CN107160367B - Control device and method for plane two-degree-of-freedom parallel mechanism - Google Patents
Control device and method for plane two-degree-of-freedom parallel mechanism Download PDFInfo
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- CN107160367B CN107160367B CN201710506750.XA CN201710506750A CN107160367B CN 107160367 B CN107160367 B CN 107160367B CN 201710506750 A CN201710506750 A CN 201710506750A CN 107160367 B CN107160367 B CN 107160367B
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- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/003—Programme-controlled manipulators having parallel kinematics
- B25J9/0045—Programme-controlled manipulators having parallel kinematics with kinematics chains having a rotary joint at the base
- B25J9/0048—Programme-controlled manipulators having parallel kinematics with kinematics chains having a rotary joint at the base with kinematics chains of the type rotary-rotary-rotary
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Abstract
The invention discloses a control device and a control method for a plane two-degree-of-freedom parallel mechanism, wherein the device comprises a parallel mechanism body and a control unit, and the parallel mechanism body comprises a movable platform, a driven movement branched chain and two driving movement branched chains; the driven movement branched chain comprises a first supporting piece, a second supporting piece, a first rigid primary rod, a second rigid primary rod, a first rigid secondary rod, a second rigid secondary rod and a first connecting rod; each active movement branched chain comprises a direct drive rotating motor, a third supporting piece, a third rigid primary rod, a fourth rigid primary rod, a third rigid secondary rod, a fourth rigid secondary rod and a second connecting rod; the movable platform is provided with an acceleration sensor, a first side of the acceleration sensor is connected with the driven movement branched chain, and a second side and a third side of the acceleration sensor are respectively connected with the two driving movement branched chains; the control unit is respectively connected with the direct drive rotating motor and the acceleration sensor. The invention has the advantages of high control precision, quick response, good rigidity and simple structure, and has high practicability.
Description
Technical Field
The invention relates to a parallel mechanism control device, in particular to a plane two-degree-of-freedom parallel mechanism control device and method, and belongs to the field of motion control of plane mechanisms.
Background
At present, with the development of technology, more and more robot devices are used in industrial production, and in order to improve the production efficiency and the product quality, the requirements on the speed and the precision of the robot devices are also higher and higher. The traditional robot device adopts motor acceleration and deceleration device or hydraulic drive and other driving modes, the driving mode of the motor acceleration and deceleration device often brings about unavoidable problems such as larger internal friction, moment of inertia lifting, backlash and the like, and friction, backlash and elastic deformation in the deceleration device can cause nonlinearity, so that the control bandwidth and operability of the robot device are not ideal, the requirements of high speed and high precision are difficult to meet, and the hydraulic drive also has the defects of poor reliability and difficult maintenance.
Disclosure of Invention
The invention aims to solve the defects in the prior art, and provides a control device for a plane two-degree-of-freedom parallel mechanism, which is used for driving a movable platform by designing three movable branched chains consisting of rigid rods to be connected, wherein two movable branched chains are directly driven by a proper direct-driving rotary motor, and the control device has the advantages of high control precision, quick response, good rigidity and simple structure, and has high practicability.
Another object of the present invention is to provide a control method for a planar two-degree-of-freedom parallel mechanism based on the above device.
The aim of the invention can be achieved by adopting the following technical scheme:
the plane two-degree-of-freedom parallel mechanism control device comprises a parallel mechanism body and a control unit, wherein the parallel mechanism body comprises a movable platform, a driven movement branched chain and two driving movement branched chains;
the driven movement branched chain comprises a first support piece, a second support piece, a first rigid primary rod, a second rigid primary rod, a first rigid secondary rod, a second rigid secondary rod and a first connecting rod, wherein the first support piece, the first rigid primary rod and the first rigid secondary rod are sequentially connected, the second support piece, the second rigid primary rod and the second rigid secondary rod are sequentially connected, and the joint between the first rigid primary rod and the first rigid secondary rod is connected with the joint between the second rigid primary rod and the second rigid secondary rod through the first connecting rod;
each active movement branched chain comprises a direct driving rotating motor with an encoder, a third supporting piece, a third rigid primary rod, a fourth rigid primary rod, a third rigid secondary rod, a fourth rigid secondary rod and a second connecting rod, wherein the direct driving rotating motor, the third rigid primary rod and the third rigid secondary rod are sequentially connected, the third supporting piece, the fourth rigid primary rod and the fourth rigid secondary rod are sequentially connected, and the joint between the third rigid primary rod and the third rigid secondary rod is connected with the joint between the fourth rigid primary rod and the fourth rigid secondary rod through the second connecting rod;
the movable platform is in an equilateral triangle shape and is provided with an acceleration sensor, a first side of the movable platform is connected with a first rigid secondary rod and a second rigid secondary rod of a driven movement branched chain, a second side of the movable platform is connected with a third rigid secondary rod and a fourth rigid secondary rod of one driving movement branched chain, and a third side of the movable platform is connected with the third rigid secondary rod and the fourth rigid secondary rod of the other driving movement branched chain;
the control unit is respectively connected with the direct drive rotating motor and the acceleration sensor.
