FI109625B - Arrangement for contact detection - Google Patents

Description

109625

CONTACT DETECTION SYSTEM

The invention relates to an arrangement for detecting contact between two objects and for performing any operations that may follow. The arrangement according to the invention is particularly suitable as a safety edge for doors, moving parts of devices.

Automatic closing of the doors may pose a security risk. A moving part of a person's or animal's body may be trapped between the moving parts of a folding or opening door. You may also get caught in a garment, backpack strap or the like. This can be very dangerous, for example in the case of bus doors. If the driver does not notice the incident, the departing bus pulls the person with fatal consequences.

15 Different types of security solutions have therefore been developed for doors. The most common of these are the various limit switches that work when touched. The coupling may be mechanical or coupled via pneumatic or hydraulic transmission. In addition, there are piezo-resistive and capacitive switches whose operation is based on the fact that the resistance or ka-20 of the sensor element changes due to compression. In addition to these, there are optical arrangements where the object breaking the light path causes precautions. It is also known to use an ultrasonic radar to detect objects in the doorway.

All of these solutions are also capable of recognizing the static compression caused by the object being trapped.

The problem with mechanical solutions is related to mechanics and electrical contacts. Optical solutions are sensitive to fouling. Piezo-resistive and capacitive solutions are often not very sensitive to small objects. The location of the compression cannot be determined and the gradual changes in material 30 further reduce the sensitivity or the electronics threshold level must be set so high that false alarms will not occur to an alarming degree.

Piezoelectric solutions are based on materials which, when deformed, also alter the internal charge distribution. This change can be detected by metal electrodes attached to the surface of the material. These solutions are 35 sensitive to the dynamic steps of compression, but static compression is very difficult if not impossible to detect. In addition, the electrical impedance of the transducer 2 109625 thus implemented is high, which makes the solution very sensitive to electrical interference. If the area to be protected is large, it is necessary to divide it into several sections to provide sufficient sensitivity and to equip each section with its own pre-amplifier mesh. This increases the complexity of the system and, at the same time, the sensitivity to error-5 functions.

Security problems such as those described above occur. On doors, windows and hatches of buses, train buildings, lifts and equipment.

10 A workable solution must meet at least the following conditions: 1) Reliable detection of the incident 2) Minimal false alarm 3) High reliability 15 4) Easy installation and commissioning 5) Easy maintenance 6) Low initial and operational costs

With the solution according to the invention, the problems of the present technology can be eliminated and an arrangement according to the requirements can be made to increase the safety of doors, windows, machine parts and the like. The invention is characterized by what is apparent from the characterizing parts of the claims.

The invention is illustrated by the following drawings, of which: · 25: Figure 1 illustrates an embodiment of an embodiment at the principle block diagram level. Fig. 2 shows pulses to be transmitted to and received from the transmission line • · · - Fig. 3 shows an arrangement according to the invention as a safety edge of the doors • · ::: - Fig. 4 shows another transmission line according to the invention shows a transmission line formed between contacting transmission lines

Figure 1 is a block diagram illustrating the operation of an arrangement according to the invention. The arrangement includes a pulse generator PULSE GENERATOR and a receiver-35 RECEIVER processor for their operation and signal processing, ···. a PROCESSOR, including control means not shown in Figs. 3 109625, for controlling the operation of the device, a display means DISPLAY, for example, for indicating the contact point, and an alarm signal ALARM for controlling the alarm means. The PROCESSOR may also be directly or indirectly connected to data communication means by means of which the status of the PROCESSOR means and the information processed by them can be transmitted wired or wireless and possibly connected to a local network or larger networks such as a telephone network or the Internet. The PULSE GENERATOR is connected to a PSTL (Pressure Sensitive Transmission Line) which is designed to change its electrical properties when exposed to external pressure. The PSTL 10 contains the conductors TLC1 (Transmission Line Conductor) and TLC2 and the insulator DEM (DielElectric Material) between them. The PROCESSOR controls the operation of the PULSE GENERATOR and RECEIVER blocks, among other things, with a SYNC control that activates the PULL short pulse TRP (Transmission Pulse) shown in Figure 2, as the TRP proceeds in the PSTL: TERM. If the impedance of the TERM deviates from the characteristic impedance of the PSTL, a reflection is produced whose intensity depends on the impedance mismatch. As is known, the reflection coefficient is p = (ZPDTL - ZTERM) / (ZPDTL + ZTERM), where ZPDTL is the specific impedance of the transmission line and ZTERM is the impedance of the terminal TERM 20. If the PSTL does not include other impedance discontinuity targets, a reflection RCP2 (Received Pulse) arrives after a TD2 (Time Delay) delay corresponding to a pulse propagation rate v, i.e. TD2 = 2 * L / v, where L is the length of the PSTL. Upon detecting the reflected signal, the RECEIVER sends the PROCESSOR to the .... signal: DETECTED. If there is some other impedance discontinuity in the PSTL-. ·. : 25 scenes arrive at RECEIVER after TD1 delay.

