DE19828376C1 - Sensor for detecting model racing cars on model racing track consists of active inductive proximity sensor either with damping evaluation and operating point regulation or with frequency detuning evaluation and operating point regulation - Google Patents

Abstract

The sensor consists of an active inductive proximity sensor with damping evaluation and operating point regulation or an active inductive proximity sensor with frequency detuning evaluation and operating point regulation. The sensor arrangement contains a transducer and signal evaluation electronics. An Independent claim is also included for a model racing track.

Description

The invention relates to a sensor with the model racing car on model racing tracks, for. B. for the Control of lap counters, can be recorded.

Model racing tracks are available in retail at various scales (1:24, 1:32, 1:87, etc.) and from offered by different manufacturers.

Almost all manufacturers offer lap counters for their model racetracks. With these it becomes more common the passage of the model racing car through the lap counter with the help of a mechanical Device or switch detected in a special track.

These track sections from different manufacturers are not even with one another on the same scale compatible. Each model racetrack must therefore have its own lap counter or at least one appropriate track section can be purchased.

The lap counter SX100 from Electro Play and the time and lap recording Fastlap from The Koehn company can be used for various model racetracks, but they also require special ones Track sections or mechanical interventions on the racetrack, around switches or light barriers to attach.

The problem of registering racing cars on model racetracks of different Manufacturers or with different scales can therefore neither with mechanical Devices or switches or light barriers, easy to use for the layperson.

DE 196 47 883 C1 generally mentions that for detecting model racing cars Model racetracks can also be used with inductive sensors. On their special Problems with the application and the execution to solve these problems Matics are not considered.

The object of the application is based on the task of a sensor for the one described above To create application that without complex assembly on the road or modification of the Model racing car, also from a layperson, with model racing tracks from every manufacturer in each Scale can be used.  

Basic remarks on the sensor according to the invention

The basic functional principles of proximity sensors (in short: sensors) can be used here known to be assumed.

Conventional sensors have for the intended application for the detection of model racing dare, however, a number of disadvantages compared to the sensor according to the invention.

a) Disadvantages of passive sensors

Passive sensors require a detection object (model racing car), which is in the sensor generates an inductive or magnetic effect.

Examples

• - Reed contact sensors that respond through a magnetic field or
• - Induction coil sensors which are generated by an external magnetic field Evaluate the induction voltage.

Sensors with this operating principle have the following difficulties with the detection:

• - It is the installation of magnets or other encoder systems (e.g. high-frequency transmitter) in the model racing car required.
• - Due to the high field strength required to operate a reed contact sensor, the Detection range very limited.
• - The evaluation of the very small induction voltages of induction coil sensors is prone to failure.
• - The evaluation of signals from a radio frequency transmitter requires a comparative complex and therefore expensive sensor electronics.

b.) Disadvantages of active inductive sensors

Active inductive sensors evaluate the influence of one generated by the sensor itself inductive process through the detection object (model racing car).

Examples

• - The evaluation of the damping of an electrical resonant circuit by a metallic Detection object (active inductive proximity sensor with damping evaluation, damping sensor for short) or
• - The evaluation of the frequency detuning of an electrical resonant circuit by a metallic or magnetizable detection object (active inductive proximity sensor with frequency detuning evaluation, short frequency detuning sensor).

The use of conventional damping or frequency detuning sensors offers in Compared to passive sensors the advantage that regardless of design differences the model racing car, the metallic motor that is always present can be detected.

However, the practical detection of model racing cars with damping or frequency detuning sensors creates the following difficulties:

• - When installing the sensor under the middle of the web:
  The metallic busbars run between the detection object (model racing car) and the sensor. The sensor of course detects the busbars.
  The usable signal of a model racing car driving over it is comparatively small compared to the signal caused by the busbars.
  Since the busbars of different model racetracks are designed differently, the signal caused by the busbar is different for each model racetrack version. The working point of the sensor would therefore have to be set individually for each model racetrack, which in practice is hardly applicable to a layperson.
• - When installing the proximity sensor on the underside of the track next to the busbar duct: In this case there is no power between the model racing car and the sensor rails, but is located outside the center of the track, especially with model racetracks on a small scale, no large enough metal parts to detect the model race dare.
• - when mounting the sensor to the side of the vehicle or from above:
  The distance to the next detectable larger metal part on the model racing car is relatively large with sensors arranged on the side or from above and is also different for each model racing car version and each model racing track version.
  The installation of the sensors would be comparatively complex (bridges or guardrail construction).
  When the proximity sensors are mounted on the side, in the case of more than 2-lane model racetracks one would also need structurally very small and directional sensors to detect the inner lanes.

In view of the different designs of model racetracks and model racing cars hence a universal application of damping or frequency detuning sensors only possible with considerable restrictions.  

The sensor according to the invention

The sensor according to the invention is generally an actively inductive proximity sensor Working point control.

The working point control of the active inductive proximity sensor can

• - Both evaluate the damping of a resonant circuit (active inductive proximity sensor with damping evaluation and working point control In short: working point controlled damping sensor (1.)) as well
• - evaluate the frequency detuning of a resonant circuit (active inductive proximity sensor with frequency detuning evaluation and working point control In short: operating point controlled frequency detuning sensor (2.)).

1.) Damping sensor controlled by operating point (See diagram)

The block LC resonant circuit and controllable amplifier together form an oscillator. At the Input S of the controllable amplifier can be the gain factor of the controllable amplifier and thus the loop gain of the oscillator can be influenced.