Further, two holes are formed in three sides of the movable platform, the two holes in the first side of the movable platform are respectively connected with a first rigid secondary rod and a second rigid secondary rod of the driven movement branched chain through a first rotating shaft, the two holes in the second side are respectively connected with a third rigid secondary rod and a fourth rigid secondary rod of one of the driving movement branched chains through a second rotating shaft, and the two holes in the third side are respectively connected with a third rigid secondary rod and a fourth rigid secondary rod of the other driving movement branched chain through a third rotating shaft.
Further, a fourth rotating shaft is arranged on the first supporting piece, a first sleeve is arranged on the fourth rotating shaft through a bearing sleeve, one end of the first rigid primary rod is fixed on the first sleeve, the other end of the first rigid primary rod is hinged with one end of the first rigid secondary rod through a fifth rotating shaft, and a second sleeve is arranged on the fifth rotating shaft through a bearing sleeve;
a sixth rotating shaft is arranged on the second supporting piece, a third sleeve is arranged on the sixth rotating shaft through a bearing sleeve, one end of the second rigid primary rod is fixed on the third sleeve, the other end of the second rigid primary rod is hinged with one end of the second rigid secondary rod through a seventh rotating shaft, and a fourth sleeve is arranged on the seventh rotating shaft through a bearing sleeve;
the other end of the first rigid secondary rod and the other end of the second rigid secondary rod are hinged with two holes on the first side of the movable platform through a first rotating shaft respectively; the two ends of the first connecting rod are respectively fixed on the second sleeve and the fourth sleeve.
Further, the direct-drive rotating motor is connected with one end of a third rigid primary rod through a flange, the flange is fixed on a rotor of the direct-drive rotating motor, one end of the third rigid primary rod is fixed on the flange, the other end of the third rigid primary rod is hinged with one end of a third rigid secondary rod through an eighth rotating shaft, and the eighth rotating shaft is sleeved with a fifth sleeve through a bearing;
a ninth rotating shaft is arranged on the third supporting piece, a sixth sleeve is arranged on the ninth rotating shaft through a bearing sleeve, one end of the fourth rigid primary rod is fixed on the sixth sleeve, the other end of the fourth rigid primary rod is hinged with one end of the fourth rigid secondary rod through a tenth rotating shaft, and a seventh sleeve is arranged on the tenth rotating shaft through a bearing sleeve;
for one of the active movement branched chains, the other end of the third rigid secondary rod and the other end of the fourth rigid secondary rod are respectively hinged with two holes on the second side of the movable platform through a second rotating shaft; for the other active movement branched chain, the other end of the third rigid secondary rod and the other end of the fourth rigid secondary rod are respectively hinged with two holes on the third side of the movable platform through a second rotating shaft; the two ends of the second connecting rod are respectively fixed on the fifth sleeve and the seventh sleeve.
Further, the first rigid primary rod, the first rigid secondary rod and the first connecting rod form a first composite hinge structure, the second rigid primary rod, the second rigid secondary rod and the first connecting rod form a second composite hinge structure, the third rigid primary rod, the third rigid secondary rod and the second connecting rod form a third composite hinge structure, and the fourth rigid primary rod, the fourth rigid secondary rod and the second connecting rod form a fourth composite hinge structure;
the first rigid primary rod, the second rigid primary rod, the third rigid primary rod and the fourth rigid primary rod have the same length, and the first rigid secondary rod, the second rigid secondary rod, the third rigid secondary rod and the fourth rigid secondary rod have the same length; the distance between the axes of the first composite hinge structure and the second composite hinge structure, the distance between the axes of the third composite hinge structure and the fourth composite hinge structure, the distance between the axes of the first supporting piece and the second supporting piece, the distance between the axes of the direct-drive rotating motor and the third supporting piece and the distance between the axes of two holes on each side of the movable platform are all the same.
Further, a first parallelogram structure is formed by a connecting line between two hole axes of the first side of the movable platform, a first rigid secondary rod, a second rigid secondary rod and a first connecting rod of the driven movement branched chain, and a second parallelogram structure is formed by a connecting line between the first connecting rod, the first rigid primary rod, the second rigid primary rod, the first supporting piece and the second supporting piece axes of the driven movement branched chain;
the connecting line between the axes of the two holes on the second side of the movable platform and the connecting line between the second connecting rod, the third rigid primary rod, the fourth rigid primary rod and the fourth rigid primary rod of the active movement branched chain and the axes of the direct driving rotary motor and the third supporting piece form a fourth parallelogram structure;
the connecting line between the axes of the two holes on the third side of the movable platform and the connecting line between the second connecting rod, the third rigid primary rod and the fourth rigid primary rod of the active movement branched chain and the axes of the direct driving rotary motor and the third supporting piece form a fifth parallelogram structure.
Further, the encoder is arranged inside the direct-drive rotary motor, and the acceleration sensor is arranged at the center of the upper surface of the movable platform.
Further, 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 supporting piece and the second supporting piece of the driven movement branched chain, the direct driving rotating motor of the two driving movement branched chains and the third supporting piece are all fixed on the base plate of the static platform.
