KR102343404B1 - Apparatus and Method for Object Detection - Google Patents

Abstract

The present invention discloses an object detection apparatus and method. According to an aspect of the present invention, there is provided an object detecting apparatus, comprising: an amplifier for amplifying a reflected wave signal of an ultrasonic wave returned after being transmitted with a variable gain; The gain of the amplifier is controlled with a first variable gain in the first area A1 in which the reflected waveform of the object to be sensed is checked, and the second variable gain is controlled in the second area A2 in which the reflected waveform of the surrounding object is checked. a gain controller for controlling the gain of the amplifier; a comparator for comparing a signal on an envelope corresponding to the signal amplified by the amplifier with a preset threshold, and outputting a signal greater than the threshold from among the signals on the envelope; a calculator for calculating an absolute value of the first differential value of the signal on the envelope and a time point at which a maximum value of the absolute value of the first differential value is calculated; and a detector configured to detect an object using a third time point at which the maximum value is calculated before a second time point at which a signal greater than the threshold value is output.

Description

Apparatus and Method for Object Detection

The present invention relates to an object detection technique, and more particularly, to an object detection apparatus and method capable of amplifying a reflected wave with a variable gain.

As shown in FIG. 1 , a conventional ultrasonic device for a vehicle converts an electric signal generated by a pulse generating device into a sound wave by a transducer and transmits it. Then, the transmitted signal is reflected by the surface of the object, returns to the transducer, and is converted into an electrical signal. In addition, the received electrical signal of several uV level is amplified into a signal of several V level by an amplifier (Amp) before digital conversion. However, since the vehicle ultrasonic signal has an audible frequency or higher of 20 kHz to 100 kHz, the amplified signal to increase the signal-to-noise ratio of the corresponding frequency band is filtered by a bandpass filter. Then, the envelope detector (Envelope Detector) calculates the envelope of the filtered signal, the calculator (ToF Calculation) and the comparator (ToF Calculation) and the comparator (Comparator) compares the calculated signal value of the envelope with a threshold value, and the signal value of the envelope is higher than the threshold value. If it is large, it is judged that there is an object. In this case, the calculator calculates the distance to the object by using the speed of the sound wave and the time it takes for an envelope signal greater than or equal to the threshold value to be received from the time of transmission.

However, as described above, since the frequency band of the ultrasonic signal for a vehicle is adjacent to the audible frequency band, it is susceptible to interference from harmonic components of noise generated in a general environment. Therefore, when the magnitude of a harmonic component of ambient noise is greater than or equal to a threshold value, the conventional ultrasonic device for a vehicle recognizes the noise as an object and detects the object even when there is no object.

In order to reduce the false alarm problem, as shown in FIG. 2 , the conventional ultrasonic device for a vehicle goes through two detection processes and determines that there is an object only when the two times of detection information match.

The ultrasonic device for a vehicle needs to detect a road bump (curb in FIG. 3 ) at a height that may damage the vehicle bumper. However, as shown in FIG. 3 , the degree of attenuation of the signal is large because the road jaw located at a short distance is located outside the vertical beam pattern, and the conventional ultrasonic device for a vehicle uses a high-gain amplifier to detect it. .

When a high-gain amplifier is used, there is a problem in that the first transmitted signal is reflected by an object having a large reflection signal, such as a distant wall, and is received at a threshold value or more in the second signal transmission/reception period.

In other words, as shown in FIG. 4 , in this case, since Time of Fight (ToF)1 of the first transmission signal and ToF2 of the second transmission signal do not match, there may be cases in which an alarm cannot be performed even if there is an object.

In addition, when the engine is started when the outside temperature is low, a temperature layer of air may be generated by the exhaust gas having a higher temperature than outside air. The signal is amplified with a high gain. Therefore, when the ultrasonic signal reflected by the temperature layer of air is greater than or equal to a threshold value, there is also a problem of erroneously recognizing it as an object.

The present invention has been made in the technical background as described above, and an object of the present invention is to provide an object detection apparatus and method capable of detecting an object using a threshold value and a first derivative value.

