Two-axis accelerometer for detecting inclination without the effect of common acceleration

1. A system for detecting inclination of an object in motion, the object having a forward-aft axis, without compensating for any acceleration of the object, the system comprising:

a multi-axis acceleration sensing device that is fixedly attached to the object such that each sensing axis of the multi-axis acceleration sensing device is co-planar with and oriented 45 degrees from the forward-aft axis of the object and the co-planar sensing axes are orthogonal to one another; and

means for determining the inclination of the object,

wherein the inclination of the object (α) is determined using the equation:

α

=

sin

-

1

(

a

x

+

a

y

2

⁢

g

)

-

45

⁢

°

,

 in which g is the acceleration due to gravity, a x is a sensed acceleration along a first sensing, x-axis and a y is a sensed acceleration along a second sensing, y-axis.

2. The system as recited in claim 1 further comprising means for determining whether the inclination is an upward slope or a downward slope.

3. The system as recited in claim 2 , wherein said means for determining whether the inclination is an upward slope or a downward slope includes:

means for calculating instantaneous accelerations a 1 and a 2 using the following equations:

a 1 =g *cos α and

a 2 =g *sin α

and

means for comparing whether the difference between a sensed acceleration along a first sensing, x-axis (a x ) and a first instantaneous acceleration (a 1 ) (a x −a 1 ) is approximately equal to the difference between a sensed acceleration along a second sensing, y-axis (a y ) and a second instantaneous acceleration (a 2 ) (a y −a 2 ) or whether the difference between the sensed acceleration along the second sensing, y-axis and the first instantaneous acceleration (a y −a 1 ) is approximately equal to the difference between the sensed acceleration along the first sensing, x-axis and the second instantaneous acceleration (a x −a 2 ); wherein

if (a x −a 1 ) is approximately equal to (a y −a 2 ), the object is traveling up an incline, but

if (a y −a 1 ) is approximately equal to (a x −a 2 ), the object is traveling down an incline.

4. The system as recited in claim 1 further comprising a second multi-axis acceleration sensing device that is fixedly attached to the object such that each sensing axis of the second multi-axis acceleration sensing device is co-planar with a backward-aft axis of the object.

5. The system as recited in claim 1 , wherein the object in motion is selected from the group consisting of a wheeled-vehicle, a tracked-vehicle, a seagoing vessel, an ocean-going vessel, an aircraft, a spacecraft, a satellite or a digital camera.

6. The system as recited in claim 1 , wherein the means for determining the inclination of the object includes a controller having a processor that is adapted to execute at least one of hardware-based or software-based applications, driver programs, and algorithms, which are determine said inclination.

7. A method of determining an inclination associated with an object in motion, the object having a forward aft axis, the method comprising:

sensing acceleration of the object using a multi-axis acceleration sensing device that is fixedly attached to the object such that each sensing axis of the multi-axis acceleration sensing device lies is coplanar with and oriented 45 degrees from the forward-aft axis of the object and the coplanar sensing axes are orthogonal to one another; and

calculating the inclination of the object (α) using the equation:

α

=

sin

-

1

(

a

x

+

a

y

2

⁢

g

)

-

45

⁢

°

,

 in which g is the acceleration due to gravity, a x is a sensed acceleration along a first sensing, x-axis and a y is a sensed acceleration along a second sensing, y-axis.

8. The method as recited in claim 7 further comprising determining whether the inclination is an upward slope or a downward slope by

calculating instantaneous accelerations a 1 and a 2 using the following equations:

a 1 −g *cos α and a 2 =g *sin α; and

comparing the difference between a sensed acceleration along a first sensing, x-axis (a x ) and a first instantaneous acceleration (a 1 ) (a x −a 1 ) with the difference between a sensed acceleration along a second sensing, y-axis (a y ) and a second instantaneous acceleration (a 2 ) (a y −a 2 ); and

comparing the difference between the sensed acceleration along the second sensing, y-axis and the first instantaneous acceleration (a y −a 1 ) with the difference between the sensed acceleration along the first sensing, x-axis and the second instantaneous acceleration (a x −a 2 ); wherein

if (a x −a 1 ) is approximately equal to (a y −a 2 ), the object is traveling up an incline, but

if (a y −a 1 ) is approximately equal to (a x −a 2 ), the object is traveling down an incline.

9. A system for detecting inclination of an object in motion, the object having a forward-aft axis, without compensating for any acceleration of the object, the system comprising:

a multi-axis acceleration sensing device that is fixedly attached to the object such that each sensing axis of the multi axis acceleration sensing device is coplanar with and oriented 45 degrees from the forward-aft axis of the object and the co-planar sensing axes are orthogonal to one another; and

means for determining the inclination of the object, wherein the inclination of the object (α) is determined using the equation:

α

=

sin

-

1

⁡

(

a

x

+

a

y

2

⁢

g

)

-

45

⁢

°

,

 in which g is the acceleration due to gravity, a x is a sensed acceleration along a first sensing, x-axis and a y is a sensed acceleration along a second sensing, y-axis.

10. The system as recited in claim 9 further comprising means for determining whether the inclination is an upward slope or a downward slope.

11. The system as recited in claim 10 , wherein said means for determining whether the inclination is an upward slope or a downward slope includes:

means for calculating instantaneous accelerations a 1 and a 2 using the following equations:

a 1 =g *cos α and

a 2 =g *sin α

and

means for comparing whether the difference between a sensed acceleration along a first sensing, x-axis (a x ) and a first instantaneous acceleration (a 1 ) (a x −a 1 ) is approximately equal to the difference between a sensed acceleration along a second sensing, y-axis (a y ) and a second instantaneous acceleration (a 2 ) (a y −a 2 ) or whether the difference between the sensed acceleration along the second sensing, y-axis and the first instantaneous acceleration (a y −a 1 ) is approximately equal to the difference between the sensed acceleration along the first sensing, x-axis and the second instantaneous acceleration (a x −a 2 ); wherein

if (a x −a 1 ) is approximately equal to (a y −a 2 ), the object is traveling up an incline, but

if (a y −a 1 ) is approximately equal to (a x −a 2 ), the object is traveling down an incline.

12. The system as recited in claim 9 further comprising a second multi-axis acceleration sensing device that is fixedly attached to the object such that each sensing axis of the second multi-axis acceleration sensing device is coplanar with a backward-aft axis of the object.

13. The system as recited in claim 9 , wherein the means for determining the inclination of the object includes a controller having a processor that is adapted to execute at least one of hardware-based or software-based applications, driver programs, and algorithms, which determine said inclination.