Further, the control unit comprises a computer, a motion control card, a terminal board and a direct-drive rotating 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 an encoder, an acceleration sensor and the direct-drive rotating motor servo driving unit, and the direct-drive rotating motor servo driving unit is connected with the direct-drive rotating motor;
the acceleration sensor measures acceleration signals of the movable platform in two directions on a horizontal plane, the acceleration 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 encoder measures an angular displacement signal which directly drives the rotating motor to rotate, the angular displacement signal is input into the motion control card through the terminal board to perform pulse counting to obtain a digital signal, and the digital signal is processed by the computer to obtain an output signal which directly drives the rotating motor;
the computer obtains a control signal according to the feedback signal of the movable platform and the output signal of the direct-drive rotary motor, the control signal is input to the servo drive unit of the direct-drive rotary motor through the motion control card and the terminal board, and the output of the direct-drive rotary motor is controlled to realize the motion control of the movable platform.
The other object of the invention can be achieved by adopting the following technical scheme:
the plane two-degree-of-freedom parallel mechanism control method based on the device comprises the following steps:
measuring acceleration signals along X, Y directions when the movable platform moves horizontally by an acceleration sensor on the movable platform, and performing kinematic inverse solution on the acceleration signals to obtain angular velocity and angular acceleration component signals of a direct-drive rotating 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 an encoder of the direct-drive rotary motor to obtain a rotation angle displacement signal of the direct-drive rotary motor, inputting the angle displacement signal into a motion control card through a terminal board to perform pulse counting to obtain a digital signal, and processing the digital signal by a computer to obtain an output signal of the direct-drive rotary motor;
and fourthly, after comparing, processing and analyzing the output signal of the direct-drive rotating motor with the feedback signal of the movable platform by the computer, comparing the output signal with expected movement and position parameters, and then running a corresponding control algorithm to obtain a required control signal, wherein the control signal is input to a direct-drive rotating motor servo driving unit through a movement control card and a terminal board, and the direct-drive rotating motor servo unit controls the output of the direct-drive rotating motor according to the control signal, so that the purpose of controlling the movement of the movable platform is achieved.
Compared with the prior art, the invention has the following beneficial effects:
1. according to the invention, three motion branched chains are designed, one is used as a driven motion branched chain, the other two are used as driving motion branched chains, the two driving motion branched chains adopt a direct driving mode, an intermediate transmission mechanism such as a speed reducer is not needed, the influence caused by friction force is reduced, the problem of tooth side clearance is avoided, the mechanical structure is simpler and more compact, the motion control precision and response speed of the mechanism are greatly improved, the reliability is higher, and the maintenance is simpler; in addition, the movable platform is provided with an acceleration sensor, so that acceleration signals along two directions on a horizontal plane can be measured when the movable platform moves, the rotary motor is directly driven to be provided with an encoder, an angular displacement signal can be measured when the rotary motor is directly driven to rotate, and the control of the movable platform is realized according to motion parameters measured by the acceleration sensor and parameters measured by the encoder.
2. The connecting line between the two primary rods, the connecting rod and the axes of the two holes on the same side of the movable platform form a parallelogram structure, the connecting line between the two primary rods, the connecting rod and the axes of the two supporting pieces in the driven movable branched chain form a parallelogram structure, and the connecting line between the connecting rod, the two secondary rods and the axes of the two holes on the same side of the movable platform form a parallelogram structure, namely, the three movable branched chains have two parallelogram structures, so that the movable platform is constrained to do translational movement only on a horizontal plane, has two degrees of freedom, and has simple control and stable structure and wide application.
3. The invention adopts a motion control loop with feedback, an acceleration sensor is arranged in the center of the upper surface of the movable platform, acceleration signals along two directions on a horizontal plane can be measured when the movable platform moves, an encoder is arranged in the direct-drive rotary motor, angular displacement signals can be measured when the rotary motor is directly driven to rotate, parameters measured by the acceleration sensor and the encoder are input into a motion control card through a terminal board to be processed to obtain digital signals, a computer processes the digital signals to obtain control signals, and the control signals control a servo unit of the direct-drive rotary motor to control the output of the direct-drive rotary motor, so that the movement of the movable platform is controlled.
Drawings
Fig. 1 is a schematic diagram of the overall structure of a control device for a planar two-degree-of-freedom parallel mechanism according to embodiment 1 of the present invention.
Fig. 2 is a plan view of a parallel mechanism body in the planar two-degree-of-freedom parallel mechanism control device according to embodiment 1 of the present invention.
Fig. 3 is a schematic diagram of a driven motion branched chain structure of a parallel mechanism body in the planar two-degree-of-freedom parallel mechanism control device according to embodiment 1 of the present invention.
Fig. 4 is a schematic diagram of one active motion branched chain structure of the parallel mechanism body in the planar two-degree-of-freedom parallel mechanism control device in embodiment 1 of the present invention.
The device comprises a 1-movable platform, a 2-static platform, a 3-acceleration sensor, a 4-substrate, 5-supporting feet, a 6-transverse support, a 7-first support, an 8-second support, a 9-first rigid primary rod, a 10-second rigid primary rod, an 11-first rigid secondary rod, a 12-second rigid secondary rod, a 13-first connecting rod, a 14-first sleeve, a 15-second sleeve, a 16-third sleeve, a 17-fourth sleeve, a 18-direct drive rotating motor, a 19-third support, a 20-third rigid primary rod, a 21-fourth rigid primary rod, a 22-third rigid secondary rod, a 23-fourth rigid secondary rod, a 24-second connecting rod, a 25-flange, a 26-fifth sleeve, a 27-sixth sleeve, a 28-seventh sleeve, a 29-computer, a 30-motion control card, a 31-terminal board and a 32-direct drive rotating motor servo drive unit.