Another object of the present invention is to provide an apparatus and method for detecting an object that can be used for object detection by amplifying an object to be detected with a variable gain.

The object of the present invention is not limited to the object mentioned above, and other objects not mentioned will be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided an object detecting apparatus, comprising: an amplifier for amplifying a reflected wave signal of an ultrasonic wave returned after being transmitted with a variable gain; a gain controller configured to set the variable gain so that the reflected wave signal received in at least one preset time domain is amplified with a higher gain compared to other time domains; a comparator for comparing a signal on an envelope corresponding to the signal amplified by the amplifier with a preset threshold, and outputting a signal greater than the threshold from among the signals on the envelope; a calculator for calculating an absolute value of the first differential value of the signal on the envelope and a time point at which a maximum value of the absolute value of the first differential value is calculated; and a detector configured to detect an object using a third time point at which the maximum value is calculated before a second time point at which a signal greater than the threshold value is output.

Here, the calculator includes: a first summer that sequentially receives the signals on the envelope and outputs a current difference signal that is a result of the difference between a current input signal and a previous input signal; a first storage for storing the previous input signal; a second storage for storing a previous difference signal that is a difference result between the previous input signal and a previous signal of the previous input signal; a first comparator configured to output the current difference signal when the current difference signal is greater than the previous difference signal; a third storage configured to store a larger value among the previous difference signal and the current difference signal; and a fourth storage configured to store the third time point at which the large value is stored, wherein when the comparator outputs a signal greater than the threshold value, the third time point may be output.

In addition, the gain controller, but measuring the current time, when the current time corresponds to the length of the section of the preset gain, a counter that is initialized; a comparator configured to initialize the counter by outputting a signal when the current time is greater than the section length; a state machine that changes state when recognizing the output of the comparator; a plurality of multiplexers outputting the preset gain value including a gain value for a section before the current time and a gain value for a section after the current time to correspond to the output of the state machine; a first summing unit for subtracting the gain values of the plurality of multiplexers; a shift register for shifting the output of the summing unit; a multiplier for multiplying the current time by an output of the shift register; a second summing unit for adding the gain value of the previous section to an output of the multiplier; a third summing unit calculating the variable gain to be used at the current time by adding the output of the second summing unit to the previously calculated variable gain; It may include a storage for storing the variable gain to be used at the current time to be used for a subsequent operation of the third summing unit.

According to another aspect of the present invention, an object detection method by an object detection apparatus amplifies a reflected wave signal of an ultrasonic wave returned after being transmitted with a variable gain, but in at least one time domain in which a reflected wave for an object to be sensed exists, other amplifying with a high gain compared to the time domain; comparing a signal on an envelope corresponding to the amplified reflected wave signal with a preset threshold value; outputting a signal greater than the threshold value from among the signals on the envelope; calculating a maximum value of an absolute value of a first derivative of a signal on the envelope; and detecting an object using a third time point at which the maximum value is calculated before a second time point at which a signal greater than the threshold value is output.

Advantageous Effects of Invention According to the present invention, it is possible to improve the conventional problems of being affected by an object having a large reflection signal such as a distant wall or interference by exhaust gas, and it is possible to increase the robustness to the environment.

In addition, the embodiment of the present invention can give the frequency of occurrence of the object position distortion according to the change of the variable gain curve.

Furthermore, the embodiment of the present invention can be configured with a relatively simple structure, thereby reducing the implementation cost and complexity.

