CN107945778B - Electronic musical instrument - Google Patents

Abstract

This application relates to an electronic musical instrument, which triggers the current sensor group in each sensor group to work and emit the first signal. Know the first striking distance, and then obtain the second striking distance according to the receiving time of the second return signal and the transmitting time of the second signal, and know the striking distance through the first striking distance, the second striking distance and the preset threshold duration. Hit the speed, and then can emit a sound with a volume corresponding to the hitting speed and a tone corresponding to the identity of the non-contact sensor that receives the first return signal. When the timing time reaches the preset time, the next sensor group in each sensor group will be used as the current sensor group, and the current sensor group will be returned to trigger the work, that is, each sensor group will be triggered in turn, so as to avoid the problem that all sensors work at the same time and easily cause interference , to improve the sensing accuracy.

Description

electronic musical instrument

technical field

The invention relates to the technical field of electronic equipment, in particular to an electronic musical instrument.

Background technique

In recent years, the electronic technology of musical instruments has gradually become the key content in the field of electronic research, resulting in a variety of electronic musical instruments, and electronic drums are one of the common electronic musical instruments. The electronic drum is a musical instrument in which the musician triggers an electronic signal by hitting the drum surface, and then uses electronic synthesis technology or sampling technology to process the new electronic signal, and then emits sound through the electro-acoustic equipment. Common electronic musical instruments with rubber electronic board and mesh simulation (also known as mesh drum head) electronic musical instruments, electronic musical instruments with rubber electronic board use rubber material as the panel, and external sensor type, such as , sensors can be installed on the edge of the drum. The mesh drumhead is the new high-tech main battlefield. The mesh drumhead combines the double texture of the drumhead and the sensor. When hitting the mesh drumhead, the sound volume is not only higher than that of the traditional rubber drum The skin is still low, and drummers can adjust its tension according to their own preferences. Inside is a fast panel with multiple sensors installed in it, so it can also be used as a drum frame effect.

At present, general electronic musical instruments have the characteristics of light weight, small size, easy disassembly, easy portability, and quick assembly and debugging. However, in the process of striking the electronic musical instrument, it is easy to cause damage to the striking surface. In order to solve the problem that the electronic musical instrument is easily damaged by hitting the drum surface, the electronic musical instrument that is hit by non-contact will be sensed by the sensor installed on the electronic musical instrument. However, interference between the sensors is easy to occur, that is, a sensor sends out The detection beam of the sensor is received by another sensor as its own detection beam, which leads to poor sensing accuracy of the sensor, which in turn causes inaccurate sounding of electronic musical instruments.

Contents of the invention

Based on this, it is necessary to provide an electronic musical instrument to solve the problem that the existing electronic musical instrument is susceptible to interference and causes inaccurate sounding.

An electronic musical instrument, comprising a main body, a processor and at least two sensor groups, each of the sensor groups is respectively arranged on the main body, any one of the sensor groups includes at least two non-contact sensors, and each of the sensor groups Each of the non-contact sensors in the group is respectively connected to the processor; wherein, each of the non-contact sensors corresponds to an identity mark;

When the processor receives the work instruction, it starts timing, and uses any sensor group in each of the sensor groups as the current sensor group, triggers the current sensor group to work, and emits a first signal, and the current sensor group When the non-contact sensor receives the first return signal corresponding to the transmitted first signal within the preset time period after starting the timing, the processor according to the receiving time of the first return signal and the Acquire the first striking distance according to the emission time of the first signal, and trigger the non-contact sensor to emit the second signal after receiving the preset threshold duration of the first return signal, within the preset duration range When receiving the second return signal corresponding to the transmitted second signal, the processor acquires the second striking distance according to the receiving time of the second return signal and the transmitting time of the second signal, according to the The first striking distance, the second striking distance and the preset threshold duration obtain the striking speed, and the processor sends out a For the sound corresponding to the timbre and the volume corresponding to the hitting speed, when the timing time reaches the preset time length, stop the current sensor group from emitting signals, reset the timing, restart the timing, and turn each of the sensors Any one of the sensor groups in the group except the current sensor group is used as the current sensor group, and the triggering of the current sensor group to emit a signal is performed back.

