CN111285107B - Contactless mobile operating device and control method - Google Patents

Abstract

The invention discloses a non-contact mobile operation device, comprising a circular upper plate, a circular lower porous medium plate and a position sensor. The upper plate is provided with a groove, and the lower porous medium plate is fixedly connected with the upper plate to form a hollow space. There are four first through holes evenly arranged in the circumferential direction of the upper layer plate, and corresponding second through holes are arranged in the corresponding positions of the lower layer porous medium plate. The first through holes are connected with the first vacuum pump, and the other two opposite first through holes are arranged The through hole is connected with the second vacuum pump, the center of the upper plate is provided with a third through hole, an air inlet connector is installed on the third through hole, and four brackets are evenly installed on the side wall of the upper plate, and each A 2-position 3-way electromagnetic reversing valve, a position sensor and an air injection port are installed on the bracket respectively. The first vacuum pump and the second vacuum pump are connected to the 2-position 3-way electromagnetic reversing valve through pipes, and the 2-position 3-way electromagnetic reversing valve is connected to the air jet. port connection. The invention relies on the suction of the micro vacuum pump to change the strength and direction of the air flow on the surface of the object so as to realize the movement of the object, and can realize complete non-contact.

Description

Contactless mobile operating device and control method

technical field

The invention relates to a non-contact mobile operation device and a control method, belonging to the field of non-contact mobile operation of light and thin objects.

Background technique

The traditional rubber vacuum suction cup has problems such as pollution due to contact with the object, and it is easy to cause scratches and cracks on the surface of the object. The current popular non-contact transportation methods mostly use non-contact vacuum suction cups, including Bernoulli suction cups and whirling flow suction cups. As shown in Figure 1, the Bernoulli principle is used where the flow rate is high and the pressure is low. The object (2) is grasped by the vacuum suction cup (1) under the action of negative pressure, and the supply air flows out from the gap between the device and the object. Objects do not touch. For example, the patent "A Simple Bernoulli Suction Cup" (publication number: CN108068136A, published on May 25, 2018)". As shown in Figure 2, the suction force generated by the swirling airflow is used to grasp objects. See the patent for details. "Swirling non-contact suction cup" (Publication No.: CN101264844, published on September 17, 2008). However, since there is no contact between the object and the suction cup, this method only provides vertical lifting force, but cannot drive Objects move horizontally. In order to prevent objects from falling off, positioning pins should be used to contact objects when moving and operating objects horizontally, which may easily cause object contamination.

SUMMARY OF THE INVENTION

Purpose of the invention: In order to overcome the deficiencies in the prior art, the present invention provides a control method for a non-contact mobile operating device, which relies on the suction of a micro vacuum pump to change the strength and direction of the airflow on the surface of the object so as to realize the movement of the object, which can achieve complete non-contact. .

Technical solution: In order to solve the above technical problems, the non-contact mobile operation device of the present invention includes a circular upper plate, a circular lower porous medium plate and a position sensor, the upper plate is provided with a groove, and the lower porous medium plate is connected with the position sensor. The upper layer plate is fixedly connected to form a cavity, four first through holes are evenly arranged in the circumferential direction of the upper layer plate, corresponding second through holes are arranged in corresponding positions of the lower layer porous medium plate, and the two opposite first through holes are connected with the first through holes. The vacuum pump is connected, and the other two opposite first through holes are connected with the second vacuum pump. The center of the upper board is provided with a third through hole, and an air inlet connector is installed on the third through hole. Four brackets are evenly installed, and a 2-position 3-way electromagnetic reversing valve, a position sensor and an air jet are respectively installed on each bracket. The first vacuum pump and the second vacuum pump are connected to the 2-position 3-way electromagnetic reversing valve through pipes. The 2-position 3-way electromagnetic reversing valve is connected with the jet port; a plurality of fourth through holes are arranged on the lower porous medium plate, and the position sensor and the 2-position 3-way electromagnetic reversing valve are connected to the controller.

Preferably, the position sensor is a non-contact sensor.

Preferably, the position sensor is an infrared or laser sensor.

A control method of the above-mentioned non-contact mobile operation device, comprising the following steps:

(1) Parameter setting, set the acceleration critical value; .