1 is a block diagram showing a conventional object detection apparatus.
2 is a diagram illustrating a ToF of a conventional object detection apparatus.
3 is a diagram illustrating a beam pattern of an object detection apparatus;
4 is a view for explaining an object misrecognition problem of a conventional object detection apparatus.
5 is a view showing a signal reflected by a conventional exhaust gas.
6 is a graph showing a reflected wave signal during static gain control and dynamic gain control of a conventional amplifier.
7 is a block diagram illustrating an object detecting apparatus according to an embodiment of the present invention.
8 is a graph illustrating a variable gain according to an embodiment of the present invention.
9 is a graph illustrating a reflection waveform according to an embodiment of the present invention.
10 is a graph illustrating a signal form of an object detection apparatus according to an embodiment of the present invention.
11 is a block diagram illustrating a calculator according to an embodiment of the present invention.
12 is a graph illustrating a variable gain curve according to an embodiment of the present invention.
13 is a block diagram illustrating a gain controller according to an embodiment of the present invention.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in a variety of different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention belongs It is provided to fully inform the possessor of the scope of the invention, and the present invention is only defined by the scope of the claims. On the other hand, the terms used herein are for the purpose of describing the embodiments and are not intended to limit the present invention. In this specification, the singular also includes the plural unless specifically stated otherwise in the phrase. As used herein, "comprises" and/or "comprising" refers to the presence of one or more other components, steps, operations and/or elements mentioned. or addition is not excluded.

Prior to describing the specific configuration of the embodiment of the present invention, a conventional static gain control method and a dynamic gain control method will be described with reference to FIGS. 1 and 6 . 6 is a graph illustrating a reflected wave signal during static gain control and dynamic gain control of an amplifier of a conventional object detection apparatus. Here, the static gain and the dynamic gain are methods of controlling the gain of the amplifier of FIG. 1 , and the reflected wave signal may be an output of the envelope detector of FIG. 1 .

In FIG. 6, line (a) is a reflected wave signal when using a static gain, line (b) is a reflected wave signal when using a dynamic gain, line (c) is a dynamic gain value of the amplifier over time, and line (d) is an object It is the threshold value of detection (Threshold in Fig. 1, 0.5V in Fig. 6).

As described above, the conventional object detection apparatus detects the position of the object using a point in time when the reflected wave signal is greater than a threshold value. Hereinafter, a case in which the conventional object detection apparatus detects an object directly adjacent to the object detection apparatus (ie, the object's position is at 0 ms) will be described as an example.

Accordingly, the conventional object detection apparatus using a static gain uses a time point of 0.15 msec exceeding the threshold value of 0.5 V, as in the point ㉠ of FIG. to calculate

However, since there is a distance offset between the actual position and the detected position of the object, the conventional object detection apparatus using a static gain compensates the distance offset (here, 2.55 cm) to the distance of the detected object, thereby increasing the calculation of the object position. increasing accuracy.

On the other hand, in the conventional object detection apparatus using a dynamic gain, the distance of the object 3.08 cm (= 0.815 ms × 340 m/s ÷ 2) using 0.181 msec when the threshold value exceeds 0.5 V, as at point ㉡ in FIG. 6 . That is, 0.53cm detection error occurs more when using a dynamic gain than when using a static gain.

However, since such a detection error varies depending on a gain curve used for dynamic gain, it is difficult to compensate with a specific offset. Moreover, when the gain curve changes rapidly, this error value may further increase.

In order to prevent such a problem, an object is detected using a threshold value and a first derivative of an amplified signal in an embodiment of the present invention.

On the other hand, the dynamic gain control of the conventional amplifier is used to compensate for a darkened image in medical ultrasound equipment. Specifically, the dynamic gain control of the medical ultrasound equipment is to make the image brightness of the entire region the same level. Therefore, the medical ultrasound equipment uses a monotonically increasing function for dynamic gain control, and stores a gain value according to depth in a memory. Therefore, the conventional dynamic gain control requires high complexity, and it is difficult to apply it to a system having a limited memory capacity, such as an auxiliary device for a vehicle.

However, since the embodiment of the present invention has a relatively simple structure, it is possible to implement dynamic gain control within a single semiconductor and may have low complexity.

Hereinafter, an object detecting apparatus according to an embodiment of the present invention will be described with reference to FIGS. 7 to 9 . 7 is a block diagram illustrating an object detection apparatus according to an embodiment of the present invention, FIG. 8 is a graph illustrating a variable gain according to an embodiment of the present invention, and FIG. 9 is a reflection waveform according to an embodiment of the present invention is a graph showing

7 , the object detection apparatus 10 according to an embodiment of the present invention includes a pulse generator 121 , a converter 122 , an amplifier 140 , a gain controller 130 , an AD converter 150 , It includes a filter 160 , an envelope detector 170 , a comparator 180 , a differential calculator 110 , and an object detector 190 .