In one of the embodiments, the distance between the non-contact sensors in any one of the sensor groups is greater than the preset anti-interference distance.

In one of the embodiments, after the preset trigger interval time of stopping the operation of the current sensor group, the timer is reset to zero.

In one of the embodiments, the processor presets a counter, the count value of the counter is initially zero, and the processor generates an interrupt command at a preset interval when receiving the work command, Each time an interrupt command is received, the count value is increased by 1, and when the count value reaches a preset number of times, the timing duration reaches the preset duration, and the counter is cleared.

In one of the embodiments, the non-contact sensor is an ultrasonic sensor.

In one of the embodiments, the non-contact sensor includes an ultrasonic transmitter and an ultrasonic receiver, and the processor is connected to the ultrasonic generator and the ultrasonic receiver respectively;

In the process of triggering the current sensor group to work and transmitting the first signal, the ultrasonic transmitters of the non-contact sensors in the current sensor group are respectively triggered to emit ultrasonic signals;

A first return signal corresponding to the first signal is received by the ultrasonic receiver, and the first return signal is a return signal corresponding to the first ultrasonic signal.

In one of the embodiments, the above-mentioned electronic musical instrument further includes a filter circuit, and the ultrasonic receiver is connected to the processor through the filter circuit.

In one of the embodiments, when the processor receives a stop instruction, it stops the operation of each of the sensor groups.

In one of the embodiments, the number of the sensor groups is three, including the first sensor group, the second sensor group and the third sensor group, and the number of the non-contact sensors in the first sensor group is three The number of the non-contact sensors in the second sensor group and the third sensor group is two respectively.

In one of the embodiments, the above-mentioned electronic musical instrument further includes a first sound-generating device and a second sound-generating device respectively connected to the processor, and the first sound-generating device and the second sound-generating device are relatively arranged on the main body , when the processor emits the corresponding sound, the processor emits the corresponding sound through the first sound generating device and the second sound generating device respectively.

The above-mentioned electronic musical instrument, in the process of inductive percussion and sounding, first uses any sensor group in each sensor group as the current sensor group, and triggers it to work, that is, to emit the first signal, and when the first signal is received When corresponding to the first return signal, according to the reception time of the first return signal and the transmission time of the first signal, the first striking distance can be known, and then according to the reception time of the second return signal and the transmission time of the second signal Obtain the second striking distance, and know the striking speed through the first striking distance, the second striking distance and the preset threshold duration, and then send out the non-contact with the volume corresponding to the striking speed and receive the first return signal The identity of the type sensor corresponds to the sound of the timbre. When the timing reaches the preset duration, stop the current sensor group from transmitting signals, reset the timing, restart timing, and use any sensor group in each sensor group except the current sensor group as the current sensor group, return to execute the trigger current The sensor group emits signals, that is, each sensor group is triggered in turn, which can avoid the problem of induction error caused by all sensors working at the same time, which will lead to the occurrence of sensing influence, improve the accuracy of sensing, and make the sound more accurate.

Description of drawings

Fig. 1 is a structural diagram of an electronic musical instrument of an embodiment;

Fig. 2 is the structural diagram of filter circuit in the electronic musical instrument of an embodiment;

FIG. 3 is a timing diagram during the sensing process of triggering the ultrasonic sensor in this embodiment;

FIG. 4 is a relationship diagram between sampling values and distance values in this embodiment.

Detailed ways

Referring to Fig. 1, an embodiment of the present invention provides an electronic musical instrument, including a main body 100, a processor (not shown) and at least two sensor groups, each sensor group is respectively arranged on the main body 100, and any sensor group includes There are at least two non-contact sensors, and each non-contact sensor in each sensor group is respectively connected to the processor; wherein, each non-contact sensor corresponds to an identity mark.

