DE3446477A1 - Method and circuit arrangement for continuous contactless distance measurement - Google Patents

Abstract

The invention is used in contactless distance measurements, particularly in the spatial orientation of non-stationary production machines. According to the invention, a defined number of ultrasonic pulses having a defined duty ratio is transmitted, the ultrasonic pulses reflected from the obstacle being counted, the same duty ratio being present, and when a preselected number of received pulses is reached, the respective distance values from the obstacle are determined in accordance with the transit-time measurement, known per se. <IMAGE>

Description

Title of the invention

Method and circuit arrangement for continuous contactless Distance measurement

Field of application of the invention

The invention takes place in the non-contact distance measurement, especially with the space orientation of non-stationary work machines, their application.

Characteristics of the known technical solutions In known technical solutions of distance measurement middle Ultrasound is the transit time or the phase shift between Transmit and receive signal measured. Either none (DD-WP 150 657 and DE-OS 31 01 410) or only an insufficient one (DD - WP 154 182) importance attached to interference noise suppression.

In the case of the first two solutions mentioned, the ultrasonic transducer is switched between sending and receiving, with the The transit time of the echo corresponds to the current meter reading of the distance to the object in question.

Every incoming interfering signal with the same carrier frequency as it is used in the respective circuit arrangement leads to Falsification of measured values.

The WP 154 182 has the formation of a long pulse as an identifier for the received signal to be transmitted to the content. Achieved with it

However, there is only limited security on the transmission route If an interfering signal with this same pulse length occurs, this will also be Variant unusable. There is generally no acoustic interference signal suppression.

Every acoustic interference signal with the related transmission frequency leads wrong measured values.

Object of the invention

The aim of the invention is to remedy the deficiencies mentioned in relation to the prior art to eliminate and a continuous, insensitive to disturbance, Uitraschaii distance measurement to ensure.

Explain the essence of the invention

The invention is based on the object by means of a novel method a circuit arrangement for non-contact distance measurement for spatial orientation by means of ultrasound using known methods to realize electronic assemblies.

According to the invention the object is achieved in that a defined Number of Uitraschaflimpuisen sent with a defined duty cycle, the ultrasonic impulses reflected by the obstacle if present of the same duty cycle is counted and when a preselected one is reached Pulse count the respective distance values to the obstacle can be determined according to the run-time measurement known per se. According to the invention, a generator is available via a frequency divider for the Modulation frequency with a gate in connection, which has a Amplifier together with the output of a frequency divider for the modulation frequency and a microcomputer via a Pulse counter controlled send / receive trigger on a send gate whose output is connected to the send / receive gate for the x coordinate, the send / receive gate for the y coordinate and is connected to the receiving gate, whereby the sending-receiving gates, which are controlled by the microcomputer via a threshold switch with a Uitraschallwandier each and the receiving gate with the negated output of the sending / receiving trigger in terms of circuitry are linked.

The output of the receiving gate is via a selective amplifier, Demodulator and reception pulse counter with the microcomputer and the stop input of a distance counter, the start input of which is included the output of the frequency divider for the modulation frequency and clock input with the output of the frequency divider for the carrier frequency is connected, is interconnected, the data outputs of the distance counter and an external limit value transmitter are also connected to the microcomputer.

The mode of operation of the circuit arrangement is based on the transmission of a pulse-duration-modulated carrier frequency which must correspond to the resonance frequency of the Schail transducer. Immediately after sending, the Schail converter is switched to receive. A defined number of the known number of transmission pulses must be received in order to be able to calculate the distance of the sensor system from the reflective surface, presented by the current counter reading, which is transferred to the computer, from the transit time of the Schails signal. As soon as the distance has been determined in a coordinate, the microcomputer switches off the sound transducer for the coordinate just determined via a threshold switch and speaks to the ultrasonic transducer for the other coordinate. The sending and receiving gates are responsible for the choice of coordinates.

