CN100552486C - Closed-loop control of optical fiber displacement feedback for two-dimensional flexible hinged workbench - Google Patents

Abstract

The optical fiber displacement feedback closed-loop control two-dimensional flexible hinged workbench relates to a flexible hinged workbench. It is equipped with a two-dimensional flexible hinge platform, a transverse piezoelectric ceramic driver, a longitudinal piezoelectric ceramic driver, a transverse optical fiber displacement sensor, and a longitudinal optical fiber displacement sensor; the two-dimensional flexible hinge platform is provided with a transverse installation hole and a longitudinal installation hole, and a transverse optical fiber installation The horizontal piezoelectric ceramic driver and the longitudinal piezoelectric ceramic driver are respectively arranged in the horizontal installation hole and the longitudinal installation hole. The horizontal optical fiber displacement sensor is provided with a horizontal optical fiber, and the longitudinal optical fiber displacement sensor is provided with a longitudinal optical fiber. The optical fiber and the longitudinal optical fiber are arranged in the horizontal optical fiber installation channel and the longitudinal optical fiber installation channel respectively. Both the horizontal optical fiber installation channel and the longitudinal optical fiber installation channel are equipped with curved tooth structures, and the output ends of the horizontal optical fiber and the longitudinal optical fiber are externally connected with a detection closed-loop control device.

Description

Closed-loop control of optical fiber displacement feedback for two-dimensional flexible hinged workbench

technical field

The invention relates to a flexible hinge workbench, in particular to a two-dimensional flexible hinge workbench with optical fiber displacement feedback closed-loop control.

Background technique

In the engineering practice of ultra-precision machining and measurement and positioning, most of the flexible hinge worktables driven by piezoelectric ceramics are used to realize nano-drive and its positioning technology. Because piezoelectric ceramics have defects such as hysteresis, creep, and nonlinearity, their accuracy and positioning stability are limited. In order to improve the accuracy, precision displacement sensors are used in the industry to perform closed-loop feedback control on the workbench. At present, the most widely used precision displacement sensors are capacitive displacement sensors integrated with the workbench. If the change has a greater impact, it is difficult to guarantee its own accuracy. Therefore, the accuracy and positioning stability of the flexible hinge workbench are still limited.

Because the precision of the optical fiber displacement sensor can reach sub-nanometer, and it has the advantages of strong anti-interference, high flexibility, and more flexible spatial arrangement; therefore, if the optical fiber displacement sensor is applied to the two-dimensional flexible The accuracy and stability of the hinged workbench are significantly improved, but there is no report on the application of optical fiber displacement sensors on the two-dimensional flexible hinged workbench.

Contents of the invention

The object of the present invention is to provide a two-dimensional flexible hinge workbench with high driving precision and good positioning stability for closed-loop control of optical fiber displacement feedback.

The invention is provided with a two-dimensional flexible hinge platform, a transverse piezoelectric ceramic driver, a longitudinal piezoelectric ceramic driver, a transverse optical fiber displacement sensor and a longitudinal optical fiber displacement sensor; The optical fiber installation track and the longitudinal optical fiber installation track, the transverse piezoelectric ceramic driver and the longitudinal piezoelectric ceramic driver are respectively arranged in the transverse installation hole and the longitudinal installation hole, the transverse optical fiber displacement sensor is provided with a transverse optical fiber, and the longitudinal optical fiber displacement sensor is provided with a longitudinal optical fiber , the horizontal optical fiber and the vertical optical fiber are arranged in the horizontal optical fiber installation path and the longitudinal optical fiber installation path respectively, both the horizontal optical fiber installation path and the longitudinal optical fiber installation path are provided with a curved tooth structure, and the output ends of the horizontal optical fiber and the longitudinal optical fiber are externally connected to a closed-loop control device for detection.

The transverse piezoelectric ceramic driver is equipped with piezoelectric ceramic elements, wires and connectors. The piezoelectric ceramic elements are arranged on the connectors. Hole connection, the longitudinal piezoelectric ceramic driver is provided with piezoelectric ceramic elements, wires and connectors, the piezoelectric ceramic elements are set on the connector, one end of the wire is connected to the piezoelectric ceramic element, and the other end of the wire is connected to an external detection closed-loop control device, the connector Connect with longitudinal mounting holes.