: Of course, TD1 <TD2. The distance from the discontinuity point to the pulse starting point is ···. L1 = v * TD1 / 2. This information can be utilized, for example, by providing the driver of the bus with display means DISPLAY indicating the location where the observed compression occurs. This will help you to quickly assess and ... 30. The display means may be, for example, a row of light emitting diodes in which the brightness, color, temporal variation of the light source, or some combination thereof, indicates': * the position of the observed compression. The display means may be implemented by any known technique, e.g. Liquid crystal, gas discharge, plastic, electroluminescent, electrochromates, cathode ray tube, mechanical indicator, or light-35 projector. Display with or without tools can indicate compression · ·. sound devices such as a buzzer, speaker, clock, or other audio-generating device. Also, voice information includes synthesized or pre-recorded speech.

In some cases, it may be advantageous that the detected contact also results in the movement of a movement of a body, such as a door, or a change in direction of movement 5.

Reflection after a certain delay can be used to monitor the condition of the transmission line. If there is no reflection, the transmission cable or the electronics connected to it will be defective.

10 The transmission line can also act as a resonator, in which case the frequency of the oscillator connected to it is lowest when the delay is long (e.g. TD2) and maximum when the delay is short (TD1). If there is no reflection at all, the oscillator shuts down or vibrates at random frequency. The energy is then supplied to the transmission line in substantially continuous oscillation.

The transmission lines, PSTL1 and PSTL2, may be located on both contact surfaces as shown in Figure 3. These can be used, for example, for doors DOOR1 and DOOR2. These transmission lines can have their own electronic units EU1 and EU2. This provides a backup because each system can detect the contact individually.

Further, the two contacting surfaces may form a transmission line as shown in Figure 6. In this case, three transmission lines PSTL1, PSTL2 and PSTL3 can be connected to the contact surfaces. If desired, more and more power lines can be laid. more reliable detection than with a smaller number of transmission lines would be achievable.

Since the detection is based on the change in impedance when the transmission line is compressed,. ; the transmission line should be constructed so that the

. ···. the properties of the tea and / or the insulator change drastically. Track OTBD

(Object To Be Detected), the compressed transmission line guide may bend as shown, as shown in Figure 4. The dielectric dielectric of the transmission line can change properties when compressed. Such a solution is shown in Figure 5, "where the dielectric material DEMS increases the permittivity when compressed. In this case, the gas bubbles inside the dielectric material are compressed, or the gas is removed under compression. The dielectric coefficient increases.

The change in the property of the dielectric DEMS layer can also be arranged so that the dielectric material is liquid and contacted. · · ·. essa squeezed out between the guides.

s 109625 In the case of electromagnetic interference, it is in many cases advantageous to arrange the outer conductor of the transmission line connected to the electronics and also, for example, to the car body. This connection may be direct galvanic or, for example, capacitive to limit low-frequency currents or inductive to limit high-frequency currents. The arrangement described suppresses interference caused, for example, by mobile phones.

