Road surface angle calculation apparatus and calculation method

A road-surface-angle-calculation apparatus comprising:

• an angle-calculation means that calculates the road-surface angle from the acceleration component Ax that is parallel to the road surface and the acceleration component Az that is perpendicular to the road surface and that are obtained from an acceleration sensor that is installed in a vehicle;
• a second calculation means that calculates the square root of the difference of the sum of squares of the average value Axav of a plurality of acceleration components Axn that are parallel with the road surface and stored at each time, and the acceleration component Axn at said each time and that are obtained from said acceleration sensor;
• and
• a second comparison means that determines whether or not the standard deviation of Ax obtained by said second calculation means is less than a certain set value.

A road-surface-angle-calculation apparatus comprising:

• an angle-calculation means that calculates the road-surface angle from the acceleration component Ax that is parallel to the road surface and the acceleration component Az that is perpendicular to the road surface and that are obtained from an acceleration sensor that is installed in a vehicle;
• a first calculation means that calculates the value |Ax2+Az2−g2| from said values Ax and Az, where g is the acceleration due to gravity;
• a first comparison means that determines whether or not said value |Ax2+Az2−g2| is positive and is less than a certain set value;
• a second calculation means that calculates the square root of the difference of the sum of squares of the average value Axav of a plurality of acceleration components Axn that are parallel with the road surface and stored at each time, and the acceleration component Axn at said each time and that are obtained from said acceleration sensor;
• a second comparison means that determines whether or not the standard deviation of Ax obtained by said second calculation means is less than a certain set value;
• and
• a third comparison means that determines whether or not the time when the first comparison means determines that said value |Ax2+Az2−g2| is positive and is less than a certain set value and the time when the second comparison means determines that said standard deviation of Ax is less than a certain set value is longer than a certain set amount of time.

A road-surface-angle-calculation method comprising:

• calculating via an angle-calculation means the road-surface angle from the acceleration component Ax that is parallel to the road surface and the acceleration component Az that is perpendicular to the road surface and that are obtained from an acceleration sensor that is installed in a vehicle;
• calculating in a first calculation means the value |Ax2+Az2−g2| from said values Ax and Az and where g is the acceleration due to gravity;
• and
• determining in a first comparison means whether or not said value |Ax2+Az2−g2| is positive and is less than a certain set value.

A road-surface-angle-calculation method comprising:

• calculating via an angle-calculation means the road-surface angle from the acceleration component Ax that is parallel to the road surface and the acceleration component Az that is perpendicular to the road surface and that are obtained from an acceleration sensor that is installed in a vehicle;
• calculating in a second calculation means the square root of the difference of the sum of squares of the average value Axav of a plurality of acceleration components Axn that are parallel with the road surface and stored at each time, and the acceleration component Axn at each said time and that are obtained from said acceleration sensor;
• and
• determining in a second comparison means whether or not the standard deviation of Ax obtained by said second calculation means is less than a certain set value.

A road-surface-angle-calculation method comprising:

• calculating in an angle-calculation means the road-surface angle from the acceleration component Ax that is parallel to the road surface and the acceleration component Az that is perpendicular to the road surface and that are obtained from an acceleration sensor that is installed in a vehicle;
• calculating via a first calculation means the value |Ax2+Az2−g2| from said values Ax and Az, where g is the acceleration due to gravity;
• determining in a first comparison means whether or not said value |Ax2+Az2−g2| is positive and is less than a certain set value;
• calculating in a second calculation means the square root of the difference of the sum of squares of the average value Axav of a plurality of acceleration components Axn that are parallel with the road surface and stored at each time, and the acceleration component Axn at each said time and that are obtained from said acceleration sensor;
• a process in which a second comparison means determines whether or not the standard deviation of Ax obtained by said second calculation means is less than a certain set value;
• and
• determining in a third comparison means whether or not the time when the first comparison means determines that said value |Ax2+Az2−g2| is positive and is less than a certain set value and the time when the second comparison means determines that said standard deviation of Ax is less than a certain set value is longer than a certain set amount of time.