CN107160368B - Control device and method for planar two-degree-of-freedom parallel mechanism driven by linear motor - Google Patents

Abstract

The invention discloses a control device and a control method for a plane two-degree-of-freedom parallel mechanism driven by a linear motor, wherein the device comprises a parallel mechanism body, a detection unit and a control unit, and the parallel mechanism body comprises a movable platform, a passive movement branched chain and two active movement branched chains; the passive movement branched chain comprises a first bracket, a first primary rod, a second primary rod, a first secondary rod, a second secondary rod and a transverse connecting rod, and each active movement branched chain comprises a linear motor module, a second bracket, a first active rod and a second active rod; the movable platform is in the shape of an equilateral triangle, the first side of the movable platform is connected with the passive movement branched chain, the second side of the movable platform is connected with one of the active movement branched chains, and the third side of the movable platform is connected with the other active movement branched chain. According to the invention, three movement branched chains are designed, and two of the three movement branched chains directly drive the driving rod to control the movement of the movable platform through the linear motor, so that the movable platform has the advantages of high control precision, simple structure, quick response and good rigidity, and has good industrial practicability.

Description

Control device and method for planar two-degree-of-freedom parallel mechanism driven by linear motor

technical field

The invention relates to a parallel mechanism control device, in particular to a linear motor-driven planar two-degree-of-freedom parallel mechanism control device and method, belonging to the field of motion control of planar mechanisms.

Background technique

At present, with the development of technology, the level of automation in the manufacturing industry is getting higher and higher, which means that robotic devices will be used more and more in the field of industrial production, and more and more robotic devices are used in industrial production. In order to improve production Efficiency and product quality, the speed and precision requirements of robotic devices are also getting higher and higher. Traditional robotic devices mostly use motor accelerators or hydraulic drives. The drive methods of motor accelerators often bring about unavoidable problems such as large internal friction, increased moment of inertia, and backlash. The friction, tooth backlash, and elastic deformation will cause nonlinearity, resulting in unsatisfactory control bandwidth and operability of the robot device, and it is difficult to meet the requirements of high speed and high precision. The hydraulic drive also has the disadvantages of poor reliability and difficult maintenance. .

Contents of the invention

The object of the present invention is to solve the defects of the above-mentioned prior art, and to provide a plane two-degree-of-freedom parallel mechanism control device driven by a linear motor. The motor directly drives the active rod to control the movement of the braking platform, which has the advantages of high control precision, simple structure, fast response and good rigidity, and has good industrial applicability.

Another object of the present invention is to provide a method for controlling a plane two-degree-of-freedom parallel mechanism based on the above device.

The purpose of the present invention can be achieved by taking the following technical solutions:

The planar two-degree-of-freedom parallel mechanism control device driven by a linear motor includes a parallel mechanism body, a detection unit and a control unit, and the parallel mechanism body includes a moving platform, a passive kinematic branch chain and two active kinematic branch chains;

The passive motion branch chain includes a first bracket, a first level rod, a second level rod, a first level two rod, a second level two rod and a transverse link, a first level level rod and a second level level rod One end of the first bracket is rotatably connected with the first bracket, the other end of the first level lever is rotatably connected with one end of the first level two lever, the other end of the second level lever is rotatably connected with one end of the second level lever, and the first level lever is rotatably connected with one end of the second level lever. The connection between the primary rod and the first secondary rod is connected with the connection between the second primary rod and the second secondary rod through a transverse connecting rod;

Each active motion branch chain includes a linear motor module, a second bracket, a first active rod and a second active rod, the linear motor module drives the second bracket to move linearly, and one end of the first active rod and the second active rod respectively rotatably connected with the second bracket;

The shape of the moving platform is an equilateral triangle, the first side of the moving platform is rotationally connected with the first two-stage rod of the passive motion branch chain and the other end of the second two-stage rod, and the second side is connected with the first two-stage rod of one of the active motion branch chains. One active rod is rotationally connected to the other end of the second active rod, and the third side is rotationally connected to the other end of the first active rod and the second active rod of another active motion branch chain;

The detection unit includes a first angular displacement sensor, a second angular displacement sensor, a displacement sensor and an acceleration sensor, the first angular displacement sensor is arranged on the first bracket, and the second angular displacement sensor is arranged on the first and second stages On the rod, the displacement sensor is arranged on the linear motor module, and the acceleration sensor is arranged on the moving platform;

The control unit is respectively connected with the first angular displacement sensor, the second angular displacement sensor, the displacement sensor, the acceleration sensor and the linear motor module.

Further, the linear motor module includes a linear motor, a guide rail, a first pad and a connecting block, the linear motor is arranged in parallel with the guide rail, the mover of the linear motor and the slider of the guide rail are located on the same horizontal plane, and the guide rail fixed on the first pad, the connecting block is fixed on the slider of the guide rail, and fixedly connected with the mover of the linear motor, and the second bracket is fixed on the connecting block;

The displacement sensor includes a magnetic grating ruler and a magnetic grating reading head, the magnetic grating ruler is attached to the side of the first pad, and the magnetic grating reading head is installed on the connecting block.