When the processor receives the work order, it starts timing, and uses any sensor group in each sensor group as the current sensor group to trigger the current sensor group to emit the first signal. When the first return signal corresponding to the transmitted first signal is received within the preset duration range, the processor obtains the first striking distance according to the receiving time of the first return signal and the transmitting time of the first signal, and upon receiving the first After the preset threshold duration of the return signal, the non-contact sensor is triggered to transmit the second signal. When the second return signal corresponding to the transmitted second signal is received within the preset duration, the processor will The emission time of the second signal obtains the second striking distance, obtains the striking speed according to the first striking distance, the second striking distance and the preset threshold duration, and the processor according to the identification and striking speed of the non-contact sensor, Make a sound corresponding to the timbre of the identity and the volume corresponding to the hitting speed. When the timing reaches the preset duration, the current sensor group will stop emitting signals, the timing will be reset, and the timing will be restarted. Any sensor group other than the sensor group is used as the current sensor group, and the return execution triggers the current sensor group to emit a signal.

Each non-contact sensor has its corresponding unique identity, such as a number, and each identity corresponds to a different timbre, that is, the identity of each non-contact sensor corresponds to the timbre, for example, the non-contact sensor in each sensor group The total number of sensors is 7, and the IDs are 1, 2, 3, 4, 5, 6, and 7 respectively. If the timbre corresponding to ID 1 corresponds to the timbre of the drum, when triggering the current sensor group to work for signal transmission, if one of them When the non-contact sensor of the non-contact sensor receives the return signal, it means that within the sensing range of the non-contact sensor, the impact on the electronic device is sensed. When the first return signal corresponds to the first signal, the processor emits the timbre corresponding to the ID 1, that is, the drum sound. For another example, the timbre corresponding to the ID 2 is the timbre of a piano. If the non-contact sensor with the ID 2 receives the first return signal corresponding to the first signal transmitted, the processor sends out the timbre corresponding to the ID 2. to play the piano sound.

In addition, the volume of the sound is related to the hitting force. In this embodiment, the hitting speed is used to characterize the hitting force, that is, the faster the hitting speed, the greater the hitting force, and the higher the volume of the sound. Large, for example, when the hitting speed is less than or equal to 1, the processor controls to emit a sound with a lower volume corresponding to the hitting speed; When the hitting speed is less than or equal to 1, the volume is louder. When the hitting speed is greater than 2 and less than or equal to 5, the processor controls the sound to be louder than when the hitting speed is greater than 1 and less than or equal to 2. When hitting When the hitting speed is greater than 5 and less than or equal to 10, the processor controls to emit a louder sound than when the hitting speed is greater than 2 and less than or equal to 5; when the hitting speed is greater than 10 and less than or equal to 15, the processor controls to emit The sound is louder than the volume when the hitting speed is greater than 5 and less than or equal to 10. When the hitting speed is greater than 15, the processor controls the sound to be louder than the volume when the hitting speed is greater than 5 and less than or equal to 10. In the process of obtaining the hitting speed, the hitting object will move during the hitting process. By sending signals to sense the hitting distance of the hitting object at different time points, the moving distance of the hitting object during this period can be known. Then the hitting speed can be known. Specifically, it is first necessary to know the striking distance difference, and obtain the striking speed through the distance difference and the preset threshold duration, wherein the distance difference is the distance difference between the first striking distance and the second striking distance. Wherein, the preset threshold duration is shorter than the preset duration. In an example, the preset threshold duration is 10 microseconds, and the preset duration is 200 milliseconds.

The above-mentioned electronic musical instrument, in the process of inductive percussion and sounding, first uses any sensor group in each sensor group as the current sensor group, and triggers it to work, that is, to emit the first signal, and when the first signal is received When corresponding to the first return signal, according to the reception time of the first return signal and the transmission time of the first signal, the first striking distance can be known, and then according to the reception time of the second return signal and the transmission time of the second signal Obtain the second striking distance, and know the striking speed through the first striking distance, the second striking distance and the preset threshold duration, and then send out the non-contact with the volume corresponding to the striking speed and receive the first return signal The identity of the type sensor corresponds to the sound of the timbre. When the timing reaches the preset duration, stop the current sensor group from transmitting signals, reset the timing, restart timing, and use any sensor group in each sensor group except the current sensor group as the current sensor group, return to execute the trigger current The sensor group emits signals, that is, each sensor group is triggered in turn, which can avoid the problem of induction error caused by all sensors working at the same time, which will lead to the occurrence of sensing influence, improve the accuracy of sensing, and make the sound more accurate.