Detailed Description
The present invention will be described in further detail with reference to examples and drawings, but embodiments of the present invention are not limited thereto.
Example 1:
the embodiment provides the control device of the planar two-degree-of-freedom parallel mechanism by selecting a proper direct-drive rotating motor and constructing a coordinated drive control system through a reasonable mechanical structure, adopts a direct-drive mode, omits an intermediate transmission device, directly connects a load with the drive motor, can fundamentally solve various problems caused by using the transmission device, greatly improves the control bandwidth and operability of the parallel mechanism, and has the advantages of high speed, high precision, light weight, small volume, high rigidity, simple maintenance, simple mechanical structure design, high reliability, good speed regulation and the like.
As shown in fig. 1 and fig. 2, the planar two-degree-of-freedom parallel mechanism control device of the present embodiment includes a parallel mechanism body and a control unit, where the parallel mechanism body includes a moving platform 1, a static platform 2, and three moving branched chains, one of the moving branched chains is a driven moving branched chain, and the other two moving branched chains are driving moving branched chains; the dashed connection in fig. 1 represents a connection diagram of the electrical signal to the parallel mechanism body, the directional arrow indicating the direction of transmission of the detection and control signal flow.
The movable platform 1 is an equilateral triangle disc-shaped platform, two holes are respectively arranged on three sides of the platform, the two holes on the first side of the movable platform are respectively connected with the driven movement branched chain through a first rotating shaft, the two holes on the second side are connected with one driving movement branched chain through a second rotating shaft, the two holes on the third side are connected with the other driving movement branched chain through a third rotating shaft, and the distances among the axes of the two holes on the first side, the second side and the third side are the same; the movable platform 1 is provided with an acceleration sensor 3, specifically, the acceleration sensor 3 is installed at the center of the upper surface of the movable platform 1, and the acceleration sensor 3 is used for measuring acceleration signals of the movable platform 1 in two directions (X direction and Y direction) on a horizontal plane.
In this embodiment, the accelerometer 3 is a capacitive low-frequency accelerometer manufactured by Kistler, switzerland, model number 8395a050.
The static platform 2 is used for supporting the movable platform 1 and three movement branched chains and comprises a base plate 4, the base plate 4 is a square base plate, four supporting feet 5 are arranged at the bottom of the base plate, a transverse bracket 6 is arranged between every two adjacent supporting feet 5, the stabilizing effect is achieved, and the base plate 4, the supporting feet 5 and the transverse bracket 6 are all formed by aluminum profiles.
As shown in fig. 1 to 3, the driven movement branched chain comprises a first supporting piece 7, a second supporting piece 8, a first rigid primary rod 9, a second rigid primary rod 10, a first rigid secondary rod 11, a second rigid secondary rod 12 and a first connecting rod 13, wherein the first rigid primary rod 9, the first rigid secondary rod 11 and the first connecting rod 13 form a first composite hinge structure, and the second rigid primary rod 10, the second rigid secondary rod 12 and the first connecting rod 13 form a second composite hinge structure;
the first supporting piece 7 is fixedly arranged on the base plate 4 of the static platform 2 through a bolt and is provided with a fourth rotating shaft, the fourth rotating shaft is provided with a first sleeve 14 through a bearing sleeve, one end of the first rigid primary rod 9 is fixed on the first sleeve 14 through a screw, the other end of the first rigid primary rod 9 is hinged with one end of the first rigid secondary rod 11 through a fifth rotating shaft, and the fifth rotating shaft is provided with a second sleeve 15 through a bearing sleeve;
the second supporting piece 8 is fixedly arranged on the base plate 4 of the static platform 2 through a bolt, a sixth rotating shaft is arranged on the second supporting piece, a third sleeve 16 is sleeved on the sixth rotating shaft through a bearing, one end of the second rigid primary rod 10 is fixed on the third sleeve 16 through a screw, the other end of the second rigid primary rod 10 is hinged with one end of the second rigid secondary rod 12 through a seventh rotating shaft, and a fourth sleeve 17 is sleeved on the seventh rotating shaft through a bearing;
the other end of the first rigid secondary rod 11 and the other end of the second rigid secondary rod 12 are respectively hinged with two holes on the first side of the movable platform 1 through a first rotating shaft; the two ends of the first link 13 are fixed to the second sleeve 15 and the fourth sleeve 17 by screws, respectively.