(2) The controller collects the position information of five groups of position sensors through the collecting device, and stores it in the controller;

(3) The controller samples the output signal of the position sensor through the data acquisition module, determines the displacement x1, x2, x3 and x4 of the object relative to the device, and calculates the relative acceleration of the object;

(4) Calculate the relative acceleration through the displacement data, and judge whether the relative acceleration is greater than the critical value. If so, open the solenoid valve, and supply air into the gap through the jet port to increase the air flow driving force; if not, there is no need to open the solenoid valve;

(5) Send the position offset difference components in the X and Y directions to the controller, the position offset difference in the X direction is x1-x3, the position offset difference in the Y direction is x2-x4, and the pulse input to the vacuum pump motor is calculated according to the controller algorithm Frequency variation, control the motor to adjust the suction volume of the vacuum pump;

(6) Repeat step (3) until the target position is reached.

e(t)为实际与理论的位置偏差，Kp和Ki是控制器的参数，根据经验设成一定数值。Preferably, the formula for calculating the pulse frequency of the input vacuum pump motor according to the controller algorithm is as follows

e(t) is the actual and theoretical position deviation, Kp and Ki are the parameters of the controller, which are set to a certain value according to experience.

e₁(t)＝x1-x3-△x₁，△x₁为理论位置计算结果，从第一真空泵到第三真空泵，第三真空泵的频率u₃＝U-u₁，第二真空泵的频率为

第四真空泵的频率为u₄＝U-u₂,U为设定的定值，K_p、K_i、K′_p、K′_i为根据经验设定的定值。Preferably, the four vacuum pumps corresponding to the four positions x1, x2, x3 and x4 are the first vacuum pump, the second vacuum pump, the third vacuum pump and the fourth vacuum pump, and the frequency of the first vacuum pump is

e ₁ (t)=x1-x3-Δx ₁ , Δx ₁ is the theoretical position calculation result, from the first vacuum pump to the third vacuum pump, the frequency of the third vacuum pump u ₃ =Uu ₁ , and the frequency of the second vacuum pump is

The frequency of the fourth vacuum pump is u ₄ =Uu ₂ , U is a fixed value set, and K _p , K _i , K′ _p , and K′ _i are fixed values set according to experience.

V₀为初始速度，由上一次检测得到的位移计算可得，

利用有限体积法对气膜压力表达式进行迭代求解，即可获得各个气膜网格的压力值，由此便可以得到气膜压力梯度

式中Δx为理论位移变化量，Δt为一个采样周期,F为理论力，m为物件质量，A为物件的上表面面积，h为气膜间距，通过激光位移传感器测得，p为气膜压力，ω₀为表面气体流速，μ为空气粘度。Preferably, the theoretical position

V ₀ is the initial velocity, which can be calculated from the displacement obtained by the last detection,

Using the finite volume method to iteratively solve the gas film pressure expression, the pressure value of each gas film grid can be obtained, and thus the gas film pressure gradient can be obtained.

In the formula, Δx is the theoretical displacement change, Δt is a sampling period, F is the theoretical force, m is the mass of the object, A is the upper surface area of the object, h is the gas film distance, measured by the laser displacement sensor, p is the gas film pressure, ω ₀ is the surface gas velocity and μ is the air viscosity.

The non-contact moving operation device of the present invention includes upper and lower layers of circular plates. The air joint is installed on the surface of the upper board, and the lower surface is provided with a groove, and the compressed air can enter the cavity through the air joint. Symmetrically distributed through holes are provided near the edge of the upper layer board, a micro vacuum pump is installed at the through holes, and the suction port of the vacuum pump is connected with the through holes. The lower porous medium plate is a porous material plate (the material can be sintered powder metal, fiber, foamed ceramics, etc.), which has the same diameter as the upper plate, and has through holes corresponding to the through holes of the upper plate. Hole inhale. After the upper and lower layers are bonded, a cavity is formed between the two layers, which can stabilize the air supply pressure to a certain extent. A number of brackets are installed symmetrically on the outside of the upper board. The position sensor and the two-position three-way microvalve are installed and fixed on the bracket. The control air port of the three-way microvalve is connected to the vacuum pump exhaust port on the opposite side. A small jet port is also mounted on the bracket, and the jet port is oriented towards the center of the plate.

