METHOD OF DETECTING OBJECTS AND CORRESPONDING APPARATUS

Abstract

A method of detecting objects includes transmitting toward an object a first acoustic signal including a first set of pulses including a first number of pulses, and checking if a first echo signal resulting from reflection of the first acoustic signal is received with an intensity reaching an echo detection threshold. If the intensity of the first echo signal reaches the echo detection threshold, the distance to the object is calculated as a function of the time delay of the first echo signal. If the intensity of the first echo signal fails to reach the echo detection threshold, one or more further acoustic signals are transmitted including a set of pulses wherein the number of pulses is increased with respect to the number of pulses in said first acoustic signal.

Claims

1. A method, comprising: transmitting toward an object a first acoustic signal including a first set of pulses including a first number of pulses, checking if a first echo signal resulting from reflection of said first acoustic signal by the object has an intensity reaching an echo detection threshold, if the intensity of said first echo signal reaches said echo detection threshold, calculating a distance to the object as a function of a time delay between transmitting the first acoustic signal and receiving said first echo signal, and if the intensity of said first echo signal fails to reach said echo detection threshold, transmitting a second acoustic signal including a set of pulses having a number of pulses that is increased with respect to the number of pulses in said first acoustic signal.

2. The method of claim 1, including: checking if a second echo signal resulting from reflection of said second acoustic signal has an intensity reaching the echo detection threshold, if the intensity of said second echo signal reaches said echo detection threshold, calculating the distance to the object as a function of a time delay between transmitting the second acoustic signal and receiving said second echo signal, and if the intensity of said second echo signal fails to reach said echo detection threshold, transmitting a third acoustic signal including a set of pulses having a number of pulses that is increased over the number of pulses in said second acoustic signal.

3. The method of claim 2, wherein the number of pulses in said second and third acoustic signals is increased unitary steps over the number of pulses in said first acoustic signal.

4. The method of claim 1, including: continuing to transmit further acoustic signals with respective numbers of pulses that are increased with respect to the first and second acoustic signals; and discontinuing transmitting said further acoustic signals as a result of checking that the number of pulses in one of said further acoustic signals has reached an upper threshold value.

5. The method of claim 1, wherein said acoustic signals include ultrasound signals.

6. The method of claim 1, including gradually decreasing said echo detection threshold as a function of time delays of said first echo signal and subsequent echo signals.

7. An object detector, comprising: a transceiver that, in operation, transmits acoustic signals including sets of pulses towards an object and receives corresponding echo signals resulting from reflection of the respective acoustic signals by the object, wherein a time delay between transmitting each acoustic signal and receiving the corresponding echo signal is indicative of a distance to the object, and a controller that, in operation: causes the transceiver to transmit toward the object a first acoustic signal including a first set of pulses including a first number of pulses, checks if a first echo signal resulting from reflection of said first acoustic signal by the object has an intensity reaching an echo detection threshold, calculates a distance to the object as a function of a time delay between transmitting the first acoustic signal and receiving said first echo signal, if the intensity of said first echo signal reaches said echo detection threshold, and causes the transceiver to transmit a second acoustic signal including a set of pulses having a number of pulses that is increased with respect to the number of pulses in said first acoustic signal, if the intensity of said first echo signal fails to reach said echo detection threshold.

8. The object detector of claim 7, wherein the controller, in operation: checks whether a second echo signal resulting from reflection of said second acoustic signal has an intensity reaching the echo detection threshold, if the intensity of said second echo signal reaches said echo detection threshold, calculates the distance to the object as a function of a time delay of said second echo signal, and if the intensity of said second echo signal fails to reach said echo detection threshold, causes the transceiver to transmit a third acoustic signal including a set of pulses having a number of pulses that is increased over the number of pulses in said second acoustic signal.

9. The object detector of claim 7, wherein the transceiver includes a transmitter and a receiver, separate from the transmitter.

10. The object detector of claim 9, wherein the receiver, in operation, receives an acoustic echo signal, produced by the object reflecting the first acoustic signal, and converts the acoustic echo signal into the first echo signal.