The carrier frequency signal is generated by a generator via a frequency divider formed, which is pulse-modulated by a gate controlled by another frequency divider. The carrier frequency signal serves at the same time as clock provision for the distance counter. With a pulse counter, which can be preset, a send-receive trigger is activated after the desired number of send impulses switched from sending to receiving. An amplifier provides the necessary transmission power. The received signal passes over a selective amplifier, which is tuned to the carrier frequency is on a demodulator and starts a reception pulse counter. When the required number of pulses is reached, the distance counter stopped and the queue to the computer via the READY signal a new meter reading is displayed. The computer takes over the counter reading for the purpose of converting it into the analog distance value and acknowledged with the "RESET" signal for all counters or possibly the changeover of the coordinate.

The invention will be explained in more detail below using an exemplary embodiment.

The associated figure shows the circuit arrangement according to the invention. With a quartz generator 1, the carrier frequency and the modulation frequency are provided via the frequency dividers 2 and 3. Both Frequencies arrive at a gate 9, which is soft via an amplifier 10 together with the output of one from the frequency divider for the modulation s frequency 3 and from a microcomputer 18 via a pulse counter 4 controlled send-receive trigger 5 to a send gate 6, the output of which with the Sen de -Em ρ fangs gate for the x-coordinate 7, the send / receive gate for the y coordinate 12 and the Receiving gate 11 is in communication. The gates 6, 7, 11 and 12 are preferably formed by two-way optocouplers. The send / receive gates 7 and 12, which are controlled by the microcomputer 18 via a threshold switch 19, each have one Ultrasonic transducers 8, 13 coupled. The receive gate 11 is connected to the negated output of the send / receive trigger 5, wherein the output of the receiving gate 11 via a selective amplifier 14, demodulator 15 and receiving pulse counter 16 with the microcomputer 18 and the stop input of a distance counter 17 is interconnected. The start input of the distance counter 17 is with the output of the frequency divider for the modulation frequency and the clock input is linked to the output of the frequency divider for the carrier frequency 2 in terms of circuitry, the data outputs of the distance counter 17 and an external limit value transmitter 20 are also connected to the computer 18. The external limit value transmitter 20 is preferably operated by a clock Distance sensor formed.

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List of the reference symbols used

1 generator

2 frequency dividers for carrier frequency

3 frequency dividers for modulation frequency

4 pulse counters

5 send / receive trigger

6 transmission gate

7 Send / receive gate for x coordinate

8 Ultrasonic transducers

9 gate

10 amplifiers

11 Reception gate

12 Send-receive gate for y-coordinate

13 ultrasonic transducers

14 selective amplifiers

15 demodulator

16 receive pulse counter

17 Distance counter

18 microcomputers

19 threshold switch

20 external limit switches

Claims (2)

1. Process for continuous non-contact distance measurement, characterized in that a defined number of ultrasonic pulses sent with a defined pulse duty factor, the ultrasonic pulses reflected by the obstacle in the presence of the counted with the same duty cycle and when a preselected one is reached Reception impuisanzahi the respective distance values determined to the obstacle according to the known transit time measurement will . 2. Circuit arrangement for performing the method according to claim 1, characterized in that a generator (1) has a frequency divider for the carrier frequency (2) and a frequency divider for the modulation frequency (3) with a gate (9) in connection, which together via an amplifier (10) with the output of a frequency divider for the modulation frequency (3) and a microcomputer (18) via a pulse counter (4) activated send / receive trigger (5) on Send gate (6) is switched, the output of which with the send / receive gate for the x coordinate (7), the send / receive gate for the y-coordinate (12) and the receiving gate (11) is in connection, the sending-receiving gates (7, 12), soft via a Threshold switch (19) can be controlled by the microcomputer (18), each with an ultrasonic transducer (8, 13) and the receiving gate (11) with the negated output of the Sen de reception trigger (5) are linked in terms of circuitry and that the output of the receiving To res (11) via a selective amplifier (14), Demodulator (15) and receiving pulse counter (16) with the microcomputer (18) and the stop input of a distance counter (17), its start input with the output of the frequency divider for the modulation frequency (3) and clock input with the output of the Frequency divider for the carrier frequency (2) is connected, is interconnected, the data outputs of the Entfemmgszählers (17) and an external limit indicator (20) also with are connected to the microcomputer (18). - For this 1 sheet of drawings -