Methods for determining the direction of rotation of rotating bodies
A method determines a direction of rotation of a rotating body about its axis of rotation by measuring two acceleration signals x and y with an acceleration sensor. The two acceleration signals x and y are at a 90° angle to each other, are oriented not parallel to the axis of rotation, and both a centrifugal acceleration generated by a circular movement and a gravitational acceleration are taken into account. The measured acceleration signals x and y are differentiated mathematically. The differentiated x acceleration signal is differentiated a further time and correlated with a y signal that has been differentiated once for obtaining a correlation function. The differentiated y acceleration signal can be differentiated a further time and correlated with the x signal that has been differentiated once for obtaining a second correlation function. The method determines the direction of rotation of rotating tires of a motor vehicle.
1. A method for determining a direction of rotation of a rotating body about an axis of rotation, which comprises the steps of:
measuring two acceleration signals x and y with at least one acceleration sensor resulting in measured acceleration signals x and y, the two acceleration signals x and y being at a 90 degree angle to each other and oriented not parallel to the axis of rotation, and both a centrifugal acceleration generated by a circular movement and a gravitational acceleration g being taken into account;
differentiating mathematically the measured acceleration signals x and y resulting in a differentiated x acceleration signal and a differentiated y acceleration signal;
differentiating a further time at least one of the differentiated x acceleration signal and the differentiated y acceleration signal resulting in a further differentiated x acceleration signal and/or a further differentiated y acceleration signal; and
performing at least one of:
correlating the further differentiated x acceleration signal with the differentiated y acceleration signal for obtaining a first correlation function; and
correlating the further differentiated y acceleration signal with the differentiated x acceleration signal for obtaining a second correlation function.
2. The method according to claim 1 , which further comprises:
performing both of the correlating steps for obtaining the first and second correlation functions; and
using the first and second correlation functions in a common evaluation procedure.
3. The method according claim 1 , which further comprises:
performing both of the correlating steps for obtaining the first and second correlation functions; and
determining a difference between the first and second correlation functions.
4. The method according to claim 1 , which further comprises approximating a differentiation by use of a difference quotient.
5. The method according to claim 1 , which further comprises:
performing both of the correlating steps for obtaining the first and second correlation functions; and
calculating integrals of the first and second correlation functions in an approximation by use of a sum total.
6. The method according to claim 1 , wherein the rotating body is a tire of a motor vehicle.
7. A method for determining a direction of rotation of a rotating body about an axis of rotation, which comprises the steps of:
measuring two acceleration signals x and y with at least one acceleration sensor resulting in measured acceleration signals x and y, the two acceleration signals x and y being at a 90 degree angle to each other and oriented not parallel to the axis of rotation, and both a centrifugal acceleration generated by a circular movement and a gravitational acceleration g being taken into account;
differentiating mathematically the measured acceleration signals x and y resulting in a differentiated x acceleration signal and a differentiated y acceleration signal;
differentiating a further time the differentiated y acceleration signal resulting in a further differentiated y acceleration signal; and
correlating the further differentiated y acceleration signal with the differentiated x acceleration signal for obtaining a correlation function.
8. A method for determining a direction of rotation of a rotating body about an axis of rotation, which comprises the steps of:
measuring two acceleration signals x and y with at least one acceleration sensor resulting in measured acceleration signals x and y, the two acceleration signals x and y being at a 90 degree angle to each other and oriented not parallel to the axis of rotation, and both a centrifugal acceleration generated by a circular movement and a gravitational acceleration g being taken into account;
differentiating mathematically the measured acceleration signals x and y resulting in a differentiated x acceleration signal and a differentiated y acceleration signal;
differentiating a further time the differentiated x acceleration signal resulting in a further differentiated x acceleration signal; and
correlating the further differentiated x acceleration signal with the differentiated y acceleration signal for obtaining a correlation function.