The pulse generator 121 generates an electric signal and transmits it to the converter 122 .

The transducer 122 (transducer) converts an electric signal into an ultrasonic wave and transmits it, and converts a reflected wave returned after being transmitted into an electric signal.

The amplifier 140 amplifies the electrical signal from the converter 122 to a variable gain under the control of the gain controller 130 .

The gain controller 130 controls the variable gain of the amplifier 140, but sets the variable gain to a value _{greater than or equal to a first value (G 1 in} FIG. 8 ) in at least one time domain in which obstacles are sensed, and in other time domains, the first Set the variable gain below the value. Here, the at least one time domain may be a region in which a nearby object to be detected is detected a predetermined number of times or more as a result of a plurality of experiments in an environment to which the object detecting apparatus 10 is applied. That is, the at least one time domain includes a time domain in which the reflected wave that is reflected and returned to an object to be sensed exists.

Referring to FIG. 8 , the gain controller 130 controls the gain of the amplifier 140 with a first variable gain in a first area A1 in which a reflected waveform for a road bump, which is an object to be sensed, is checked, and In the second region A2 in which the reflected waveform is checked, the gain of the amplifier 140 may be controlled with the second variable gain. Also, the gain controller 130 may control the gain of the amplifier 140 with a first value G1 that is a static gain in other regions.

At this time, the gain controller 130 checks the slope value of the gains of a plurality of sections stored in advance, and controls the variable gain of the amplifier 140 using a gain curve calculated by linearly interpolating the slope values of the gains for each section. . This will be described later with reference to FIGS. 12 and 13 .

The AD converter 150 converts an electric signal amplified with a variable gain to analog to digital.

The filter 160 band-pass filters the digitally converted signal to increase the signal-to-noise ratio.

The envelope detector 170 calculates an envelope corresponding to the signal received from the filter 160 .

The comparator 180 receives a signal on the envelope and checks whether it is greater than a preset threshold.

The differential value calculator 110 calculates a first differential value of the signal on the envelope, and a time point at which the maximum value of the absolute value of the first differential value is detected after the first time point and before the second time point (hereinafter, “third time point”). ") is printed. Here, the first time point is a transmission time point of the ultrasound, and the second time point is a time point at which a signal on an envelope higher than the threshold value is received.

The object detector 190 calculates the distance to the object by using the speed of the ultrasonic wave and the time required from the first time point to the third time point as shown in Equation 1 below.

9, the output of the amplifier 140 using the dynamic gain according to the embodiment of the present invention is exhaust gas or the reflected wave by the wall (ambient noise) is less than the threshold value, and the target to be detected, It can be seen that the reflected wave by the object is above the threshold value. Moreover, the difference in magnitude between the reflected wave due to ambient noise and the reflected wave by the target to be sensed is large, so it can be seen that the embodiment of the present invention is robust to environmental changes.

In this way, the embodiment of the present invention can improve the problems of the conventional object detection apparatus, such as interference by an object having a large reflection signal such as a distant wall or the effect by exhaust gas, and increase the robustness to the environment. can

Hereinafter, various signal types of the object detecting apparatus according to an embodiment of the present invention will be described with reference to FIG. 10 . 10 is a graph illustrating a signal form of an object detection apparatus according to an embodiment of the present invention. Assume that the object is located at 0 ms.

In FIG. 10, line (e) is a signal on the envelope when using a static gain, and line (f) is a signal on the envelope when using a variable gain. And, line (g) is the variable gain value, line (h) is the threshold value, line (i) is the absolute value of the first derivative when using the static gain, and line (j) is the value using the dynamic gain. It is the absolute value of the first derivative of the case. Here, the signal on the envelope may be an output of the envelope detector 170 .

