PROCEDURE FOR DETECTING THE MOVEMENTS OF AN ULTRASOUND EMITTER AND DEVICE DETECTING THE THREE-DIMENSIONAL MOVEMENTS OF AN ULTRASOUND EMITTER
DESCRIPTION
Field of the invention
The invented procedure and device are included in the electronics technology field. The invention concern a method for determining the displacement along the axes x, y, z of an ultrasound emitter and a device that can detect with great accuracy the movements of the ultrasound emitter.
The invented procedure uses the measurement of phase difference between an ultrasonic signal emitted by a mobile emitter and a similar reference signal located in a fixed receiver. The emitter and the receiver are synchronized by a signal transmitted by wire, radio or something else.
By equipping the receiver with three or more microphones, it is possible to determine in the three dimensions x, y, z the movement of the ultrasound emitter that, for example, could be incorporated into a computer mouse or can also be used for three-dimensional drawings or for a joystick for game consoles.
There are also other possible scientific applications in all areas where it is necessary to accurately detect the movement in real-time on a bidimensional plane or in three-dimensional space, of individual objects located within a few meters.
The invented procedure can detect the movement even when there are obstacles between the emitter module (1) and the receiver module (3). The device working with this invented process does not require a supporting or reference surface. In addition, the energy consumption is low.
As a variant for the comparison of the phases it is also conceivable that can be used only the ultrasound reflected by the examined mobile object, thus making the emitter module unnecessary. This process would greatly improve the sensitivity and accuracy of current proximity sensors and ecographs which are currently based solely on the detection of ultrasound echo. The initial position of the emitter module can be determined by measuring the travelling time of the ultrasounds from the emitter module (1 ) to the various microphones (12).
This technology is known, however it is original and inedited its combination with a movement detection system by measuring the phase difference.
The initial position of the emitter module (1 ) can also be detected by counting the number of waves (6) present between the emitter module (1 ) and the receiver module (3).
The number of waves (6) can be counted by stopping the emission of the ultrasonic signal (2) and counting the waves (6, Fig 1) that are still reaching the microphone (12) until the end of the signal (2). Because the wave length (6) is well known it is easy to determine the distance (9) of the emitter module (1 ) or the reflecting surface (23). The quantification of the distance (9) will later allow to determine with a good approximation the location of the emitter module (1 ) in relation to the receiver module (3).
An application of the invented principle and device could be, for example, to monitor and quantify with precision the movements in close range space of an object or a remote control.
A variant of the invented device contemplates that the displacements are detected by comparing the ultrasonic signal reflected by an object or a surface, with one equal default signal already present in the device. The phase difference between the two signals will quantify the movement of the object or the reflecting surface.
To avoid interferences, the frequencies of the ultrasonic signal may be adjusted and adapted to each case.
Moving the emitter module generates a Doppler effect. If the emitter module does not move at high speeds, the Doppler effect does not have much influence. In case of fast movements, it is possible compensate the Doppler effect with appropriate adjustments. Prior art
To determine the location and movement of an object in space the ultrasonic detectors and similar devices known today are based on the echo and the speed of the sound in air. An emitter emits an ultrasonic signal or similar and it is measured the time that the reflection of that signal takes to return to the starting point. Knowing the speed of sound or of the signal it is possible calculate the distance between the emitter and the detected object. These detectors use the same operating principle of SONAR or RADAR.
It is known the method to detect movements in three dimensions by using a video camera combined with an image processor that calculates the distance based on the size of the object. It is also well known the method of using two cameras to determine the location of the object by a triangulation procedure, but this requires a lot of energy and a complex image analysis and therefore calculation power.
Another possibility is to use infrared sensors which, however, determine the location and distance of the object with a certain approximation. With this method it is difficult to determine the position or the movements of an object in the three dimensions.
The mouses that are actually being used, detect the movement by a mechanical relationships or through a light emitted to a surface on which they move.
In portable computers a small surface is used as a sensor. In other cases it is the hand of the operator that is being used as a reference surface. Anyway there is always the need for a supporting or reference surface.
There are no known systems for detecting the movement of one ultrasound emitter by measuring the phase difference. It is also not known the combination of a system quantifying the distance by using the travelling time of ultrasonic waves with the movement detection system measuring the phase difference. Detailed description of the drawings
Referring to the drawings:
- Fig. 1 represents the theoretical principles underlying the invented process
- Fig. 2 shows an operational diagram of an example of realization of the invention
- Fig. 3 represents an application variant of the invented process Fig. 1 represents the invented process:
No. 1 represents the emitter module emitting the ultrasounds 2. Preferably the emitter module 1 is mobile.
No. 2 shows the ultrasounds waves emitted by the emitter module 1. A single wave of the emitted ultrasounds is represented by no 6.
No. 3 shows the receiver module in which there is the ultrasound reference signal 4.
