A tomato picking and sorting method and system

Abstract

The present invention relates to a tomato picking and sorting method and system, and belongs to the field of agricultural picking technology. The tomato picking and sorting method includes controlling the pressure applied by the actuator to the tomatoes during picking until a preset pressure value is reached; performing an electrical impedance test on the tomatoes based on the preset pressure value; determining a pressure curve based on a bioimpedance equivalent circuit; using the pressure curve to compensate for the pressure during picking; performing an electrical impedance test on the tomatoes based on the compensated pressure to obtain the electrical impedance of the tomatoes; comparing the acquired electrical impedance of the tomatoes with a constructed database to obtain tomato quality information, and then sorting. The present invention obtains a more accurate pressure curve through an electrical impedance test during picking, and uses the pressure curve to compensate for the pressure during picking to achieve more accurate non-destructive picking; at the same time, a tomato electrical impedance test is performed through the compensated pressure to obtain a more accurate electrical impedance of the tomatoes to judge the quality of the tomatoes, thereby realizing the composite operation of picking and sorting, and saving secondary sorting time.

Description

Technical Field

[0001] The invention relates to a tomato picking and sorting method and system, belonging to the technical field of agricultural picking. Background Art

[0002] Although my country has a large tomato planting area and a large output, it still has problems such as low tomato quality sorting ability, high cost and low efficiency. In agriculture, tomato picking and sorting in my country are separate. The process of tomato picking and sorting relies on a lot of manpower, which is time-consuming, labor-intensive and inefficient. The manual picking and sorting method has become increasingly unable to meet market demand due to the increasing labor cost.

[0003] Therefore, the market began to use visual recognition methods to sort tomato quality. Traditional visual sorting equipment relies on identifying phenotypic physical characteristics such as tomato size and color to sort quality. Although visual recognition saves time compared to manual secondary sorting, it can only judge the internal quality of the tomato by its appearance and cannot detect the internal substance content of the tomato, so it has certain limitations.

[0004] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgement or any form of suggestion that the information constitutes the prior art already known to ordinary technicians in this field. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a tomato picking and sorting method and system to solve the technical problems in the related art that tomato picking and sorting are performed separately, manual sorting efficiency is low, and visual recognition cannot detect the internal substance content of tomatoes.

[0006] In order to solve the above technical problems, the present invention is implemented by adopting the following technical solutions:

[0007] In one aspect, the present invention provides a method for picking and sorting tomatoes, characterized in that it comprises:

[0008] When picking tomatoes, the actuator is controlled to apply pressure to the tomatoes until the preset pressure value is reached;

[0009] Tomato electrical impedance test based on preset pressure value;

[0010] According to the bioimpedance equivalent circuit, the pressure curve is determined;

[0011] Use the pressure curve to compensate for the pressure during picking;

[0012] Perform a tomato electrical impedance test based on the compensated pressure to obtain the tomato electrical impedance;

[0013] The acquired electrical impedance of tomatoes is compared with the constructed database to obtain the tomato quality information and then sort them.

[0014] Furthermore, controlling the pressure applied by the actuator to the tomato until a preset pressure value is reached includes:

[0015] Output constant voltage signal;

[0016] When picking, the feedback voltage signal is used to determine whether the preset pressure value has been reached. If not, the constant pressure signal continues to be output; if reached, the constant pressure signal is stopped and the tomato electrical impedance test is performed.

[0017] Further, the tomato electrical impedance test based on the preset pressure value includes:

[0018] Generate multi-frequency sinusoidal voltage signals;

[0019] A multi-frequency sinusoidal current signal is generated by exciting a constant current source with a multi-frequency sinusoidal voltage signal;

[0020] Inject multi-frequency sinusoidal current signals into tomatoes;

[0021] Collect the voltage signal on the tomato when the multi-frequency sinusoidal current signal is injected into the tomato.

[0022] Further, determining the pressure curve according to the bioimpedance equivalent circuit includes:

[0023] According to the bioelectrical impedance equivalent circuit, the resistance value of the tomato equivalent external fluid in the tomato electrical impedance test is obtained;

[0024] The resistance value of the tomato equivalent external liquid is taken as the vertical intercept of the pressure curve to obtain the pressure curve;

[0025] Use the pressure curve to compensate for the pressure during picking.