As shown in FIG. 10 , when an object is determined using only the threshold value, (e) the time point (about, 0.15 ms) where the line and the threshold value (h) meet, or (f) the line and the threshold value (h) meet A viewpoint (about 0.18 ms) (hereinafter, referred to as a "second viewpoint") is determined as an object position. In this way, when the position of the object is determined using only the threshold value, a point having a difference from the actual position of the object can be recognized as the position of the object.

However, looking at the absolute values of the first derivatives of lines (i) and (j) of FIG. 10 , before the second time point, the maximum value of the absolute value of the first derivative is detected at 0 ms. As described above, it can be seen that when an object is detected based on the first differential value, the object can be accurately detected regardless of whether a variable gain is applied.

Hereinafter, a calculator for calculating a time point at which the maximum value of the absolute value of the first differential value is detected according to an embodiment of the present invention will be described with reference to FIG. 11 . 11 is a block diagram illustrating a calculator according to an embodiment of the present invention. 11, the input signal of the differential value calculator 110 is a signal on the envelope output from the envelope detector 170, and the output signal is the first differential value of the input signal before the third time point, that is, the second time point. It is the point at which the maximum value of the absolute value is detected.

11 , the differential calculator 110 according to the embodiment of the present invention includes a first register 111 , a second register 112 , a third register 113 , and a fourth register 114 . , a first summing unit 115_1 , a second summing unit 115_2 , a first comparator 116 , a second comparator 117 , a counter 119 , and a switch 118 .

The first register 111 receives an n-th signal x[n] and outputs an n-1 th signal x[n-1].

The first summing unit 115_1 sums the (-) value of the n-th signal x[n] and the n-1 th signal x[n-1]. That is, the difference signal (x[n]-x[n-1]) between the n-th signal x[n] and the n-1 th signal x[n-1] is output.

The second register 112 receives the nth differential signal and stores the maximum value among the input differential signals. That is, when the current difference signal, the nth difference signal {Diff(x[n]=B}), is greater than the previously stored difference signal {max(Diff(x[n])=A}), the nth difference signal is stored Here, the initial value of the second register 112, that is, the initial value of max(Diff(x[n]) may be 0.

The first comparator 116 outputs TRUE if the n-th difference signal {Diff(x[n]=B} is greater than the previously stored difference signal {max(Diff(x[n])=A}), otherwise Otherwise, FALSE is output, where TRUE may be a digital “1” signal and FALSE may be a digital “0” signal.

The third register 113 stores the previous differential signal, that is, the n-1 th differential signal Diff(x[n-1]).

The second summing unit 115_2 adds an offset to the n-th difference signal. Here, the offset may be a calibration value. In detail, the offset may be a value set in consideration of the degree to which the value of the n-th difference signal increases when the reflected wave by the object is affected by noise according to a plurality of experiments.

The second comparator 117 outputs when the nth difference signal corrected by the offset is greater than the n−1th difference signal. Accordingly, the third time point stored in the fourth register 114 is reset. That is, as _{at time t 4} of FIG. 10 , an object is not detected in a section in which the differential signal increases after the maximum value, and even if the maximum value of the absolute value of the first differential value is detected, it is not detected from the reflected wave of the object. Thus, the fourth register 114 is initialized. However, since the _{differential signal may temporarily increase due to noise while it is decreasing even before time t 4} , in this case, a certain offset is added to the n-th differential signal so that the fourth register 114 is not initialized.

The counter 119 is driven to check a time point (third time point) at which the maximum value of the absolute value of the first differential value is detected after the ultrasound transmission time point (first time point). That is, the counter 119 measures the current time.

The fourth register 114 is activated when TRUE is input from the first comparator 116 at the point in time when it is the maximum value of the absolute value of the first differential value, and is activated (Enable), and the current time (third time point) from the counter 119 ) and save it. Also, the fourth register 114 outputs a third time point when the switch 118 is short-circuited.

The switch 118 is short-circuited when the output of the comparator 180 of FIG. 7 is 1, and transfers the third time point from the fourth register 114 to the object detector 190 .

