Vehicle with independently adjustable suspension

1 . A vehicle, comprising:

a frame structure;

four wheels;

four independent suspension systems coupled to the frame structure and configured to support the wheels relative to the frame structure, each suspension system comprising:

a suspension arm movably coupling a respective wheel to the frame structure;

and

a preload adjustment system configured to adjust a suspension preload on the suspension arm; and

a control system operably coupled to the four independent suspension systems and configured to, in response to detecting at least one of a pitch motion or a roll motion of the vehicle, change a preload of at least two of the four independent suspension systems to compensate for the at least one of the pitch motion or the roll motion of the vehicle.

2 . The vehicle of claim 1 , wherein:

each independent suspension system of the four independent suspension systems further comprises:

a torsion bar coupled to the suspension arm and imparting a spring force on the suspension arm;

a preload arm coupled to the torsion bar; and

a preload adjustment motor coupled to the preload arm and configured to rotate the torsion bar to adjust the suspension preload on the suspension arm;

the preload arm defines a set of gear teeth;

each independent suspension system further comprises a worm gear coupled to the preload adjustment motor and engaged with the set of gear teeth; and

the preload adjustment motor is configured to adjust the preload on the torsion bar by rotating the worm gear against the gear teeth, thereby rotating the preload arm.

3 . The vehicle of claim 2 , wherein:

each suspension system further comprises:

a nut coupled to the preload arm; and

a screw engaged with the nut and configured to be rotated by the preload adjustment motor; and

the preload adjustment motor is configured to adjust the preload on the torsion bar by rotating the screw within the nut, thereby rotating the preload arm.

4 . The vehicle of claim 1 , wherein the suspension arm is an A-arm.

5 . The vehicle of claim 1 , wherein the control system is further configured to lower the frame structure onto a rigid support structure by reducing the suspension preload on the suspension arms of each of the four independent suspension systems.

6 . The vehicle of claim 1 , wherein the control system is further configured to increase the suspension preload on the suspension arms of each of the four independent suspension systems in response to detecting additional payload weight on the vehicle.

7 . The vehicle of claim 6 , wherein the increasing of the suspension preload on the suspension arms of each of the four independent suspension systems substantially maintains a ride height of the vehicle despite the additional payload weight.

8 . The vehicle of claim 1 , wherein changing the preload of the at least two of the four independent suspension systems to compensate for the at least one of the pitch motion or the roll motion of the vehicle comprises changing the preload of the at least two of the four independent suspension systems to configure the vehicle in a level attitude when the vehicle is on an inclined road surface.

9 . The vehicle of claim 1 , wherein changing the preload of the at least two of the four independent suspension systems to compensate for the at least one of the pitch motion or the roll motion of the vehicle comprises changing the preload of the at least two of the four independent suspension systems to configure the vehicle in a level attitude when the vehicle is on a crowned road surface.

10 . A vehicle, comprising:

a frame structure;

a set of wheels;

an adjustable suspension system supporting the set of wheels relative to the frame structure and configured to adjust a suspension preload of each respective wheel of the set of wheels; and

a control system operably coupled to the adjustable suspension system and configured to:

dynamically adjust the suspension preload of respective wheels of the set of wheels to maintain the vehicle in a level attitude when the vehicle is travelling on an inclined road surface; and

dynamically adjust the suspension preload of respective wheels of the set of wheels to maintain the vehicle in the level attitude when the vehicle is travelling on a crowned road surface.

11 . The vehicle of claim 10 , wherein the control system is further configured to dynamically adjust the suspension preload of respective wheels of the set of wheels to maintain the vehicle in the level attitude when the vehicle is travelling on a crowned and inclined road surface.

12 . The vehicle of claim 10 , wherein the adjustable suspension system comprises, for each respective wheel of the set of wheels:

a suspension arm movably coupling the respective wheel to the frame structure; and

a preload adjustment system configured to adjust the suspension preload on the suspension arm.

13 . The vehicle of claim 10 , wherein the control system is further configured to dynamically adjust the suspension preload of respective wheels of the set of wheels to tilt the vehicle away from the level attitude in response to detecting a wind condition.

14 . The vehicle of claim 10 , wherein the control system is further configured to dynamically adjust the suspension preload of respective wheels of the set of wheels to tilt the vehicle away from the level attitude in response to detecting that the vehicle is turning.

15 . The vehicle of claim 10 , wherein the control system is further configured to dynamically adjust the suspension preload of respective wheels of the set of wheels to tilt the vehicle away from the level attitude in response to the vehicle receiving a command to turn.

16 . A vehicle comprising:

a frame structure;

a set of wheels comprising:

a first pair of wheels proximate a first end of the vehicle and configured to steer the vehicle when the vehicle is travelling in a direction of the first end of the vehicle;

a second pair of wheels proximate a second end of the vehicle and configured to steer the vehicle when the vehicle is travelling in a direction of the second end of the vehicle; and

an adjustable suspension system supporting the set of wheels relative to the frame structure; and

a control system operably coupled to the adjustable suspension system and configured to:

operate the adjustable suspension system in a first mode to increase a suspension preload of the first pair of wheels when the vehicle is traveling in the direction of the first end of the vehicle and is travelling downhill; and

operate the adjustable suspension system in a second mode to increase a suspension preload of the second pair of wheels when the vehicle is travelling in the direction of the second end of the vehicle and is travelling downhill.

17 . The vehicle of claim 16 , wherein the control system is further configured to:

operate the adjustable suspension system in a third mode during transit to a passenger loading station, wherein in the third mode the frame structure is suspended, relative to a road surface, by the adjustable suspension system; and

operate the adjustable suspension system in a fourth mode upon arrival at a passenger loading zone, wherein in the fourth mode the frame structure is lowered onto a rigid support structure at the passenger loading zone.

18 . The vehicle of claim 17 , wherein the adjustable suspension system is further configured to operate in a fifth mode to change a roll angle of the vehicle in response to detecting a wind condition.

19 . The vehicle of claim 16 , wherein:

operating the adjustable suspension system in the first mode configures the vehicle in a level attitude when the vehicle is traveling in the direction of the first end of the vehicle and is travelling downhill; and

operating the adjustable suspension system in the second mode configures the vehicle in the level attitude when the vehicle is traveling in the direction of the second end of the vehicle and is travelling downhill.

20 . The vehicle of claim 16 , wherein the adjustable suspension system is configured to independently adjust at least one of a suspension preload or a ride height of each wheel of the set of wheels.