The two active movement branched chains have the same structure, and take one active movement branched chain as an example, as shown in fig. 1, 2 and 4, the active movement branched chain comprises a direct driving rotating motor 18, a third supporting piece 19, a third rigid primary rod 20, a fourth rigid primary rod 21, a third rigid secondary rod 22, a fourth rigid secondary rod 23 and a second connecting rod 24, wherein the third rigid primary rod 20, the third rigid secondary rod 22 and the second connecting rod 24 form a third composite hinge structure, and the fourth rigid primary rod 21, the fourth rigid secondary rod 23 and the second connecting rod 24 form a fourth composite hinge structure;
the encoder is arranged in the direct-drive rotary motor 18, and is used for measuring the rotation parameter (rotating angular displacement signal) of the direct-drive rotary motor 18, the direct-drive rotary motor 18 is fixedly arranged on the base plate 4 of the static platform 2 through bolts and is connected with one end of a third rigid primary rod 20 through a flange 25, the flange 25 is fixedly arranged on a rotor of the direct-drive rotary motor 18 through bolts, one end of the third rigid primary rod 20 is fixedly arranged on the flange 25 through bolts, the other end of the third rigid primary rod 20 is hinged with one end of a third rigid secondary rod 22 through an eighth rotating shaft, and the eighth rotating shaft is provided with a fifth sleeve 26 through a bearing sleeve;
the third supporting piece 19 is fixedly installed on the base plate 4 of the static platform 2 through a bolt, a ninth rotating shaft is arranged on the third supporting piece, a sixth sleeve 27 is arranged on the ninth rotating shaft through a bearing sleeve, one end of the fourth rigid primary rod 21 is fixed on the sixth sleeve 27, the other end of the fourth rigid primary rod 21 is hinged with one end of the fourth rigid secondary rod 23 through a tenth rotating shaft, and a seventh sleeve 28 is arranged on the tenth rotating shaft through a bearing sleeve;
for one of the active movement branched chains, the other end of the third rigid secondary rod 22 and the other end of the fourth rigid secondary rod 23 are respectively hinged with two holes on the second side of the movable platform 1 through a second rotating shaft; for the other active movement branched chain, the other end of the third rigid secondary rod 22 and the other end of the fourth rigid secondary rod 23 are respectively hinged with two holes on the third side of the movable platform 1 through a second rotating shaft; the two ends of the second connecting rod 24 are respectively fixed on the fifth sleeve 26 and the seventh sleeve 28;
after the direct driving rotating motor 18 drives, the third rigid primary rod 20 is driven, and then the third rigid secondary rod 22, the second connecting rod 24, the fourth rigid primary rod 21 and the fourth rigid secondary rod 23 are sequentially driven, so that the movable platform 1 moves, a direct driving mode is adopted, the low-speed high-torque direct driving rotating motor 18 is directly connected with the third rigid primary rod 20 to be driven through the flange 25, an intermediate transmission mechanism such as a speed reducer is not needed, the influence of friction force is reduced, the problem of tooth side clearance is avoided, the mechanical structure is simpler and more compact, the motion control precision and the response speed of a parallel mechanism are greatly improved, the reliability is higher, and the maintenance is simpler.
In the embodiment, the direct-drive rotary motor 18 is an ACW 220 type direct-drive rotary motor manufactured by Akribis corporation of Singapore, and the type of an encoder in the motor is AB-7500; the lengths of the first rigid primary rod 9, the second rigid primary rod 10, the third rigid primary rod 20 and the fourth rigid primary rod 21 are the same, the first rigid primary rod 9 is parallel to the second rigid primary rod 10, the third rigid primary rod 20 and the fourth rigid primary rod 21 are parallel, the lengths of the first rigid secondary rod 11, the second rigid secondary rod 12, the third rigid secondary rod 22 and the fourth rigid secondary rod 23 are the same, the first rigid secondary rod 11 and the second rigid secondary rod 12 are parallel, and the third rigid secondary rod 22 and the fourth rigid secondary rod 23 are parallel; the distance between the axes of the first support piece and the second support piece, the distance between the axes of the first composite hinge structure and the second composite hinge structure and the distance between the axes of the two holes on the first side of the movable platform 1 are the same, the connecting line between the axes of the two holes on the first side of the movable platform 1 is parallel to the first connecting rod 13, and the connecting line between the axes of the two holes on the first side of the movable platform 1 is parallel to the connecting line between the axes of the first support piece 7 and the second support piece 8; the distance between the axes of the third and fourth composite hinge structures, the distance between the axes of the direct drive rotary motor 18 and the third support 19, and the distance between the axes of the two holes on the second side (or the third side) of the movable platform 1 are all the same, the connecting line between the axes of the two holes on the second side (or the third side) of the movable platform 1 is kept parallel to the second connecting rod 24, and the connecting line between the axes of the two holes on the second side (or the third side) of the movable platform 1 is kept parallel to the connecting line between the axes of the direct drive rotary motor 18 and the third support 19;
the connecting line between the axes of the two holes on the first side of the movable platform 1, the first rigid secondary rod 10, the second rigid secondary rod 12 and the first connecting rod 13 of the driven movement branched chain form a first parallelogram structure, and the connecting line between the axes of the first connecting rod 13, the first rigid primary rod 9, the second rigid primary rod 11, the first supporting piece 7 and the second supporting piece 8 of the driven movement branched chain form a second parallelogram structure;
the connecting line between the axes of the two holes on the second side of the movable platform 1 and the connecting line between the axes of the third rigid secondary rod 22, the fourth rigid secondary rod 23 and the second connecting rod 24 of an active movement branched chain form a third parallelogram structure, and the connecting line between the second connecting rod 24, the third rigid primary rod 20, the fourth rigid primary rod 21 of the active movement branched chain, the direct driving rotating motor 18 and the axis of the third supporting piece 19 form a fourth parallelogram structure;
the connecting line between the axes of the two holes on the third side of the movable platform 1 and the connecting line between the axes of the second rigid secondary rod 22, the fourth rigid secondary rod 23 and the second connecting rod 24 of the other active movement branched chain form a fifth parallelogram structure, and the connecting line between the second connecting rod 24, the third rigid primary rod 20, the fourth rigid primary rod 21 of the active movement branched chain, the direct driving rotating motor 18 and the axis of the third supporting piece 19 form a sixth parallelogram structure;
the two parallelogram structures on the three moving branched chains restrict the movable platform 1 to do translational movement only on the horizontal plane, and the movable platform 1 with two degrees of freedom has simple control, stable structure and wide application; in addition, the connection line between the axes of the first support 7 and the second support 8 of the driven movement branch chain and the connection line between the axes of the direct drive rotary motor 18 and the third support 19 of the two driving movement branch chains can form an equilateral triangle by extension.