Meanwhile, the fourth register 114 is reset when the nth differential signal is smaller than the previous differential signal by a preset offset or more.

Meanwhile, in the above-described example, the case in which the differential value calculator 110 receives the second viewpoint from the comparator 180 and outputs the third viewpoint has been described as an example. However, alternatively, the differential value calculator 110 may output a third time point whenever the maximum value of the absolute value of the first differential value is detected. In this case, when the object detector 190 identifies the second viewpoint, it goes without saying that the object may be identified using the third viewpoint. In this case, the differential value calculator 110 may not include the switch 118 .

As described above, according to an embodiment of the present invention, the maximum value of the absolute value of the first derivative and the time of its calculation can be confirmed by a relatively simple structure including three storages, two adders, and two comparators. Accordingly, it is possible to lower the implementation complexity and reduce the implementation cost.

On the other hand, as described above, since the embodiment of the present invention is preferably implemented in a single semiconductor, such as a vehicle parking assistance device, it is difficult to use the variable gain control method applied to medical ultrasound equipment using a large-capacity memory as it is. it's difficult. Furthermore, since the variable gain according to the embodiment of the present invention is accompanied by a sudden change in gain, in this case, a problem of position distortion of an object may be added.

In order to prevent this problem, the embodiment of the present invention stores the slope value of the gain for each time specified, and uses a value obtained by interpolating the stored slope value when applying the variable gain, so that the variable gain can be controlled using a continuous gain curve. have.

Hereinafter, a gain controller according to an embodiment of the present invention will be described with reference to FIGS. 12 and 13 . 12 is a graph illustrating a variable gain curve according to an embodiment of the present invention, and FIG. 13 is a configuration diagram illustrating a gain controller according to an embodiment of the present invention. In FIG. 12 , the slope value of the gain at time _{t k is α 1} , the slope value of the gain at time _{t k+1 is α 2} , and the slope value of the gain at time _{t k+2 is α 3} . Here, dt is t _k+1 - t _k , which is 2 ⁿ , where n is a positive integer.

12 , the gain controller according to the embodiment of the present invention has a continuous curve shape obtained by interpolating gain values for each section. In addition, since the reflected signal for the object does not change rapidly, the object position can be more accurately calculated by estimating the object based on the first differential value according to an embodiment of the present invention.

The variable gain applied by the gain controller 130 of the present invention to the amplifier 140 at an arbitrary time is expressed in Equation 2 below. Here, the static gain may be the same as G1 of FIG. 8 .

Here, the static gain is a gain for amplifying a reflected wave signal for a time domain that does not include an object to be sensed (G1 in FIG. 9), t is the current time, and t _k is the previous section of the current time among the preset sections. time, tk+1 is a time corresponding to a subsequent section among the preset sections, α(t _k ) is the slope value of the gain at time _{t k , and α(t k+1} ) is the gain at time _{t k+1} It may be a slope value.

13 , the gain controller 130 according to an embodiment of the present invention includes a state machine 131 , a counter 132 , a shift register 135 , a first multiplexer 134_1 , and a second multiplexer 134_2 . ), a comparison unit 133 , a multiplication unit 136 , a storage 138 , an upper summing unit 139 , a left summing unit 137_1 , and a right summing unit 137_2 .

The counter 132 measures the current time t, but is initialized whenever the current time is the length of the preset gain value interval (dt = t _k+1 -t _k or t _k+2 -t _k+1) do.

The comparator 133 outputs a signal when the current time calculated by the counter 132 is greater than the section length of the preset gain value.

When the state machine 131 recognizes the output of the comparator 133, the state is changed.

The first and second multiplexers 134_1 and 134_2 obtain a preset gain value including a gain value for a section before the current time and a gain value for a section after the current time to correspond to the output of the state machine 131 . print out

The upper summing unit 139 subtracts the gain values of the plurality of multiplexers.

The shift register 135 may perform a division operation by performing a shift operation on the output of the summing unit.

The multiplication unit 136 multiplies the current time and the output of the shift register.

The left summing unit 137_1 adds the gain value for the previous section and the output of the multiplier 136 .