When the object is moved, compressed air flows in from the air inlet of the upper plate, and at the same time, the input pulse frequency of the vacuum pump motor is changed to control the speed of the motor for suction, thereby forming a partial vacuum between the object and the lower porous medium plate. Under the action of suction, the object is lifted close to the lower porous medium plate, and at the same time, the gas flowing out of the surface of the porous medium plate forms a pressure film on the surface of the object. Under the combined action of suction and pressure, the object can be suspended without contact.

The operating device is installed on the horizontal slide table or mechanical arm. In the initial state, after the airflow flows out through the porous material plate, a part of the symmetrical radial shape is drawn out from the edge through holes, and the other part flows out from the gap, and the object is in a state of horizontal force balance. When operating the device to move the object, since there is no surface contact between the object and the device, the center of the object will deviate from the center of the porous medium plate. The position change of the object is detected by the position sensor on the edge, and the difference between the two position sensors in the same direction is used as the input. Incoming controller. After correcting the input through the theoretical model position state observation value, the error state quantity e(t) is obtained, and then the PI control algorithm is used to calculate the control pulse frequencies u ₁ and u ₃ of the motor 1 and the motor 3 (the sum of u ₁ and u ₃ It is a fixed value) u ₁ and u ₃ are a group, and u ₂ and u ₄ are a group, which makes the suction flow of different vacuum pumps different. Thus, a directional airflow is generated on the upper surface of the object, and the airflow provides a horizontal driving force for the object. The corresponding relationship between the suction flow of the vacuum pump and the control pulse frequency is determined by the characteristics of the vacuum pump. The surface gas velocity is calculated from the suction flow Q1 and Q2, and then the theoretical model is entered to solve the viscous driving force of the airflow acting on the surface of the object, and then the position state of the object is determined according to the kinematic equation. The controller input is corrected by using the observation value of the theoretical position state of the object as a feedback, and the above steps are repeated continuously.

When the object is in the center position, the two-position three-way solenoid valve is in a power-off state, and the air flow from the vacuum pump outlet is discharged to the atmosphere. When the deviation of the object from the center exceeds a certain threshold (measured by the displacement sensor), the three-way solenoid valve is energized, and the exhaust gas from the vacuum pump outlet enters the gap through the jet port, enhancing the airflow driving force, improving the control effect, and reducing the occurrence of touch phenomenon. At this time, different from the above steps, when calculating the theoretical position state of the object, it is necessary to consider the air intake on both sides and modify the calculation conditions.

In the pulse frequency solution, first of all, we need to control the speed of the motor to change the suction flow. The motor speed of the vacuum pump has a certain relationship with the suction flow. This relationship is determined by the working characteristics of the pump, which can usually be found in the manual. The PI algorithm in the figure determines the pulse frequency by the position error input by the position sensor. In this way, the rotational speed and the suction flow rate are determined, and the relationship of u ₁ →Q is obtained;

(z为竖直方向)，这部分的推导有些专业知识。简单来说，对间隙内简化的一维纳维斯托克斯方程

在竖直z方向进行积分，考虑边界条件为u＝0(z＝0)和u＝0(z＝h))，可以得到流速表达式

根据牛顿粘性定律，可得F与压力梯度

之间的关系式

而

的计算则通过求解

获得，利用有限体积法对气膜压力表达式进行迭代求解，即可获得各个气膜网格的压力值，由此便可以得到气膜压力梯度

这样，由抽吸流量就确定了Q→F的关系。Secondly, after the suction flow rate is changed, the flow rate of the airflow on the surface of the object also changes. This flow rate change causes the airflow driving force F on the object to also change. The relationship between the flow rate u and the force F is:

(z is the vertical direction), the derivation of this part has some professional knowledge. In simple terms, for the simplified one-dimensional Navier-Stokes equation in the gap

Integrating in the vertical z direction, considering the boundary conditions as u=0 (z=0) and u=0 (z=h)), the flow velocity expression can be obtained

According to Newton's law of viscosity, F and pressure gradient can be obtained

relationship between

and

is calculated by solving

Obtain, using the finite volume method to iteratively solve the gas film pressure expression, the pressure value of each gas film grid can be obtained, and thus the gas film pressure gradient can be obtained

In this way, the relationship of Q→F is determined by the suction flow.