No. 5 represents the phase difference (or phase shift) between the ultrasounds 2 emitted by the mobile emitter module 1 and the given ultrasound reference signal 4. The difference of the phase 5 is due to the physical movement of the emitter module 1 , for example, in the direction of the arrow 7. Inside the receiver module 3 the phase difference 5 is detected by comparing the phases and is measured with close intermittences. This measurement allows to precisely quantifying the physical movement performed by the ultrasound emitter module 1 in relation to the receiver module 3.
No. 6 shows a single wave of the ultrasonic signal.
No. 7 shows the direction arrow of a possible movement direction of the mobile emitter module 1.
No. 8 indicates the connection used to synchronize the ultrasounds 2 emitted by the emitter module 1 with the reference signal 4 located in the receiver module 3. Preferably, this synchronization connection 8 is done through a radio signal, a wire or something else. The emitted ultrasound signal 2 has therefore the same frequency as the reference signal 4. The synchronization may be omitted if, through the use of two identical frequency generators, the output signal of the emitter module is perfectly identical to the reference signal.
SUBSTITUTE SHEET^RULE 26) No. 9 shows the distance between the emitter module 1 and the receiver module 3. This distance can be detected and quantified by measuring the travelling time of the ultrasound from the emitter module 1 to a receiver module 3. This technology is known, however it is original and inedited its combination with a movement detection system by measuring the phase difference.
The quantification of the distance 9 allows to define with a good approximation the initial position of the emitter module 1 in relation to the receiver module 3.
Fig. 2 shows an operational diagram of an example of realization of the invention:
From the ultrasound frequency generator 16 (frequency multiplier, filters, oscillator, etc.) the default synchronization signal 20 is transmitted as a radio signal through the radio emitter 17 and the radio receiver 19 to the emitter module 1. Here the default signal passes through the regulation 18 (filter, amplifier, etc.) and arrives synchronized to the same frequency as the reference signal (4, fig. 1 ) to the ultrasound speaker 10. From here the signal leaves in the form of ultrasounds 2 and is detected by one or more microphones 12 of the receiver module 3 arranged in a triangle. The ultrasound signal 2 picked up by the microphones 12 passes into the regulation block 13 (typically one for each microphone) which is processed in various ways (amplification, AGC, power control, filters, etc.). From here the signal arrives in phase comparator 14 (there should be one for each microphone and can be composed of a logic gate AND or OR, but can be integrated directly into the microcontroller 15). In the phase comparator 14 the incoming signal is compared with the signal generated by the reference frequency generator 16, then the phase difference (5, Fig. 1) between the two signals is detected and highlighted all the time. The result of the comparison, i.e. the phase difference, is directly related to the movement of the source of ultrasounds. The phase difference is measured and quantified in the microcontroller MCU 15. The variation of this phase difference (5, fig.1 ) allows to detect and to quantify the physical movement of the emitter module 1. By using three microphones the microcontroller can calculate the movement and the position in the three dimensions x, y, z. The microcontroller 15 can also measure and quantify the travelling time of an ultrasonic signal from the emitter module to the receiver module quantifying with a good approximation the distance between the two modules, thus also the initial position of the emitter module in three dimensions x, y, z. At the end of the process, the data processed by the microcontroller MCU 15 are transmitted to the user computer through for example a cable, USB door or something else.
Fig. 3 represents a variant of realization of the invented device:
From the ultrasonic frequency generator 16 (frequency multiplier, filters, oscillator, etc.) the signal with the predefined frequency passes through the regulation 18 and arrives to the ultrasound speaker 10. From there it leaves as an ultrasonic signal 2 to the object or a surface 23 from which is reflected 22 and arrives to one or more microphones 12.
The signal 22 picked up by one or more microphones 12 passes through the control block 13 (typically one for each microphone) where is processed in various ways. From here the signal arrives into the phase comparator 14 (there should be one for each microphone and can be composed by a logic gate AND or OR, but can be also integrated directly into the microcontroller 15). In the phase comparator 14 the incoming signal is compared with the reference signal generated by the frequency generator 16, then the phase difference (5, Fig. 1 ) between the two signals is detected and highlighted all the time. The result of the comparison is directly related to the movement of the object or the surface 23 which reflects ultrasounds.
The phase difference is measured and quantified in the microcontroller MCU 15. The variation of this phase difference (5, Fig.1 ) allows to continuously detect and to quantify the physical movements of the object 23.
The microcontroller 15 can also detect, measure and quantify the travelling time of the ultrasound signal 2 from speaker 10 to the object/surface and return 22, therefore quantifying with a good approximation the distance between speaker and object/surface in order to define the initial position of object/surface 23. At the end of the process, the data processed by the microcontroller MCU 15 are transmitted to the user computer 21 through for example a cable, USB door or something else.