In addition, each of the non-contact sensors corresponds to the timbre, and after the non-contact sensor senses the return signal, when the processor emits a sound, it emits a sound corresponding to the timbre of the identity of the contact sensor. In this embodiment, the formula for obtaining the first distance is: first distance=(the time difference between the receiving time of the first return signal and the transmitting time of the first signal)*sound velocity/2, and the sound velocity is 340M/S. The formula for obtaining the second distance is: second distance=(time difference between the receiving time of the second return signal and the transmitting time of the second signal)*sound speed/2.

In one of the embodiments, the distance between the non-contact sensors in any sensor group is greater than the preset anti-interference distance.

If the distance between the non-contact sensors in the same sensor group is too close, cross-interference may occur, that is, the detection beam emitted by one non-contact sensor may be more than the other non-contact sensor as its own detection beam. In order to avoid interference between the non-contact sensors in the same sensor group, when the non-contact sensors are arranged on the main body 100, the distance between the non-contact sensors in any one sensor group is greater than the preset anti-interference distance , that is, the distance between the non-contact sensors is greater than the preset anti-interference distance, so that the occurrence of interference between the non-contact sensors can be reduced.

In one of the embodiments, after the preset triggering interval time when the current sensor group stops working, the timer is reset to zero.

That is, when each sensor group is triggered in turn to work, the sensor groups are triggered at a preset trigger interval time, that is, the trigger interval is the preset trigger interval time. After the current sensor group is triggered and sensed, it is necessary to wait for the preset trigger interval time , and then trigger the next group of sensor groups to work for sensing. In this way, aftermath interference between sensor groups can be avoided. In an example, the preset trigger interval may be 20 milliseconds.

In one of the embodiments, the processor presets the counter, and the count value of the counter is initially zero. When the processor receives the work instruction, it generates an interrupt instruction at a preset interval time, and each time it receives an interrupt instruction, it will The counting value is increased by 1, and when the counting value reaches the preset number of times, the timing duration reaches the preset duration, and the counter is cleared.

It can be understood that the product of the preset interval length and the preset number of times is the preset time length. When the count value reaches the preset number of times, it means that the timing duration has reached the preset time length. At this time, the counter can be reset to zero for the next The work of each sensor group is timed. In one example, the preset interval time is 10 milliseconds, and the preset number of times is 20.

In one embodiment, the non-contact sensor is an ultrasonic sensor.

Ultrasonic sensors are sensors developed using the characteristics of ultrasonic waves. Ultrasound is a mechanical wave with a vibration frequency higher than that of sound waves, which is generated by the vibration of the transducer chip under the excitation of voltage. It has high frequency, short wavelength, small diffraction phenomenon, especially good directionality, and can be oriented as rays dissemination characteristics. Ultrasound has a great penetrating ability to liquids and solids, especially in solids that are opaque to sunlight, it can penetrate to a depth of tens of meters. When the ultrasonic wave hits the impurity or the interface, it will produce a significant reflection to form an echo. In this embodiment, when the ultrasonic sensor is triggered to work, the ultrasonic sensor emits ultrasonic waves. When the electronic device is hit in a non-contact manner, the ultrasonic waves will be reflected by the hitting object, and the ultrasonic sensor can receive the return signal to realize the Induction of hitting objects.

In one of the embodiments, the non-contact sensor includes an ultrasonic transmitter and an ultrasonic receiver, and the processor is connected to the ultrasonic generator and the ultrasonic receiver respectively; The ultrasonic transmitter of each non-contact sensor in the sensor group transmits the first ultrasonic signal; the first return signal corresponding to the first signal is received by the ultrasonic receiver, and the first return signal is the return signal corresponding to the first ultrasonic signal.

It can be understood that, in this embodiment, the first signal is the first ultrasonic signal, the first return signal is the first ultrasonic return signal, and the return signal corresponding to the first ultrasonic signal is the first ultrasonic return signal.

In one of the embodiments, a filter circuit is also included, and the ultrasonic receiver is connected with the processor through the filter circuit.

In order to eliminate the interference in the first return signal and ensure the accuracy of the signal, a filter circuit can be connected between the ultrasonic receiver and the processor, and the first return signal can be filtered through the filter circuit to eliminate interference and improve the accuracy of the first return signal. accuracy.

