Model free semi-active vehicle suspension system
View Patent ↗A method for controlling a shock absorber system of a vehicle that includes a plurality of controlled shock absorbers linearizes the system. The method includes transforming original control inputs of the shock absorbers into virtual damper force input signals based on a bilinear damper characteristic. The system dynamics are then decoupled into modal components using static decoupling matrices, and the system is controlled with a linear decentralized controller.
1. A method of controlling a shock absorber system of a vehicle comprising a plurality of controlled shock absorbers, said method comprising:
linearizing the system by transforming original control inputs of the shock absorbers into virtual damper force input signals based on a bilinear damper characteristic;
decoupling system dynamics into modal components using static decoupling matrices that comprise the virtual damper force input signals to modal body accelerations of the vehicle; and
controlling the system with a linear decentralized controller based on the modal components.
2. The method of claim 1 , wherein the system is linearized using model free inputs.
3. The method of claim 1 , the modal components comprising a modal decoupling matrix that has a parameter representing a longitudinal offset of a center of gravity of the vehicle.
4. The method of claim 1 , wherein the system is controlled by generating a control signal, i v , for each of the controlled shock absorbers, wherein
i
v
∼
f
c
v
r
-
i
0
and wherein v r is a rattle velocity of the shock absorber, f c is a related force of the shock absorber, and i o is a control current bias.
5. The method of claim 1 , wherein the shock absorbers are semi-active shock absorbers.
6. The method of claim 1 , wherein the shock absorbers are current controlled shock absorbers.
7. A semi-active shock absorber of a shock absorber system of a vehicle comprising:
a cylinder;
a rod inserted within said cylinder;
a piston coupled to said rod;
a controlled valve coupled to said cylinder; and
a controller coupled to said controlled valve for controlling said valve, said controller comprising:
a linear controller;
a linearizing controller coupled to said linear controller, said linearizing controller based on a bilinear damper characteristic.
8. The semi-active shock absorber of claim 7 , wherein said controller controls said valve using a virtual damper force input signal, i v , and wherein
i
v
∼
f
c
v
r
-
i
0
,
wherein v r is a rattle velocity of the shock absorber, f c is a related force of the shock absorber, and i o is a control current bias.
9. The semi-active shock absorber of claim 7 , said controller further comprising a modal decoupling matrix.
10. The semi-active shock absorber of claim 9 , said modal decoupling matrix comprising a parameter representing a longitudinal offset of a center of gravity of the vehicle.
11. The semi-active shock absorber of claim 7 , wherein said controlled valve is a current controlled valve.
12. The semi-active shock absorber of claim 7 , wherein said controller is based on a skyhook principle.
13. A shock absorber system of a vehicle comprising a plurality of controlled shock absorbers, said system comprising:
means for linearizing the system by transforming control inputs of the shock absorbers into virtual damper force input signals based on a bilinear damper characteristic;
means for decoupling system dynamics into modal components using static decoupling matrices that comprise the virtual damper force input signals to modal body accelerations of the vehicle; and
means for controlling the system with a linear decentralized controller based on the modal components.
14. The shock absorber system of claim 13 , wherein the system is linearized using model free inputs.
15. The shock absorber system of claim 13 , the modal components comprising a modal decoupling matrix that has a parameter representing a longitudinal offset of a center of gravity of the vehicle.
16. The shock absorber system of claim 13 , wherein the system is controlled by generating a control signal, i v , for each of the controlled shock absorbers, wherein
i
v
∼
f
c
v
r
-
i
0
and wherein v r is a rattle velocity of the shock absorber, f c is a related force of the shock absorber, and i o is a control current bias.
17. The shock absorber system of claim 13 , wherein the shock absorbers are semi-active shock absorbers.
18. The shock absorber system of claim 13 , wherein the shock absorbers are current controlled shock absorbers.