Further, two holes are provided on the three sides of the moving platform, and the two holes on the first side of the moving platform pass through the first rotating shaft and the first two-level rod and the second two-level rod of the passive motion branch chain respectively. One end is hinged, the two holes on the second side are respectively hinged to the first active rod of one of the active movement branches and the other end of the second active rod through the second rotating shaft, and the two holes on the third side are respectively connected to the other end through the third rotating shaft. The other ends of the first active rod and the second active rod of an active motion branch chain are hinged.

Further, one end of the first first-level rod is hinged to the first bracket through the fourth rotating shaft, and the other end of the first first-level rod is hinged to one end of the first and second-level rod through the fifth rotating shaft; One end of the rod is hinged to the first bracket through the sixth rotating shaft, the other end of the second level rod is hinged to one end of the second and second level rod through the seventh rotating shaft, and the two ends of the transverse connecting rod are respectively connected to the fifth rotating shaft , the seventh shaft connection;

One end of the first active rod is hinged to the second bracket through the eighth rotating shaft, and one end of the second active rod is hinged to the second bracket through the ninth rotating shaft.

Further, the first angular displacement sensor is a first code wheel, the first code wheel is fixed on the first bracket through a third bracket, and the shaft of the first code wheel is connected to the fourth rotating shaft through a first coupling connect;

The second angular displacement sensor is a second code wheel, and the second code wheel is fixed on the first secondary rod through the fourth bracket, and the shaft of the second code wheel is connected with the fifth rotating shaft through the second shaft coupling .

Further, the first bracket is provided with a first ear piece and a second ear piece with holes, the hole on the first ear piece is hinged to one end of the first stage rod through the fourth rotating shaft, and the first ear piece The hole on the two lugs is hinged with one end of the second level rod through the sixth rotating shaft;

The second bracket is provided with a third ear piece and a fourth ear piece with holes, the hole on the third ear piece is hinged with one end of the first active rod through the eighth rotating shaft, and the fourth ear piece is The hole of the hole is hinged with one end of the second active lever through the ninth rotating shaft.

Further, for the passive motion branch chain, the lengths of the first and second primary rods are the same, the lengths of the first and second secondary rods are the same, and the two ears of the first bracket The distance between the axes of the holes on the piece is the same as the distance between the axes of the two holes on the first side of the moving platform; the line between the axes of the holes on the two ear pieces of the first bracket, the A first-stage rod, a second-stage rod and a transverse connecting rod form a first parallelogram structure, and the transverse connecting rod, the first-two-stage rod, the second-two-stage rod and the axes of the two holes on the first side of the moving platform The connecting line between constitutes the second parallelogram structure;

For one of the active motion branch chains, the length of the first active rod and the second active rod are the same, and the distance between the axes of the holes on the two ear pieces of the second bracket is the same as the axis of the two holes on the second side of the moving platform. The distance between them is the same; the connecting line between the axis centers of the holes on the two lugs of the second bracket, the axis of the two holes on the second side of the first active rod, the second active rod and the moving platform The connection line constitutes the third parallelogram structure;

For another active motion branch chain, the lengths of the first active rod and the second active rod are the same, and the distance between the axis centers of the holes on the two lugs of the second support is the same as the axis centers of the two holes on the third side of the moving platform. The distance between them is the same; the connecting line between the axis of the holes on the two ear pieces of the second bracket, the axis of the two holes on the third side of the first active rod, the second active rod and the moving platform The connecting lines form the fourth parallelogram structure.

Further, the parallel mechanism body also includes a static platform, the static platform includes a base plate, four supporting feet are provided at the bottom of the base plate, and a transverse bracket is installed between every two adjacent supporting feet;

The first bracket is fixed on the base plate of the static platform through the second pad, and the linear motor and the first pad are fixed on the base plate of the static platform in parallel.

Further, the control unit includes a computer, a motion control card, a terminal board and a linear motor servo drive unit, the computer is connected to the motion control card, and the motion control card integrates A/D conversion and pulse counting functions, and communicates with The terminal board is connected, and the terminal board is respectively connected to the first angular displacement sensor, the second angular displacement sensor, the displacement sensor, the acceleration sensor and the linear motor servo drive unit, and the linear motor servo drive unit is connected to the linear motor;

The acceleration sensor measures the acceleration signals of the moving platform in two directions on the horizontal plane, the first angular displacement sensor measures the angular displacement signal of the first stage rod relative to the first bracket, and the second angular displacement sensor measures the first The angular displacement signal, acceleration signal and angular displacement signal of the first and second poles relative to the first one are input to the motion control card through the terminal board for A/D conversion to obtain digital signals, and the digital signals are processed by the computer to obtain the moving platform. Feedback signal;

The displacement sensor measures the displacement signal of the linear motor mover, the displacement signal is input to the motion control card through the terminal board for pulse counting to obtain a digital signal, and the computer processes the digital signal to obtain the output signal of the linear motor;

The computer obtains the control signal according to the feedback signal of the moving platform and the output signal of the linear motor, and the control signal is input to the linear motor servo drive unit through the motion control card and the terminal board to control the output of the linear motor and realize the motion control of the moving platform.

