CN109894906B - Redundant drive parallel machine tool dead point avoidance system and method - Google Patents
Redundant drive parallel machine tool dead point avoidance system and method Download PDFInfo
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Abstract
The invention discloses a redundant drive parallel machine tool dead point avoidance system and a method, wherein the system comprises a tachogenerator and a photoelectric encoder which are connected with servo motors of three shrinkage rod groups; the linear induction synchronizer is connected with the redundant sliding block, and the dead point monitoring processor is connected with the redundant sliding block; the tachogenerator is used for acquiring the output rotating speed of the servo motors of the three telescopic rod groups; the photoelectric encoder is used for acquiring the number of turns of the lead screws of the three telescopic rod groups; the linear induction synchronizer is used for acquiring the position of the redundant slide block on the guide rail of the linear induction synchronizer; the dead point monitoring processor is used for judging whether the parallel mechanism is close to a dead point position or not, and controlling the three telescopic rod groups to stretch and retract and the movement direction of the redundant slide block to avoid the dead point position; the method comprises the steps of obtaining the output rotating speed of three telescopic rod groups, the number of turns of a lead screw, and the coordinates of a redundant slide block on a guide rail; calculating the speed of the movable platform; determining whether a dead point position is approached; and controlling each telescopic rod group and the redundant slide block to move to avoid dead point positions. The invention can predict the dead point and avoid the dead point.
Description
Technical Field
The invention belongs to the field of parallel machine tool motion control, and particularly relates to a dead point avoidance system and method for a redundant drive parallel machine tool.
Background
Since the Stewart mechanism was proposed in the 60's of the 20 th century, the parallel mechanism has been widely applied due to its advantages of high precision, good dynamic response, large rigidity-weight ratio, etc. The parallel machine tool is a modern machining device with high efficiency as a result of combining a parallel mechanism and a machine tool technology, so that the parallel machine tool is more and more important to research on the parallel mechanism applied to the parallel machine tool. However, the parallel mechanism has dead point positions as the traditional mechanism, and because the motion of the parallel mechanism is complex, the driving rods are mutually matched and restricted, and the dead point positions are more difficult to accurately predict and avoid in the motion space. The existence of the dead point of the mechanism has great influence on the normal operation of the mechanism, so that the dead point position can be accurately and efficiently predicted, and the avoidance of the dead point position is particularly important. Do Ye, contain two redundant driven numerical control research [ D ] of C shape longmen parallel machine tool Nanjing: nanjing university of science and engineering, 2017, discloses dead point position analysis of a parallel mechanism in a C-shaped gantry parallel machine tool, but a specific dead point monitoring and avoiding method is not provided.
Disclosure of Invention
The invention aims to provide a dead point avoidance system and method for a redundant driving parallel machine tool, which aim to solve the problem that the redundant driving parallel machine tool accurately predicts a dead point and avoids the dead point.
The technical solution for realizing the purpose of the invention is as follows:
a redundant drive parallel machine tool dead point avoidance system comprises three tachogenerators respectively connected with servo motors of an upper telescopic rod group, a middle telescopic rod group and a lower telescopic rod group, three electric encoders respectively connected with lead screws of the upper telescopic rod group, the middle telescopic rod group and the lower telescopic rod group, a linear induction synchronizer connected with a redundant slide block and a dead point monitoring processor;
the three speed measuring generators are respectively used for acquiring the output rotating speeds of the servo motors in the upper telescopic rod group, the middle telescopic rod group and the lower telescopic rod group; the three photoelectric encoders are respectively used for collecting the number of turns of the screw rod in the upper telescopic rod group, the middle telescopic rod group and the lower telescopic rod group; the linear induction synchronizer is used for acquiring the position of the redundant slide block on the guide rail of the linear induction synchronizer; and the dead point monitoring processor is used for calculating the ratio of the speed of the movable platform to the speed of the telescopic rod groups, comparing the ratio with a dead point set value, judging whether the parallel mechanism is close to a dead point position, and controlling the telescopic of the three telescopic rod groups and the movement direction of the redundant slide block to avoid the dead point position according to the judgment result.