In one example, the filter circuit includes a first diode D1, a second diode D2, a capacitor C and a resistor R, that is, an RC filter circuit, and the ultrasonic receiver is respectively connected to one end of the capacitor C, the first two The positive pole of the diode D1, the negative pole of the second diode D2 and one end of the resistor R are connected, the other end of the capacitor C and the positive pole of the second diode D2 are respectively grounded, and the negative pole of the first diode D1 is connected to the power supply (one In an example, it can be a 3.3V power supply), and the other end of the resistor R is connected to the processor. Specifically, the capacity of the capacitor C may be 0.01 microfarads.

In one of the embodiments, when the processor receives the stop instruction, it stops the work of each sensor group.

When there is no need to use the electronic musical instrument for inductive sounding, the electronic musical instrument can be controlled to stop working. Specifically, the stop button on the main body 100 of the electronic musical instrument can be operated, for example, the stop button can be pressed to generate a stop command. When the controller receives the stop instruction, it controls each sensor group to stop working, so that the situation that each sensor group has been working non-stop, resulting in easy damage and shortened service life can be avoided.

In one of the embodiments, the number of sensor groups is three, including the first sensor group, the second sensor group and the third sensor group, the number of non-contact sensors in the first sensor group is three, and the second sensor group And the number of non-contact sensors in the third sensor group is two respectively.

That is, there are seven non-contact sensors on the main body 100 of the electronic device, and each non-contact sensor performs obstacle sensing during the corresponding working time period, that is, when the user performs non-contact hitting, the hitting object will The signal sent by the sensor is reflected to realize the distance detection of the hitting object, that is, the obstacle. In this implementation, the timbres corresponding to the seven non-contact sensors may be partly the same, or all may be different, or all may be the same.

Specifically, please continue to refer to FIG. 1, the first sensor group includes the first non-contact sensor 201, the second non-contact sensor 202 and the third non-contact sensor 203, the second sensor group includes the fourth non-contact sensor The sensor 204 and the fifth non-contact sensor 205, the third sensor group includes the sixth non-contact sensor 206 and the seventh non-contact sensor 207. Each group of sensors is triggered at a preset trigger interval, for example, it can be triggered at an interval of 20 milliseconds, and the aftermath interference between each group can be ignored.

In one of the embodiments, the connecting line between the three non-contact sensors in the first sensor group is an isosceles triangle, and the two non-contact sensors in the second sensor group are connected with the two non-contact sensors in the third sensor group respectively. The connection line between the non-contact sensors surrounds one non-contact sensor in the first sensor group, and the connection line is an isosceles trapezoid.

The distance between two of the three non-contact sensors in the first sensor group and the remaining other non-contact sensors is the same. It can be understood that the distance between the three non-contact sensors in the first sensor group is the same. The connecting line is an isosceles triangle. In addition, the connection lines between the two non-contact sensors in the second sensor group and the two non-contact sensors in the third sensor group respectively surround one non-contact sensor in the first sensor group, and the connection lines are in the form of Isosceles trapezoid. In this way, a more regular positional relationship between the non-contact sensors on the main body 100 can be ensured, the appearance is more beautiful, and the risk of interference between the non-contact sensors can be reduced.

In one of the embodiments, the above-mentioned electronic musical instrument also includes a first sound generating device 208 and a second sound generating device 209 respectively connected to the processor. In emitting the corresponding sound, the processor emits the corresponding sound through the first sound generating device 208 and the second sound generating device 209 respectively. In this embodiment, the first sound generating device 208 and the second sound generating device 209 may be speakers respectively.

The working process of the above-mentioned electronic musical instrument will be described below with a specific embodiment, specifically taking the sensing of the ultrasonic sensor of the HC-SR04 model as an example.

The HC-SR04 model ultrasonic sensor can provide non-contact distance sensing function from 2cm to 400cm, and the ranging accuracy can be as high as 3mm. When the ultrasonic sensor is triggered by the processor, it first emits the ultrasonic wave, and at the same time opens the timer. When the echo is received, the timer is closed, and the transit time of the ultrasonic wave is calculated (that is, the time difference between the time of receiving the echo and the time of emitting the ultrasonic wave) ), according to the length of the transit time, output a level whose voltage is linearly related to the transit time. Ultrasonic sensors have the characteristics of high ranging accuracy and low price, which can improve the sensing accuracy.