11. The object detector of claim 7, wherein the controller, in operation: causes the transceiver to continue to transmit further acoustic signals with respective numbers of pulses that are increased with respect to the first and second acoustic signal; and causes the transceiver to discontinue transmitting said further acoustic signals as a result of checking that the number of pulses in one of said further acoustic signals has reached an upper threshold value.

12. The object detector of claim 7, wherein the controller, in operation, gradually decreases said echo detection threshold as a function of time delays of said first echo signal and subsequent echo signals.

13. A method, comprising: transmitting toward an object a first acoustic signal including a first set of pulses including a first number of pulses; transmitting toward the object a second acoustic signal including a second set of pulses including a second number of pulses that is increased with respect to the first number of pulses; calculating a time of flight between transmitting the second acoustic signal and receiving an echo signal resulting from reflection of the second acoustic signal by the object; and calculating a distance to the object based on the calculated time of flight.

14. The method of claim 13, wherein transmitting the second acoustic signal includes transmitting the second acoustic signal in response to determining that another echo signal, resulting from reflection of the first acoustic signal by the object, has an intensity that fails to reach an echo detection threshold.

15. The method of claim 14, including gradually decreasing said echo detection threshold as a function of time delays of said echo signal and subsequent echo signals.

16. The method of claim 13, including: transmitting a third acoustic signal including a set of pulses having a number of pulses that is greater than the number of pulses in the first acoustic signal and less than the second acoustic signal, wherein: transmitting the third acoustic signal includes transmitting the third acoustic signal in response to determining that a first further echo signal, resulting from reflection of the first acoustic signal by the object, has an intensity that fails to reach an echo detection threshold, and transmitting the second acoustic signal includes transmitting the second acoustic signal in response to determining that a second further echo signal, resulting from reflection of the third acoustic signal by the object, has an intensity that fails to reach the echo detection threshold.

17. The method of claim 16, wherein the number of pulses in said third and second acoustic signals is increased unitary steps over the number of pulses in said first acoustic signal.

18. The method of claim 13, including: continuing to transmit further acoustic signals with respective numbers of pulses that are increased with respect to the first and second acoustic signals; and discontinuing transmitting said further acoustic signals as a result of checking that the number of pulses in one of said further acoustic signals has reached an upper threshold value.

19. The method of claim 13, wherein said acoustic signals include ultrasound signals.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0029] One or more embodiments will now be described, by way of example only, with reference to the annexed figures, wherein:

[0030] FIG. 1 is a block diagram exemplary of a possible context of use of one or more embodiments;

[0031] FIG. 2 is a block diagram exemplary of one or more embodiments;

[0032] FIG. 3 is a flow chart exemplary of possible operation of one or more embodiments; and

[0033] FIG. 4, including three portions, designated a), b) and c), respectively, is exemplary of a possible time behavior of signals in one or more embodiments.

DETAILED DESCRIPTION

[0034] In the ensuing description, one or more specific details are illustrated, aimed at providing an in-depth understanding of examples of embodiments of this description. The embodiments may be obtained without one or more of the specific details, or with other methods, components, materials, etc. In other cases, known structures, materials, or operations are not illustrated or described in detail so that certain aspects of embodiments will not be obscured.

[0035] Reference to an embodiment or one embodiment in the framework of the present description is intended to indicate that a particular configuration, structure, or characteristic described in relation to the embodiment is comprised in at least one embodiment. Hence, phrases such as in an embodiment or in one embodiment that may be present in one or more points of the present description do not necessarily refer to one and the same embodiment. Moreover, particular conformations, structures, or characteristics may be combined in any adequate way in one or more embodiments.

[0036] The references used herein are provided merely for convenience and hence do not define the extent of protection or the scope of the embodiments.

[0037] In FIG. 1, reference number 10 describes an apparatus including a distance measuring system 100, a transmitter TX and a receiver RX.

[0038] Such apparatus may be used, e.g., for detecting the presence and measuring the distance D from apparatus 10 to a target object, e.g., an obstacle O.

[0039] In one or more embodiments the transmitter TX and the receiver RX may include transmission/reception transducer(s) e.g., of the piezoelectric type.

[0040] In one or more embodiments, the transmitter TX and the receiver RX may include distinct transmission and reception transducers.

[0041] In one or more embodiments, the transmitter TX and the receiver RX may share a common transmission/reception transducer.