Another object of the present invention can be achieved by taking the following technical solutions:

Based on the control method of the plane two-degree-of-freedom parallel mechanism of the above-mentioned device, the method comprises the following steps:

Step 1: The acceleration sensor on the moving platform measures the acceleration signals along the X and Y directions when the moving platform is moving horizontally, and at the same time the first angular displacement sensor measures the angular displacement of the first stage rod relative to the first bracket signal, the second angular displacement sensor measures the angular displacement signal of the first secondary rod relative to the first primary rod, and after performing kinematic inverse solution to the acceleration signal and angular displacement signal, the velocity and acceleration component signals of the linear motor are obtained;

Step 2. Input the analog signal measured in step 1 to the motion control card through the terminal board for A/D conversion to obtain a digital signal, and process the digital signal by the computer to obtain the feedback signal of the moving platform;

Step 3. Use the displacement sensor to measure the displacement signal of the linear motor mover. The displacement signal is input to the motion control card through the terminal board for pulse counting to obtain a digital signal, and the computer processes the digital signal to obtain the output signal of the linear motor;

Step 4. The computer compares the output signal of the linear motor with the feedback signal of the moving platform, then compares it with the expected motion and position parameters, and runs the corresponding control algorithm to obtain the required control signal. The control signal passes through the motion The control card and the terminal board are input to the linear motor servo drive unit, and the linear motor servo drive unit controls the output of the linear motor according to the control signal, thereby realizing the motion control of the moving platform.

Compared with the prior art, the present invention has the following beneficial effects:

1. The present invention designs three kinematic branch chains, one of which is used as a passive kinematic branch chain, and the other two are used as active kinematic branch chains. The two active kinematic branch chains are directly driven by a linear motor module without an intermediate transmission mechanism. , so the linear motor module can directly drive the two active rods to move, and the two active rods control the movement of the braking platform. The direct drive method does not need to use an intermediate transmission mechanism such as a reducer, which reduces the impact of friction. The problem of tooth backlash, the mechanical structure is simpler and more compact, which greatly improves the motion control accuracy and response speed of the parallel mechanism, the reliability is higher, and the maintenance is simpler; in addition, an acceleration sensor is set on the moving platform to measure Acceleration signals along two directions on the horizontal plane during motion. Angular displacement sensors are installed on the bracket of the passive motion branch chain and a secondary rod, which can measure the angular displacement signal of the primary rod relative to the bracket, and measure the angular displacement signal of the secondary rod Relative to the angular displacement signal of the primary rod, a displacement sensor is installed on the linear motor module to measure the displacement signal of the linear motor module. According to these measured parameters, the motion control of the moving platform is realized.

2. In the passive motion branch chain of the present invention, the primary rod and the secondary rod are rigid rods and are hinged. In each active motion branch chain, the two active rods are rigid rods, which makes the system simple in structure and high in quality , High rigidity, compared with the flexible structure, it has the advantages of stable torque transmission, large system rigidity, and little influence of flexible deformation on the motion trajectory. At the same time, high rigidity has the characteristics of small deformation, smaller torque transmission loss, and more accurate motion parameter acquisition and system motion control.

3. In each active motion branch chain of the present invention, the line between the axis centers of the holes on the two ear pieces of the bracket, the line between the two active rods and the axis centers of the two holes on the same side of the moving platform A parallelogram structure is formed. In the passive motion branch chain, the line between the axes of the holes on the two ear pieces of the bracket, the two primary rods and the transverse connecting rod form a parallelogram structure. The transverse connecting rod, the two The connection line between the secondary rod and the axes of the two holes on the same side of the moving platform also forms a parallelogram structure. Under the constraints of the parallelogram structure of the moving branch chain, the moving platform can only do translational movement and cannot rotate, so the moving platform The platform has only two degrees of freedom, and the two-degree-of-freedom platform is simple to control, stable in structure, and widely used.

4. The present invention adopts a feedback control loop. The acceleration sensor installed on the moving platform can measure the acceleration signals along two directions on the horizontal plane when the moving platform moves, and the code disc on the moving branch chain can measure the angular displacement of the corresponding rod of the moving branch chain Signal, the linear motor uses a magnetic scale to measure the displacement signal of the linear motor mover. The parameters measured by each sensor are input to the motion control card through the terminal board to process the digital signal, and the computer processes the digital signal to obtain the control signal. The control signal controls The rotating motor servo unit is used to control the output of the rotating motor, thereby controlling the movement of the braking platform.

Description of drawings

Fig. 1 is a schematic diagram of the overall structure of a planar two-degree-of-freedom parallel mechanism control device driven by a linear motor according to Embodiment 1 of the present invention.

2 is a structural diagram of a parallel mechanism body in a planar two-degree-of-freedom parallel mechanism control device driven by a linear motor according to Embodiment 1 of the present invention.

3 is a top view of the parallel mechanism body in the planar two-degree-of-freedom parallel mechanism control device driven by a linear motor according to Embodiment 1 of the present invention.

4 is a schematic diagram of the passive motion branch chain structure of the parallel mechanism body in the planar two-degree-of-freedom parallel mechanism control device driven by a linear motor according to Embodiment 1 of the present invention.