V₀为初始速度，由上一次检测得到的位移计算可得。这样就建立了由F→Δx的关系式。Again, the theoretical position of the object is determined by the force F according to the equations of kinematics (Newton's second law). The displacement of the object is calculated by the formula

V ₀ is the initial velocity, which can be calculated from the displacement obtained by the last detection. In this way, the relational expression from F→Δx is established.

The relationship between the rotational speed and the suction flow can be obtained from the characteristics of the vacuum pump, thereby determining the suction flow Q1 and Q2, and comparing the flow with the area to obtain the flow velocity. The flow velocity is introduced into the model as a calculation condition, and the shear stress τ ( F=τA), thereby obtaining the viscous force of the air flow that drives the object, and then determining the theoretical position of the object by the kinematic equation (Newton’s second law), and using the observation value of the theoretical position state of the object as feedback to correct the controller input”

中，e(t)为位置偏移差分量x1-x3或x2-x4与理论位置的差值，X方向和Y方向分别控制。即X方向的两个电机为一组，通过一个u₁和u₃控制电机转速；而Y方向的两个电机为另一组，通过另一组u₂和u₄控制电机转速。Kp和Ki是控制器的参数，要根据经验设成一定数值，这个数值与电机转速和抽流流量的关系有关联，需要由它们的关系来确定。这里，两个方向独立控制，写成

和

Among them, e(t) is the difference between the position offset difference component x1-x3 or x2-x4 and the theoretical position, and the X direction and the Y direction are controlled separately. That is, the two motors in the X direction are a group, and the motor speed is controlled by one u ₁ and u ₃ ; the two motors in the Y direction are another group, and the motor speed is controlled by another group of u ₂ and u ₄ . Kp and Ki are the parameters of the controller, which should be set to a certain value according to experience. This value is related to the relationship between the motor speed and the pumping flow, and needs to be determined by their relationship. Here, the two directions are independently controlled, written as

and

In the present invention, the theoretical position is the position obtained according to the theoretical calculation, which is used to feed back the theoretical position state to make a correction to the input of the controller (meaning, for example, if the theoretical calculation finds that the deviation of the object is large, the position deviation will be further increased input so that the pump can operate with more suction power). In the present invention, each sampling period needs to solve the acceleration and determine the acceleration, because the position must always be in an adjustable state, even when the acceleration is relatively small, but at this time, the speed of the pump is low, and the effect of changing the position is weak. . The purpose of judging whether the acceleration exceeds the critical value is whether to open the solenoid valve to supply air to the gap. After the valve is opened, the force output can be greatly increased.

利用有限体积法对气膜压力表达式进行迭代求解，即可获得各个气膜网格的压力值，这是计算得到的值，ω₀为表面气体流速，多孔介质表面处，ω₀为Q/A，供气流量除以表面积得到流速；在吸气口处，即真空泵位置的通孔，ω₀为Q1/通孔面积，或Q2/通孔面积)，μ为空气粘度(常值1.82×10^-5Pa·s)。In the present invention, the displacement of the object is calculated according to the uniform acceleration linear motion, where Δx is the theoretical displacement change, Δt is a sampling period, F is the theoretical force, m is the mass of the object, A is the upper surface area of the object, and h is the gas membrane spacing, p is the gas membrane pressure,

Using the finite volume method to iteratively solve the gas film pressure expression, the pressure value of each gas film grid can be obtained, which is the calculated value, ω ₀ is the surface gas velocity, and at the surface of the porous medium, ω ₀ is Q/ A, the flow rate of the supply air is divided by the surface area to obtain the flow rate; at the suction port, that is, the through hole at the position of the vacuum pump, ω ₀ is Q1/through hole area, or Q2/through hole area), μ is the air viscosity (constant 1.82× 10 ^-5 Pa·s).

Beneficial effect: Because of adopting the above-mentioned technical scheme, the present invention has the following beneficial effects compared with the prior art:

1) Relying on the suction of the micro vacuum pump to change the strength and direction of the airflow on the surface of the object to realize the movement of the object, which can achieve complete non-contact.

2) Use the electromagnetic reversing valve to switch the exhaust channel of the micro vacuum pump. When the solenoid valve is de-energized, the exhaust channel of the micro vacuum pump is connected to the atmosphere. The airflow in the gap is increased, so the airflow driving force can be effectively increased.