The control unit comprises a computer 29, a motion control card 30, a terminal board 31 and a direct-drive rotary motor servo drive unit 32, wherein the computer 29 is connected with the motion control card 30, the motion control card 30 is connected with the terminal board 31, the terminal board 31 is respectively connected with an encoder, an acceleration sensor 3 and the direct-drive rotary motor servo drive unit 32, and the direct-drive rotary motor servo drive unit 32 is connected with the direct-drive rotary motor 18;
the acceleration sensor 3 measures acceleration signals of the moving platform 1 along two directions on a horizontal plane, the acceleration signals are input into the motion control card 30 through the terminal board 31 to be subjected to A/D conversion to obtain digital signals, and the digital signals are processed by the computer 29 to obtain feedback signals (namely displacement information of the moving platform 1) of the moving platform 1;
the encoder measures an angular displacement signal which directly drives the rotary motor 18 to rotate, the angular displacement signal is input into the motion control card 30 through the terminal board 31 to perform pulse counting to obtain a digital signal, and the digital signal is processed by the computer 29 to obtain an output signal which directly drives the rotary motor 18;
the computer 29 obtains a control signal according to the feedback signal of the movable platform 1 and the output signal of the direct-drive rotary motor, and the control signal is input to the direct-drive rotary motor servo driving unit 32 through the motion control card 30 and the terminal board 31 to control the output of the direct-drive rotary motor 18, thereby realizing the motion control of the movable platform 1.
In this embodiment, the computer 29 is a desktop computer with a CPU of core i7-7700k, 8GB of memory, and a PCI-e card slot for inserting a motion control card; the selected motion control card (19) is a GTS-400-PV-PCI series motion controller produced by solid high company in the United states, the motion controller integrates the functions of multichannel A/D conversion, D/A conversion and code disc counting, the motion controller has 4 paths of shaft resource channels (each shaft signal has one path of analog output, incremental encoder input, motor control output and alarm reset function), the input and output of an optical coupler isolated universal digital signal are respectively provided with 16 paths, the input of a quadruple frequency incremental auxiliary encoder is 2 paths, the sampling input of the A/D analog is 8 paths, and the voltage range of the analog input and output is as follows: -10V to +10v.
As shown in fig. 1 to 4, the present embodiment further provides a control method for a planar two-degree-of-freedom parallel mechanism, which is implemented based on the above device, and includes the following steps:
step one, an acceleration sensor 3 on a movable platform 1 measures and obtains acceleration signals along X, Y directions when the movable platform 1 moves horizontally in a horizontal plane, and angular velocity and angular acceleration component signals of a direct-drive rotating motor 18 are obtained after the acceleration signals are subjected to kinematic inverse solution;
step two, the analog signal measured in the step one is input into a motion control card 30 through a terminal board 31 to be subjected to A/D conversion to obtain a digital signal, the digital signal is processed by a computer 29, specifically, a feedback signal of the movable platform 1 is obtained after the computer 29 runs a control algorithm and performs filtering processing;
step three, the encoder of the direct-drive rotary motor 18 measures and obtains a rotation angle displacement signal of the direct-drive rotary motor 18, the angle displacement signal is input into the motion control card 30 through the terminal board 31 to perform pulse counting to obtain a digital signal, and the digital signal is processed by the computer 29 to obtain an output signal of the direct-drive rotary motor 18;
and step four, after the computer compares and analyzes the output signal of the direct-drive rotating motor 18 with the feedback signal of the movable platform 1, and compares the output signal with the expected movement and position parameters, a corresponding control algorithm is operated to obtain a required control signal, the control signal is input to the direct-drive rotating motor servo driving unit 32 through the movement control card 30 and the terminal board 31, and the direct-drive rotating motor servo unit 32 controls the output of the direct-drive rotating motor 18 according to the control signal, so that the purpose of controlling the movement of the movable platform 1 is achieved.
In summary, the invention designs three motion branched chains, one of which is used as a driven motion branched chain, and the other two of which is used as a driving motion branched chain, wherein the two driving motion branched chains adopt a direct driving mode, and an intermediate transmission mechanism such as a speed reducer is not needed, so that the influence caused by friction force is reduced, the problem of tooth side clearance is avoided, the mechanical structure is simpler and more compact, the motion control precision and response speed of the mechanism are greatly improved, the reliability is higher, and the maintenance is simpler; in addition, an acceleration sensor is arranged on the movable platform, so that acceleration signals along two directions on a horizontal plane can be measured when the movable platform moves, an encoder is arranged in the direct-drive rotary motor, an angular displacement signal can be measured when the direct-drive rotary motor rotates, and the movable platform is controlled according to motion parameters measured by the acceleration sensor and parameters measured by the encoder.
