Double-motor-driven vibrator with controllable vibration direction and control method thereof

Abstract

The invention discloses a vibration-direction-controllable double-motor-driven vibrator and a control method thereof, and relates to the technical field of vibrator design and control. The base is arranged at the bottom of the support, shells of the two motors are coaxially fixed to the two sides of the support, the two eccentric mass blocks are provided with connecting arms and installed at the outer ends of rotors of the two motors respectively, the two eccentric mass blocks are equal in mass, and the two motors rotate at the same speed so that the two eccentric mass blocks can move reversely at the same speed in the space and intersect twice per circle. And the centrifugal force of the two eccentric mass blocks generates unidirectional vibration force along the direction of the two intersection points. The two eccentric mass blocks are controlled by the two motors to move cooperatively in the same speed in the opposite directions, unidirectional vibration force is generated, precise online adjustment of the vibration force and the vibration direction can be achieved, and the device has the advantages of being concentrated in vibration energy, high in efficiency, low in damage, small in size and wide in application range.

Description

Technical Field

[0001] The present invention relates to the technical field of vibrator design and control, and specifically relates to a dual-motor-driven vibrator with controllable vibration direction and its control method. Background Art

[0002] For various non-fresh dried fruits, nuts, and juicing fruits represented by red dates, walnuts, and juicing apples, vibrating harvesting machines are commonly used to complete the harvesting, which can greatly improve the harvesting efficiency and reduce the harvesting cost.

[0003] Among them, the vibrator is the core component of the vibrating harvesting machine. The vibration type, frequency, amplitude, acting position, and direction output by the vibrator are all key factors affecting the harvesting efficiency. Most of the vibrators of existing vibrating harvesting machines use a single eccentric mass driven by fuel power to rotate to generate vibration. The vibration state cannot be accurately controlled, the vibration direction is not focused and adjustable. Moreover, to ensure the harvesting effect, when providing sufficient vibration force in the direction with the weakest vibration, the force in other directions may have exceeded the normal range. At the same time, the single eccentric mass will generate a rotational force, including the shear force in the tangential direction of the bark, which will cause an increase in the bark damage rate and even affect future yields in severe cases.

[0004] In summary, the problems existing in the vibrators of existing vibrating harvesting machines can be summarized into the following four aspects:

[0005] 1. The vibration direction cannot be flexibly changed, especially during operation. An ideal vibrator should be able to flexibly change the vibration direction to more comprehensively transmit the vibration force to the branches and fruits in all directions, thereby improving the harvesting efficiency;

[0006] 2. It generates shear force to damage the bark. The shear force generated by the rotation of the single eccentric mass alone easily damages the bark. Existing equipment with multiple eccentric masses lacks the ability of synchronous movement and cannot change the vibration direction. The non-synchronous rotational vibration generated also has the problem of shear force damaging the bark;

[0007] 3. It is difficult to achieve independent and precise vibration frequency control, and precise frequency control is crucial for improving the harvesting efficiency by utilizing the resonance frequency characteristics of the tree itself and reducing damage to the tree;

[0008] 4. It has a large volume and weight. To meet the requirements of operating at different positions, especially at higher positions of fruit trees, the vibrator needs to reduce its volume and weight. However, most existing equipment is generally large in volume and heavy in weight in order to provide sufficient force to act on the branches. This not only limits the use of vibrating harvesting machines in hilly and mountainous areas where fruits and nuts are widely planted, but also makes it difficult to lift the vibrator to higher positions of the trees, making it difficult to further improve the performance. Summary of the Invention

[0009] To address the deficiencies in the background art, the present invention provides a dual-motor-driven vibrator with controllable vibration direction and its control method. It controls two eccentric masses to move in the same speed and opposite directions in coordination through dual motors, generating a unidirectional vibration force. Moreover, it can achieve precise on-line adjustment of the vibration force and vibration direction, featuring concentrated vibration energy, high efficiency, low damage, miniaturization, and a wide range of applications.

[0010] To achieve the above object, the present invention adopts the following technical solutions:

[0011] A dual-motor-driven vibrator with controllable vibration direction includes a bracket, a base, two motors, and two eccentric masses. The base is provided at the bottom of the bracket. The housings of the two motors are coaxially fixed on both sides of the bracket. The two eccentric masses are provided with connecting arms and are respectively installed at the outer ends of the rotors of the two motors. The two eccentric masses have equal mass. The two motors rotate at the same speed, causing the two eccentric masses to move in the same speed and opposite directions in space and intersect twice per revolution. A unidirectional vibration force is generated by the centrifugal forces of the two eccentric masses along the direction of the two intersection points.