[0026] Further, the tomato electrical impedance test is performed based on the compensated pressure to obtain the tomato electrical impedance including:

[0027] Generate multi-frequency sinusoidal voltage signals;

[0028] A multi-frequency sinusoidal current signal is generated by exciting a constant current source with a multi-frequency sinusoidal voltage signal;

[0029] Inject multi-frequency sinusoidal current signals into tomatoes;

[0030] Collect the voltage signal on the tomato and calculate the voltage amplitude and phase;

[0031] Comparing the magnitude and phase of the voltage with the current injected into the tomato gives the electrical impedance of the tomato.

[0032] Furthermore, the constructed database is a database of the influence of maturity on bioelectrical impedance.

[0033] On the other hand, the present invention provides a tomato picking and sorting system, which adopts the above-mentioned tomato picking and sorting method, and is characterized by comprising:

[0034] Actuators, used to pick tomatoes;

[0035] A pressure analysis module for controlling the pressure applied by the actuator to the tomatoes, as well as determining the pressure curve and using the pressure curve to compensate for the pressure during picking;

[0036] A bioelectrical impedance analysis module for generating a multi-frequency sinusoidal voltage signal;

[0037] The impedance front-end detection module is used to convert the multi-frequency sinusoidal voltage signal into a multi-frequency sinusoidal current signal and calculate the resistance of the tomato equivalent external liquid and the tomato electrical impedance;

[0038] Electrode sheet, used to inject multi-frequency sinusoidal current signal into tomatoes;

[0039] A sensor for collecting a voltage signal on the tomato when a multi-frequency sinusoidal current signal is injected into the tomato;

[0040] Wherein, the actuator, pressure analysis module, bioelectrical impedance analysis module, impedance front-end detection module, electrode sheet and sensor are all electrically connected.

[0041] Furthermore, the sensor is a sensor with the insulating film of the sensing area removed, comprising two conductive materials, and the two conductive materials are connected in series with the tomato.

[0042] Furthermore, the actuator is a mechanical gripper.

[0043] Furthermore, the robotic gripper has four fingers, and the four fingers are respectively equipped with two electrode sheets and two conductive materials.

[0044] Compared with the prior art, the beneficial effects achieved by the present invention include:

[0045] The present invention obtains a more accurate pressure curve through electrical impedance testing during picking, and uses the pressure curve to compensate for the pressure during picking, so as to achieve more accurate non-destructive picking; at the same time, electrical impedance testing of tomatoes is performed through the compensated pressure to obtain a more accurate electrical impedance of tomatoes to judge the quality of tomatoes, thereby realizing the composite operation of picking and sorting, and saving the time of secondary sorting. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 is a process framework diagram of a tomato picking and sorting method provided by an embodiment of the present invention;

[0047] Figure 2 is a structural framework diagram of a tomato picking and sorting system provided by an embodiment of the present invention;

[0048] Figure 3 It is a bioelectrical impedance equivalent model provided by an embodiment of the present invention;

[0049] Figure 4 is a pressure curve diagram provided by an embodiment of the present invention;

[0050] Figure 5 is a schematic diagram of the structure of a sensor provided by an embodiment of the present invention;

[0051] Figure 6 It is a schematic diagram of the structure of the sensor and the tomato connected in series according to an embodiment of the present invention. DETAILED DESCRIPTION

[0052] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0053] Embodiment 1:

[0054] like Figure 1 As shown, this embodiment provides a tomato picking and sorting method, comprising:

[0055] When picking tomatoes, the actuator is controlled to apply pressure to the tomatoes until the preset pressure value is reached;

[0056] Tomato electrical impedance test based on preset pressure value;

[0057] According to the bioimpedance equivalent circuit, the pressure curve is determined;

[0058] Use the pressure curve to compensate for the pressure during picking;

[0059] Perform a tomato electrical impedance test based on the compensated pressure to obtain the tomato electrical impedance;

[0060] The acquired electrical impedance of tomatoes is compared with the constructed database to obtain the tomato quality information and then sort them.

[0061] In this embodiment, controlling the pressure applied by the actuator to the tomato until the preset pressure value is reached includes:

[0062] Output constant voltage signal;

[0063] When picking, the feedback voltage signal is used to determine whether the preset pressure value has been reached. If not, the constant pressure signal continues to be output; if reached, the constant pressure signal is stopped and the tomato electrical impedance test is performed.