The above-mentioned embodiments are only preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto, and any person skilled in the art can make equivalent substitutions or modifications according to the technical solution and the inventive concept of the present invention within the scope of the present invention disclosed in the present invention patent, and all those skilled in the art belong to the protection scope of the present invention.
Claims (8)
1. The plane two-degree-of-freedom parallel mechanism control device is characterized in that: the parallel mechanism comprises a parallel mechanism body and a control unit, wherein the parallel mechanism body comprises a movable platform, a static platform, a driven movement branched chain and two driving movement branched chains;
the driven movement branched chain comprises a first support piece, a second support piece, a first rigid primary rod, a second rigid primary rod, a first rigid secondary rod, a second rigid secondary rod and a first connecting rod, wherein the first support piece, the first rigid primary rod and the first rigid secondary rod are sequentially connected, the second support piece, the second rigid primary rod and the second rigid secondary rod are sequentially connected, and the joint between the first rigid primary rod and the first rigid secondary rod is connected with the joint between the second rigid primary rod and the second rigid secondary rod through the first connecting rod;
each active movement branched chain comprises a direct driving rotating motor with an encoder, a third supporting piece, a third rigid primary rod, a fourth rigid primary rod, a third rigid secondary rod, a fourth rigid secondary rod and a second connecting rod, wherein the direct driving rotating motor, the third rigid primary rod and the third rigid secondary rod are sequentially connected, the third supporting piece, the fourth rigid primary rod and the fourth rigid secondary rod are sequentially connected, and the joint between the third rigid primary rod and the third rigid secondary rod is connected with the joint between the fourth rigid primary rod and the fourth rigid secondary rod through the second connecting rod;
the movable platform is in an equilateral triangle shape and is provided with an acceleration sensor, a first side of the movable platform is connected with a first rigid secondary rod and a second rigid secondary rod of a driven movement branched chain, a second side of the movable platform is connected with a third rigid secondary rod and a fourth rigid secondary rod of one driving movement branched chain, and a third side of the movable platform is connected with the third rigid secondary rod and the fourth rigid secondary rod of the other driving movement branched chain;
the control unit is respectively connected with the direct-drive rotating motor and the acceleration sensor;
the encoder is arranged in the direct-drive rotary motor, and the acceleration sensor is arranged at the center of the upper surface of the movable 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 supporting piece and the second supporting piece of the driven movement branched chain, the direct driving rotating motor of the two driving movement branched chains and the third supporting piece are all fixed on the base plate of the static platform.
2. The planar two-degree-of-freedom parallel mechanism control device of claim 1, wherein: 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 connected with a first rigid secondary rod and a second rigid secondary rod of the driven movement branched chain through a first rotating shaft, the two holes on the second side are respectively connected with a third rigid secondary rod and a fourth rigid secondary rod of one of the driving movement branched chains through a second rotating shaft, and the two holes on the third side are respectively connected with the third rigid secondary rod and the fourth rigid secondary rod of the other driving movement branched chain through a third rotating shaft.
3. The planar two-degree-of-freedom parallel mechanism control device according to claim 2, wherein:
the first support piece is provided with a fourth rotating shaft, the fourth rotating shaft is provided with a first sleeve through a bearing sleeve, one end of the first rigid primary rod is fixed on the first sleeve, the other end of the first rigid primary rod is hinged with one end of the first rigid secondary rod through a fifth rotating shaft, and the fifth rotating shaft is provided with a second sleeve through a bearing sleeve;
a sixth rotating shaft is arranged on the second supporting piece, a third sleeve is arranged on the sixth rotating shaft through a bearing sleeve, one end of the second rigid primary rod is fixed on the third sleeve, the other end of the second rigid primary rod is hinged with one end of the second rigid secondary rod through a seventh rotating shaft, and a fourth sleeve is arranged on the seventh rotating shaft through a bearing sleeve;
the other end of the first rigid secondary rod and the other end of the second rigid secondary rod are hinged with two holes on the first side of the movable platform through a first rotating shaft respectively; the two ends of the first connecting rod are respectively fixed on the second sleeve and the fourth sleeve.
4. The planar two-degree-of-freedom parallel mechanism control device according to claim 2, wherein:
the direct-drive rotary motor is connected with one end of a third rigid primary rod through a flange, the flange is fixed on a rotor of the direct-drive rotary motor, one end of the third rigid primary rod is fixed on the flange, the other end of the third rigid primary rod is hinged with one end of a third rigid secondary rod through an eighth rotating shaft, and the eighth rotating shaft is sleeved with a fifth sleeve through a bearing;
a ninth rotating shaft is arranged on the third supporting piece, a sixth sleeve is arranged on the ninth rotating shaft through a bearing sleeve, one end of the fourth rigid primary rod is fixed on the sixth sleeve, the other end of the fourth rigid primary rod is hinged with one end of the fourth rigid secondary rod through a tenth rotating shaft, and a seventh sleeve is arranged on the tenth rotating shaft through a bearing sleeve;
for one of the active movement branched chains, the other end of the third rigid secondary rod and the other end of the fourth rigid secondary rod are respectively hinged with two holes on the second side of the movable platform through a second rotating shaft; for the other active movement branched chain, the other end of the third rigid secondary rod and the other end of the fourth rigid secondary rod are respectively hinged with two holes on the third side of the movable platform through a second rotating shaft; the two ends of the second connecting rod are respectively fixed on the fifth sleeve and the seventh sleeve.
