Measuring apparatus comprising two or a plurality of sensors

The invention relates to a measuring device comprising two or more sensors for one or more measured values, connected by input wires to a power supply and transmitting via output wires signals which are a function of the measured value, and further comprising devices for transmitting and processing sensor output signals. .

The invention is particularly applicable to an apparatus for indicating an absolute angular position of a shaft which comprises position sensors with a rotating member, wherein the rotating member of the first sensor is mechanically connected to the shaft and the rotating members of the other sensor or sensors are connected sequentially to the rotating member of the first sensor by gears. wheels, the sensors being arranged for sinusoidal or pulse supply. voltage and transmit output signals which are a function of the angular position of their rotary member.

In such devices, the sensors must be connected both to the power supply and to the device for processing their output signals. In the case of inductive sensors, such as a decomposer type, these output signals appear at the two-phase terminals and, as a result, up to four lines are required for each sensor to transmit output signals to a processing device generally located at a certain distance from the sensors. When used to measure the angular position of a shaft, the number of sensors required depends on the operating range of the device, i.e. the maximum speed of the input shaft that the device is to indicate, so a large number of connecting wires is often required.

reduction and · sensors necessary for the given Ϊ

Due to the limitation of the number of connecting conductors, which in this particular case are not possible, somer gears can be used between the individual sensors. to reduce the number

í) working range However, this solution also requires sensors

gears with high precision, so the total cost of the equipment is relatively high.

The object of the invention is to provide a device of this type so as to considerably reduce the number of connecting wires between the sensors, the signal processing device and the power supply, and thus to reduce the cost of the whole device, which can be considerably high in some cases.

The essence of the invention lies in the fact that a sensor and a multiplexer unit are connected to the sensors, further connected to the signal processing device by transmission wires in the number of at least approximately equal to the output wires of each sensor, and with power supply and multiplexer unit control unit.

The number of connecting wires is therefore independent of the number of sensors. In the specific case of the device for measuring the angular position of the shaft by means of inductive sensors, the number of sensors can be increased, for example, to such an extent that it is possible to use lower reduction ratios or more generally | fewer teeth and therefore significantly cheaper gears. |

The first sensor, which is directly connected to the input shaft whose angular position is to be measured, is generally the same^withbe very accurate, which marks^{and} Jian}^_rmUses have a transmission of nezbyinon to indicate the position of the shaft during ice speed. while the other sensor ”serves: an indication of the number of full revolutions of the shaft between the initial and final position and must therefore be of such accuracy. which is sufficient to determine this number of revolutions and gradually decreases with the reduction ratio used. Low cost sensors can be made, such as sensors based on the phase change between the primary winding and the secondary windings in phase quadrature, and sensors with a passive moving member that can transmit signals of the same format as decomposer inductive type sensors, which are significantly more expensive.

According to a particularly advantageous embodiment of the invention, the addressing of the individual sensors in a multiplexing manner is very simple by means of coding with respect to the supply voltage, which requires only two supply wires for the transmission of address information.

Further advantages of the invention will become apparent from the following description in connection with the drawings, in which FIG. 3 is a diagram of the soldering and multiplexer units in the device of FIG. I.

According to FIG. 1, the input shaft 1, whose absolute angular position, i.e. the position with respect to the initial position including the number of full revolutions between the two positions, is to be induced, is mechanically connected to the first position sensor C1, which in this case is a decomposer. This sensor Ci ΐ

i is fed through two input wires MCi and sends output signals through four output wires^withWhose.

Giant. I further show, in an exemplary embodiment to which the invention is not limited, three further sensors Cz, Cj, C4, jj which can also be decomposers, but are preferably formed by

4) inductive sensors with a passive moving member, transmitting output signals of the same format as the decomposer, which can therefore be processed by the same converter, Rotary, sensor members C + and C4, stored on the respective shafts <2--3-4--5 -— j The dosers are connected, each with a moving member of the previous sensor, by means of gears. \ For example, reduction gears such as. wheels 6, γ ί between sensor Ci and £ 2, wheels 8, p between sensor Cz and C3 and 5

ΙζοΊα / ΙΧΓ, ll, between sensor £ 3 and £ 4. The reduction ratio can be, for example, ló; l, which makes it possible to produce this.

wheels very, cheaply compared to gears with a ratio of 100: 1, which is normally used in such a device.