The right summing unit 137_2 calculates a variable gain to be used at the current time by adding the output of the left summing unit 137_1 to the previously calculated variable gain.

The storage 138 stores a variable gain to be used at the current time to be used for a subsequent operation of the right summing unit 137_2.

Hereinafter, the variable gain setting process of the gain controller 130 will be described by dividing the _{t k} ≤ t < t _k+1 section and the t _k+1 ≤ t < t _{k+2 section.}

▶ t _k ≤t ＜ t _k+1 ; If the counter value is less than or equal to dt

When the output of the counter 132 exceeds the period length dt of the preset gain value (here, t _k ), the comparator 133 initializes the counter 132 and supplies a signal to the state machine 131 .

The counter 132 is _{reset to 0 at time t k} , and its output indicates the current time. That is, the counter 132 _{outputs (tt k} ).

The state machine 131 outputs an initial output Mux=0 at time _{t k , so that the first multiplexer 134_1 outputs α 1} and the second multiplexer 134_2 outputs _{α 2 .}

The upper summing unit 139 sums the negative _{value of the output α 1} of the first multiplexer 134_1 and the output α ₂ of the second multiplexer 134_2 .

The shift register 135 receives (α ₂ -α ₁ ) as an input, and outputs _{(α 2} -α ₁ )/2 ^{n by performing a shift operation.} However, since (t _k+1 - t _k )=2 ⁿ , the output of the shift register can also be viewed as _{(α 1} -α ₂ )/(t _k+1 - t _{k ).}

The multiplication unit 136 receives (tt _k ) and (α ₂ -α ₁ )/(t _k+1 - t _k ) as inputs, {(α ₂ -α ₁ )/(t _k+1 - t _k ) }x(tt _k ) is printed.

The left summing unit 137_1 receives {(α ₂ -α ₁ )/(t _k+1 - t _k )}×(tt _k ) and α ₁ , and receives {(α ₂ -α ₁ )/(t _{k ) +1} - t _k )}×(tt _k )+ α ₁ is output.

The right summing unit 137_2 adds the current input to the existing output previously stored in the storage 138 , that is, it performs integration. Accordingly, the output of the right summing unit 137_2 is the right item except for the static gain of Equation 2 above.

The storage 138 stores the output of the right summing unit 137_2 and is used for subsequent calculations.

On the other hand, the left summing unit 137_1 and the right summing unit 137_2 change according to the output change of the counter 132 until the output of the counter 132 exceeds dt {(α ₂ -α ₁ )/(t) The integral of _k+1 - t _k )}×(tt _k )+α ₁ } and {(α ₂ -α ₁ )/(t _k+1 - t _k )}×(tt _k )+ α _{1 }} output each.

▶ t _k+1 ≤ t < t _k+2 - When the counter value exceeds dt

When the value of the counter 132 is greater than dt, the comparator 133 outputs a signal. At this time, the counter 132 is reset to 0 again.

Then, the state machine 131 recognizes the signal of the comparator 133 as a clock, the state is changed, and Mux=1 is output. At this time, the first multiplexer 134_1 and the second multiplexer 134_2 output _{α 2} and α _{3 , respectively.}

However, since tk+2 - tk+1 = tk+1 - tk = dt, in this case, the operation for the next section of Equation 2 is performed.

Meanwhile, in FIG. 13 , a case in which there are three gain sections will be described as an example. If the number of gain sections is larger, the structure of the gain controller 130 may be changed. For example, the gain controller 130 may include a larger number of multiplexers, and the number of inputs or outputs of the multiplexers may vary.

As described above, the embodiment of the present invention can be implemented using a shift register having a simple structure instead of a divider having high complexity as the length of the section of the variable gain value is selected as one of the powers of two. Accordingly, it can be configured with a relatively simple structure, and implementation cost and complexity can be reduced.

In addition, the embodiment of the present invention can give the frequency of occurrence of the object position distortion according to the change of the variable gain curve.