5 is a schematic structural diagram of a linear motor module of one of the active motion branches of the parallel mechanism body in the planar two-degree-of-freedom parallel mechanism control device driven by a linear motor according to Embodiment 1 of the present invention.

Among them, 1-moving platform, 2-static platform, 3-base plate, 4-supporting feet, 5-horizontal bracket, 6-first bracket, 7-first level rod, 8-second level rod, 9- The first two rods, 10-the second two rods, 11-transverse connecting rod, 12-the first ear piece, 13-the second ear piece, 14-the second bracket, 15-the first active rod, 16-the first Two active rods, 17-third ear piece, 18-fourth ear piece, 19-linear motor, 20-guide rail, 21-first pad, 22-connecting block, 23-second pad, 24-acceleration sensor , 25-first code disc, 26-third bracket, 27-first coupling, 28-second code disc, 29-fourth bracket, 30-second coupling, 31-magnetic scale, 32 - Magnetic grid reading head, 33 - computer, 34 - motion control card, 35 - terminal board, 36 - linear motor servo drive unit.

Detailed ways

The present invention will be further described in detail below in conjunction with the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

Example 1:

Due to the advantages of high load-carrying capacity, low inertia, high rigidity, compact structure, and easy realization of kinematic inverse solution, parallel mechanism has application value in many fields. Especially the planar two-degree-of-freedom parallel mechanism is more widely used because of its relatively simple structure, good stability, and simple control algorithm.

This embodiment designs a reasonable mechanical structure, selects a suitable linear motor, builds a coordinated drive control system, and provides a plane two-degree-of-freedom parallel mechanism control device driven by a linear motor. The device adopts a direct drive mode, omitting the intermediate transmission The device directly connects the load with the driving motor, which can fundamentally solve various problems caused by the use of transmission devices, greatly improves the control bandwidth and operability of parallel mechanisms, and has high speed, high precision, light weight, small size, It has the advantages of high rigidity, simple maintenance, simple mechanical structure design, high reliability, and good speed control.

As shown in Figures 1 to 3, the control device for a planar two-degree-of-freedom parallel mechanism in this embodiment includes a parallel mechanism body, a detection unit, and a control unit. The parallel mechanism body includes a moving platform 1, a static platform 2, and three active supports. chain, one of which is a passive kinematic branch, and the other two are active kinematic branches; the static platform is hidden in Fig. Detect and control the direction of signal flow.

The moving platform 1 is a triangular plate, the shape of which is an equilateral triangle, and two holes are arranged on its three sides. The two holes on the first side of the moving platform 1 are respectively connected with the passive movement branch chain through the first rotating shaft, and the second The two holes on one side are connected to an active motion branch chain through the second rotating shaft, the two holes on the third side are connected to another active motion branch chain through the third rotating shaft, and the two holes on the first side, the second side and the third side The distances between the axes of the holes are the same.

The static platform 2 is used to support the dynamic platform 1 and three motion branch chains, including a base plate 3, the base plate 3 is a square base plate, and its bottom is provided with four supporting feet 4, and each two adjacent supporting feet 4 are installed A horizontal support 5 plays a stable role. The base plate 3, the supporting feet 4 and the horizontal support 5 are all made of aluminum profiles.

As shown in Figures 1 to 4, the passive motion branch chain includes a first bracket 6, a first primary rod 7, a second primary rod 8, a first secondary rod 9, a second secondary rod 10 and a transverse The connecting rod 11, the first bracket 6 is provided with a first ear piece 12 and a second ear piece 13 with holes, the hole on the first ear piece 12 is hinged with one end of the first stage rod 7 through the fourth rotating shaft, the second The other end of the first level rod 7 is hinged with one end of the first second level rod 9 through the fifth rotating shaft; the hole on the second ear piece 13 is hinged with one end of the second level rod 8 through the sixth rotating shaft, and the second level The other end of bar 8 is hinged with an end of second secondary lever 10 by the seventh rotating shaft; two holes are hinged; the two ends of the transverse connecting rod 11 are respectively connected with the fifth rotating shaft and the seventh rotating shaft, that is, the hinge of the first primary rod 7 and the first secondary rod 9 is connected with the second primary rod 8 and the first secondary rod 9. The hinges of the second and second poles 10 are connected by a transverse link 11, so that the first level lever 7, the first second level lever 9 and the transverse link 11 form a compound hinge structure, which can rotate with each other, and the second level The rod 8, the second two-stage rod 10 and the transverse connecting rod 11 also constitute a composite hinge structure, which can rotate with each other.

In this embodiment, the lengths of the first primary rod 7 and the second primary rod 8 are the same, the lengths of the first secondary rod 9 and the second secondary rod 10 are the same, and the two ears of the first bracket 6 The distance between the axis centers of the holes on the part is the same as the distance between the axis centers of the two holes on the first side of the moving platform 1, the line between the axis centers of the holes on the two lugs of the first bracket 6, the One level rod 7, the second level rod 8 and the transverse connecting rod 11 form the first parallelogram structure, the transverse connecting rod 11, the first two level rod 9, the second two level rod 10 and the first side of the moving platform 1 The line connecting the axes of the two holes constitutes a second parallelogram structure.

