Dot-matrix flexible agricultural robot grabbing device based on inverse piezoelectric effect

Abstract

According to the dot-matrix flexible agricultural robot grabbing device based on the inverse piezoelectric effect, different voltages are applied to the front faces or the back faces of inverse piezoelectric material blocks in different rows or columns in a grabbing unit array, so that different voltage differences are generated in the positive and negative directions of the inverse piezoelectric material blocks in different positions in the grabbing unit array; the inverse piezoelectric material blocks at different positions in the grabbing unit array can generate different deformations respectively by rotating the grabbing unit array, the inverse piezoelectric material blocks are matched with scanning equipment during use, the deformation requirements of the inverse piezoelectric material blocks can be obtained by scanning the shape of a grabbed object in advance, and then the inverse piezoelectric material blocks at the required positions are controlled to be accurately deformed, so that the deformation requirements of the grabbed object are met. In this way, the inverse piezoelectric material blocks in the multiple grabbing unit arrays can make accurate contact with a grabbed object according to the shape of the grabbed object, and grabbing is achieved.

Description

TECHNICAL FIELD

[0001] The application relates to the field of agricultural robot gripping devices, in particular to a dot matrix type flexible agricultural robot gripping device based on inverse piezoelectric effect. BACKGROUND

[0002] The agricultural robot is used for fine operations such as fruit picking and flower pollination in agricultural production, and usually uses rigid clamping jaws or vacuum suction cups for gripping, but cannot dynamically adapt to the natural form of biological tissues, resulting in concentrated contact stress such as indentation of the fruit by the edge of the clamping jaw, or insufficient adhesion such as gap between the suction cup and the concave surface, and the essence is the lack of local micro-deformation regulation and control capability. For soft fruits such as strawberries and blueberries, the traditional rigid clamping jaws are easy to press and damage the fruit skin, and the vacuum suction cup is not stable in adsorption on irregular curved surfaces. For hard fruits such as apples and oranges, the adhesion of the clamping surface to the curved surface of the fruit such as the apple cavity and the orange petal is poor, resulting in sliding during the gripping process, affecting the picking efficiency and fruit quality, and for flower pollination operations, the traditional brush type pollination machine cannot guarantee the precision of the contact between the brush and the flower, and is easy to damage the flower structure. SUMMARY

[0003] The purpose of the application is to provide a dot matrix type flexible agricultural robot gripping device based on inverse piezoelectric effect, which can effectively protect plant tissues and has high adhesion.

[0004] The technical scheme adopted by the application to solve the above technical problems is: a dot matrix type flexible agricultural robot gripping device based on inverse piezoelectric effect, comprising a base, one side of the base being connected with an end effector of an agricultural robot, the other side of the base being provided with a plurality of gripping unit arrays, each gripping unit array comprising a plurality of inverse piezoelectric material blocks distributed in multiple rows and multiple columns, and a rigid support block being connected between any two adjacent inverse piezoelectric material blocks in the same row or the same column, the plurality of gripping unit arrays cooperating to form a space for accommodating a gripped object, the side of the gripping unit array facing the gripped object being defined as the front side, and the side of the gripping unit array away from the gripped object being defined as the back side, the base being further provided with a plurality of driving circuit modules corresponding to the plurality of gripping unit arrays respectively, the driving circuit modules being connected with a plurality of driving lines, the driving lines being divided into row control lines and column control lines, the plurality of row control lines being respectively covered on one side of the front side or the back side of the multiple rows of inverse piezoelectric material blocks, and the plurality of column control lines being respectively covered on the remaining side of the front side or the back side of the multiple columns of inverse piezoelectric material blocks, the driving circuit modules being capable of controlling the voltage of the plurality of driving lines respectively, so that a voltage difference is generated between the front side and the back side of the inverse piezoelectric material blocks, so that the inverse piezoelectric material blocks are deformed and contact the gripped object for gripping.

[0005] Preferably, the inverse piezoelectric material block and the rigid support block are both rectangular structures, and the thickness between the front side and the back side of the inverse piezoelectric material block is greater than the thickness of the rigid support block.

[0006] Preferably, the driving line is in a straight state or a bent state. When in the bent state, the bent portion of the driving line covers the side surfaces in the thickness direction of two adjacent inverse piezoelectric material blocks and the surface of the rigid support block between the two adjacent inverse piezoelectric material blocks, and the bent portion is wrapped with an insulating layer.

[0007] Preferably, a strain force sensor or a thin film pressure sensor is provided on the front side of the inverse piezoelectric material block.