[0042] In operation of an arrangement as exemplified in FIG. 1, the (electro-acoustical) transducer in the transmitter TX may be driven by a transmission signal TS (e.g., as produced by the system 100) to generate a transmitted acoustic (e.g., ultrasonic) wave TW.

[0043] The acoustic wave may impinge on the object O and be reflected as an echo wave EW travelling back to the receiver RX. The (acoustic-electrical) transducer of the receiver RX translates the acoustic wave EW into an electrical echo signal ES to be fed to the system 100.

[0044] As discussed previously, the total time of flight, TOF, that is the time taken by the acoustic wave to leave the transducer TX and be detected by the transducer RX may permit to calculate the distance D.

[0045] Save for what is discussed in detail in the following, the structure and operation of apparatus 10 as exemplified in FIG. 1 are known in the art, thus making it unnecessary to provide a more detailed description herein.

[0046] In one or more embodiments, operation of the system 100 may involve comparison of received signals against a certain threshold T (see, e.g., FIG. 4, to be discussed in the following). In one or more embodiments, processing to generate a measurement of the distance D may in fact be performed (only) if an echo signal ES of sufficient strength is received. This kind of operation may permit, e.g., to reject spurious signals of various types (e.g., noise) and/or to avoid processing being activated unnecessarily when no echo signal proper is received and/or when an echo signal received is too weak to permit accurate/reliable distance calculation.

[0047] In one or more embodiments, the system 100 may be configured to perform different tasks, including, e.g.:

[0048] selecting a (e.g., user selectable) number of pulses (e.g., cycles of a square wave) in a signal TS to be transmitted by the transmitter TX, by driving the (e.g., piezoelectric) transducer in the transmitter TX to generate a respective acoustic wave TW,

[0049] detecting (e.g., waiting a fixed time) echo signals ES as obtainable by the (e.g., piezoelectric) transducer in the receiver RX by converting a received echo wave EW.

[0050] In one or more embodiments, the system 100 may be configured to operate in such a way that:

[0051] i) if a valid echo signal ES (e.g., reaching the threshold T) is detected, the distance D from the object O is calculated, or

[0052] ii) if no valid echo signal ES is detected (e.g., no signal at all is detected or a detected signal fails to reach the threshold T) a new signal TS is transmitted wherein the number of pulses is increased (e.g., by a unitary step) with respect to the previous transmission.

[0053] In one or more embodiments, operation as discussed above may be repeated by step-wise increasing (e.g., by unitary steps) the number of pulses at each re-transmission until a valid echo signal is received.

[0054] In one or more embodiments, an upper limit for the number of re-transmissions may be set (e.g., at a user selectable value) and re-transmission with a gradually increased number of pulses discontinued as a result of that upper limit being reached.

[0055] In FIG. 2, an exemplary block diagram of a system 100 shown together with a transmitter TX and a receiver RX.

[0056] For instanceand merely by way of examplein one or more embodiments, the system 100 may be supplied by a battery 101 (e.g., a lithium polymer (LiPo) battery with a capacity of 250 mAh with two cells=8.4V), which supplies a DC-DC converter 102 and a (micro) controller 103 (e.g., as STM32F334 available with the companies of the STMicroelectronics group).

[0057] The DC-DC converter 102 may be enabled (e.g., via a signal EN) by the microcontroller 103 and may be used to magnify the battery voltage to drive the, e.g., piezo-electric transducer(s) of the transmitter TX and the receiver RX.

[0058] In one or more embodiments, the microcontroller 103 may be coupled (e.g., via a serial interface) to a transducer driver 104 (e.g., an ultrasonic piezo driver).

[0059] Such coupling may include:

[0060] the microcontroller 103 sending to the driver 104 a digital driving signal DDS to produce transmission of a transmission wave TW from the transmitter TX,

[0061] the microcontroller 103 receiving from the driver 104 an (e.g., conditioned) echo signal CES which may correspond to an echo wave EW received at the receiver RX.

[0062] In one or more embodiments, the signal DDS may include information on the number of cycles (pulses), the piezo driving frequency and a start command. In one or more embodiments, the start command may enable also a TOF timer and a timeout timer.