The principle of the HC-SR04 ultrasonic sensor for inductive distance measurement is as follows:

Among them, the main technical parameters involved are as follows:

1. Working voltage: DC5V;

2. Static current: less than 2mA;

3. Level output: high 5V;

4. Level output: bottom 0V;

5. Induction angle: no more than 15 degrees;

6. Detection distance: 2cm-450cm 7: High precision can reach 0.2cm;

7. Wiring mode, VCC, trig (control terminal), echo (receiving terminal), GND.

It works as follows:

1. Use IO to trigger ranging, and give a high-level signal of at least 10us;

2. Send 8 square waves of 40khz after triggering, and automatically detect whether there is a signal return;

3. When there is a signal return, a high level is output through the IO, and the high level time is the time from the ultrasonic wave to its return. Test distance = (high level time * speed of sound (340M/S))/2.

Ultrasonic sensors mainly use the Doppler principle to emit high-frequency ultrasonic waves beyond the perception of the human body through the crystal oscillator. Generally, 25-40kHz waves are typically used, and then the frequency of the reflected wave is detected. If there is an object moving in the area, the frequency of the reflected wave There will be slight fluctuations, that is, the Doppler effect, to judge the movement of objects in the lighting area, so as to achieve the purpose of controlling the switch.

The longitudinal oscillation characteristics of ultrasonic waves can propagate in gas, liquid and solid with different propagation speeds; it also has refraction and reflection phenomena, and its frequency is lower when propagating in air, and the attenuation is faster, while it is attenuated in solid and liquid Smaller and spread farther. Ultrasonic sensors utilize these characteristics of ultrasonic waves. Ultrasonic sensors have the characteristics of large sensitive range, no visual blind zone, and no interference from obstacles. It is the most effective way to detect the movement of small objects.

ULTD5N-350 ultrasonic sensor can provide 3cm--3.5m non-contact distance sensing function, which includes ultrasonic transmitter, receiver and control circuit. Its basic working principle is to give the ultrasonic sensor a trigger signal and then emit ultrasonic waves. When the ultrasonic waves are projected to the object and reflected back, the module outputs an echo signal to determine the distance of the object based on the time difference between the trigger signal and the echo signal.

The principle of the above-mentioned ultrasonic sensor sensing is described through the timing diagram. Please refer to the timing diagram in Figure 3. From the timing diagram of the above module, it can be seen that only a short-term 10uS pulse trigger signal is provided, and the ultrasonic sensor can perform distance detection. Measure work. After the ultrasonic sensor is triggered, the ultrasonic sensor transmitter will send out 8 40kHz cycle levels and detect the echo at the same time. Once an echo signal is detected, an echo signal is output. An echo signal is a pulse whose width is proportional to the distance from the object. The distance can be calculated from the time interval between the transmitted signal and the received echo signal. In this embodiment, the measurement period is 60 ms or greater than 60 ms to prevent the influence of the transmitted signal on the echo signal.

In addition, the development module uses Arduino ProMini, which is a semi-customized version of Arduino Mini (the most concise miniature version of Arduino, a convenient, flexible, and easy-to-use open source electronic prototype platform for Arduino). All external pin through holes are not soldered. Versions are pin compatible. The processor core of Arduino ProMini is ATmega168, and it has 14 digital input/output ports (6 of which can be used as PWM output), working voltage 5V, input voltage 5-12V, IO pin (input and output pin) DC current 40mA, Flash The storage size of Memory (flash memory) is 16KB (of which 2KB is used for bootloader, that is, boot loading), the storage of SRAM (static random access memory) is 1KB (ATmega328), and the storage of EEPROM (electrically erasable programmable read-only memory) is 0.5 KB (ATmega328), working clock 16MHz. In order to ensure the accuracy of the signal, an RC filter circuit is designed between the ultrasonic receiver and the processor to filter out the interference signal and effectively suppress the spike noise. The RC filter circuit is shown in Figure 2 in detail. The two diodes in the figure play the role of limiting, limiting the pin voltage between 0V and 5V to protect the ATmega168 processor.