[0064] In this embodiment, the tomato electrical impedance test based on the preset pressure value includes:

[0065] Generate multi-frequency sinusoidal voltage signals;

[0066] A multi-frequency sinusoidal current signal is generated by exciting a constant current source with a multi-frequency sinusoidal voltage signal;

[0067] Inject multi-frequency sinusoidal current signals into tomatoes;

[0068] Collect the voltage signal on the tomato when the multi-frequency sinusoidal current signal is injected into the tomato.

[0069] Specifically, determining the pressure curve according to the bioimpedance equivalent circuit includes:

[0070] According to the bioelectrical impedance equivalent circuit, the resistance value of the tomato equivalent external fluid in the tomato electrical impedance test is obtained;

[0071] The resistance value of the tomato equivalent external liquid is taken as the vertical intercept of the pressure curve to obtain the pressure curve;

[0072] Use the pressure curve to compensate for the pressure during picking.

[0073] In this embodiment, the tomato electrical impedance test is performed based on the compensated pressure to obtain the tomato electrical impedance including:

[0074] Generate multi-frequency sinusoidal voltage signals;

[0075] A multi-frequency sinusoidal current signal is generated by exciting a constant current source with a multi-frequency sinusoidal voltage signal;

[0076] Inject multi-frequency sinusoidal current signals into tomatoes;

[0077] Collect the voltage signal on the tomato and calculate the voltage amplitude and phase;

[0078] Comparing the magnitude and phase of the voltage with the current injected into the tomato gives the electrical impedance of the tomato.

[0079] In this embodiment, the constructed database is a database of the influence of maturity on bioelectrical impedance.

[0080] Specifically, electrical impedance testing can analyze internal factors such as the maturity or moisture content of tomatoes. It can also determine whether there are diseases and pests inside the tomatoes through experimental data, further strengthening the level of tomato sorting. Sorting can be carried out while picking, greatly improving work efficiency.

[0081] Embodiment 2:

[0082] like Figure 2 As shown, this embodiment provides a tomato picking and sorting system, including:

[0083] Actuators, used to pick tomatoes;

[0084] The pressure analysis module is used to control the pressure applied by the actuator to the tomato;

[0085] A bioelectrical impedance analysis module for generating a multi-frequency sinusoidal voltage signal;

[0086] An impedance front-end detection module, used for converting a multi-frequency sinusoidal voltage signal into a multi-frequency sinusoidal current signal;

[0087] Electrode sheet, used to inject multi-frequency sinusoidal current signal into tomatoes;

[0088] The sensor is used to collect the voltage signal on the tomato when the multi-frequency sinusoidal current signal is injected into the tomato.

[0089] Wherein, the actuator, pressure analysis module, bioelectrical impedance analysis module, impedance front-end detection module, electrode sheet and sensor are all electrically connected.

[0090] In this embodiment, the actuator is a mechanical gripper having four fingers, each of which is provided with two electrode sheets and two conductive materials.

[0091] Specifically, when picking tomatoes, the pressure analysis module outputs a constant pressure signal to the sensor bound to the robotic claw. When the sensor contacts the tomato to form a pathway, pressure measurement begins. The sensor will correspond to different resistances under different pressures. As the grasping force on the tomato increases, the resistance of the sensor becomes smaller and smaller, and the voltage on it will also change accordingly. The pressure analysis module analyzes the voltage signal flowing into the sensor to obtain the pressure of the robotic claw on the tomato. The pressure analysis module determines whether to stop outputting the constant pressure signal based on the feedback voltage. When the pressure of the robotic claw on the tomato reaches the preset value, the pressure analysis module stops outputting the constant pressure signal.

[0092] The bioelectrical impedance analysis module starts to generate a multi-frequency sinusoidal voltage signal, and after AD conversion, outputs the multi-frequency sinusoidal voltage signal to the impedance front-end detection module, which converts the multi-frequency sinusoidal voltage signal into a multi-frequency sinusoidal current signal. The impedance front-end detection module outputs the multi-frequency sinusoidal current signal to the electrode sheet, and the electrode sheet injects the multi-frequency sinusoidal current signal into the tomato. At the same time, the sensor collects the voltage signal on the tomato and sends the collected voltage signal to the impedance front-end detection module for processing.