5. The planar two-degree-of-freedom parallel mechanism control device according to claim 2, wherein:
the first rigid primary rod, the first rigid secondary rod and the first connecting rod form a first composite hinge structure, the second rigid primary rod, the second rigid secondary rod and the first connecting rod form a second composite hinge structure, the third rigid primary rod, the third rigid secondary rod and the second connecting rod form a third composite hinge structure, and the fourth rigid primary rod, the fourth rigid secondary rod and the second connecting rod form a fourth composite hinge structure;
the first rigid primary rod, the second rigid primary rod, the third rigid primary rod and the fourth rigid primary rod have the same length, and the first rigid secondary rod, the second rigid secondary rod, the third rigid secondary rod and the fourth rigid secondary rod have the same length; the distance between the axes of the first composite hinge structure and the second composite hinge structure, the distance between the axes of the third composite hinge structure and the fourth composite hinge structure, the distance between the axes of the first supporting piece and the second supporting piece, the distance between the axes of the direct-drive rotating motor and the third supporting piece and the distance between the axes of two holes on each side of the movable platform are all the same.
6. The planar two-degree-of-freedom parallel mechanism control device according to claim 2, wherein:
the connecting line between the axes of the two holes on the first side of the movable platform, the first rigid secondary rod, the second rigid secondary rod and the first connecting rod of the driven movement branched chain form a first parallelogram structure, and the connecting line between the axes of the first connecting rod, the first rigid primary rod, the second rigid primary rod, the first supporting piece and the second supporting piece of the driven movement branched chain form a second parallelogram structure;
the connecting line between the axes of the two holes on the second side of the movable platform and the connecting line between the second connecting rod, the third rigid primary rod, the fourth rigid primary rod and the fourth rigid primary rod of the active movement branched chain and the axes of the direct driving rotary motor and the third supporting piece form a fourth parallelogram structure;
the connecting line between the axes of the two holes on the third side of the movable platform and the connecting line between the second connecting rod, the third rigid primary rod and the fourth rigid primary rod of the active movement branched chain and the axes of the direct driving rotary motor and the third supporting piece form a fifth parallelogram structure.
7. The 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 direct-drive rotating motor servo driving unit, wherein the computer is connected with the motion control card, the motion control card integrates the functions of A/D conversion and pulse counting and is connected with the terminal board, the terminal board is respectively connected with an encoder, an acceleration sensor and the direct-drive rotating motor servo driving unit, and the direct-drive rotating motor servo driving unit is connected with the direct-drive rotating motor;
the acceleration sensor measures acceleration signals of the movable platform in two directions on a horizontal plane, the acceleration 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 encoder measures an angular displacement signal which directly drives the rotating motor to rotate, the angular displacement signal is input into the motion control card through the terminal board to perform pulse counting to obtain a digital signal, and the digital signal is processed by the computer to obtain an output signal which directly drives the rotating motor;
the computer obtains a control signal according to the feedback signal of the movable platform and the output signal of the direct-drive rotary motor, the control signal is input to the servo drive unit of the direct-drive rotary motor through the motion control card and the terminal board, and the output of the direct-drive rotary motor is controlled to realize the motion control of the movable platform.
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 along X, Y directions when the movable platform moves horizontally by an acceleration sensor on the movable platform, and performing kinematic inverse solution on the acceleration signals to obtain angular velocity and angular acceleration component signals of a direct-drive rotating 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 an encoder of the direct-drive rotary motor to obtain a rotation angle displacement signal of the direct-drive rotary motor, inputting the angle displacement signal into a motion control card through a terminal board to perform pulse counting to obtain a digital signal, and processing the digital signal by a computer to obtain an output signal of the direct-drive rotary motor;
and fourthly, after comparing, processing and analyzing the output signal of the direct-drive rotating motor with the feedback signal of the movable platform by the computer, comparing the output signal with expected movement and position parameters, and then running a corresponding control algorithm to obtain a required control signal, wherein the control signal is input to a direct-drive rotating motor servo driving unit through a movement control card and a terminal board, and the direct-drive rotating motor servo unit controls the output of the direct-drive rotating motor according to the control signal, so that the purpose of controlling the movement of the movable platform is achieved.
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| EP1560681A1 (en) * | 2002-11-06 | 2005-08-10 | McGILL UNIVERSITY | Four-degree-of-freedom parallel manipulator for producing schönflies motions |
| CN101844349A (en) * | 2010-05-17 | 2010-09-29 | 清华大学 | Redundant parallel robot system |
| ES2555302T3 (en) * | 2013-04-12 | 2015-12-30 | Sabanci University | Series elastic holonomic mobile platform for upper limb rehabilitation |
| CN106426090B (en) * | 2016-09-30 | 2018-09-14 | 华南理工大学 | The planar three freedom parallel robot control device and method of rodless cylinder driving |
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