[0063] In one or more embodiments, the transducer driver 104 may receive a magnified voltage HV from the DC-DC converter 102 and use it to drive the transmitter transducer with a transmission signal TS.

[0064] In one or more embodiments, the transducer driver 104 may also be configured to receive an echo signal ES from the receiver transducer and create (e.g., with an embedded analogue front-end) a conditioned echo signal CES to be fed to the microcontroller 103.

[0065] In one or more embodiments the microcontroller 103 may have an embedded analogue comparator used to detect the conditioned echo signal CES.

[0066] In one or more embodiments, the microcontroller 103 may thus be configured to performas discussed previouslycomparison of the signal CES against a threshold T.

[0067] In one or more embodiments, such comparison may reveal that a valid echo signal is available for calculating the distance D to the object.

[0068] In one or more embodiments, such comparison may likewise reveal those situations wheree.g., within a certain timeout from transmissionno valid echo signal has reached the transducer driver 104, so that re-transmission with an increased number of pulses may take place as exemplified previously. In one or more embodiments, the timeout may be user programmable.

[0069] The flow chart of FIG. 3 is exemplary of possible operation of a system 100 as discussed previously.

[0070] After beginning (START) operation in a step 1000 a transmitter transducer may be driven with a plurality of N pulses at a selected frequency (e.g., natural resonant frequency of the piezo crystal. In one or more embodiments the number N of pulses may be first set to a (e.g., user selectable) starting value Min, e.g., N=Min.

[0071] In a step 1001 a TOF (time of flight) counter may be started (e.g., after resetting).

[0072] In a step 1002 an echo signal may be waited for (e.g., until a certain time out).

[0073] Step 1003 is exemplary of a validating step where a check is made as to whether a valid echo was received.

[0074] If the outcome of step 1003 is positive, the distance D may be calculated in a step 1004 and (possibly after resetting the number N of pulses to the starting value Min in a step 1005) operation may come to an END, e.g., in view of starting a new detection event.

[0075] If the outcome of step 1003 is negative, the number N of pulses in the transmission signal may be increased in order to produce a transmission signal with a higher energy.

[0076] This may involve a first step 1006 where a check is made as to whether the number of pulses (possibly increased with respect to the starting value Min) has reached an upper limit Max N (possibly user selectable).

[0077] If the outcome of step 1006 is negative (that is the upper limit is not reached yet), in a step 1007 the number of pulses in the transmission signal TS is increased (e.g., of an increase step, e.g., increased by one) and operation returns upstream of the step 1000, that is with a new transmission signal TS having an increased energy due to the increased number of pulses therein.

[0078] Operation as discussed herein may involve one or more negative outcomes of the step 1003, with transmission repeated correspondingly with energy levels of the signal TS increased step-wise (e.g., with the number N of pulses increased via unitary increases, e.g., N=Min+1, N=Min+2, N=Min+3 and so on) until step 1003 yields a positive outcome, that is a valid echo signal is received permitting the distance D to be calculated.

[0079] If, despite repeated transmissions with gradually increased number N of pulses, no valid echo signal is received and the upper limit of step 1006 (e.g., Max N) is reached (positive outcome of step 1006) the number N of pulses may be reset to the starting value (e.g., N=Min) in a step 1008 while in a step 1009 feedback may be provided, e.g., indicating to the user that the distance could not be calculated, while the system may be configured to start a new detection attempt.

[0080] The three diagrams of FIG. 4 are exemplary of possible time behaviors of:

[0081] a transmission signal TS corresponding to the transmission wave TW,

[0082] a received signal ES corresponding to a received echo wave EW,

[0083] a validation threshold T (which, in one or more embodiments may be made time dependent, e.g., decreasing over time in order to allow for the decrease of the strength of those echo signals that are received with a longer TOF, that is from a larger distance, this exhibiting a higher attenuation.

[0084] The three diagrams of FIG. 4 also show that, in one or more embodiments, the receiver RX may be disabled during transmission in order to avoid false positive echoes due, e.g., to transmitter signal leaking into the receiver.

[0085] The three cases of FIG. 4 are exemplary of a transmitted signal TS resulting in a valid echo signal ES, that is an echo signal ES strong enough to reach the threshold T is shown, with possible previous transmissions leading to failure (negative outcome of step 1003 in FIG. 3) and adjustment (e.g., increase) of the number of pulses (step 1007 in FIG. 3) not illustrated.