The connection between the connecting piece of the transverse piezoelectric ceramic driver and the transverse installation hole is preferably threaded.

The connection between the connecting piece of the longitudinal piezoelectric ceramic driver and the longitudinal installation hole is preferably threaded.

The lateral installation hole is preferably provided on the side of the two-dimensional flexible hinge platform, and is located on the lateral centerline of the two-dimensional flexible hinge platform.

The longitudinal installation hole is preferably provided on the side of the two-dimensional flexible hinge platform, and is located on the longitudinal centerline of the two-dimensional flexible hinge platform.

The curved tooth structure of the transverse optical fiber installation channel is a tooth-shaped mating groove.

The curved tooth structure of the longitudinal optical fiber installation channel is a tooth-shaped mating groove.

The technical principle of the present invention is: because the optical fiber has a characteristic, the refractive index of the fiber core in the optical fiber is slightly larger than the refractive index of the cladding, so the light is bound to propagate in the optical fiber. When the optical fiber is in a slightly bent state, some light that can originally propagate in the straight optical fiber will radiate out of the optical fiber, resulting in optical power loss. Using this characteristic, a curved tooth structure is set on the two-dimensional flexible hinge platform. When the piezoelectric ceramic driver drives the workbench to move, the curved tooth structure will squeeze the optical fiber, causing the optical fiber to undergo micro-bending deformation. Therefore, as long as the optical fiber is detected at the output end The modulation amount (that is, the displacement amount) can be detected by the change of the light intensity, and then the modulation amount is fed back to the control system for control, forming a closed-loop control system for optical fiber displacement feedback.

Since the present invention adopts the optical fiber displacement sensor with the advantages of high displacement precision and strong anti-interference to realize the closed-loop control of the workbench, it can improve the driving precision of the workbench and the stability of long-term working positioning. Compared with the existing two-dimensional flexible hinge platform, the present invention has the following outstanding advantages: the optical fiber is used as the sensitive element of the feedback sensor, which has the advantages of strong anti-interference and high displacement measurement accuracy; the optical fiber displacement sensor and the piezoelectric ceramic driven The two-dimensional flexible hinge workbench is integrated, with compact structure and greater flexibility in use; the optical fiber itself has the characteristics of good electrical insulation performance, no electromagnetic interference, no sparks, and can be used in flammable and explosive environments. High, fast response, small size. The measurement accuracy of the optical fiber displacement sensor is high, which can reach the sub-nanometer level; the application of the optical fiber displacement sensor to the two-dimensional flexible hinge platform driven by piezoelectric ceramics can greatly improve the dynamic test range and sensitivity of the mechanism, and the driving accuracy and positioning stability Sex is improved.

Description of drawings

Fig. 1 is a schematic structural diagram of an embodiment of the present invention.

FIG. 2 is a top view of FIG. 1 .

Fig. 3 is a left side view of Fig. 1 .

FIG. 4 is an enlarged view of part A of FIG. 1 .

Detailed ways

1 to 3, the present invention is provided with a two-dimensional flexible hinge platform 1 (consisting of a platform base 12 and a mobile platform 11), a transverse piezoelectric ceramic driver 2, a longitudinal piezoelectric ceramic driver 3, and a transverse optical fiber displacement sensor (not shown in the figure). Draw) and longitudinal optical fiber displacement sensor (not drawn in the figure). The two-dimensional flexible hinge platform 1 is provided with a transverse installation hole 111 on the transverse centerline and a longitudinal installation hole 112 on the longitudinal centerline, as well as a transverse fiber installation channel 13 and a longitudinal fiber installation channel 14 . The transverse optical fiber displacement sensor is provided with a main body and a transverse optical fiber, and the longitudinal optical fiber displacement sensor is provided with a main body and a longitudinal optical fiber. The horizontal optical fiber and the vertical optical fiber are arranged in the horizontal optical fiber installation channel 13 and the longitudinal optical fiber installation channel 14 respectively, and the horizontal optical fiber installation channel 13 and the longitudinal optical fiber installation channel 14 are arranged between the platform base 12 and the mobile platform 11 . The horizontal optical fiber installation path 13 and the longitudinal optical fiber installation path 14 are respectively provided with curved tooth structures 132 and 142, the horizontal optical fiber is input from the entrance 131 of the horizontal optical fiber installation path 13, and is output from the outlet 132 of the horizontal optical fiber installation path 13 through the curved tooth structure 132, The input end of the transverse optical fiber is connected to the light source, and the output end of the transverse optical fiber is connected to the body of the transverse optical fiber displacement sensor. The longitudinal optical fiber is input from the entrance 141 of the longitudinal optical fiber installation channel 14, and output from the outlet 143 of the longitudinal optical fiber installation channel 14 through the curved tooth structure 142. The input end of the longitudinal optical fiber is connected to the light source, and the output end of the longitudinal optical fiber is connected to the body of the longitudinal optical fiber displacement sensor. The lateral optical fiber displacement sensor and the longitudinal optical fiber displacement sensor are externally connected to a detection closed-loop control device (not shown in the figure).