3) By installing a position sensor on the side of the device to detect the position change of the object, as a feedback input control module, the moving state of the object can be detected and controlled.

4) Using the porous medium plate as the air supply element can avoid the stress concentration on the surface of the object, and it is not easy to cause deformation for the moving operation of the thin object.

Description of drawings

Fig. 1 is the schematic diagram of the working situation of the contact vacuum suction cup;

Figure 2 is a schematic diagram of the working situation of Bernoulli's non-contact vacuum suction cup;

Fig. 3 is the schematic diagram of the working situation of the rotating flow non-contact vacuum suction cup;

Fig. 4 is the working principle schematic diagram of the present invention;

Fig. 5 is the change diagram of the air flow on the surface of the object for explaining the working principle of the present invention; wherein Fig. (a) is the change diagram of the air flow on the surface of the object when the position sensor 5 detects that the object is located at the center of the device; Fig. (b) is the position sensor on the left and right sides The change of airflow on the surface of the object when the object is detected to be offset; Figure (c) The position sensor on the upper and lower sides detects the change of the airflow on the surface of the object when the object is offset.

Figure 6 is an isometric view of the contactless mobile operating device of the present invention;

7 is a front view of the contactless mobile operating device of the present invention;

8 is a top view of the contactless mobile operating device of the present invention;

Fig. 9 is the A-A sectional view of Fig. 8;

Fig. 10 is the whole exploded view of the contactless mobile operation device;

Fig. 11 is the control principle diagram of the contactless mobile operating device;

12 is a schematic diagram of a specific control principle;

Fig. 13 is the program flow chart of the control method of the contactless mobile operation device;

FIG. 14 is a schematic diagram of the working situation when multiple contactless mobile operation devices are used in parallel.

Detailed ways

As shown in FIG. 1 to FIG. 14 , a non-contact mobile operation device of the present invention includes a circular upper plate 1 , a circular lower porous medium plate 2 and a position sensor 5 , and the upper plate 1 is provided with a groove , the lower layer porous medium plate 2 is fixedly connected with the upper layer plate 1 to form a cavity, four first through holes are evenly arranged in the circumferential direction of the upper layer plate 1, and corresponding second through holes are arranged at the corresponding positions of the lower layer porous medium plate 2. The two first through holes are connected to the first vacuum pump 7, and the other two opposite first through holes are connected to the second vacuum pump. The center of the upper board 1 is provided with a third through hole, which is installed on the third through hole. There is an air inlet joint 8, four brackets 3 are evenly installed on the side wall of the upper board 1, and a 2-position 3-way electromagnetic reversing valve 4, a position sensor 5 and an air injection port 6 are installed on each bracket 3 respectively. A vacuum pump 7 and a second vacuum pump are connected with the 2-position 3-way electromagnetic reversing valve 4 through pipelines, and the 2-position 3-way electromagnetic reversing valve 4 is connected with the air injection port 6; Four through holes, the position sensor 5 and the 2-position 3-way electromagnetic reversing valve 4 are both connected to the controller, the position sensor 5 is a non-contact sensor, and the position sensor 5 is an infrared or laser sensor.

A control method for a contactless mobile operating device, comprising the following steps:

(1) Parameter setting, set the acceleration critical value;

(2) The controller collects the position information of five groups of position sensors 5 through the collecting device, and stores it in the controller;

(3) The controller samples the output signal of the position sensor 5 through the data acquisition module, determines the displacements x1, x2, x3 and x4 of the object relative to the device, and calculates the relative acceleration of the object 12. Acceleration calculation description: Assuming three consecutive samples The position of the cycle is x, x' and x" (x, x' and x" are all derived from x1-x3 or x2-x4), then the relative acceleration

(4) Calculate the relative acceleration through the displacement data, and judge whether the relative acceleration is greater than the critical value. If so, open the solenoid valve, and supply air to the gap through the jet port 6 to increase the airflow driving force; if not, then there is no need to open the solenoid valve;

(5) The X and Y direction position offset difference components are introduced into the controller, and the pulse frequency of the input vacuum pump motor is calculated according to the controller algorithm, and the motor is controlled to adjust the suction volume of the vacuum pump;

(6) Repeat step (3) until the target position is reached.

