Abstract:
An analog compensation circuit for compensating for mechanical instrumentation resonance. The transfer function of the instrumentation resonance phenomenon is determined, and the compensation circuit is constructed to produce the inverse transfer function of the instrumentation resonance transfer function. The input of the compensation circuit is connected to the electrical instrumentation output signal. With the instrumentation resonance modeled as the equivalent of a second order filter, the compensation circuit includes sections for producing at a combined output a first intermediate signal representative of a constant term, a second intermediate signal representative of a first derivative term, and a third intermediate signal representative of a second derivative term.
Abstract:
An apparatus and method for improving the measurement of force variation in a tire (20) being tested on a tire uniformity machine. The apparatus includes a loadwheel assembly (500) including a rotatable loadwheel (510) connected to load sensors (530, 540) for detecting forces imposed on the loadwheel (510) by a tire (20) being tested. Vibration sensors (700, 702, 704) are associated with the loadwheel assembly (500) for detecting vibrations in the loadwheel (510) caused by forces other than the forces applied by the tire (20). Means is provided for subtracting the vibration induced forces from the tire (20) imposed forces in order to provide more precise tire uniformity data. The vibration sensors (700, 702, 704) which comprise accelerometers are used to determine vibration induced forces in the lateral and radial direction with respect to the loadwheel (510). The signals provided by the accelerometers (700, 702, 704) are communicated to a differential amplifier which also receives signals from the load cells (530, 540). The net signal more closely represents the actual force variation generated by the tire (20) being tested.
Abstract:
A machine for measuring force variation or imbalance of tires particularly at high speeds. A rotating roadwheel is engaged by a tire mounted on a spindle. Force sensing means, such as load cells, are operably interposed between the tire spindle and a force sensor mount. To minimize the adverse effects of mechanical resonance of the machine on force measurement accuracy, the roadwheel and/or the force sensor mount are connected to ground through dampers which provide a damping ratio of at least about five percent and preferably higher. Where the force sensor mount is to be supported by such damping means, the invention further contemplates interposing a large mass between that damping means and the force sensor mount.
Abstract:
A tire rim for a tire testing machine has a stepped contour providing multiple positions to accommodate tires of differing bead diameters. One or more filler rings are mountable on a bead seat to provide the proper contour for inflating a tire having the next smaller diameter bead seated on the adjacent bead seat.
Abstract:
A rim mount for a tire uniformity machine. The upper rim has bolts that cooperate with keyhole slots in an adaptor to mount the upper rim. The lower rim has keyhole slots that cooperate with bolts threaded into a lower chuck to mount the lower rim.
Abstract:
Methods and apparatus for determining an angular location on a round object during a current operation in order to facilitate positioning the object for subsequent operation. At a first station, an angular location identifying feature is sensed, and an angle at which a predetermined desired angular location is located with respect to the feature is determined. At a second station, the feature is sensed, the object is indexed from the feature in an amount equal to the angle, and the object is marked at the relocated predetermined desired angular location. Another method eliminates the marking step at the second station, and the subsequent operation is performed instead. Apparatus comprises a first station means and a second station means. The first station means includes means for sensing an angular location identifying feature on the object and measurement means for determining an angle at which a predetermined desired angular location on the object is located with respect to the feature. Second station means includes sensing means for sensing the feature, indexing means for indexing from the feature in an amount equal to the angle, and marking means for marking the object at the relocated desired location.
Abstract:
Steering pull to which a vehicle is subjected due to tire non-uniformity is measured accurately even in the presence of wind. An anemometer mounted in proximity of and in positionally fixed relation to the vehicle measures the speed and direction of wind apparent to the vehicle. Those measurements are used by a computer to determine a wind correction quantity which is subtracted from the steering pull measured at the steering wheel.
Abstract:
An object is positioned in fixed relation to a measuring axis without regard to centering the object on the axis and at least one series of data samples correlated to the distance between the measuring axis and a series of points located at angularly spaced intervals on at least one surface feature of the object are generated and stored. To determine the center of a first surface feature, the corresponding series of samples is analyzed to identify samples therein corresponding to points lying on a maximum inscribed circle whose center corresponds to that of the surface feature. To measure a second surface feature of an object with reference to the center of a first surface feature thereof, a first signal and a second signal correlated to the distance between the measuring axis and points on the first surface feature and second surface feature, respectively are generated. The center of the first surface feature is then determined to define a vector indicating the positional offset between the measuring axis and that center. The second signal is then adjusted in accordance with that vector to provide a coordinate-corrected signal to be used as a basis for a centered measurement.
Abstract:
An apparatus and method for imposing a desired average radial load force on a tire by calculating the current average force between the tire and a loadwheel based on the average radial force and radial distance between the tire and a loadwheel over the last previous complete revolution of the tire, the spring constant of the tire and the current radial distance between the tire and the loadwheel. The calculated average force value is applied as a feedback signal to the loadwheel position controller in order to achieve the desired average radial load. The spring constant of the tire may be determined from the change in force per unit distance as the tire is loaded or programmed as a constant to be applied for testing all tires of a given type.