[0012] Furthermore, the two eccentric masses are detachably installed with the two motors. By adjusting the mass of the eccentric mass, the distance from the center of mass to the rotation center, and the motor speed, the magnitude of the vibration force can be changed.

[0013] Furthermore, the intersection position of the two eccentric masses can be adjusted in real time through the control of the two motors. By adjusting the intersection position of the two eccentric masses, the vibration direction can be changed.

[0014] A control method for a dual-motor-driven vibrator with controllable vibration direction includes the following steps:

[0015] Step 1: Calculate the motor speed corresponding to the vibration force;

[0016] When the two motors rotate at the same speed to generate a vibration force, the required motor speed is jointly determined by three factors, expressed as follows:

[0017]

[0018] In the formula, ω represents the angular velocity of the motor, F max represents the maximum vibration force required by the vibrator, m represents the mass of the eccentric mass, and r represents the distance from the center of mass of the eccentric mass to the rotation center;

[0019] Step 2: Determine the initial positional relationship between the two motors according to the vibration direction;

[0020] Let the vertically downward direction be the reference zero position. The offset angles of the initial positions of the two motors from the reference zero position are θ A_OFFSET and θ B_OFFSET, the initial positional relationship between the two motors satisfies:

[0021] θ B_OFFSET = θ A_OFFSET - 2θ vib

[0022] In the formula, θ vib represents the angle between the vibration direction and the reference zero position;

[0023] Step Three: Generate the position curves of the two motors;

[0024] Generate motor position commands to control the actual movement of the two motors, and the calculation is as follows:

[0025]

[0026] In the formula, θ A * (t) and θ B * (t) respectively represent the position commands of the two motors changing with time.

[0027] Furthermore, when the vibration force and the vibration direction need to change during the operation of Step Three, arrange a transition process for the ω, θ A_OFFSET and θ B_OFFSET signals, and realize the gradual change from the initial value to the target value through linear interpolation or low-pass filtering.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention controls two eccentric masses to move in the same speed and cooperate with each other through two motors, synthesizes the variable-direction centrifugal forces generated during the reverse rotation of the two eccentric masses into a single-direction vibration force with an unchanged spatial direction, not only avoids the generation of shear forces, but also helps to improve the harvesting efficiency, and has the characteristics of concentrated vibration energy, high efficiency, and low damage. By adjusting the motor speed and the intersection position of the two eccentric masses, precise on-line adjustment of the vibration force and the vibration direction can be achieved. In addition, the vibrator is miniaturized and portable, does not require supporting large fuel-powered equipment, can be powered by a storage battery, is especially suitable for use in hilly and mountainous areas, and can be placed and operated on higher tree branches, with a wide range of adaptability. Description of the Drawings

[0029] Figure 1 is the overall structural schematic diagram of the double-motor-driven vibrator of the present invention;

[0030] Figure 2 is Figure 1 the front view of

[0031] Figure 3 is Figure 1 the left view of

[0032] Figure 4 It is a schematic diagram of the motion states, centrifugal forces, and vibration forces of two eccentric mass blocks in the dual-motor-driven vibrator of the present invention. Among them, part (a) is the state of generating the vibration force in the vertical direction; part (b) is the state of generating the vibration force in the horizontal direction;

[0033] Figure 5 It is a schematic diagram of the angular relationship between the vibration direction of the dual-motor-driven vibrator of the present invention and the rotational position of the eccentric mass block;

[0034] Figure 6 It is the curve graph of the linear interpolation transition change of θ when the vibration direction changes in the embodiment; B_OFFSET with linear interpolation for transitional change;

[0035] Figure 7 It is the curve graph of the vibration force and the acceleration of the tree trunk changing with the motor speed in the embodiment;

[0036] Figure 8 It is the curve graph of the vibration force and the acceleration of the tree trunk generated at different frequencies in the embodiment. Among them, part (a) is the acceleration generated under vibration at a frequency of 5 Hz; part (b) is the acceleration generated under vibration at a frequency of 10 Hz; part (c) is the acceleration generated under vibration at a frequency of 15 Hz; part (d) is the acceleration generated under vibration at a frequency of 20 Hz;

[0037] Figure 9 It is a schematic diagram of the effective vibration area of the traditional vibrator;

[0038] Figure 10 It is a schematic diagram of the effective vibration area of the dual-motor-driven vibrator of the present invention;

[0039] Figure 11 It is a schematic diagram of the principle of the influence of different vibrators on tree trunk damage.