The structures of the two active motion branch chains are identical. Taking one of the active motion branch chains as an example, as shown in FIGS. 1 to 3 and 5, each active motion branch chain includes a linear motor module, a second bracket 14, The first active rod 15 and the second active rod 16, the linear motor module drives the second bracket 14 to move linearly, the second bracket 14 is provided with a third ear piece 17 and a fourth ear piece 18 with holes, the third ear piece The hole on 17 is hinged with one end of the first active rod 15 through the eighth rotating shaft, and the hole on the fourth ear piece 18 is hinged with one end of the second active rod 16 through the ninth rotating shaft. For one of the active motion branch chains, The other end of the first active link 15 and the second active link 16 are respectively hinged with two holes on the second side of the moving platform 1 through the second rotating shaft. For another active motion branch chain, the first active link 15 and the second active link The other end of 16 is respectively hinged with two holes on the third side of the moving platform 1 through the third rotating shaft.

The linear motor module of each active motion branch chain includes a linear motor 19, a guide rail 20, a first pad 21 and a connecting block 22, and the linear motor 19 and the first pad 21 are installed in parallel on the base plate 3 of the static platform 2, wherein The linear motor 19 is installed sideways on the static platform 2 and fixed by bolts. The guide rail 20 is fixed on the first pad 21 by screws and is parallel to the linear motor 19. The connecting block 22 is an L-shaped connecting block. The connecting block 22 One right-angled side of one side is fixedly installed on the slide block of the guide rail 20 through screws, the other right-angled side of the connecting block 22 is fixedly connected with the mover of the linear motor 19 through screws, and the second bracket 14 is fixed on the connecting block 22. In the linear motor Driven by 19, the connecting block 22 drives the second bracket 14 to move linearly within a certain range along the guide rail 20, driving the first active rod 15 and the second active rod 16 to move, thereby controlling the motion of the braking platform 1; the passive motion support The first bracket 6 of the chain is fixed on the base plate 3 of the static platform 2 through the second spacer 23 .

In this embodiment, the linear motor 19 is a linear motor produced by American Rockwell Company, the mover model is LZ-030-0-240, and the corresponding stator model is LZM-030-0-600; the guide rail 20 is selected from Shanghai Misi The SSE2B H16 guide rail produced by Mi Company uses double sliders; for one of the active motion branch chains, the first active rod 15 and the second active rod 16 have the same length and remain parallel, and the two ears of the second bracket 14 The distance between the axis centers of the holes on the part is the same as the distance between the axes of the two holes on the second side of the moving platform 1, the line between the axes of the holes on the two lugs of the second bracket 14, The connecting line between the two hole axes on the second side of an active rod 15, the second active rod 16 and the moving platform 1 constitutes the third parallelogram structure; for another active motion branch chain, the first active rod 15 and the second active rod The length of the two active rods 16 is the same, the distance between the axis of the holes on the two ears of the second support 14 is the same as the distance between the axes of the holes on the third side of the moving platform 1, and the distance between the axes of the holes on the two ears of the second support 14 is identical. The line between the axes of the holes on the two earpieces, the line between the first active rod 15, the second active rod 16 and the axes of the two holes on the third side of the moving platform 1 constitutes a fourth parallelogram structure .

The two parallelogram structures on the three motion branch chains restrict the moving platform 1 to translational motion on the horizontal plane, and have two degrees of freedom. The two-degree-of-freedom moving platform 1 is easy to control, stable in structure, and widely used; in addition In this embodiment, the linear motor modules of the two active motion branch chains and the first support of the passive motion branch chain form an angle of 60 degrees with each other, but do not form an equilateral triangle.

Described detection unit comprises the first angular displacement sensor, the second angular displacement sensor, displacement sensor and acceleration sensor 24; The first angular displacement sensor is the first code wheel 25, and the first code wheel 25 is fixed on the first by the 3rd bracket 26. On the bracket 6, and the shaft of the first code wheel 25 is connected with the fourth rotating shaft through the first coupling 27, because the fourth rotating shaft is the rotating shaft hinged between the first bracket 6 and the first primary rod 7, so the first The code disc 25 can measure the angular displacement signal of the first level rod 7 relative to the first bracket 6; the second angular displacement sensor is the second code disc 28, and the second code disc 28 is fixed on the first and second level by the fourth bracket 29. on the rod 9, and the shaft of the second code wheel 28 is connected with the fifth rotating shaft through the second coupling 30, since the fifth rotating shaft is the hinged rotating shaft between the first secondary rod 9 and the first primary rod 7, therefore The second code disc 28 can measure the angular displacement signal of the first secondary rod 9 relative to the first primary rod 7; the displacement sensor includes a magnetic grating scale 31 and a magnetic grating reading head 32, and the magnetic grating scale 31 is attached to the first pad On the side of 21, the magnetic grid reading head 32 is installed on the connecting block 22, which can move with the connecting block 22 under the drive of the linear motor 19, and the magnetic grating scale 31 can measure the displacement signal of the linear motor 19 movers; the acceleration sensor 24 is installed On the moving platform 1, specifically installed at the center of the upper surface of the moving platform 1, the acceleration signals of the moving platform 1 along two directions (X direction, Y direction) on the horizontal plane can be measured.