To reduce the false alarms, the PROCESSOR means may require the arrival of more than one character signal DETECTED, substantially corresponding to the TRP pulses transmitted substantially. For example, if the repetition rate of the TRP pulses is 10 kHz, then 10,000 events can be registered within one second, and if a greater number of a certain threshold (e.g., 80%) results in a DETECTED pulse arriving at the touch point, the PROCESSOR sends the corresponding data to DISPLAY and mah-15 for the alarm signal ALARM.

The system can also adapt to slow changes in the environment and equipment such as gradual changes in transmission line materials or accumulation of dirt on the contact surfaces. This may require digital processing of the received signal and adaptive filters. Fuzzy logic is one method by which adaptability can be achieved, at least in part. In an adaptive system, an abnormal situation is clearly observed when a stronger touch is applied.

],.; There are also several ways to carry out back-up and supervision of the arrangement. . 25 hardware operation. This is possible by connecting two or more parallel! ! conveyor cable for electronics. Two or more transmission lines may be located on the same object to be monitored. For example, the bus sides of a bus closed with a -! :: have an independent transmission line arrangement on each side.

Furthermore, the opposing transmission lines PSTL1 and PSTL2 in Figure 6 may provide a third transmission line PSTL3, the properties of which may be monitored. So ';;; 'Can increase system reliability.

:: Although the electric transmission line is in many cases an inexpensive solution, the transmission line can also be acoustic. This is the case, for example, with a tube in which sound waves propagate. The surface-wave transmission line is also a useful or, for example, a · · vibrating wire, the contact of which will cause the vibration to change.

6 109625

Only some embodiments of the arrangement according to the invention have been described above. Many other embodiments may be contemplated within the scope of the inventive idea set forth in the appended claims.

Claims (10)

1. A device for establishing mechanical contact between two objects which is in respect of each other characterized in that it contains one or more transmission line (PSTL) for the electrical, acoustic or mechanical energy of transport and contact between said objects in this area , where said transmission line (PSTL) is, a change in characteristics associated with the transmission of energy by this transmission line (PSTL) and this change is ascertained by means of device (RECEIVER, PROCESSOR) either as a change of reflection of energy or a change of power of the dissemination of energy. 2. A device according to claim 1, characterized in that said energy is conducted in transmission line (PSTL) as one or more time-limited pauses. 3. A device according to any one of the preceding claims, characterized in that said energy is conducted in the transmission line as a continuous oscillation ·: 1 ·: 20. \ i 4. An apparatus according to any of the preceding claims, characterized in that location information of contact is obtained from: 2: time information connected to the advancement of energy, as in example M 1: ''; recording time of reflection in relation to time of transmission or to length of oscillation cycle. 3 .2. An apparatus according to any one of the preceding claims 2 ·· / 'contact of any other object, such as proportion of body of person, proportion of:: clothing, proportion of carrying case, with said article (DOOR1) on it: · ·: The part where the said transmission line is registered and the said registration leads to action, such as for example to alarm or stopping movement of the first object or change of course. 3, ·. characterized in that said transmission line (PSTL) is *; § / affixed to the first item (DOOR1), as for example on vehicle door and 109625 A device according to any of the preceding claims, characterized in that transmission line (PSTL) is an electrical transmission line, the dielectric material of which conductors have been arranged to change the dielectric property influence of contact, for example, in such a way that dielectric material includes at least partially compressible material such as gas. 7. A device according to any of the preceding claims, characterized in that transmission line (PSTL) is an electrical transmission line, the dielectric material of which conductors have been arranged to change their location. A device according to any of the preceding claims, characterized in that it contains one or more transmission line 15 (PSTL), the means (PULSE GENERATOR) for supplying energy in the transmission line and the means (RECEIVER) for receiving energy and the means (PROCESSOR). ) to check their activity and the means (DISPLAY) to indicate the location of the means of the signaling device and possibly to indicate the location of the contact and the means (ALARM) to indicate the event of contact *: · * : 20 A device according to any one of the preceding claims, characterized in that information on the event of contact has been: "": arranged to be further mediated, for example through information networks or III: "*: information network with trees or outside trees . 25. · ·: 10. A device according to any of the preceding claims • *. ···. characterized in that signal reflected from terminal (TERM) of • »·, ·. transmission line is used to assess equipment operations »* • · ·