The transverse piezoelectric ceramic driver is provided with a piezoelectric ceramic element 21, a connector 22 and a wire (not shown in the figure), the piezoelectric ceramic element 21 is arranged on the connector 22, one end of the wire is connected to the piezoelectric ceramic element 21, and the other end of the wire is connected to the piezoelectric ceramic element 21. One end is externally connected to a detection closed-loop control device. The connecting piece 22 is screwed to the transverse installation hole 111 of the two-dimensional flexible hinge platform 1 .

The longitudinal piezoelectric ceramic driver 3 is provided with a piezoelectric ceramic element 31, a connector 32 and a wire (not shown in the figure), the piezoelectric ceramic element 31 is located on the connector 32, and one end of the wire is connected to the piezoelectric ceramic element 31, and the wire The other end is externally connected to a detection closed-loop control device. The connecting piece 32 is screwed to the longitudinal installation hole 112 of the two-dimensional flexible hinge platform 1 .

The curved tooth structure 132 of the transverse optical fiber installation channel is a tooth-shaped mating groove.

The curved tooth structure 142 of the longitudinal optical fiber installation channel is a tooth-shaped mating groove.

Referring to FIG. 4 , the curved tooth structure 132 of the horizontal optical fiber installation path is arranged between the platform seat 12 and the mobile platform 11 (the curved tooth structure 142 of the longitudinal optical fiber installation path is also arranged between the platform seat 12 and the mobile platform 11 ). The provided curved tooth structure 132 is a tooth-shaped matching groove, and the optical fiber 4 passes through the tooth-shaped matching groove. Unidirectional arrows indicate the directions of light input and light output of the optical fiber 4 . The two-way arrow indicates the direction of displacement generated by the two-dimensional flexible hinge platform 1. When the piezoelectric ceramic driver drives the mobile platform 11 to move, the small displacement generated by the mobile platform 11 will cause the optical fiber to be squeezed by the toothed groove, causing the optical fiber to undergo microbending deformation. , therefore, as long as the change of light intensity is detected at the output end of the optical fiber, the modulation amount (that is, the displacement amount) can be detected, and then the modulation amount is fed back to the control system to control and adjust the mobile platform 11, so that the mobile platform 11 can achieve precise Positioning can effectively improve the precision of the two-dimensional flexible hinge workbench 1 . Thus, a reliable optical fiber displacement feedback closed-loop control system is formed.

The curved tooth structure 142 of the longitudinal optical fiber installation track is also arranged between the platform base 12 and the mobile platform 11. The structure and working principle of the curved tooth structure 142 are the same as those of the curved tooth structure 132 of the horizontal optical fiber installation track. The single-headed arrow in FIG. 4 represents the light transmission direction of the optical fiber, and the double-headed arrow represents the displacement direction of the mobile platform 11 .