In the present embodiment, the acceleration sensor 24 selects the capacitive, low-frequency accelerometer of Swiss Kistler Company for use, and the model is 8395A2D0, and the first code disc 25 and the second code disc 28 all adopt the absolute value type AC36 type produced by Hengstler Company; Both the coupling 27 and the second coupling 30 are PCMR29-12-6-A produced by Ruland Company of the United States; the magnetic scale 31 is the magnetic scale MSR50H produced by Ningbo Eberg Measurement and Control Technology Co., Ltd. .

Described control unit comprises computer 33, motion control card 34, terminal board 35 and linear motor servo drive unit 36, and computer 33 is connected with motion control card 34, and motion control card 34 is connected with terminal board 35, and terminal board 35 is connected with first respectively. The code disc 25, the second code disc 28, the magnetic scale 31, the acceleration sensor 24 are connected with the linear motor servo drive unit 36, and the linear motor servo drive unit 36 is connected with the linear motor 19;

The acceleration sensor 24 measures the acceleration signals of the moving platform 1 in two directions on the horizontal plane, the first code disc 25 measures the angular displacement signal of the first level rod 7 relative to the first bracket 6, and the second code disc 28 measures the first two The angular displacement signal, acceleration signal and angular displacement signal of the stage rod 9 relative to the first stage rod 7 are input to the motion control card 34 through the terminal board 35 for A/D conversion to obtain a digital signal, which is obtained by processing the digital signal by a computer 33 The feedback signal of moving platform 1 (that is, the motion information of moving platform 1);

The magnetic scale 31 measures the displacement signal of the mover of the linear motor 19, and the displacement signal is input to the motion control card 34 through the terminal board 35 for pulse counting to obtain a digital signal, and the computer processes the digital signal to obtain the output signal of the linear motor;

The computer 33 obtains the control signal according to the feedback signal of the moving platform 1 and the output signal of the linear motor 19, and the control signal is input to the linear motor servo drive unit 36 through the motion control card 34 and the terminal board 35 to control the output of the linear motor 19 to realize the control of the linear motor 19. Motion control of moving platform 1.

In this embodiment, the CPU model selected by the computer 33 is core i7 7700k, the internal memory is 8GB, the motherboard has a PCI-e card slot, and a motion control card can be inserted; the motion control card 34 is selected from the GTS-400- PV-PCI series motion controller, the motion controller integrates multi-channel A/D conversion, D/A conversion and pulse counting functions, has 4 axis resource channels (each axis signal has an analog output, incremental Encoder input, motor control output and alarm reset function), optocoupler isolation general digital signal input and output each have 16 channels, quadruple frequency incremental auxiliary encoder input 2 channels, A/D analog sampling input 8 channels, The voltage range of analog input and output is: -10V～+10V.

As shown in Figures 1 to 5, this embodiment also provides a method for controlling a planar two-degree-of-freedom parallel mechanism, which is implemented based on the above-mentioned device, and includes the following steps:

Step 1, the acceleration sensor 24 on the moving platform 1 measures the acceleration signals along the X and Y directions of the moving platform 1 during the horizontal plane translational movement, and the first code disc 25 measures the first stage rod 7 relative to the first For the angular displacement signal of the bracket 6, the second code disc 28 measures the angular displacement signal of the first two-stage rod 9 relative to the first one-stage rod 7, and after the kinematic inverse solution is performed on the acceleration signal and the angular displacement signal, the linear motor is obtained 19 velocity and acceleration component signals;

Step 2: Input the analog signal measured in step 1 to the motion control card 34 through the terminal board 35 for A/D conversion to obtain a digital signal, and the computer 33 runs the corresponding control algorithm to process the digital signal to obtain the feedback signal of the moving platform 1 ;

Step 3: Use the magnetic grating ruler 31 to measure the displacement signal of the mover of the linear motor 19. The displacement signal is input to the motion control card 34 through the terminal board 35 for pulse counting to obtain a digital signal, and the computer 33 processes the digital signal to obtain the linear motor 19. output signal;

Step 4: The computer 19 compares the output signal of the linear motor with the feedback signal of the moving platform 1, then compares it with the expected motion and position parameters, and runs the corresponding control algorithm to obtain the required control signal, control signal Input the linear motor servo drive unit 36 through the motion control card 34 and the terminal board 35, the linear motor servo drive unit 36 controls the output of the linear motor 19 according to the control signal, drives the first active rod 15 and the second active rod 16, thereby realizing Motion control of moving platform 1.

In summary, the present invention designs three kinematic branch chains, one of which is used as a passive kinematic branch chain, and the other two are used as active kinematic branch chains. The intermediate transmission mechanism, so the linear motor module can directly drive the movement of the two active rods, and the two active rods control the movement of the braking platform. The direct drive method does not need to use an intermediate transmission mechanism such as a reducer, which reduces the impact caused by friction. impact, without the problem of backlash, the mechanical structure is simpler and more compact, which greatly improves the motion control accuracy and response speed of the parallel mechanism, with higher reliability and easier maintenance; in addition, an acceleration sensor is set on the moving platform, which can Measure the acceleration signals along the two directions on the horizontal plane when the moving platform is moving. Angular displacement sensors are installed on the bracket of the passive motion branch chain and a secondary rod, which can measure the angular displacement signal of the primary rod relative to the bracket, and measure For the angular displacement signal of the second-stage rod relative to the first-stage rod, a displacement sensor is installed on the linear motor module to measure the displacement signal of the linear motor module. According to these measured parameters, the motion control of the moving platform is realized.

