A power steering apparatus includes: a first detection element arranged to sense a rotation angle of the first gear based on a variation of a magnetic field generated by the first magnetic member; a second detection element arranged to sense a rotation angle of the second gear based on a variation of a magnetic field generated by the second magnetic member; an absolute steering angle calculating circuit configured to calculate an absolute steering angle of the steering wheel from an neutral position of the steering wheel at which the steered wheel directs in a straight direction, by a combination between the rotation angle of the first gear and the rotation angle of the second gear; and a control section configured to drive and control the electric motor based on the absolute steering angle.

To reduce the influence of an unintended magnetic flux of a permanent magnet on detection accuracy. An absolute encoder (2) includes a magnet provided at a tip end side of any one of a first worm gear portion (11) and a second worm gear portion (22), and an angle sensor configured to detect a rotation angle of the magnet in response to a change in magnetic flux generated from the magnet. In the magnet, a first magnetic pole portion of a first polarity and a second magnetic pole portion of a second polarity different from the first polarity are formed adjacent to each other as viewed from an axial end surface of the magnet. The first magnetic pole portion and the second magnetic pole portion are formed adjacent to each other in a radial direction with a radial center of the magnet as a boundary, and the first magnetic pole portion and the second magnetic pole portion are formed adjacent to each other in an axial direction with an axial center as a boundary. The absolute encoder (2) is provided with a magnetic interference reduction member formed of a magnetic material on a radially outer peripheral surface of the magnet.

To reduce the influence of backlash in a reduction mechanism on detection accuracy. An absolute encoder includes a first worm gear portion rotating according to rotation of a main shaft and a first worm wheel portion meshing with the first worm gear portion. The absolute encoder is provided coaxially with the first worm wheel portion and includes a second worm gear portion rotating according to rotation of the first worm wheel portion and a second worm wheel portion meshing with the second worm gear portion. The absolute encoder also includes a biasing mechanism biasing the second worm gear portion in the direction of the second worm wheel portion.

The invention relates to a method for ascertaining a rotational angle (E) of a shaft (2). In order to increase the accuracy of the ascertainment within a greater predefined angle range in relation to the prior art, the following steps are provided: detecting respective rotational angles (W1, W2, W3) of three toothed gears (Z1, Z2, Z3) of a toothed gear arrangement, wherein the three toothed gears (Z1, Z2, Z3), with different numbers of teeth (z1, z2, z3), are meshed directly with a gear ring (10) of the shaft (2), and ascertaining the rotational angle (E) of the shaft (2) on the basis of the respective rotational angles (W1, W2, W3) of the three toothed gears (Z1, Z2, Z3) in accordance with a predetermined extraction rule, wherein the rotational angle (E) of the shaft (2) is distinctly defined within a predefined angle range by the entirety of the respective rotational angles (W1, W2, W3).

The present disclosure provides a method of monitoring the magnetic field in which a magnetic sensor is operating in to ensure that the sensor is operating within its defined magnetic window. For example, the method uses the sensor output of either a multi-turn sensor, or some other magnetoresistive sensor that is being used in conjunction with the multi-turn sensor, for example, a magnetic single turn sensor or a second multi-turn sensor, to monitor the operating magnetic field.

A device comprises a magnet and an angle sensor, wherein the angle sensor is configured to detect a rotation angle of the magnet. The device also contains a rotation counter, wherein the rotation counter is configured to record a number of rotations of the magnet. The angle sensor and the rotation counter are implemented in physically separate components.

A sensor apparatus (01) is for determining a rotation angle position of a rotatable shaft (02). The sensor apparatus (01) comprises a main gear wheel (03), which is coaxially coupled to the rotatable shaft (02), and a secondary gear wheel (04), which is arranged so as to be rotatably coupled on the main gear wheel (03). The sensor apparatus (01) furthermore comprises two targets (06, 07), each of which is arranged on a lateral face of the main gear wheel (03) or of the secondary gear wheel (04), and two rotation angle sensors (08, 09), which are arranged in the immediate vicinity of the main gear wheel (03) and the secondary gear wheel (04) on a circuit board (05). The angles of the main gear wheel (03) and of the secondary gear wheel (04) are determined and forwarded as an angular signal to an evaluating unit (10) arranged on the circuit board.

A system includes a magnetic sensor that can store a magnetic state associated with a number of accumulated turns of a magnetic target. The magnetic sensor may work in conjunction with a magnetic target. The magnetic target may produce a magnetic field that, at some positions, drops below a magnetic window of the magnetic sensor. The magnetic target may produce a magnetic field that is within the magnetic window when needed to update the magnetic state of the sensor to keep track of the accumulated turns of the magnetic target. The magnetic sensor may be initialized with one or more domain walls.

The present invention provides a rotation angle detection device that detects a steering state quantity of steer-by-wire. The rotation angle detection device includes a drive gear that rotates along with the rotation of a rotating shaft part, first through third driven gears that rotate in conjunction with the drive gear and have different numbers of teeth that are indivisible by each other, sensors that detect the amounts of rotation and are provided for the respective first through third driving gears, a rotation amount generating unit that generates the amount of rotation of the drive gear by combining the amounts of rotation of different driven gears, and power supply circuits each of which is provided for a combination of sensors that detect the amounts of rotation of different driven gears. This configuration makes it possible to improve robustness against failure of sensor elements and power supply circuits.

Systems and methods for determining absolute position. A system includes a first bull gear and a second bull gear rigidly connected to the first bull gear. The system includes a first pinion gear rotationally engaged with the first bull gear. The system includes a second pinion gear rotationally engaged with the second bull gear. The system includes a first sensor that senses a first angular position of the first pinion gear. The system includes a second sensor that senses a second angular position of the second pinion gear.