[0040] In the figure: 1. Motor 1; 2. Eccentric mass block 1; 3. Bracket; 4. Base; 5. Eccentric mass block 2; 6. Motor 2. Specific implementation manners

[0041] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0042] Such as Figures 1 to 4As shown in the figure, a double-motor-driven vibrator with controllable vibration direction includes a bracket 3, a base 4, two motors, and two eccentric mass blocks. Among them, the two motors are the first motor 1 and the second motor 6, and the two eccentric mass blocks are the first eccentric mass block 2 and the second eccentric mass block 5.

[0043] Combined with Figure 1 As shown in the figure, the housings of the first motor 1 and the second motor 6 are horizontally fixed coaxially on both sides of the bracket 3. At the same time, the output ends of the first motor 1 and the second motor 6 are arranged back to back. The bottom of the bracket 3 is fixedly installed with the base 4. The first eccentric mass block 2 and the second eccentric mass block 5 are provided with connecting arms and are respectively detachably installed at the outer ends of the rotors of the first motor 1 and the second motor 6. The first eccentric mass block 2 and the second eccentric mass block 5 have equal mass, and a hammer-shaped mass block is preferably used.

[0044] By controlling the rotation of the two motors, the two eccentric mass blocks rotate in opposite directions in space at the same speed. The centrifugal forces generated by the rotation of the two eccentric mass blocks intersect twice per week at fixed spatial positions, thereby generating a unidirectional vibration force along the direction of the two intersection points. The forces perpendicular to the vibration direction are canceled out to zero due to the spatial symmetry of the two eccentric mass blocks. By adjusting the mass of the eccentric mass block, the distance from the center of mass to the center of rotation, and the motor speed, the magnitude of the vibration force can be changed. By adjusting the intersection position of the two eccentric mass blocks, the vibration direction can be changed.

[0045] Combined with Figure 4 As shown in the figure, it shows the motion states of the two eccentric mass blocks when generating vertical vibration and horizontal vibration. The centrifugal forces generated by the two eccentric mass blocks are respectively F cA and F cB , and the finally synthesized vibration force is F. It can be seen that when the two eccentric mass blocks are at different initial positions, the directions of the generated vibration forces are different.

[0046] As Figures 1 to 5 shown in the figure, a control method for a double-motor-driven vibrator with controllable vibration direction includes the following steps:

[0047] Step 1: Calculate the motor speed corresponding to the vibration force

[0048] When the two motors rotate at the same speed to generate a vibration force, the required motor speed is jointly determined by three factors, as shown below:

[0049]

[0050] In the formula, ω represents the angular velocity of the motor, F max represents the maximum vibration force required by the vibrator, m represents the mass of the eccentric mass block, and r represents the distance from the center of mass of the eccentric mass block to the center of rotation;

[0051] Step 2: Determine the initial positional relationship between the two motors according to the vibration direction

[0052] Combined with Figure 5 As shown, assuming the vertically downward direction as the reference zero position, the offset angles of the initial positions of the two motors from the reference zero position are θ A_OFFSET and θ B_OFFSET respectively. To obtain the vibration force in the required direction, the initial positional relationship between the two motors should satisfy:

[0053] θ B_OFFSET = θ A_OFFSET - 2θ vib

[0054] In the formula, θ vib represents the angle between the vibration direction and the reference zero position;

[0055] Step 3: Generate the position curves of the two motors

[0056] Generate motor position commands to control the actual movement of the two motors, and the calculation is as follows:

[0057]

[0058] In the formula, θ A * (t) and θ B * (t) respectively represent the position commands of the two motors changing with time;

[0059] Step 4: Changes in the vibration force and vibration direction

[0060] During the operation of the vibrator, when the vibration force and vibration direction need to change, as variables, the values of ω, θ A_OFFSET and θ B_OFFSET also need to change accordingly. Arrange a transition process for the ω, θ A_OFFSET and θ B_OFFSET signals, and gradually change the variables from the initial value to the target value through linear interpolation or low-pass filtering to avoid causing sudden impacts on the positions of the two motors.