FIG. 4 is a schematic diagram of the working principle of the device of the present invention. When the object 12 is moved, the object is suspended under the device under the combined action of the positive pressure on the surface of the porous medium plate 2 and the negative pressure at the suction port of the micro vacuum pump 7 . When moving the device, since the object is not in contact with the air flotation platform, the two will have a relative movement trend. When the position sensor 5 installed on the outside of the device detects the deviation of the object below, it transmits the detection amount to the controller to control the corresponding micro vacuum pump 7 to enhance the suction flow. Objects can move with the device. For example, if the object is shifted to the right relative to the device, the controller controls the vacuum pump on the opposite side (the left vacuum pump in the figure) to increase the suction volume. The micro-vacuum pump exhaust hole 7-1 is connected to the electromagnetic reversing valve 4 on the opposite side, and the micro-vacuum pump exhaust channel is switched through the control of power-on and power-off. When the solenoid valve is de-energized, the exhaust channel of the micro vacuum pump communicates with the atmosphere, and when the solenoid valve is energized, the exhaust channel of the micro vacuum pump communicates with the jet port, and the air flow into the gap increases, so the airflow driving force can be increased. The laser displacement sensor 13 is used to detect the distance h between the object and the surface of the porous medium. The laser displacement sensor 13 is fixed on the adjustable bracket 14, and the bracket 14 is fixedly connected with the operating device. When the object is initially grabbed and loaded, the displacement sensor is first removed to facilitate grabbing from above. After the initial loading is completed, the bracket 14 is adjusted to move the sensor 13 to the center of the object and then the detection begins.

FIG. 5 is a diagram showing the change of air flow on the surface of the object for illustrating the working principle of the present invention. As shown in Figure a, when the position sensor 5 detects that the object is located in the center of the device, the suction flow of each vacuum pump is the same, and the air flows through the porous medium plate 2 in a symmetrical radial shape to the edge and the suction port, and the object is balanced by lateral force and has no movement. trend. As shown in Figure b, the position sensors on the left and right sides detect the displacement of the object, and control the right vacuum pump 7 to increase the suction volume, so that the outflow of the air flow from the right side of the object surface is greater than that of the left side, and the object is restored to its original state by the action of the air flow. Location. As shown in Figure c, for the same reason, when the position sensors on the upper and lower sides detect the deviation of the object, the suction volume is increased by controlling the lower side vacuum pump, so that the outflow of the air flow from the lower side of the object surface is greater than that of the upper side.

As shown in Figure 6, Figure 7, Figure 8, the contactless mobile operation device mainly includes a micro vacuum pump 7, an upper layer plate 1, a lower layer porous medium plate 2, an air inlet connector 8, an outer bracket 3, and a 2-position 3-way electromagnetic Reversing valve 4, position sensor 5. In the operating device, the micro vacuum pumps are installed symmetrically above the upper board, and brackets equivalent to the number of vacuum pumps are installed on the side of the upper board. The air source is connected to the air inlet connector 8 through the connecting hose, the signal output port of the position sensor 5 is connected to the input conversion module 9 , the input conversion module is connected to the data acquisition module 10 , and the data acquisition module is connected to the controller 11 . The input conversion module is a signal conditioning circuit, which can transmit the analog current and voltage signals output by the position sensor 5 to the data acquisition module. The data acquisition module is an A/D conversion circuit, which is used to convert the analog signal output by the position sensor into a digital signal. The controller can be an industrial computer, a single-chip computer, or a programmable controller. According to the set control algorithm, the vacuum pump is controlled to change the suction flow to make the object move synchronously with the device.

FIG. 9 is a cross-sectional view of the contactless moving operation device. The device includes two layers of circular plates, the upper circular plate 1 is provided with a groove at the bottom, and four through holes 1-2 are symmetrically distributed near the edge. A micro vacuum pump 7 is installed at each through hole, and the suction port of the vacuum pump is 7-2 is connected with the through hole. The lower porous medium plate 2 is a porous material plate, and the surface of the porous material plate is evenly ventilated. After the upper and lower boards are connected by glue or bolts, a cavity is formed between the two boards, and the vacuum pump can inhale through the two through holes. Four brackets 3 are installed symmetrically on the outside of the upper board. The position sensor 5 and the two-position three-way micro-valve 4 are installed and fixed on the bracket. The control air port A of the three-way micro-valve and the vacuum pump exhaust port on the opposite side connected. A small jet port 6 is also mounted on the bracket, and the jet port is oriented towards the center of the plate.

