Ride height control system and method

1. A control system for controlling a target ride height of a vehicle comprising:

an electronic control unit (ECU) configured to receive a driving mode signal; and

a driving mode selector configured to output the driving mode signal, the driving mode selector being operable manually by a driver or automatically in relation to automatically detected terrain parameters to signal that an on-road or an off-road driving mode has been selected, the control system being configured to implement an altered throttle response when in the off-road driving mode compared with the on-road driving mode,

the control system being configured, upon receipt of the driving mode signal signalling that an off-road driving mode has been selected, to automatically select one of a plurality of predefined target off-road ride heights by comparing a vehicle speed with a plurality of speed thresholds, wherein when in said selected off-road driving mode, the control system is configured to select a first of said target off-road ride heights when the vehicle speed is below a first speed threshold and to select a second of said target off-road ride heights when the vehicle speed is above said first speed threshold, wherein said first target off-road ride height is higher than said second target off-road ride height, and is configured to select a target on-road ride height lower than the second target off-road height when the vehicle speed increases above a second speed threshold.

2. A control system as claimed in claim 1 , wherein said first target off-road ride height is higher than said second target off-road ride height.

3. A control system as claimed in claim 1 configured automatically to select said first target off-road ride height when the vehicle speed decreases below said first speed threshold for a defined first time period.

4. A control system as claimed in claim 3 , wherein the first time period is dependent on the transfer case operating range.

5. A control system as claimed in claim 1 configured automatically to select the first or second target off-road ride height once the vehicle speed has decreased below said second speed threshold for a defined second time period.

6. A control system as claimed in claim 1 configured to output a signal to dis-engage the off-road driving mode when the vehicle speed remains above said second speed threshold for a defined third time period.

7. A control system as claimed in claim 1 configured to enable manual selection of said first off-road ride height when the second off-road ride height is selected and the vehicle speed is less than a predefined threshold.

8. A control system as claimed in claim 1 configured to select said target off-road ride height in dependence on a detected terrain parameter.

9. A vehicle comprising a control system as claimed in claim 1 .

10. A control system as claimed in claim 1 wherein the terrain types include at least one of sand, grass, rocks, and mud.

11. A control system as claimed in claim 1 , wherein the control system is configured to transition a target ride height from the off-road ride height to an on-road ride height when the vehicle speed exceeds a speed threshold.

12. A control system for controlling a target ride height of a vehicle, the control system comprising:

a driving mode selector configured to output a driving mode signal;

an electronic control unit (ECU) configured to receive the driving mode signal, the ECU configured to implement an automated ride height control to increase the target ride height of the vehicle to an off-road ride height when the vehicle speed falls below one or more predefined thresholds and to implement said automated ride height control when the vehicle is in an off-road driving mode indicated by the driving mode selector, the off-road driving mode determined manually by a driver or automatically from automatically detected terrain parameters, the control system configured to implement an altered throttle response when in the off-road driving mode compared with the on-road driving mode, wherein the electronic control unit is configured, upon receipt of the driving mode signal signalling that an off-road driving mode has been selected, to automatically select one of a plurality of predefined target off-road ride heights by comparing a vehicle speed with a plurality of speed thresholds, wherein when in said selected off-road driving mode, the control system is configured to select a first of said target off-road ride heights when the vehicle speed is below a first speed threshold and to select a second of said target off-road ride heights when the vehicle speed is above said first speed threshold, wherein said first target off-road ride height is higher than said second target off-road ride height, and is configured to select a target on-road ride height lower than the second target off-road height when the vehicle speed increases above a second speed threshold.

13. A control system as claimed in claim 12 configured to increase the target ride height only once the vehicle speed has been below said one or more predefined thresholds for one or more predefined periods.

14. A method of controlling a target ride height of a vehicle, the method comprising:

receiving a driving mode signal, the driving mode signal being an output from a driving mode selector which is operable manually by a driver or automatically in relation to automatically detected terrain parameters to signal that an on-road or an off-road driving mode has been selected, an altered throttle response being implemented when in the off-road driving mode compared with the on-road driving mode, and

upon receipt of the driving mode signal signalling that an off-road driving mode has been selected, automatically setting a target off-road ride height in dependence on

a comparison of a vehicle speed with a speed threshold, wherein upon receipt of the driving mode signal signalling that an off-road driving mode has been selected, the method comprises automatically selecting one of a plurality of predefined target off-road ride heights by comparing a vehicle speed with a plurality of speed thresholds, wherein when in said selected off-road driving mode, the method selects a first of said target off-road ride heights when the vehicle speed is below a first speed threshold and selects a second of said target off-road ride heights when the vehicle speed is above said first speed threshold, wherein said first target off-road ride height is higher than said second target off-road ride height, and wherein the method selects a target on-road ride height lower than the second target off-road height when the vehicle speed increases above a second speed threshold.

15. A method of controlling a target ride height of a vehicle, the method comprising:

receiving a driving mode signal, the driving mode signal being an output from a driving mode selector which is operable manually by a driver or automatically in relation to automatically detected terrain parameters to signal that an on-road or an off-road driving mode has been selected, an altered throttle response being implemented when in the off-road driving mode compared with the on-road driving mode, and

automatically increasing the target ride height of the vehicle to an off-road ride height when the driving mode signal indicates that an off-road driving mode has been selected and the vehicle speed falls below one or more predefined thresholds, wherein upon receipt of the driving mode signal signalling that an off-road driving mode has been selected, the method comprises automatically selecting one of a plurality of predefined target off-road ride heights by comparing a vehicle speed with a plurality of speed thresholds, wherein when in said selected off-road driving mode, the method selects a first of said target off-road ride heights when the vehicle speed is below a first speed threshold and selects a second of said target off-road ride heights when the vehicle speed is above said first speed threshold, wherein said first target off-road ride height is higher than said second target off-road ride height, and wherein the method selects a target on-road ride height lower than the second target off-road height when the vehicle speed increases above a second speed threshold.