[0093] Referring to the bioimpedance equivalent circuit in the prior art, since direct current is injected into the tomato during pressure analysis, C1 is equivalent to an open circuit, and the tomato can be equivalent to a resistor R3. After considering the resistance of the sensor itself, the simplified bioimpedance equivalent circuit is as follows: Figure 3 shown.

[0094] In this embodiment, the sensor is a sensor without an insulating film in the sensing area, and includes two conductive materials, and the two conductive materials are connected in series with the tomato.

[0095] For details, see Figure 5 In order to conduct the circuit and collect voltage, the insulating film in the sensor sensing area is removed. Since the original function of the sensor is to conduct the circuit, the sensor is equivalent to two pieces of conductive material connected in series with a thicker wire with a resistance of 0. In this case, the magnitude of conductivity and pressure is a ray extending through the origin. Because conductivity is the reciprocal of resistance, the reciprocal of resistance and pressure is also a ray extending through the origin.

[0096] Then, see Figure 6 If the ideal wire is replaced by a tomato, the resistance and the inverse of the pressure are still a ray, but this time it does not go through the origin. Instead, when the inverse of the pressure is 0 (the pressure is infinite, the resistance of the force-sensitive material on the FSR is theoretically 0), the resistance is equal to the resistance shown by the tomato. At this time, the entire ray is equivalent to the normal ray moved up by one unit of the tomato resistance, which is R3. The ray of the FSR under normal circumstances without removing the film can be accurately drawn by a precision push-pull force gauge.

[0097] like Figure 3 As shown, T represents the bioelectrical impedance equivalent model of tomato, R1 represents the resistance of the first conductive material under the current force, R2 represents the resistance of the second conductive material under the current force, R3 represents the equivalent external fluid resistance of tomato, R4 represents the internal fluid resistance of tomato, C1 represents the membrane capacitance of tomato, UF1 represents the voltage transmitted from the first conductive material to the impedance front-end detection module, and UF2 represents the voltage transmitted from the second conductive material to the impedance front-end detection module.

[0098] After the multi-frequency sinusoidal current signal and the collected voltage signal are processed, their amplitudes satisfy the following relationship:

[0099]

[0100] Where |Z| represents the modulus of the tomato impedance, I m Indicates the magnitude of the injected current.

[0101] When AC is applied, the equivalent circuit of the tomato can be analyzed to obtain:

[0102]

[0103]

[0104] In the formula, f represents the frequency of the injected current, C represents the membrane capacitance of the tomato, and X c1It represents the capacitive reactance of the tomato when a current with a frequency of f is injected.

[0105] From formula (2), it can be seen that the equation contains three unknowns, but it is impossible to solve only two real equations, the real part and the imaginary part. Therefore, formula (2) at multiple frequencies is required to solve R3, R4 and C1 more accurately.

[0106] At this time, the impedance relative error Z is defined as E , select Z by comparison E The impedance and phase corresponding to the smaller frequency f:

[0107]

[0108] In the formula, Z T represents the theoretical real impedance amplitude of the tomato measured using the electrode patch, Z S Represents the actual impedance magnitude of the tomato measured using FSR.

[0109] See also Figure 4 In the actual pressure measurement of picking tomatoes, the force-conductance relationship in the preliminary experiment cannot be used to directly calculate the force at this time, because this does not take into account the resistance of the tomato itself, which will cause a large error when the force is large and the sensor resistance is small. Therefore, the R3 value calculated in the impedance measurement is used as the vertical intercept of the pressure control curve for compensation. The slope remains unchanged and is the same as the slope of the preliminary experiment. A new pressure curve is obtained, and the new curve is used to control the pressure during picking.

[0110] After obtaining the corrected pressure control curve, the pressure is controlled by changing the voltage signal output by the pressure analysis module. When the pressure of the robot claw on the tomato reaches this value, the impedance test is performed again. The bioimpedance analysis module generates a multi-frequency sinusoidal voltage signal, which is output to the impedance front-end detection module after AD conversion. The impedance front-end detection module converts the multi-frequency sinusoidal voltage signal into a multi-frequency sinusoidal current signal. The impedance front-end detection module outputs the multi-frequency sinusoidal current signal to two electrode sheets. The two electrode sheets inject the multi-frequency sinusoidal current signal into the tomato. At the same time, the sensor collects the voltage signal on the tomato and sends the collected voltage signal to the impedance front-end detection module for processing. The impedance front-end detection module calculates the amplitude and phase of the voltage, and compares the amplitude and phase of the voltage with the multi-frequency sinusoidal current signal to obtain the electrical impedance of the tomato. According to the constructed database of the influence of maturity on electrical impedance, the tomato quality information is obtained for sorting.

