Motor vehicle with active suspensions and control method of the motor vehicle
A motor vehicle comprises a suspended mass comprising a body, an unsprung mass comprising a plurality of wheels to allow the motor vehicle to move forward on a road, an active suspension assembly configured to suspend the suspended mass relative to the unsprung mass and controllable to move the suspended mass relative to the unsprung mass, an engine carried by the body, a transmission connecting the engine to at least two of said wheels, thereby defining traction wheels, such that the engine can deliver torque to the traction wheels causing acceleration of the motor vehicle, and a control unit configured to control the active suspension assembly during said acceleration and/or in a steady state of the motor vehicle prior to said acceleration imposing a displacement of the suspended mass relative to the unsprung mass according to a yaw axis of the motor vehicle to increase the maximum transmissible force from the traction wheels to the road.
1 . A motor vehicle, comprising:
a suspended mass comprising a body;
an unsprung mass comprising a plurality of wheels to allow the motor vehicle to move forward on the road;
an active suspension assembly configured to suspend the suspended mass relative to the unsprung mass and controllable to move the suspended mass relative to the unsprung mass;
an engine carried by the body;
a transmission connecting the engine to at least two of said wheels, thereby defining traction wheels, such that the engine can deliver torque to the traction wheels causing acceleration of the motor vehicle; and
a control unit configured to control the active suspension assembly during said acceleration and/or in a steady state of the motor vehicle preceding said acceleration by imposing a displacement of the suspended mass relative to the unsprung mass according to a yaw axis of the motor vehicle to increase a maximum transmissible force from the traction wheels to the road.
2 . The motor vehicle according to claim 1 , wherein the control unit is configured to impose said displacement at the time when said acceleration starts with the motor vehicle in the steady state.
3 . The motor vehicle according to claim 1 , wherein the control unit is configured to predict an occurrence of said acceleration during the steady state via reception of a signal indicating a request for acceleration, wherein the control unit is further configured to impose said displacement during the steady state when predicting the occurence of said acceleration.
4 . The motor vehicle according to claim 1 , wherein the traction wheels are arranged in front of a centre of mass of the motor vehicle according to a direction of said acceleration, and wherein the displacement imposed by the control unit is a lowering of the suspended mass relative to the unsprung mass.
5 . The motor vehicle according to claim 4 , wherein the control unit is configured to calculate a minimum limit for the height of the centre of mass, relative to a reference point, based on operating conditions of the motor vehicle comprising the speed of the motor vehicle, wherein the lowering imposed by the control unit brings the height of the centre of mass, relative to the reference point, to coincide with the minimum limit.
6 . The motor vehicle according to claim 1 , wherein the traction wheels are arranged behind a centre of mass of the motor vehicle according to a direction of said acceleration, and wherein the displacement imposed by the control unit is a lifting of the suspended mass relative to the unsprung mass.
7 . The motor vehicle according to claim 6 , wherein the control unit is configured to calculate a maximum limit for a height of the centre of mass, relative to a reference point, based on operating conditions of the motor vehicle comprising the speed of the motor vehicle, wherein the lifting imposed by the control unit brings the height of the centre of mass, relative to the reference point, to coincide with the maximum limit.
8 . The motor vehicle according to claim 1 , wherein the control unit is configured to resolve a problem of optimisation calculating an optimal height of a centre of mass of the motor vehicle, relative to a reference point, that maximises said maximum transmissible force, wherein the displacement imposed by the control unit brings the height of the centre of mass, relative to the reference point, to coincide with the optimal height calculated.
9 . The motor vehicle according to claim 1 , wherein the body comprises a front, a rear, and a longitudinal axis extending between the front and the rear, and wherein said acceleration is a longitudinal acceleration along the longitudinal axis.
10 . A method for controlling a motor vehicle comprising a suspended mass comprising a body, an unsprung mass comprising a plurality of wheels to allow the motor vehicle to move forward on a road, an active suspension assembly configured to suspend the suspended mass relative to the unsprung mass and controllable to move the suspended mass relative to the unsprung mass, an engine carried by the body, and a transmission connecting the engine to at least two of said wheels, thereby defining traction wheels, such that the engine can deliver torque to the traction wheels causing acceleration of the motor vehicle, the method comprising the step of imposing during said acceleration and/or in a stationary state of the motor vehicle prior to said acceleration a displacement of the suspended mass relative to the unsprung mass via the active suspension assembly according to a yaw axis of the motor vehicle to increase the maximum transmissible force from the traction wheels to the road.
11 . The method according to claim 10 , wherein the displacement is imposed at the time when said acceleration starts with the motor vehicle in a steady state.
12 . The method according to claim 10 , further comprising the steps of predicting the event of acceleration during the steady state and imposing said displacement during the steady state when the event of acceleration is predicted.
13 . The method according to claim 10 , wherein the displacement is a lowering of the suspended mass relative to the unsprung mass when the traction wheels are arranged in front of a centre of mass of the motor vehicle according to a direction of said acceleration.
14 . The method according to claim 13 , wherein the lowering brings the height of the centre of mass to coincide with a related minimum limit calculated based on operating conditions of the motor vehicle comprising the speed of the motor vehicle.
15 . The method according to claim 10 , wherein the displacement is a lifting of the suspended mass relative to the unsprung mass when the traction wheels are arranged behind a centre of mass of the motor vehicle according to a direction of said acceleration.
16 . The method according to claim 15 , wherein the lifting brings the height of the centre of mass to coincide with a related maximum limit calculated based on operating conditions of the motor vehicle comprising the speed of the motor vehicle.
17 . The method according to claim 10 , wherein the displacement brings the height of a centre of mass of the motor vehicle to coincide with a relative optimal height calculated by solving an optimisation problem, wherein solving the optimisation problem is the calculation of the optimal height that maximises said maximum transmissible force.
18 . The method according to claim 10 , wherein the body comprises a front, a rear, and a longitudinal axis extending between the front and the rear, and wherein said acceleration is a longitudinal acceleration along the longitudinal axis.
19 . A motor vehicle, comprising:
a suspended mass comprising a body;
an unsprung mass comprising a plurality of wheels to allow the motor vehicle to move forward on the road;
an active suspension assembly configured to suspend the suspended mass relative to the unsprung mass and controllable to move the suspended mass relative to the unsprung mass;
an engine carried by the body;
a transmission connecting the engine to at least two of said wheels, thereby defining traction wheels, such that the engine can deliver torque to the traction wheels causing forward acceleration of the motor vehicle; and
a control system configured to control the active suspension assembly in response to an input to create said forward acceleration by imposing a displacement of the suspended mass relative to the unsprung mass according to a yaw axis of the motor vehicle to increase a maximum transmissible force from the traction wheels to the road.