The above is only a preferred embodiment of the patent of the present invention, but the scope of protection of the patent of the present invention is not limited thereto. Equivalent replacements or changes to the technical solutions and their inventive concepts all fall within the scope of protection of the invention patent.

Claims (8)

1. The plane two-degree-of-freedom parallel mechanism control device driven by the linear motor is characterized in that: the parallel mechanism comprises a parallel mechanism body, a detection unit and a control unit, wherein the parallel mechanism body comprises a movable platform, a passive movement branched chain and two active movement branched chains;

the passive movement branched chain comprises a first bracket, a first primary rod, a second primary rod, a first secondary rod, a second secondary rod and a transverse connecting rod, one ends of the first primary rod and the second primary rod are respectively connected with the first bracket in a rotating way, the other end of the first primary rod is connected with one end of the first secondary rod in a rotating way, the other end of the second primary rod is connected with one end of the second secondary rod in a rotating way, and the joint of the first primary rod and the first secondary rod is connected with the joint of the second primary rod and the second secondary rod through the transverse connecting rod;

each active movement branched chain comprises a linear motor module, a second bracket, a first active rod and a second active rod, wherein the linear motor module drives the second bracket to linearly move, and one ends of the first active rod and the second active rod are respectively connected with the second bracket in a rotating way;

the movable platform is in an equilateral triangle shape, a first side of the movable platform is rotationally connected with the other ends of a first secondary rod and a second secondary rod of a passive movement branched chain, a second side of the movable platform is rotationally connected with the other ends of a first driving rod and a second driving rod of one of the driving movement branched chains, and a third side of the movable platform is rotationally connected with the other ends of the first driving rod and the second driving rod of the other driving movement branched chain;

the detection unit comprises a first angular displacement sensor, a second angular displacement sensor, a displacement sensor and an acceleration sensor, wherein the first angular displacement sensor is arranged on the first bracket, the second angular displacement sensor is arranged on the first secondary rod, the displacement sensor is arranged on the linear motor module, and the acceleration sensor is arranged on the movable platform;

the control unit is respectively connected with the first angular displacement sensor, the second angular displacement sensor, the acceleration sensor and the linear motor module;

the linear motor module comprises a linear motor, a guide rail, a first cushion block and a connecting block, wherein the linear motor is arranged in parallel with the guide rail, a rotor of the linear motor and a sliding block of the guide rail are positioned on the same horizontal plane, the guide rail is fixed on the first cushion block, the connecting block is fixed on the sliding block of the guide rail and is fixedly connected with the rotor of the linear motor, and the second bracket is fixed on the connecting block; the displacement sensor comprises a magnetic grating ruler and a magnetic grating reading head, wherein the magnetic grating ruler is attached to the side edge of the first cushion block, and the magnetic grating reading head is arranged on the connecting block;

the three sides of the movable platform are respectively provided with two holes, the two holes on the first side of the movable platform are respectively hinged with the first secondary rod and the second secondary rod of the passive movement branched chain through a first rotating shaft, the two holes on the second side are respectively hinged with the first driving rod and the second driving rod of one of the driving movement branched chains through a second rotating shaft, and the two holes on the third side are respectively hinged with the first driving rod and the second driving rod of the other driving movement branched chain through a third rotating shaft.

2. The linear motor driven planar two-degree-of-freedom parallel mechanism control device of claim 1, wherein:

one end of the first primary rod is hinged with the first bracket through a fourth rotating shaft, and the other end of the first primary rod is hinged with one end of the first secondary rod through a fifth rotating shaft; one end of the second primary rod is hinged with the first bracket through a sixth rotating shaft, the other end of the second primary rod is hinged with one end of the second secondary rod through a seventh rotating shaft, and two ends of the transverse connecting rod are respectively connected with the fifth rotating shaft and the seventh rotating shaft;

one end of the first driving rod is hinged with the second bracket through an eighth rotating shaft, and one end of the second driving rod is hinged with the second bracket through a ninth rotating shaft.

3. The linear motor driven planar two-degree-of-freedom parallel mechanism control device of claim 2, wherein:

the first angular displacement sensor is a first code disc, the first code disc is fixed on the first bracket through a third bracket, and a shaft of the first code disc is connected with a fourth rotating shaft through a first coupler;

the second angular displacement sensor is a second code disc, the second code disc is fixed on the first secondary rod through a fourth bracket, and a shaft of the second code disc is connected with the fifth rotating shaft through a second coupler.

