A speed detection device includes a comparator module, a sensor lead with a node connected to the comparator module, and a limit set module. The limit set module is connected to the sensor lead node and to the comparator by an upper limit lead and a lower limit lead to provide upper and lower limits to the comparator that vary according to amplitude variation in voltage applied to the sensor lead.

A device rotates at least one static magnetic field about an axis, producing a rotating magnetic dipole field, and is movable in relation to the surface of the ground. The field is periodically sensed using a receiver to produce a receiver output responsive to the field. A positional relationship between the receiver and the device is monitored using the output. In one aspect, changing the positional relationship, by moving the device nearer to a boring tool which supports the receiver, causes an increase in accuracy of depth determination. In another aspect, determination of an actual overhead position of the boring tool, and its application, are described. Use of a plurality of measurements over at least one-half revolution of each magnet is disclosed. Establishing a surface radial direction toward a boring tool and resolution of multi-valued parameters is described. Calibration techniques, as well as a three transmitter configuration are also described.

An inductive sensor device includes a reference sensor head that is used to adjust the characteristics of an operational sensor head that is used to detect movement of a conductive target. The reference sensor head has near it a fixed reference target that is similar to the target for which the operational sensor head detects movement, with the difference that the reference target is fixed with respect to a reference sensor coil of the reference sensor head. The reference sensor head includes a variable reference capacitor or variable reference inductor that is adjusted to maintain constant (or nearly constant) output, such as a constant (or nearly constant) resonant frequency, during operation of the sensor device. Adjustments of the variable reference element (variable capacitor or variable inductor) may be undertaken to compensate for changes in characteristics of the reference sensor due to changes in temperature, for example.

Methods and apparatus for high speed location determinations are disclosed. An example apparatus includes at least two coils arranged along a zone of interest to generate a magnetic field, and a sensor to measure a change in the magnetic field associated with the at least two coils as an object of interest moves within or into the zone of interest. The example apparatus also includes a processor to determine a position of the object of interest based on the measured change.

A sensor device is provided for detecting a shifting position of a vehicle transmission. The vehicle transmission includes a transmission chamber, in which transmission elements are arranged. The sensor device includes a bar element, which extends from the transmission chamber into a secondary chamber sealed off from the transmission chamber and is arranged such that the bar element can be moved in dependence on the shifting position. The bar element has an interface arranged in the transmission chamber for coupling the bar element to a transmission element positioned in dependence on the shifting position and an accommodating segment arranged in the secondary chamber. The sensor device also has a transducer element, which is attached to the accommodating segment of the bar element. The sensor device also has a detecting device for detecting a position of the transducer element depending on the shifting position or a motion of the transducer element depending on a change in the shifting position.

A linear travel measurement apparatus for a compression travel of a telescopic spring unit includes an electrically conductive spring. A telescopic spring unit includes a linear travel measurement apparatus of this kind. The spring is configured to form a measurement inductance, which is dependent on an effective length of the spring. The spring has a respective electrical contact at each of its ends and is connected to a measurement capacitance and to an evaluation and control unit by corresponding electrical connections. The measurement inductance forms an electrical LC resonant circuit with the measurement capacitance, the evaluation and control unit are configured to measure the resonant frequency of said LC resonant circuit, and the resonant frequency is given as a function of the compression travel.

A method for adapting to the tolerances of a system including at least one position sensor and a rotary target. When the target rotates, the sensor(s) detects (detect) a predefined singularity on the target at an instant T_i, including: acquisition of a series of n+1 instants T_0 to T_N corresponding to a rotation R of the target; determination of theoretical values Theo_i for each instant T_i while considering that the time corresponds to the time that the target takes to effect the rotation R, taking account of any acceleration during the rotation R and as a function of a position of the predefined singularities on an ideal target produced without tolerance; conversion of the time difference between Theo_i and T_i into an angular difference A_i for a corresponding singularity of the target detected by a sensor; and memory-storage of the angular differences A_i for each singularity of the target.

Systems and methods are provided for calibrating electromagnetic position tracking systems commonly used in virtual reality systems by compensating for steady state magnetic field distortions that can occur within a tracking volume and distort magnetic sensor readings. The calibration system includes a calibration device that holds magnetic sensor(s) in a fixed position relative to a reference position sensor object provided on the calibration device. The calibration data collection process includes positioning the calibration device at multiple locations within a tracking volume and measuring magnetic position readings using a magnetic tracking system and a corresponding reference position using the reference position tracking system. The calibration data is then algorithmically processed using a data processor to generate a magnetic distortion correction function for adjusting the magnetic tracking system measurements based on a known position of said sensors, which is determined from the measured position of the reference tracking object.

An apparatus and method of detecting movement of a plunger of the solenoid includes detecting a peak (I.sub.PEAK) in a current signal applied to a coil of the solenoid. A predetermined threshold is added to the current signal applied to the coil of the solenoid to generate a level shifted signal. The level shifted signal and the peak signal are compared to detect movement of a plunger of the solenoid.

A proximity sensor and a method of changing a detection distance are provided to suppress changes in a consumption current of an oscillation circuit. The proximity sensor includes an oscillation circuit having an oscillation amplitude that changes with a feedback current, a comparing part comparing the oscillation amplitude with a threshold, a detecting part detecting a target object based on a comparison result of the comparing part, a voltage value signal generating part generating a voltage value signal based on the feedback current and the detection distance, a threshold setting part setting an analog signal converted from the voltage value signal as the threshold, a current value signal generating part generating a current value signal based on the detection distance and the voltage value signal, and a current value setting part setting an analog signal converted from the current value signal as a current value of the feedback current.