DE4237076A1 - Angle measuring using rotor - rotating rotor at known angular speed exchanging directionally dependent signals with measurement and reference points - Google Patents

Abstract

The method of measuring angles using a rotor (6) involves rotating a rotor at a known angular speed by driving a motor (8), in a housing (7) at a constant speed. Two signallers, permanent magnets (9), are positioned in the rotor opposite two sensors, reed switches (2,5). One sensor is fixed to the housing as a reference sensor (5). The other sensor is fixed to a movable measuring plate around the rotor, as a measuring sensor (2). Directionally dependent signals are exchanged with the measurement and reference points. The angle from the measurement point to the rotor axis and to the reference point is determined from the angular speed of the rotor and the time required for the rotor to rotate between the measurement and reference signals. ADVANTAGE - Enables accurate, quasi-continuous angular measurement without use of measuring scale.

Description

Angles have so far been measured or compared by comparing them with a material measure measured lengths calculated. Measuring standards are complex and limitedly precise, Length measurements are cumbersome.

The problem of the claim is to use any angle without measuring scale to measure any signals with basically high measuring accuracy quasi-continuously.

Solution:
The angle α between the measuring point - rotor axis and rotor axis - reference point perpendicular to the axis of rotation of the rotor should be measured.

The routes are measured by suitable signal transmitters, sensors or reflectors in measuring and Reference points on the one hand and on the rotor on the other hand limited (measuring sections).

The rotor turns around its axis. The sensors measure at a certain angle One signal each for the respective measuring section (measuring signal, reference signal). The time between Signals and the angular velocity of the rotor are measured.

The angle α is determined from:
- the angular velocity of the rotor,
- the elapsed time between the signals.

The signal output, the calculation of the angle α and the consideration of geometric and metrological boundary conditions (arrangement of signal transmitter and sensors on the rotor, Threshold detection etc.) are state of the art.

Application example 1 Angular load cell

A motor ( 8 ) which drives a shaft ( 6 ) at a constant speed is fastened in a housing ( 7 ). Together they form the rotor. Two signal transmitters ( 9 : here permanent magnets) are embedded in the rotor, opposite two sensors ( 2 , 5 : here reed switches). One sensor is permanently connected to the housing ( 5 : reference sensor), the second sensor ( 2 : measuring sensor) is permanently connected to a measuring plate ( 1 ) which can be rotated about the rotor axis.

With each revolution of the rotor, the reed switches emit a measurement signal ( 3 ) and a reference signal ( 4 ).

The speed of the rotor can be determined from the time between several reference signals. Out the time interval between the measurement and reference signal, the angle between the measuring plate and the housing can be determined.  

Example of use 2 Positioning of a vehicle from the outside

A portable vehicle ( 1 : measurement signal) and a fixed reference point ( 3 : reference signal) emit light. Two rotors ( 2 , 4 ) with photodiodes detect the two light spots when they pass over the corresponding areas as they rotate. The angles α₁ and α₂ can be calculated as in application example 1 from the timing and angular velocity of the rotor.

The position of the vehicle results from both angles and the locations of the rotors. Out Additional rotors may be necessary for geometric reasons.  

Example of use 3 Position determination of a vehicle from the inside

At least three fixed points emit light ( 2 : target signals). A rotor ( 1 : here with photodiode) on the vehicle picks up the incident light signals. From the time sequence of the light signals, the angles α₁ and α₂ between the rotor axis-target signals are determined, from the angles the position of the vehicle is calculated.

The reference signal ( 3 : here electrical contact) between the vehicle and the rotor makes it possible to determine the angle of the vehicle in space. In addition, the angular velocity of the rotor can be measured in this way.

Benefits to be expected

The measurement uncertainty is no longer dependent on an exact measuring standard, but on the uniformity of a rotor speed. Since the measurement of angle and Angular velocity can be repeated and then averaged, are accurate measurement results can be expected with comparably little hardware expenditure.

The method is suitable for any type of signals with directional characteristics, can be several combine and can therefore be used very flexibly. Are conceivable a. following assignments: Non-contact position determination with light (e.g. autonomous vehicles with bearings, milling cutters opposite the work table), microtechnology and general tasks.

Use of a single sensor for similar signals and the use of right and counterclockwise rotors reduces problems with the threshold values of the sensor signal and increases the measuring accuracy.

The measurement is quasi-continuous and enables the monitoring of variable angles. Electronic data processing is particularly suitable for recording and calculation. This simplifies adjustment, zeroing and use in a control system. Systems with Several measuring points, reference points or rotors enable position determination and enable reliability.

Claims (1)

Method for angular measurement with the aid of a rotor, characterized in that a rotor with known angular velocity exchanges direction-dependent signals with measuring and reference points and that the angular measuring point - rotor axis - reference point from the angular velocity of the rotor and the time it takes for the rotor to rotate between measuring - and reference signal required is determined.