The parts in Figure 10 are as follows: 1. Upper board; 2. Lower porous media board; 3. Mounting bracket; 4. Two-position three-way solenoid valve; 5. Position sensor; 6. Air jet; 7. First vacuum pump ; 8. Intake connector; 13. Sealing ring.

Figure 11 shows a block diagram of the control principle. By reading the signal of the position sensor, the displacements in 4 directions x1, x2, x3 and x4 are obtained. If the relative acceleration is less than γ, the solenoid valve does not need to be opened at this time, and the exhaust gas of the vacuum pump is discharged into the atmosphere through the solenoid valve; if the relative acceleration is greater than γ, the solenoid valve is opened at this time, and the exhaust gas of the vacuum pump is fed into the porous medium plate and the object through the solenoid valve connected to the jet port. In the gap between, increase the airflow driving force. Input the differential signal of the position sensor into 2 controllers, each controller independently controls the suction volume of the 2 vacuum pumps in the X direction and the Y direction according to the control algorithm, thereby changing the distribution state of the air flow on the surface of the object, and realizing the non-contact movement of the object following the device .

Figure 12 shows a schematic diagram of the specific control principle. The supply air flows through the porous media plate and enters the gap formed by it and the object, and then is sucked out by the micro vacuum pump through the gap. The pressure distribution and viscous driving force of the air in the gap can be calculated by the simultaneous simplified Navier-Stokes equation and the continuity equation. The simplified expressions of the basic equations are as follows,

式中，p为气膜压力，x和z分别为位置，u_x为x方向流速，μ为空气粘度。Navier-Stokes equation in the x direction:

In the formula, p is the air film pressure, x and z are the positions, u _x is the flow velocity in the x direction, and μ is the air viscosity.

式中，z为位置，u_z为z方向流速，μ为空气粘度。Navier-Stokes equation in z direction:

In the formula, z is the position, u _z is the flow velocity in the z direction, and μ is the air viscosity.

式中，p为气膜压力，x和z分别为位置，u_x为x方向流速，u_z为z方向流速，t为时间。Continuity Equation:

In the formula, p is the gas film pressure, x and z are the positions, u _x is the flow velocity in the x direction, u _z is the flow velocity in the z direction, and t is the time.

Combining the above equations, we can get

具体的做法是：对表面网格区域利用流量除以面积从而得到表面平均流速ω₀。同时，利用有限体积法对气膜压力表达式进行迭代求解，即可获得各个气膜网格的压力值。获得气膜压力值后，可根据气膜压力梯度

计算气流驱动力F。式中，ω₀为表面出流气体流速或抽吸气体流速，两者气流方向相反。

The specific method is to divide the flow rate by the area for the surface mesh area to obtain the surface average velocity ω ₀ . At the same time, by using the finite volume method to iteratively solve the gas film pressure expression, the pressure value of each gas film grid can be obtained. After obtaining the gas film pressure value, it can be calculated according to the gas film pressure gradient

Calculate the airflow driving force F. In the formula, ω ₀ is the surface outflow gas flow rate or the suction gas flow rate, and the two gas flow directions are opposite.

的运算得到输入真空泵电机的脉冲频率u₁和u₂。由真空泵特性可得转速与吸气流量关系，从而确定抽吸流量Q₁和Q₂，并通过流量与面积相比得到流速。将流速作为计算条件导入模型，通过牛顿粘性定律可以计算剪切应力τ，从而获得驱动物件的气流粘性力，进而由运动学方程(牛顿第二定律)确定物件的理论位置，将物件的理论位置状态观测值作为反馈对控制器输入进行修正。当电磁阀开启时，真空泵排气通过气流喷口进入缝隙，此时需考虑两侧进气情况，修改计算条件，此时气膜压力计算公式变为