[0086] For instance (it is stressed that the diagrams of FIG. 4 are merely exemplary and shall not be construed in a limiting sense of the embodiments):

[0087] diagram a) in FIG. 4 is exemplary of a possible behavior with a wood target material at a distance D=15 cm, with a transmission signal TS including four pulses;

[0088] diagram b) in FIG. 4 is exemplary of a possible behavior with a wood target material at a distance D=25 cm, with a transmission signal TS including seven pulses, that is a higher number of pulses in comparison to diagram a) due to the longer distance to the target;

[0089] diagram c) in FIG. 4 is exemplary of a possible behavior with a target material including a wall surface at a distance D=70 cm, with a transmission signal TS including four pulses, that is a number of pulses equal to diagram a) and lower than diagram b) irrespective of the longer distance to the target due to the higher reflectivity of the wall target material in comparison with wood.

[0090] One or more embodiments may thus provide a method of detecting objects, the method including:

[0091] transmitting acoustic signals (e.g., TW) including sets of pulses towards an object (e.g., O) to induce echo signals (e.g., EW) resulting from reflection of the acoustic signals at the object, wherein the time delay of the echo signals is indicative of the distance (e.g., D) to the object, the method including: [0092] transmitting (e.g., 1000) a first acoustic signal including a first set of pulses including a first number of pulses, [0093] checking (e.g., 1003) if a first echo signal resulting from reflection of said first acoustic signal is received with an intensity reaching an echo detection threshold (e.g., T), and [0094] i) if the intensity of said first echo signal reaches said echo detection threshold, calculating (e.g., 1004) the distance to the object as a function of the time delay of said first echo signal, [0095] ii) if the intensity of said first echo signal fails to reach said echo detection threshold, transmitting at least one further acoustic signal including a set of pulses wherein the number of pulses is increased (e.g., N=Min+1, N=Min+2, N=Min+3, . . . ; 1007) with respect to the number of pulses in said first acoustic signal.

[0096] One or more embodiments may include:

[0097] checking (e.g., 1003) if at least one further echo signal resulting from reflection of said at least one further acoustic signal is received with an intensity reaching a respective echo detection threshold, and [0098] i) if the intensity of said at least one further echo signal reaches said echo detection threshold, calculating the distance to the object as a function of the time delay of said at least one further echo signal, [0099] ii) if the intensity of said at least one further echo signal fails to reach said respective echo detection threshold, transmitting at least one still further acoustic signal including a set of pulses wherein the number of pulses in the at least one still further acoustic signal is still further increased over the number of pulses in said at least one further acoustic signal.

[0100] In one or more embodiments the number of pulses in said at least one further acoustic signal may be increased (1007) stepwise (e.g., N=Min+1, N=Min+2, N=Min+3, . . . ); over the number of pulses in said first acoustic signal.

[0101] In one or more embodiments, the number of pulses in said at least one further acoustic signal may be increased by unitary steps over the number of pulses in said first acoustic signal.

[0102] One or more embodiments may include discontinuing transmitting said acoustic signals as a result of checking (e.g., 1006) that the number of pulses in said at least one further acoustic signal has reached an upper threshold value with the intensity of the corresponding echo signal failing to reach a respective echo detection threshold. In one or more embodiments, said acoustic signals may include ultrasound signals.

[0103] One or more embodiments may include gradually decreasing said echo detection threshold (see, e.g., FIG. 4) as a function of the time delay of said echo signals.

[0104] In one or more embodiments, an object detector may include:

[0105] a transmitter (e.g., 103, TX) for transmitting acoustic signals including sets of pulses towards an object to receive echo signals resulting from reflection of the acoustic signal at the object, wherein the time delay of the echo signal is indicative of the distance to the object,

[0106] a receiver (e.g., 103, RX) for receiving said echo signals, the receiver configured for operating accordingly to the method of one or more embodiments.

[0107] Without prejudice to the underlying principles, the details and embodiments may vary, even significantly, with respect to what has been described in the foregoing by way of example only, without departing from the extent of protection.

[0108] The various embodiments described above can be combined to provide further embodiments. These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.