[0008] According to the above technical solution, the beneficial effects of the present invention are: The present invention applies different voltages to the front or back sides of the inverse piezoelectric material blocks in different rows or columns in the grasping unit array, so that different pressure differences are generated in the positive and negative directions of the inverse piezoelectric material blocks at different positions in the grasping unit array, which can cause the inverse piezoelectric material blocks at different positions in the grasping unit array to produce different deformations. When used, it cooperates with the scanning equipment and obtains the deformation requirements of the inverse piezoelectric material blocks by pre-scanning the shape of the grasped object. Then, by controlling the precise deformation of the inverse piezoelectric material blocks at the required positions, the inverse piezoelectric material blocks in multiple grasping unit arrays can be precisely contacted with the grasped object according to the shape of the grasped object to achieve grasping. The piezoelectric material is a core component with good flexibility, which can better protect plant tissues and reduce mechanical damage. The inverse piezoelectric effect drives the response time to the millisecond level, and the energy consumption is reduced by more than 90% compared with the pneumatic gripper. It can also operate stably in harsh environments such as high temperature, high humidity, and dust, effectively solving the difficulty of existing grasping devices in achieving refined and flexible operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a three-dimensional schematic diagram of the present invention; Figure 2 It is a front view schematic diagram of the present invention.

[0010] Markings in the figure: 1. Base, 2. Driving circuit module, 3. Inverse piezoelectric material block, 4. Rigid support block, 5. Driving line. DETAILED DESCRIPTION

[0011] With reference to the accompanying drawings, the specific implementation is as follows: like Figure 1 、 2 As shown, a lattice-type flexible agricultural robot grasping device based on the inverse piezoelectric effect includes a base 1, one side of the base 1 is connected to the end effector of the agricultural robot, and the other side of the base 1 is provided with three grasping unit arrays, each grasping unit array includes a plurality of inverse piezoelectric material blocks 3 spaced apart in multiple rows and columns, and a rigid support block 4 is connected between any two adjacent inverse piezoelectric material blocks 3 in the same row or column, and the three grasping unit arrays cooperate to form a space for accommodating the grasped object.

[0012] The inverse piezoelectric material block 3 and the rigid support block 4 are both rectangular structures, and the thickness between the front surface and the back surface of the inverse piezoelectric material block 3 is greater than the thickness of the rigid support block 4. The inverse piezoelectric material block 3 is made of PVDF material and is cut by laser. The edges are chamfered to avoid scratching the biological tissue. The rigid support block 4 is made of PLA material and is printed by 3D. The PVDF unit is adhered by conductive silver glue, and the resistance is less than or equal to 10Ω.

[0013] The side of the grabbing unit array facing the grabbed object is defined as the front surface, and the side of the grabbing unit array away from the grabbed object is defined as the back surface. The base 1 is also provided with a plurality of driving circuit modules 2 corresponding to the plurality of grabbing unit arrays respectively. The driving circuit module 2 is connected with a plurality of driving lines 5. The driving lines 5 are divided into row control lines and column control lines. The plurality of row control lines are respectively covered on one side of the front surface or the back surface of the plurality of rows of inverse piezoelectric material blocks 3. The plurality of column control lines are respectively covered on the remaining side of the front surface or the back surface of the plurality of columns of inverse piezoelectric material blocks 3. The driving circuit module 2 can control the voltage of the plurality of driving lines 5 respectively, so as to generate a voltage difference between the front surface and the back surface of the inverse piezoelectric material block 3, so as to make the inverse piezoelectric material block 3 deform and contact the grabbed object for grabbing.

[0014] The driving line 5 can be in a straight state or a bent state. The straight state is that the driving line 5 covers the surfaces of the plurality of inverse piezoelectric material blocks 3 at the same time, passes through the gap between the adjacent two inverse piezoelectric material blocks 3, and does not contact the rigid support block 4. When in the bent state, the bent part of the driving line 5 covers the side surface of the thickness direction of the adjacent two inverse piezoelectric material blocks 3 and the surface of the rigid support block 4 between the adjacent two inverse piezoelectric material blocks 3, and the bent part is wrapped with an insulating layer, so as to ensure that the voltage is only applied to the front and back surfaces of the inverse piezoelectric material block 3.

[0015] In work, first, the grabbing device is moved to the grabbed object between the three grabbing unit arrays by the agricultural robot end effector, then the grabbed object is scanned by the scanning device, the deformation requirement of the inverse piezoelectric material block is obtained according to the shape of the grabbed object, then the driving circuit module 2 activates and controls the voltage difference in time, and selects the target row: the driving circuit applies voltage (such as +V) to a certain row line, and the row end of all units in the row is activated; the target column is selected: the target column line is applied with reverse voltage (such as -V) at the same time, the unit at the intersection of the row and the column is triggered to produce mechanical deformation (such as bending or stretching) due to the voltage difference between the two ends, and the lines that are not selected remain grounded. The non-target unit does not perform the grabbing action because the voltage difference is insufficient and the deformation amount is below the threshold.