α为根据经验确定的固定值，1<α<2。Divide the air film between the device and the object into n one-dimensional grids. In the surface mesh of the porous media plate, there is a top-down gas outflow, and the flow rate _ω0 is obtained by comparing the flow rate with the area. In the surface mesh of the suction port, there is a bottom-up gas outflow, and the flow rate is also obtained by comparing the flow rate to the area. The specific control process is as follows: the differential signal of the position sensor is transmitted to the controller. When its value is less than the critical threshold, the solenoid valve does not open, and the theoretical position state observation value is used as feedback to correct the input of the controller and then control the micro vacuum pump motor 1 and the motor. 2 RPM, by PI algorithm

The operation of can get the pulse frequency u ₁ and u ₂ of the input vacuum pump motor. The relationship between the rotation speed and the suction flow can be obtained from the characteristics of the vacuum pump, so as to determine the suction flow Q ₁ and Q ₂ , and obtain the flow rate by comparing the flow with the area. The flow velocity is imported into the model as a calculation condition, and the shear stress τ can be calculated through Newton's law of viscosity, so as to obtain the airflow viscous force of the driving object, and then the theoretical position of the object is determined by the kinematic equation (Newton's second law). The state observations are used as feedback to correct the controller input. When the solenoid valve is opened, the exhaust gas of the vacuum pump enters the gap through the airflow nozzle. At this time, the intake conditions on both sides should be considered, and the calculation conditions should be modified. At this time, the calculation formula of the air film pressure becomes

α is a fixed value determined by experience, 1<α<2.

FIG. 13 is a flow chart of the control program of the contactless mobile operating device. The program starts, after completing the parameter and state initialization settings, go to step 2, and sample the output signal of the position sensor through the data acquisition module. Go to step 3 and determine the displacements x1, x2, x3 and x4 of the object relative to the device. Go to step 4, calculate the relative acceleration through the displacement data, and judge whether the relative acceleration is greater than the critical value. If yes, go to step 5 to open the solenoid valve, and go to step 6 to supply air into the gap through the air jet port to increase the airflow driving force; if not, there is no need to open the solenoid valve. Go to step 7, and transmit the position offset difference components in the X and Y directions to the controller. Go to step 8, calculate the pulse frequency of the input vacuum pump motor according to the controller algorithm. Go to step 9, control the motor to adjust the suction volume of the vacuum pump. In step 10, determine whether the object is synchronized with the device according to the data of the position sensor, if not, return to step 2 to repeat the above process; if yes, keep the current working state of the vacuum pump.

Figure 14 shows a schematic diagram of the working situation of four contactless mobile operating devices when they are used together, which can be used to move and operate large-sized objects. Four operating devices are installed on the cross-shaped bracket 14, and the bracket is installed and fixed on the mechanical arm. When multiple devices are used together, only the bracket 3 on the outside of the object is reserved for installing the position sensor 5 , the solenoid valve 4 and the air outlet 6 .

The above is only the preferred embodiment of the present invention, it should be pointed out that: for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can also be made, and these improvements and modifications are also It should be regarded as the protection scope of the present invention.

Claims (3)

1. a non-contact mobile operating device, it is characterized in that: comprise circular upper layer plate, circular lower layer porous medium plate and position sensor, described upper layer plate is provided with groove, and lower layer porous medium plate is fixedly connected with upper layer plate A cavity is formed, four first through holes are evenly arranged in the circumferential direction of the upper layer plate, corresponding second through holes are arranged in corresponding positions of the lower layer porous medium plate, and the two opposite first through holes are connected with the first vacuum pump, and the other The two opposite first through holes are connected to the second vacuum pump, the center of the upper plate is provided with a third through hole, an air inlet connector is installed on the third through hole, and four are evenly installed on the side wall of the upper plate. Each bracket is installed with a 2-position 3-way electromagnetic reversing valve, a position sensor and an air injection port, the first vacuum pump and the second vacuum pump are connected to the 2-position 3-way electromagnetic reversing valve through pipes, and the 2-position 3-way The electromagnetic reversing valve is connected with the jet port; a plurality of fourth through holes are arranged on the lower porous medium plate, and the position sensor and the 2-position 3-way electromagnetic reversing valve are both connected to the controller. 2 . The contactless mobile operation device according to claim 1 , wherein the position sensor is a contactless sensor. 3 . 3 . The contactless mobile operation device according to claim 2 , wherein the position sensor is an infrared or laser sensor. 4 .

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