[0061] Embodiment

[0062] The parameters involved in this embodiment are as follows: the mass of the motor is 7.2 kg, the maximum rotational speed of the motor is 1500 r / min, the mass of the eccentric mass block is 0.21 kg, and the distance from the centroid of the eccentric mass block to the rotation center is 0.09 m.

[0063] Combined with the working state of horizontal vibration, the control method steps of the dual-motor-driven vibrator of the present invention are as follows:

[0064] Step 1: Calculate the motor speed corresponding to the vibration force

[0065] When the two motors rotate in the same speed but in opposite directions, the rotational speed of the motors is determined jointly by the maximum vibration force F max required by the vibrator, the mass m of the eccentric mass block, and the distance r from the centroid of the eccentric mass block to the rotation center. When F max is 400 N, the angular velocity ω and the rotational speed n of the motor are respectively:

[0066]

[0067] Step 2: Determine the initial positional relationship between the two motors according to the vibration direction

[0068] Combined with Figure 5 as shown, in the figure, θ A and θ B respectively represent the actual positions of the two motors. Assuming the vertically downward direction is the reference zero position, the offset angles of the initial positions of the two motors from the reference zero position are respectively θ A_OFFSET and θ B_OFFSET . To obtain the vibration force in the required direction, the initial positional relationship between the two motors should satisfy:

[0069] θ B_OFFSET = θ A_OFFSET - 2θ vib

[0070] Taking any value for θ A_OFFSET , such as θ A_OFFSET = 0, the initial offset values of the two motors can be uniquely determined, then:

[0071]

[0072] Step 3: Generation of the position curves of the two motors

[0073] According to the parameters in the previous two steps, generate the motor position commands to control the actual movement of the two motors. The calculation is as follows:

[0074]

[0075] Step 4: Changes in the vibration force and the vibration direction

[0076] At the moment t = 1 during the operation of the vibrator, when it is necessary to change the vibration direction from horizontal to vertical (θ vib changes from to 0), keeping θ A_OFFSET = 0 unchanged, then θ B_OFFSET will change from -π to 0. After arranging the transition process in a linear interpolation manner with a slope of , the curve of the change of θ B_OFFSET is combined with Figure 6 as shown.

[0077] Fix the dual-motor-driven vibrator of the present invention on the test bench, keep the mass of the eccentric mass block unchanged, set the vibration direction to be perpendicular to the base 4, change the rotational speeds of the two motors, measure the relationship between the motor rotational speed and the magnitude of the generated vibration force, and then, with the same mass of the eccentric mass block and the same vibration direction, fix the vibrator on the trunk of a fruit tree. Combine the results of the changes in the vibration force and the acceleration of the trunk with the motor rotational speed Figure 7 As shown, change the rotational speeds of the two motors, and measure the acceleration generated on the trunk of the fruit tree by the vibrator at different frequencies Figure 8 As shown, among them, part (a) is the acceleration generated under vibration at a frequency of 5 Hz; part (b) is the acceleration generated under vibration at a frequency of 10 Hz; part (c) is the acceleration generated under vibration at a frequency of 15 Hz; part (d) is the acceleration generated under vibration at a frequency of 20 Hz.

[0078] Through the above design, the dual-motor-driven vibrator and the control method of the present invention have the following effects:

[0079] ① Multi-directional flexible vibration expands the efficient harvesting area

[0080] Traditional vibrators can only vibrate in one direction, and the vibration direction is not adjustable. As shown, since the branches of trees grow in all directions, for some branches that grow in the direction of the vibration force, the vibration effect is not good; the vibrator of the present invention can flexibly change the vibration direction during operation. As shown, compared with traditional vibrators, it has more effective vibration areas and can transmit the vibration force to the branches in all directions more comprehensively. Figure 9 As shown, since the branches of trees grow in all directions, for some branches that grow in the direction of the vibration force, the vibration effect is not good; the vibrator of the present invention can flexibly change the vibration direction during operation. As shown, compared with traditional vibrators, it has more effective vibration areas and can transmit the vibration force to the branches in all directions more comprehensively. Figure 10 As shown, compared with traditional vibrators, it has more effective vibration areas and can transmit the vibration force to the branches in all directions more comprehensively.