4. The linear motor driven planar two-degree-of-freedom parallel mechanism control device of claim 2, wherein:

the first bracket is provided with a first ear piece and a second ear piece with holes, the holes on the first ear piece are hinged with one end of a first level rod through a fourth rotating shaft, and the holes on the second ear piece are hinged with one end of a second level rod through a sixth rotating shaft;

the second bracket is provided with a third ear piece and a fourth ear piece with holes, the holes in the third ear piece are hinged with one end of the first driving rod through an eighth rotating shaft, and the holes in the fourth ear piece are hinged with one end of the second driving rod through a ninth rotating shaft.

5. The linear motor driven planar two-degree-of-freedom parallel mechanism control device of claim 4, wherein:

for the passive movement branched chain, the lengths of the first primary rod and the second primary rod are the same, the lengths of the first secondary rod and the second secondary rod are the same, and the distance between the axes of the holes on the two ear pieces of the first bracket is the same as the distance between the axes of the two holes on the first side of the movable platform; the connecting line between the hole axes on the two ear pieces of the first bracket, the first primary rod, the second primary rod and the transverse connecting rod form a first parallelogram structure, and the connecting line between the transverse connecting rod, the first secondary rod, the second secondary rod and the two hole axes on the first side of the movable platform form a second parallelogram structure;

for one of the active movement branched chains, the lengths of the first active rod and the second active rod are the same, and the distance between the axes of the holes on the two ear pieces of the second bracket is the same as the distance between the axes of the two holes on the second side of the movable platform; a third parallelogram structure is formed by a connecting line between the axes of the holes on the two ear pieces of the second bracket, a connecting line between the axes of the holes on the second side of the movable platform and the first driving rod and the second driving rod;

for the other active movement branched chain, the lengths of the first active rod and the second active rod are the same, and the distance between the axes of the holes on the two ear pieces of the second bracket is the same as the distance between the axes of the two holes on the third side of the movable platform; and a fourth parallelogram structure is formed by a connecting line between the axes of the holes on the two ear pieces of the second bracket, the first driving rod, the second driving rod and the connecting line between the axes of the two holes on the third side of the movable platform.

6. The linear motor driven planar two-degree-of-freedom parallel mechanism control device of claim 1, wherein: the parallel mechanism body further comprises a static platform, the static platform comprises a base plate, four supporting feet are arranged at the bottom of the base plate, and a transverse bracket is arranged between every two adjacent supporting feet;

the first support is fixed on the base plate of the static platform through the second cushion block, and the linear motor and the first cushion block are fixed on the base plate of the static platform in parallel.

7. The linear motor driven planar two-degree-of-freedom parallel mechanism control device of claim 1, wherein: the control unit comprises a computer, a motion control card, a terminal board and a linear motor servo driving unit, wherein the computer is connected with the motion control card, the motion control card integrates an A/D conversion function and a pulse counting function and is connected with the terminal board, the terminal board is respectively connected with a first angular displacement sensor, a second angular displacement sensor, a displacement sensor, an acceleration sensor and the linear motor servo driving unit, and the linear motor servo driving unit is connected with a linear motor;

the acceleration sensor measures acceleration signals of the movable platform in two directions on a horizontal plane, the first angular displacement sensor measures angular displacement signals of the first primary rod relative to the first bracket, the second angular displacement sensor measures angular displacement signals of the first secondary rod relative to the first primary rod, the acceleration signals and the angular displacement signals are input into the motion control card through the terminal board to be subjected to A/D conversion to obtain digital signals, and the digital signals are processed by the computer to obtain feedback signals of the movable platform;

the displacement sensor measures displacement signals of the linear motor rotor, the displacement signals are input into the motion control card through the terminal board to be subjected to pulse counting to obtain digital signals, and the digital signals are processed by the computer to obtain output signals of the linear motor;

the computer obtains a control signal according to the feedback signal of the movable platform and the output signal of the linear motor, the control signal is input to the linear motor servo driving unit through the motion control card and the terminal board, the output of the linear motor is controlled, and the motion control of the movable platform is realized.

8. The control method of the plane two-degree-of-freedom parallel mechanism based on the device of claim 7, which is characterized in that: the method comprises the following steps:

measuring acceleration signals of the movable platform along X, Y directions during horizontal translational movement of the movable platform by an acceleration sensor, measuring an angular displacement signal of a first primary rod relative to a first bracket by a first angular displacement sensor, measuring an angular displacement signal of a first secondary rod relative to the first primary rod by a second angular displacement sensor, and performing kinematic inverse solution on the acceleration signals and the angular displacement signals to obtain speed and acceleration component signals of a linear motor;

step two, the analog signal measured in the step one is input into a motion control card through a terminal board to be subjected to A/D conversion to obtain a digital signal, and the digital signal is processed by a computer to obtain a feedback signal of the movable platform;

measuring displacement signals of the linear motor rotor by using a displacement sensor, inputting the displacement signals into a motion control card through a terminal board to perform pulse counting to obtain digital signals, and processing the digital signals by a computer to obtain output signals of the linear motor;

and fourthly, the computer compares the output signal of the linear motor with the feedback signal of the movable platform, compares the output signal with expected motion and position parameters, runs a corresponding control algorithm to obtain a required control signal, and inputs the control signal into a linear motor servo driving unit through a motion control card and a terminal board, and the linear motor servo driving unit controls the output of the linear motor according to the control signal, so that the motion control of the movable platform is realized.

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