnew of the vehicle along the horizon when the engine torque T is a value which depends on a result of said first comparison in an immediately preceding simulation cycle s j−1 ;
comparing, as a second comparison, the second predicted vehicle speed V pred — Tnew with at least one of second lower and upper limit values v min and v max , wherein the second lower and upper limit values v min and v max delineate a range within which the speed of the vehicle is maintained, and adding an offset v offset to at least one of said second lower and upper limit values v min and v max when the vehicle is in a route segment with a route characteristic indicating a steep hill; and
determining the at least one reference value along the horizon based on the second comparison and/or the second predicted vehicle speed V pred — Tnew in this simulation cycle s j ; and
a providing unit configured to supply a control system of the vehicle with the at least one reference value for regulating the speed of the vehicle.
13. A module according to claim 12 , wherein said offset v offset is positive when the vehicle is in a route segment with a route characteristic indicating a steep upgrade.
14. A module according to claim 12 , wherein said offset v offset is negative when the vehicle is in a route segment with a route characteristic indicating a steep downgrade.
15. A module according to claim 12 , wherein the value of said offset v offset varies over time.
16. A module according to claim 12 , wherein the value of said offset v offset is at least partly based on a driving mode applied by the vehicle.
17. A module according to claim 16 , wherein said driving mode is chosen by a driver of the vehicle.
18. A module according to claim 12 , wherein the calculation unit is configured to allow only one of acceleration and retardation within a section L where a steep upgrade is followed by a steep downgrade within the length of section L from said steep upgrade.
19. A module according to claim 12 , wherein the calculation unit is configured to allow only one of acceleration and retardation within a section L where a steep downgrade is followed by a steep upgrade within the length of section L from said steep downgrade.
20. A module according to claim 18 , wherein the length of section L depends on
the vehicle's speed, and/or
a driving mode applied.
21. A module according to claim 12 , wherein the calculation unit is configured to determine threshold values used to control the speed of the vehicle, based on at least one from among a current transmission ratio, a current vehicle weight, a maximum torque curve for the engine of the vehicle, a mechanical friction, and a running resistance at current speed of the vehicle.
22. A module according to claim 12 , wherein the calculation unit is configured to calculate threshold values in the form of gradient threshold values l min and l max .
23. A module according to claim 12 , wherein an offset on the respective second lower and upper limit values v min and v max is allowed when the current speed of the vehicle is outside the range bounded by the second lower and upper limit values v min and v max , and when the second prediction V pred — Tnew of the speed of the vehicle indicates that the set speed v set will be reached by imparting the reference value which resulted in the second prediction V pred — Tnew of the speed of the vehicle.
24. A vehicle comprising the module of claim 12 .