In addition, the embodiment of the present invention can improve the conventional problems of being affected by interference by an object having a large reflection signal, such as a distant wall, or by exhaust gas, and can improve robustness to the environment.

As mentioned above, although the configuration of the present invention has been described in detail with reference to the accompanying drawings, this is merely an example, and those skilled in the art to which the present invention pertains can make various modifications and changes within the scope of the technical spirit of the present invention. Of course, this is possible. Therefore, the protection scope of the present invention should not be limited to the above-described embodiments and should be defined by the description of the following claims.

Claims (10)

an amplifier for amplifying the reflected wave signal of the ultrasonic wave returned after being transmitted with a variable gain;
The gain of the amplifier is controlled with a first variable gain in the first area A1 in which the reflected waveform of the object to be sensed is checked, and the second variable gain is controlled in the second area A2 in which the reflected waveform of the surrounding object is checked. a gain controller for controlling the gain of the amplifier;
a comparator for comparing a signal on an envelope corresponding to the signal amplified by the amplifier with a preset threshold, and outputting a signal greater than the threshold from among the signals on the envelope;
a calculator for calculating an absolute value of the first differential value of the signal on the envelope and a time point at which a maximum value of the absolute value of the first differential value is calculated; and
A detector for detecting an object using a third time point at which the maximum value is calculated before a second time point at which a signal greater than the threshold value is output,
The gain controller is
and a value on a gain curve formed by linearly interpolating a slope value of a preset gain for each section is used as the variable gain. According to claim 1,
The gain controller is
In other regions, the object detection device is to control the gain of the amplifier with a first value (G1), which is a static gain. According to claim 1,
The calculator is
a first summing unit for sequentially receiving signals on the envelope and outputting a current difference signal that is a result of difference between a current input signal and a previous input signal;
a first storage for storing the previous input signal;
a second storage for storing a previous difference signal that is a difference result between the previous input signal and a previous signal of the previous input signal;
a first comparator configured to output the current difference signal when the current difference signal is greater than the previous difference signal;
a third storage configured to store a larger value among the previous difference signal and the current difference signal; and
A fourth storage for storing the third time point, which is the time point at which the large value is stored;
and outputting the third time point when the comparator outputs a signal greater than the threshold value. 4. The method of claim 3,
When the current difference signal to which a preset offset is added is greater than the previous difference signal, a second comparator initializes the third time point stored in the third storage.
The object detection device further comprising a. delete The method of claim 1 , wherein the gain controller comprises:
and setting the length of the preset section to a power of two. An object detection method by an object detection device, comprising:
The gain of the amplifier is controlled with the first variable gain in the first area A1 where the reflected waveform of the target to be sensed is checked, and the second variable gain is used in the second area A2 where the reflected waveform for the surrounding object is checked. controlling the gain of the amplifier;
comparing a signal on an envelope corresponding to the amplified reflected wave signal with a preset threshold;
outputting a signal greater than the threshold value from among the signals on the envelope;
calculating a maximum value of an absolute value of a first derivative of a signal on the envelope; and
Detecting an object using a third time point at which the maximum value is calculated before a second time point at which a signal greater than the threshold value is output,
The amplifying step is
and using a value on a gain curve formed by linearly interpolating a slope value of a gain for each section as the variable gain.
How to detect objects. delete The method of claim 7, wherein the calculating comprises:
receiving the signals on the envelope sequentially and outputting a current difference signal that is a result of the difference between the current input signal and the previous input signal;
storing the previous input signal in a first storage;
storing a previous difference signal that is a result of a difference between the previous input signal and a previous signal of the previous input signal in a second storage;
outputting the current difference signal when the current difference signal is greater than the previous difference signal;
storing a larger value among the previous difference signal and the current difference signal in a third storage;
storing the third time point at which the large value is stored in a fourth storage; and
outputting the third time point when a signal greater than the threshold value is output
An object detection method comprising a. 10. The method of claim 9,
adding a preset offset to the current difference signal; and
If the current difference signal to which the offset is added is greater than the previous difference signal, initializing the third time point stored in the third storage;
Object detection method further comprising a.

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