[0016] The drive circuit module 2 has a capacitive load compensation module to offset the parasitic capacitive coupling (crosstalk) between adjacent units, ensuring that the voltage difference of the activated unit is not affected by the adjacent units (crosstalk suppression ratio > 40dB). Field programmable gate array (FPGA) is used to generate nanosecond-level precision row / column selection pulses, ensuring that the row line voltage and column line voltage are switched within 50ns, avoiding multi-unit misactivation caused by delay. Some units integrate piezoelectric sensing elements (positive piezoelectric effect) to synchronously collect contact force signals during scanning, forming a "scanning - grabbing - feedback" closed loop to adjust the voltage output of subsequent rows / columns in real time (such as automatically reducing the voltage when overloaded).

[0017] In this embodiment, the front surface of the inverse piezoelectric material block 3 is provided with a strain force sensor or a thin film pressure sensor to monitor the force in real time when the flower is grabbed or touched, avoiding damage to the pistil or petals due to the mechanical arm moving too hard; feedback contact force data to assist in adjusting the contact pressure of the pollination tool (such as a brush), ensuring effective pollen transfer without damaging the flower structure. In addition, infrared proximity sensors, laser radars, etc. can also be set up to quickly detect the distance between the flower and the end of the mechanical arm, assisting in coarse positioning (reducing the computational load of the vision sensor); real-time correction of the mechanical arm motion trajectory in a dynamic environment (such as greenhouse ventilation causing the flower to sway), improving response speed.

[0018] This embodiment can also be used for anther vibration pollination, that is, first contact the anther through the grabbing device, and then drive the anther together through the entire grabbing device to vibrate, at which time a piezoelectric vibration sensor needs to be set up to detect the frequency and amplitude of the mechanical arm vibration pollination, such as through vibrating the flower to make the pollen fall off, ensuring that the vibration parameters match the characteristics of the tomato flower, avoiding excessive vibration leading to flower drop. When the grabbing operation is completed, the unit voltage is zeroed, returning to a flat state, and the mechanical arm is withdrawn to avoid touching other pistils.

[0019] Although embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A lattice-type flexible agricultural robot grasping device based on the inverse piezoelectric effect, characterized by: The invention comprises a base (1), one side of the base (1) is connected to the end effector of the agricultural robot, and the other side of the base (1) is provided with a plurality of grasping unit arrays, each grasping unit array comprises a plurality of inverse piezoelectric material blocks (3) spaced in multiple rows and columns, and a rigid support block (4) is connected between any two adjacent inverse piezoelectric material blocks (3) in the same row or column, and the plurality of grasping unit arrays cooperate to form a space for accommodating grasped objects, and the side of the grasping unit array facing the grasped object is defined as the front side, and the side of the grasping unit array facing away from the grasped object is defined as the back side, and the base (1) is further provided with a plurality of grasping unit arrays. The columns respectively correspond to a plurality of driving circuit modules (2), the driving circuit modules (2) are connected to a plurality of driving lines (5), the driving lines (5) are divided into row control lines and column control lines, the plurality of row control lines respectively cover one side of the front side or the back side of the plurality of rows of inverse piezoelectric material blocks (3), and the plurality of column control lines respectively cover the remaining side of the front side or the back side of the plurality of columns of inverse piezoelectric material blocks (3), and the driving circuit modules (2) can respectively control the voltages of the plurality of driving lines (5), thereby generating a voltage difference between the front side and the back side of the inverse piezoelectric material block (3), so that the inverse piezoelectric material block (3) is deformed and contacts with the grasped object for grasping.

2. The lattice-type flexible agricultural robot grasping device based on the inverse piezoelectric effect according to claim 1 is characterized in that: The inverse piezoelectric material block (3) and the rigid support block (4) are both rectangular structures, and the thickness between the front and back surfaces of the inverse piezoelectric material block (3) is greater than the thickness of the rigid support block (4).

3. The lattice-type flexible agricultural robot grasping device based on the inverse piezoelectric effect according to claim 2 is characterized in that: The driving line (5) is in a straight state or a bent state. When in the bent state, the bent portion of the driving line (5) covers the side surfaces in the thickness direction of two adjacent inverse piezoelectric material blocks (3) and the surface of the rigid support block (4) between the two adjacent inverse piezoelectric material blocks (3), and the bent portion is wrapped with an insulating layer.

4. The lattice-type flexible agricultural robot grasping device based on the inverse piezoelectric effect according to claim 1, characterized in that: A strain type force sensor or a thin film pressure sensor is provided on the front side of the inverse piezoelectric material block (3).

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