Abstract: Distance measurements are made using two or more signal frequencies. Ultrasonic energy is transmitted from a transducer to an object. Returned ultrasonic energy is received by the transducer and processed to provide an accurate determination of the distance between the transducer and the point on the object receiving the ultrasonic energy. In connection with the processing, a number of relationships are utilized. Using certain of the relationships, a range of integers is determined using high and low frequency ultrasonic energy, as well as propagation time. A time-related phase shift determination is also made for each of the high and low frequencies using certain of the other known relationships. Using a range of distance values and the measured time-related values, an accurate determination of distance from the transducer to the object can be made. In one application, a number of different distance values are obtained to define the surface plane of the object, such as a wheel or tire.

Abstract: The present invention discloses apparatus and method for centering the steering wheel of a vehicle prior to alignment of the vehicle wheels using a wheel aligner. A portion of the apparatus is mounted to the vehicle steering wheel for sensing deviation in the position of the steering wheel from a centered position. This portion of the apparatus can be mounted on vehicle steering wheels having different configurations and can wirelessly transmit signals corresponding to the deviations. The apparatus can be used with differently configured steering wheels by virtue of a linked cam assembly in which rotation of either of a pair of cams causes rotation of the other cam in an opposite direction of equal magnitude. In operation, the deviation in the position of the steering wheel from a centered position with a pre-selected tolerance is determined. When the deviation is greater than the pre-selected tolerance, alignment of the vehicle wheels by the wheel aligner is prevented.

Abstract: Apparatus and method are provided for use in determining information relating to the plane of rotation of an object, particularly a vehicle wheel. The apparatus includes a probe that is maintained at the same contact point relative to the wheel during the rotation of the wheel. The position of the probe is monitored and position-related data is analyzed by a processing system. The processing system implements a least squares method for defining the plane of rotation utilizing a number of the position-related data points, which were obtained during rotation of the wheel. In one embodiment, the probe is connected to a pivotable wobble plate for use in maintaining a predetermined position of the probe relative to the wheel during rotation thereof. A carriage assembly also acts to maintain the predetermined position of the probe. In another embodiment, instead of a carriage assembly, rotatable arms and counter-weight are employed so that the probe moves as a direct result of rotation of the wheel.

Abstract: An automatic calibrator is provided in combination with a wheel aligner used in determining the toe angle and camber angle of a wheel. A target is connected to the wheel aligner to move therewith. When the wheel aligner is at a predetermined angle, the target is used to provide a signal indicating that the wheel aligner is at the predetermined angle. A transducer output signal is then checked to determine if the transducer output signal accurately corresponds to the predetermined angle.