The electronic musical instrument in this embodiment senses the process of striking objects as follows:

First, the entire electronic musical instrument is powered on, that is, the processor (ATMEGA168 processor in this embodiment) and each non-contact sensor are powered on respectively, the reset pin of the ATMEGA168 processor is pulled low, and the ATMEGA168 processor performs a system power-on reset work, the reset time is 20ms. After the reset is completed, the system is initialized and guided, which completes the initialization of the control system kernel, global parameters and various peripherals. The system initialization guide module completes the following functions: initialization of ATMEGA168 processor internal registers, self-test function of hardware resources such as processor and memory, initialization of IO pins and hardware resources of various peripherals (AD, SCI, EVM), and initialization of system variables and interrupt initialization. After the system initialization is completed, the system enters the standby working mode. Once the command sent by the host computer is received, that is, when the processor receives the working command, it can trigger the sensor to quickly enter the working mode. In the working mode, the ATmega168 processor divides the control of the ultrasonic sensor into three parts: multi-sensor group trigger, A/D sampling and data processing. The specific process is as follows:

When the processor receives the work instruction, it starts the timer interrupt, and the timer generates an interrupt instruction every 10ms. In the interrupt instruction, design a count value PT2, the initial value is 0, every time it enters an interrupt, it will perform an interrupt on itself once. Auto-increment operation. Trigger a group of ultrasonic sensors at the same time. Whenever the value of PT2 increases to 20, it is reset to 0 and triggers the next group of ultrasonic sensors. In this way, a group of ultrasonic sensors are triggered in turn every 200ms. In this embodiment, the ultrasonic sensors are divided into three groups, so the time for all the sensors to trigger one cycle is 600 ms. After the triggering of the sensor is realized, A/D sampling is performed on the data returned by the sensor. The ATMEGA168 processor comes with 14 channels of 10-bit analog-to-digital converters on-chip, and the minimum conversion time is 500ns.

Specifically, this implementation uses 7-way A/D sampling, so the A/D module is configured as a cascade mode, and the register MAXCONV=9 (the maximum conversion channel of the register is 9), and the trigger mode of the A/D module is interrupt trigger. Since it takes a certain amount of time between ultrasonic emission and return, the time calculation is as follows: the maximum measurement distance is 4m, assuming that the ultrasonic speed is 340m/s, considering the round trip, the time needs to be multiplied by 2, and the final result is 19ms, leaving a certain margin The amount, the interval between trigger and A/D sampling is determined as 20ms. Therefore, when the value of PT2 is 4, that is, when the intermediate interval is 50ms, the A/D sampling module is turned on to realize the sampling function. The ultrasonic sensor returns an analog voltage, and the value obtained after A/D conversion is a value that has a positive linear relationship with the distance, rather than the distance value between the sensor and the surrounding objects, and then converts the value after A/D conversion into The real distance value. The process of this algorithm is as follows: Since the A/D sampling value has a positive linear relationship with the distance, and the maximum and minimum values of the sampling value correspond to the maximum and minimum values of the distance, so the coordinates of the maximum and minimum values can be calculated For the equation of a straight line, bring the A/D conversion value into the equation to obtain the corresponding distance value. The functional relationship between the sampling value and the distance value is shown in Figure 4.

In addition, due to the inevitable error in the distance measurement of the ultrasonic sensor, the accuracy is not accurate, and there may be some outliers that deviate from the real distance. Since the environment around the robot is uncertain and dynamic, the sensor measurement values may have sudden changes due to sudden changes in the environment. In order to distinguish whether this value is an abnormal value or a normal mutation value, the arithmetic mean filter method is used in this embodiment to record the previous N times of values and calculate the average value. When the current value and the average value are within a certain difference It is regarded as valid, and if it is outside the difference, it is regarded as an invalid value and will be eliminated. The arithmetic mean filtering method has the following characteristics: when the N value is large, the signal smoothness is high, but the sensitivity is low; when the N value is small, the signal smoothness is low, but the sensitivity is high. In this embodiment, the requirement for the sensitivity of the system is relatively high. The interference signal is a very large value that appears randomly, so the requirement for smoothness of the signal is low, so a small N value is selected here. The value of N in this paper is 3, which can well meet the requirements of the system.