[0081] ② Unidirectional vibration force focuses the energy action range

[0082] As shown Figure 11 In traditional vibrators, usually a single eccentric mass block is used, or two eccentric mass blocks are not synchronized. Referring to part (b) in the figure, the directions of the generated rotational forces are randomly distributed, which will lead to the loss of direction focusing, and the vibration amplitude of the tree will be significantly reduced; while the vibration energy of the vibrator of the present invention is more concentrated. Referring to part (a) in the figure, it avoids the low efficiency caused by the inability to concentrate energy in the rotational shaking vibration of traditional vibrators, and the problem that the tangential shear force generated during rotational vibration is likely to damage the tree bark.

[0083] ③ Precise control ability

[0084] Compared with the uncontrollable characteristics of fuel power, the vibrator of the present invention uses a motor as an actuator, and can precisely control vibration parameters such as vibration frequency, vibration direction, and vibration force magnitude. Cooperating with an appropriate eccentric mass block, it can adapt to the resonance frequency characteristics of different trees, and while improving the fruit harvesting efficiency, it can reduce the damage to the trees.

[0085] ④Small, lightweight and practical

[0086] Due to efficient area expansion and vibration force concentration, miniaturization and lightweight design can be achieved, meeting the operation requirements at different positions of trees, especially at higher positions, facilitating use in terrains such as hills and mountains, and solving the problems of large size and heavy weight of existing equipment, which limit the use scenarios and are difficult to lift to higher positions of trees and cannot improve performance on large-diameter tree trunks.

[0087] ⑤Wide range of applications

[0088] Driven by electric energy, only a storage battery or a mobile power source needs to be configured during operation, and large power equipment such as tractors is not required to provide power. It is also applicable to dense orchards and high-position branch harvesting.

[0089] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent conditions of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed claim.

[0090] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A dual-motor-driven vibrator with controllable vibration direction, characterized in that: It includes a bracket, a base, two motors and two eccentric masses. The base is provided at the bottom of the bracket. The housings of the two motors are coaxially fixed on both sides of the bracket. The two eccentric masses are provided with connecting arms and are respectively installed at the outer ends of the rotors of the two motors. The two eccentric masses have equal mass. The two motors rotate at the same speed so that the two eccentric masses perform the same-speed reverse movement in space and meet twice a week. The centrifugal forces of the two eccentric masses generate a unidirectional vibration force along the direction of the two meeting points.

2. The double-motor-driven vibrator with controllable vibration direction according to claim 1, wherein: The two eccentric masses are detachably installed with the two motors. The vibration force is changed by adjusting the mass of the eccentric mass, the distance from the center of mass to the rotation center, and the motor speed.

3. A double-motor-driven vibrator with controllable vibration direction according to claim 1 or 2, characterized in that: The meeting position of the two eccentric masses can be adjusted in real time through the control of the two motors. The vibration direction is changed by adjusting the meeting position of the two eccentric masses.

4. A control method for a double-motor-driven vibrator with controllable vibration direction, characterized in that: For the double-motor-driven vibrator according to claim 1, its control method includes the following steps: Step 1: Calculate the motor speed corresponding to the vibration force. When the two motors rotate at the same speed to generate the vibration force, the required motor speed is jointly determined by three factors, which are expressed as follows: where ω represents the angular velocity of the motor, F max represents the maximum vibration force required by the vibrator, m represents the mass of the eccentric mass block, and r represents the distance from the centroid of the eccentric mass block to the rotation center; Step 2: Determine the initial position relationship between the two motors according to the vibration direction. Set the vertically downward direction as the reference zero position. The offset angles of the initial positions of the two motors from the reference zero position are θ A_OFFSET and θ B_OFFSET respectively. The initial position relationship of the two motors satisfies: θ B_OFFSET = θ A_OFFSET - 2θ vib where θ vib represents the angle between the vibration direction and the reference zero position; Step 3: Generate the position curves of the two motors. Generate motor position commands for controlling the actual movement of the two motors, and the calculation is as follows: where θ A * (t) and θ B * (t) respectively represent the position commands of two motors varying with time.

5. The control method of a dual-motor-driven vibrator with controllable vibration direction according to claim 4, characterized in that: When the vibration force and vibration direction need to change during the operation of the third step, they are ω, θ A_OFFSET and θ B_OFFSET Arrange a transition process for the signal to achieve a gradual change from the initial value to the target value through linear interpolation or low-pass filtering.

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