The determination of the tooth pitch Λ of the curved tooth structure is very important. The design principle of the tooth pitch Λ is given below: due to the different bending periods of the optical fiber, the bending loss is also different, and the modulation sensitivity is also different. The optical fiber will produce the greatest bending loss only under the optimal bending tooth spacing, that is, the modulation is the most sensitive. For a fiber whose refractive index distribution is n ² (r)=n ₀ ² [1-2Δ(r/a) ^a ], theoretical analysis shows that the propagation constant β in the core and the propagation constant β in the cladding satisfy:

$\mathrm{<span\; class="notranslate">\; \&Delta;\&beta;</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; g</span>}}{\mathrm{<span\; class="notranslate">\; g</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\sqrt{\mathrm{<span\; class="notranslate">\; \&Delta;</span>}}}{\mathrm{<span\; class="notranslate">\; a</span>}}{<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; )</span>}^{\frac{\mathrm{<span\; class="notranslate">\; g</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; g</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

In the formula: a—core radius, α—constant characterizing the refractive index distribution of the fiber, m—the ordinal number of the mode,

M——the total number of modes, Δ=[n ² (0)-n ² (a)]/2n ² (0), n(0)——refractive index at the axis

n(a)——Refractive index at radius a.

The optimal tooth spacing Λ of the optimal curved tooth satisfies: ${\mathrm{\&Lambda;}}_o=\frac{2\mathrm{\&pi;}}{\mathrm{\&Delta;\&beta;}}={(1+\frac{2}{g})}^{\frac{1}{2}}\frac{\mathrm{\&pi;a}}{\sqrt{\mathrm{\&Delta;}}}{\left(\frac{m}{m}\right)}^{\frac{g-2}{g+2}}---\left(2\right)$

Claims (7)

1. two-dimension flexible hinge work bench of fiber optics displacement feedback closed-loop control is characterized in that being provided with two-dimension flexible hinge platform, horizontal piezoelectric ceramic actuator, vertical piezoelectric ceramic actuator, horizontal optical fibre displacement sensor and vertical optical fibre displacement sensor; The two-dimension flexible hinge platform is provided with horizontal mounting hole and vertical mounting hole, and laterally optical fiber is installed road and vertical optical fiber installation road, laterally piezoelectric ceramic actuator and vertically piezoelectric ceramic actuator be located in the horizontal mounting hole respectively and vertically in the mounting hole, laterally optical fibre displacement sensor is provided with horizontal optical fiber, vertically optical fibre displacement sensor is provided with vertical optical fiber, horizontal optical fiber installation road is located at respectively by horizontal optical fiber and vertical optical fiber and vertical optical fiber is installed in the road, laterally optical fiber installation road and vertical optical fiber are installed the road and are equipped with curved toothing, laterally optical fiber and the vertically external detection closed-loop control device of output terminal of optical fiber;

Described horizontal piezoelectric ceramic actuator is provided with piezo ceramic element, lead and web member, piezo ceramic element is located on the web member, lead one end is connected with piezo ceramic element, the external detection closed-loop control device of the lead other end, web member is connected with horizontal mounting hole, vertically piezoelectric ceramic actuator is provided with piezo ceramic element, lead and web member, piezo ceramic element is located on the web member, lead one end is connected with piezo ceramic element, the external detection closed-loop control device of the lead other end, web member is connected with vertical mounting hole.

2. two-dimension flexible hinge work bench of fiber optics displacement feedback closed-loop control as claimed in claim 1 is characterized in that the web member of horizontal piezoelectric ceramic actuator is threaded with horizontal being connected to of mounting hole.

3. two-dimension flexible hinge work bench of fiber optics displacement feedback closed-loop control as claimed in claim 1 is characterized in that the web member of vertical piezoelectric ceramic actuator is threaded with vertical being connected to of mounting hole.

4. two-dimension flexible hinge work bench of fiber optics displacement feedback closed-loop control as claimed in claim 1 is characterized in that horizontal mounting hole is to be located at the two-dimension flexible hinge platform side, and is positioned on the cross central line of two-dimension flexible hinge platform.

5. two-dimension flexible hinge work bench of fiber optics displacement feedback closed-loop control as claimed in claim 1 is characterized in that vertical mounting hole is to be located at the two-dimension flexible hinge platform side, and is positioned on the longitudinal centre line of two-dimension flexible hinge platform.

6. two-dimension flexible hinge work bench of fiber optics displacement feedback closed-loop control as claimed in claim 1 is characterized in that it is the involutory groove of profile of tooth that horizontal optical fiber is installed the curved toothing in road.

7. two-dimension flexible hinge work bench of fiber optics displacement feedback closed-loop control as claimed in claim 1 is characterized in that it is the involutory groove of profile of tooth that vertical optical fiber is installed the curved toothing in road.

Images