For the electronic musical instruments mentioned above, multiple ultrasonic sensors are installed on different positions of the main body, and the ATMEGA168 processor is used to control the grouping triggering, data collection, and data processing of these sensors in turn, thereby constructing a multi-ultrasonic sensor triggering system. The system has the advantages of low cost, high precision and good real-time performance. It can be applied to the field of electronic musical instruments, and provides a reliable basis for the design of colorful electronic devices.

The technical features of the above embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be It is considered to be within the range described in this specification.

The above embodiments only express several embodiments of the present invention, and the description thereof is relatively specific and detailed, but it should not be construed as limiting the patent scope of the invention. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (10)

1. An electronic musical instrument, characterized in that it comprises a main body, a processor and at least two sensor groups, each of the sensor groups is respectively arranged on the main body, and any one of the sensor groups includes at least two non-contact sensors , each of the non-contact sensors in each of the sensor groups is respectively connected to the processor; wherein each of the non-contact sensors corresponds to an identity mark; When the processor receives the work instruction, it starts timing, and uses any sensor group in each of the sensor groups as the current sensor group, triggers the current sensor group to work, and emits a first signal, and the current sensor group When the non-contact sensor receives the first return signal corresponding to the transmitted first signal within the preset time period after starting the timing, the processor according to the receiving time of the first return signal and the Acquire the first striking distance according to the emission time of the first signal, and trigger the non-contact sensor to emit the second signal after receiving the preset threshold duration of the first return signal, within the preset duration range When receiving the second return signal corresponding to the transmitted second signal, the processor acquires the second striking distance according to the receiving time of the second return signal and the transmitting time of the second signal, according to the The first striking distance, the second striking distance and the preset threshold duration obtain the striking speed, and the processor sends out a When the count value of the counter preset by the processor reaches the preset number of times corresponding to the sound of the timbre and the volume corresponding to the hitting speed, the timing duration reaches the preset duration, and the current sensor is stopped. The group emits a signal, the count value of the counter is cleared, and the timing is restarted, and any one of the sensor groups except the current sensor group in each of the sensor groups is used as the current sensor group, and the execution process is returned. triggering the current sensor group to transmit a signal; Wherein, the count value of the counter is initially zero, and when the processor receives the work command, it generates an interrupt command every preset interval time, and increments the count value every time an interrupt command is received. 1. 2. The electronic musical instrument according to claim 1, characterized in that, the distance between the non-contact sensors in any one of the sensor groups is greater than the preset anti-interference distance. 3. The electronic musical instrument according to claim 1, characterized in that, after the preset trigger interval time for stopping the operation of the current sensor group, the timer is reset. 4. The electronic musical instrument according to claim 1, wherein the preset threshold duration is shorter than the preset duration. 5. The electronic musical instrument according to claim 1, wherein the non-contact sensor is an ultrasonic sensor. 6. The electronic musical instrument according to claim 1, wherein the non-contact sensor includes an ultrasonic transmitter and an ultrasonic receiver, and the processor is connected to the ultrasonic generator and the ultrasonic receiver respectively; In the process of triggering the current sensor group to work and transmitting the first signal, the ultrasonic transmitters of the non-contact sensors in the current sensor group are respectively triggered to emit ultrasonic signals; A first return signal corresponding to the first signal is received by the ultrasonic receiver, and the first return signal is a return signal corresponding to the first ultrasonic signal. 7. The electronic musical instrument according to claim 6, further comprising a filter circuit, the ultrasonic receiver is connected to the processor through the filter circuit. 8. The electronic musical instrument according to claim 1, wherein the processor stops the operation of each of the sensor groups when receiving a stop command. 9. The electronic musical instrument according to claim 1, wherein the number of the sensor groups is three, including a first sensor group, a second sensor group and a third sensor group, and all the sensor groups in the first sensor group The number of the non-contact sensors is three, and the number of the non-contact sensors in the second sensor group and the third sensor group is two respectively. 10. The electronic musical instrument according to claim 1, further comprising a first sounding device and a second sounding device respectively connected to the processor, the first sounding device and the second sounding device are opposite to each other It is arranged on the main body, and when the processor emits the corresponding sound, the processor emits the corresponding sound through the first sound generating device and the second sound generating device respectively.

Images