In a method for determining an equivalent modal unbalance for the first bending characteristic form of a shaft-elastic rotor, which unbalance is to be compensated for, a rotor model is created describing the geometric shape and material properties of the shaft-elastic rotor. The magnitude of compliance of the rotor model is calculated at a measurement point and at the center of gravity of the rotor at an assumed speed. The shaft-elastic rotor is received in a rotatable bearing and accelerated to the assumed speed which is below its first critical speed. Subsequently, the magnitude of outward deflection at the measurement point of the shaft-elastic rotor rotating at the assumed speed can be measured. The equivalent modal unbalance for the first bending characteristic form of the shaft-elastic rotor, which unbalance is to be compensated for, can be calculated from the magnitudes of the calculated compliance and the measured outward deflection.

In a method for determining an equivalent modal unbalance for the first bending characteristic form of a shaft-elastic rotor, which unbalance is to be compensated for, a rotor model is created describing the geometric shape and material properties of the shaft-elastic rotor. The magnitude of compliance of the rotor model is calculated at a measurement point and at the center of gravity of the rotor at an assumed speed. The shaft-elastic rotor is received in a rotatable bearing and accelerated to the assumed speed which is below its first critical speed. Subsequently, the magnitude of outward deflection at the measurement point of the shaft-elastic rotor rotating at the assumed speed can be measured. The equivalent modal unbalance for the first bending characteristic form of the shaft-elastic rotor, which unbalance is to be compensated for, can be calculated from the magnitudes of the calculated compliance and the measured outward deflection.

In a tire uniformity testing apparatus which measures uniformity of a tire by measuring a load applied to the tire pressed against a rotary drum, a load estimation model is generated which is used to control a pressing position of the rotary drum, and generates a load estimation model indicating a relation between the pressing position of the tire with respect to the rotary drum and the load applied to the tire. The load estimation model is generated by: holding the tire in which uniformity has already been measured for each characteristic value; acquiring a nominal model depending on the characteristic value of the tire; and generating based on the acquired nominal model.

In a tire uniformity testing apparatus which measures uniformity of a tire by measuring a load applied to the tire pressed against a rotary drum, a load estimation model is generated which is used to control a pressing position of the rotary drum, and generates a load estimation model indicating a relation between the pressing position of the tire with respect to the rotary drum and the load applied to the tire. The load estimation model is generated by: holding the tire in which uniformity has already been measured for each characteristic value; acquiring a nominal model depending on the characteristic value of the tire; and generating based on the acquired nominal model.

A method for detecting a loosened bolted wheel joint on a wheel of a vehicle. The angular velocity of a hub of the wheel is evaluated. A periodic wheel modulation of the angular velocity is ascertained. An oscillation of the wheel generated due to the loosened bolted wheel joint is detected, using a step-change in a phase angle of the modulation by an expected angular increment, which is a function of the number of bolts.

A method for detecting a loosened bolted wheel joint on a wheel of a vehicle. The angular velocity of a hub of the wheel is evaluated. A periodic wheel modulation of the angular velocity is ascertained. An oscillation of the wheel generated due to the loosened bolted wheel joint is detected, using a step-change in a phase angle of the modulation by an expected angular increment, which is a function of the number of bolts.

A method is provided for determining a location to place a mass on a wheel assembly. A first set of acceleration data is collected from a plurality of inertial measurement units (IMU's) that are mounted to a removably attachable object that is attached to a wheel of the vehicle in a manner that inhibits the object from coming off of the vehicle when the vehicle is in motion. The first set of acceleration data is collected while operating the vehicle at a first speed. The first set of acceleration data is used to determine an offset between a center of the object and a bearing center of the wheel assembly. A second set of acceleration data is collected from the plurality of inertial measurement units (IMU's). The second set of acceleration data is collected while operating the vehicle at second speed that is greater than the first speed. The second set of acceleration data and the offset determined from the first set of acceleration data is used to determine the location to place the mass on a wheel assembly with respect to the bearing center of the wheel assembly.

A method is provided for determining a location to place a mass on a wheel assembly. A first set of acceleration data is collected from a plurality of inertial measurement units (IMU's) that are mounted to a removably attachable object that is attached to a wheel of the vehicle in a manner that inhibits the object from coming off of the vehicle when the vehicle is in motion. The first set of acceleration data is collected while operating the vehicle at a first speed. The first set of acceleration data is used to determine an offset between a center of the object and a bearing center of the wheel assembly. A second set of acceleration data is collected from the plurality of inertial measurement units (IMU's). The second set of acceleration data is collected while operating the vehicle at second speed that is greater than the first speed. The second set of acceleration data and the offset determined from the first set of acceleration data is used to determine the location to place the mass on a wheel assembly with respect to the bearing center of the wheel assembly.

A method is provided for collecting measurement parameters related to imbalance forces of a tire/hub assembly of a vehicle during motion of the vehicle. An apparatus is removably attached to the tire/hub assembly of the vehicle via lug nuts of the tire/hub assembly. The apparatus includes a disk, a plurality of cup-shaped objects, and one or more inertial measurement units (IMU's) mounted to the disk. Each of the cup-shaped objects are rigidly fixed at one end to the disk and extend perpendicularly outward from the disk. The plurality of cup-shaped objects are arranged a fixed radial distance from a radial center of the disk in a pattern that matches the lug nuts of the tire/hub assembly. The one or more inertial measurement units (IMU's) are mounted to the disk and configured to measure parameters that are used for calculating the imbalance forces during motion of the vehicle.

A method is provided for collecting measurement parameters related to imbalance forces of a tire/hub assembly of a vehicle during motion of the vehicle. An apparatus is removably attached to the tire/hub assembly of the vehicle via lug nuts of the tire/hub assembly. The apparatus includes a disk, a plurality of cup-shaped objects, and one or more inertial measurement units (IMU's) mounted to the disk. Each of the cup-shaped objects are rigidly fixed at one end to the disk and extend perpendicularly outward from the disk. The plurality of cup-shaped objects are arranged a fixed radial distance from a radial center of the disk in a pattern that matches the lug nuts of the tire/hub assembly. The one or more inertial measurement units (IMU's) are mounted to the disk and configured to measure parameters that are used for calculating the imbalance forces during motion of the vehicle.