In the case of a vernier-type bond between sensors, it is advantageous to use, by analogy, a lower number of teeth than conventional devices of this type, for example a vernier ratio of 6: ly,

The input wires ΐ · Λ £ ζ lead through the sensor £ 2 to C4,

....... · .- -— - -.....- · - · ---- - · <- '- Ý

MC3, IÁC4 and their output terminals are connected to the beverage and multiplexer unit I2 by output conductors SCz, I SC3, SC4, analogous to the first sensor £ 1. 1

Power and multiplexer. unit Ϊ £ is located close to sensors £ 1 to £ 4, for example on a machine such as an industrial robot, and is connected on the one hand to the basic I

-j-^Edno-t-ce --pr-o-- zprasován-í — si-gn-á.i-ů -—- na-znašené-ssh-emati-ckv'— - ·^!like blocks lg. ' U- & 7edviaTs to control devices, indicated by blocks I5, ,ό, I7. as shown in FIG. 1, this connection is realized on the one hand by four transmission conductors S1, S2, S3: S4 and on the other hand by two supply conductors M1, Mz, i.e. a total of six conductors. The signals on the transmission wires S1 to S4 are first processed in block Ϊ3, which in the illustrated embodiment consists mainly of the analog-to-digital converter Ry®, which serves to convert the analog signals from the deinterleaver format to digital signals. which are then further processed in the base unit 4 in order to determine the angular position, the input shaft 1 and / or the rotational speed of this shaft 1,

The sensors C1 to C4 and the power supply and multiplexer unit Is are supplied from a power supply ls which supplies via the supply conductors. 'Mi, Ma.

The selection of the sensors C1 to C4 'for the transmission of the respective output signals to the block I3 in a multiplexing manner is performed by means of addressing signals which are transmitted by the control device Ϊ7 connected to the base unit I4 via the addressing line A.¹, Ac, A3, A4, as shown schematically in FIG.

Gbr-2 shows schematically an example of a coding circuit lc. which makes it possible to superimpose on the supply voltage between the supply conductors R1 and R2 different displacement voltages, defined by the level of the DC voltages, applied selectively to the addressing conductors A1 to A4. The superimposed DC voltages, given for example by the choice of resistors π to ró in FIG. 2, preferably have a substantially lower value than the supply voltage, but must be high enough to allow easy discrimination. It is noted. that the voltages on the supply conductors JAi and í.íe are newly cored.

Giant. 3 is a simplified diagram of a power supply and multiplexer. -fig — l-Voltage supplied by supply wires M1 and M2 to the supply and multiplexer. unit I2 is rectified and filtered by circuits IS to. In order to obtain a DC power supply, in particular for power supply multiplexers. In addition, the voltage on the supply conductors Μ *, Mz supplied to the individual sensors C1 to C4 by the input conductors MCz to MC4j is filtered by a high-pass filter 23 to remove the DC component, which filter may be located downstream of the supply in the example according to the invention. to the first sensor C¹. In addition, the voltage on the supply conductors M *, M2 is filtered by the low-pass filter 24 in order to obtain a DC shunt voltage [. The level 25 discriminator transmits an addressing signal to the addressing inputs A * ', Az' A4 ', which causes the output signals of the respective sensors C1 to C4 to reach the transmission signals. conductors S * to S4. | in

In case the sensors are supplied with a current, the detection of the DC shunt voltage is preferably performed in the interval between two consecutive pulses.¹

In general, the multiplexing according to the invention does not complicate the overall design of the device, as it allows the use of a single analog-to-digital converter or similar device for pulse processing. The use of a minimum number of connecting conductors, and in particular in the case of the example described, the possibility of using sensors of simple and economical design and gears with a relatively small number of teeth, represents decisive technical and economic advantages.