[0111] The bioelectric parameters of tomatoes can not only determine the quality of tomatoes, but also compensate for the pressure measurement stage to achieve more accurate and lossless picking.

[0112] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0113] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that specifies the functions of a block or multiple blocks.

[0114] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0115] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the function specified in one or more boxes.

[0116] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for picking and sorting tomatoes, characterized in that: include: When picking tomatoes, the actuator is controlled to apply pressure to the tomatoes until the preset pressure value is reached; Tomato electrical impedance test based on preset pressure value; According to the bioimpedance equivalent circuit, the pressure curve is determined; Use the pressure curve to compensate for the pressure during picking; Perform a tomato electrical impedance test based on the compensated pressure to obtain the tomato electrical impedance; The acquired electrical impedance of tomatoes is compared with the constructed database to obtain the tomato quality information and then sort them; The tomato electrical impedance test based on the preset pressure value includes: Generate multi-frequency sinusoidal voltage signals; A multi-frequency sinusoidal current signal is generated by exciting a constant current source with a multi-frequency sinusoidal voltage signal; Inject multi-frequency sinusoidal current signals into tomatoes; Collect the voltage signal on the tomato when the multi-frequency sinusoidal current signal is injected into the tomato; The tomato electrical impedance test is performed based on the compensated pressure, and the tomato electrical impedance includes: Generate multi-frequency sinusoidal voltage signals; A multi-frequency sinusoidal current signal is generated by exciting a constant current source with a multi-frequency sinusoidal voltage signal; Inject multi-frequency sinusoidal current signals into tomatoes; Collect the voltage signal on the tomato and calculate the voltage amplitude and phase; Comparing the magnitude and phase of the voltage with the current injected into the tomato gives the electrical impedance of the tomato; Determining the pressure curve according to the bioimpedance equivalent circuit includes: According to the bioelectrical impedance equivalent circuit, the resistance value of the tomato equivalent external fluid in the tomato electrical impedance test is obtained; The resistance value of the tomato equivalent external liquid is taken as the vertical intercept of the pressure curve to obtain the pressure curve; Use the pressure curve to compensate for the pressure during picking.

2. The tomato picking and sorting method according to claim 1, characterized in that: The controlling the pressure applied by the actuator to the tomato until a preset pressure value is reached comprises: Output constant voltage signal; When picking, the feedback voltage signal is used to determine whether the preset pressure value has been reached. If not, the constant pressure signal continues to be output; if reached, the constant pressure signal is stopped and the tomato electrical impedance test is performed.

3. The tomato picking and sorting method according to claim 1, characterized in that: The constructed database is a database of the influence of maturity on bioelectrical impedance.

4. A tomato picking and sorting system, using the tomato picking and sorting method according to any one of claims 1 to 3, characterized in that: include: Actuators, used to pick tomatoes; A pressure analysis module for controlling the pressure applied by the actuator to the tomatoes, as well as determining the pressure curve and using the pressure curve to compensate for the pressure during picking; A bioelectrical impedance analysis module for generating a multi-frequency sinusoidal voltage signal; The impedance front-end detection module is used to convert the multi-frequency sinusoidal voltage signal into a multi-frequency sinusoidal current signal and calculate the resistance of the tomato equivalent external liquid and the tomato electrical impedance; Electrode sheet, used to inject multi-frequency sinusoidal current signal into tomatoes; A sensor for collecting a voltage signal on the tomato when a multi-frequency sinusoidal current signal is injected into the tomato; Wherein, the actuator, pressure analysis module, bioelectrical impedance analysis module, impedance front-end detection module, electrode sheet and sensor are all electrically connected.

5. The tomato picking and sorting system according to claim 4, characterized in that: The sensor is a sensor with the insulating film of the sensing area removed, and comprises two conductive materials, and the two conductive materials are connected in series with a tomato.

6. The tomato picking and sorting system according to claim 4, characterized in that: The actuator adopts a mechanical gripper.

7. The tomato picking and sorting system according to claim 6, characterized in that: The robot gripper has four fingers, and the four fingers are respectively equipped with two electrode sheets and two conductive materials.

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