• - When the gain is set high, this function block generates an oscillation of the LC Resonant circuit, the amplitude of which increases steadily.
• - When the amplification is set low, the amplitude of the vibration decreases steadily until finally the vibration completely breaks off.

The downstream control loop, consisting of amplitude detector, control amplifier and  Low pass filter, ensures that exactly that via the input S of the controllable amplifier Gain is set, which maintains a uniformly large amplitude of the vibration. The amplitude of the resulting vibration is determined by the interpretation of the threshold of the  Amplitude detector determined. The control amplifier amplifies with a high gain factor Changes in the oscillator amplitude.

The downstream low-pass filter is designed for the longest possible time constant. Is now by a metallic object in the vicinity of the inductance of the resonant circuit suddenly damped, this reduces the amplitude of the vibration.

The control loop ensures in the long term that the original oscillator is restored Vibration amplitude sets, but since the downstream low-pass filter is a very large one Has time constant, the gain of the oscillator circuit can be adjusted very slowly become.

At the output of the control amplifier there is a very highly amplified and therefore sensitive one Signal for evaluating dynamic damping changes available. This signal can then at the output of the control amplifier z. B. via a downstream threshold switches can be easily evaluated.  

2.) Operating point controlled frequency detuning sensor (See diagram)

A similar control principle as described for the working point controlled damping sensor, can also be implemented with an inductive proximity sensor that does not use damping, but the frequency detuning of an LC resonant circuit by the detection object evaluates.

Analogous to the method of the working point-controlled damping sensor, the Frequency detuning sensor is a regulation application.

Instead of the amplitude, however, the frequency of the LC oscillator becomes very low with a low-pass filter sluggish working regulation adjusted to the frequency of a reference oscillator.

Dynamic detuning of the frequency by the detection object generates analogous to the Working point controlled damping sensor a strong deflection at the output of the phases or frequency comparator.

The principle of this frequency control is known as the so-called PLL control loop.

The threshold switch symbolized at the output of the phase or frequency comparator is not as a simple voltage comparator as with the working point controlled damping sensor see, but must have its own signal processing, which the signals of Phase or frequency comparator suppressed when the control loop is engaged. The necessary Circuit technology for this (signal evaluation electronics) can be assumed to be known and is also not the subject of the device according to the invention.  

Advantages of the sensor according to the invention Working point controlled damping sensor

Due to the amplitude control of the oscillator, it is precisely at one operating point operated, in which the vibration amplitude neither increases nor decreases. Therefore are least Damping changes with high sensitivity can be detected as a change in amplitude. Advantage: metal parts on model racing cars, e.g. B. the electric motor that is always present safely grasped.

Operating point controlled frequency detuning sensor

By frequency control of the oscillator, its frequency is exactly on the reference frequency controlled. So at the output of the phase or frequency comparator Frequency detuning influences (driving through a model racing car) on the frequency of the LC oscillator with great sensitivity as unidirectional signal swings from the distinguish between normal control actions of the locked control loop. Advantage: metal parts on model racing cars, e.g. B. the electric motor that is always present safely grasped.

Both sensors according to the invention with working point control have in common:

• - Due to the high basic sensitivity of the two functional principles, air coils (Inductors without ferromagnetic core) can be used as a signal generator. In particular, baked enamel coils or coils are available as a printed circuit (Print spools).

benefits

• 1. 1.) baking varnish coils and print spools without ferromagnetic cores inexpensive.
• 2. 2.) They are flat so that they can be placed under the racetrack.
• 3. 3 ..) They can also be easily laid or glued under the model railroad by laymen. Mechanical interventions on the model racetrack are not necessary.
  • - The automatic control of static damping (operating point control) on the resonant circuit almost completely compensates for the influence of the busbars of any model racetrack.

benefits

• 1. 1.) The coils can be located at the most convenient point on the racetrack, centrally under the Busbar can be placed or attached without the busbar safe detection negatively affected.
• 2. 2.) The design of the racetrack is irrelevant, which means that the sensor can be used for tracks of all manufacturers and standards alike.
  • - The operating point control completely compensates for the influence of other damping materials in the vicinity (e.g. antistatic floors, metal table frames, floors with steel mesh, underfloor heating, etc.). Advantage: The sensors react exclusively to moving metal, i.e. only to the model racing car. They therefore offer a high level of security.
  • - The high sensitivity of the method also tolerates a static basic damping of the resonant circuit by connecting the signal transmitter and the signal evaluation electronics by cable.

benefits

• 1. 1.) The cables can be relatively long.
• 2. 2.) Standard cables can be used. Expensive low-loss High frequency lines are not required.

Claims (6)

1. Sensor for detecting model racing cars on model racing tracks, consisting of a active inductive proximity sensor with damping evaluation and working point control or an active inductive proximity sensor with frequency detuning evaluation and Working point control. 2. Sensor according to claim 1, consisting of a signal generator and signal evaluation electronics. 3. Sensor according to claim 2, wherein the signal evaluation electronics both in the signal generator itself, as can also be carried out remotely from the signal generator. 4. model racetrack, in which several of the sensors according to one of the preceding claims for the detection of a model racing car is used at several locations on the model racing track are. 5. Model racetrack, in order to improve the detection security also several sensors according to one of claims 1-3 for the detection of a model racing car at a specific Position or a specific section of position are used. 6. model racetracks according to claim 4 or 5, in which both mentioned in claim 1 Versions of sensors are used together.