A method for redundantly driving a dead point avoidance system of a parallel machine tool comprises the following steps:
step 1, obtaining output rotating speed n of servo motors in an upper telescopic rod group, a middle telescopic rod group and a lower telescopic rod group1、n2、n3(ii) a The number of turns a of the screw rod in the upper telescopic rod group, the middle telescopic rod group and the lower telescopic rod group1、a2、a3(ii) a The position of the redundant slide block on the guide rail of the redundant slide block is determined to determine the coordinate of the redundant slide block on the guide rail;
step 2, calculating the stretching speed v of the upper stretching rod group, the middle stretching rod group and the lower stretching rod group respectively1、v2、v3(ii) a The rod lengths l of the upper telescopic rod group, the middle telescopic rod group and the lower telescopic rod group are respectively calculated1、l2、l3；
Step 3, calculating the speed of the moving platform: the speed v of each telescopic rod is obtained1、v2、v3And length of rod l1、l2、l3Calculating the motion speed v of the movable platform through a speed Jacobian matrixd(ii) a Solving the modulus of the speed of the telescopic rod and the speed of the movable platform which are not zero;
step 4, judging whether the mechanism is close to the dead point position: calculating the ratio of the motion speed value of the movable platform to the telescopic speed values of the telescopic rods, and comparing the obtained ratio with a dead point set value S in the data setting module; if any ratio is larger than a set value, the mechanism is close to a dead point; if the ratio is not greater than the set value, the mechanism is not close to the dead point;
and 5, controlling the telescopic rod groups and the redundant slide blocks to move to avoid dead point positions.
Compared with the prior art, the invention has the following remarkable advantages:
(1) the system can judge whether the parallel mechanism is close to the dead point position by collecting the output rotating speed of the motors of the three telescopic rods, the number of turns of the lead screw and the position of the redundant slide block on the guide rail of the lead screw, and can control the telescopic directions of the three telescopic rod groups and the moving direction of the redundant slide block to avoid the dead point position according to the judgment result.
(2) The dead point approach judgment method adopted by the invention is simple and quick, has higher calculation speed and good real-time performance, and can meet the high requirement of a machine tool on real-time performance.
(3) The method has the advantages of easy acquisition of required data, simple acquisition mode, easy realization of data processing, accurate judgment of the approach of the dead point and capability of completely avoiding the position of the dead point.
(4) The invention adopts the user to input the dead point set value, and the user can input different dead point set values according to the structural parameters of the parallel mechanism and the requirements on different dead point approaching degrees.
Drawings
FIG. 1 is a schematic diagram of a dead point avoidance system and method for redundant drive parallel machine tools according to the present invention.
FIG. 2 is a flow chart of the dead point avoidance system and method for driving the parallel machine tool according to the invention.
Fig. 3 is a schematic mechanical diagram of a parallel mechanism in the redundant drive parallel machine of the present invention.
Fig. 4 is a simplified mechanism diagram of a parallel mechanism in a redundant drive parallel machine tool according to the present invention.
Detailed Description
The invention is further described with reference to the following figures and embodiments.
With reference to fig. 2, a parallel mechanism in a redundant drive parallel machine tool comprises an upper telescopic rod group, a lower telescopic rod group, a middle telescopic rod group, a redundant slide block, a guide rail and four servo motors; one end of the upper telescopic rod group is fixed by a spherical hinge, and the other end of the upper telescopic rod group is connected with the upper part of the movable platform by a spherical hinge; one end of the lower telescopic rod group is fixed by a spherical hinge, and the other end of the lower telescopic rod group is connected with the lower part of the movable platform by a spherical hinge; one end of the middle telescopic rod group is connected with the redundant slide block by adopting a spherical hinge, and the other end of the middle telescopic rod group is connected with the rear part of the movable platform by adopting a spherical hinge; each telescopic rod group is connected with a servo motor, and the servo motors synchronously drive the screw rods in the two telescopic rods to enable the two telescopic rods to do the same telescopic motion; the redundant slide block guide rail is fixed, and the redundant slide block can freely move on the guide rail; the redundant sliding block is driven by a servo motor; each telescopic rod is composed of two telescopic rod groups with the same structure, and the two telescopic rods in each telescopic rod group are always parallel and have the same rod length, so that the parallel structure can be simplified into a mechanism shown in fig. 4.
With reference to fig. 1, the dead point avoidance system for the redundant drive parallel machine tool comprises a first tachogenerator 1, a second tachogenerator 2 and a third tachogenerator 3 which are respectively connected with servo motors of an upper telescopic rod group, a middle telescopic rod group and a lower telescopic rod group, a first photoelectric encoder 11, a second photoelectric encoder 12 and a third photoelectric encoder 13 which are respectively connected with lead screws of the upper telescopic rod group, the middle telescopic rod group and the lower telescopic rod group, a linear induction synchronizer connected with a redundant slide block and a dead point monitoring processor.
The first tachogenerator 1, the second tachogenerator 2 and the third tachogenerator 3Are respectively used for collecting the output rotating speed n of the servo motors in the upper telescopic rod group, the middle telescopic rod group and the lower telescopic rod group1、n2、n3(ii) a The first photoelectric encoder 11, the second photoelectric encoder 12 and the third photoelectric encoder 13 are respectively used for collecting the number of turns a of the screw rod in the upper telescopic rod group, the middle telescopic rod group and the lower telescopic rod group1、a2、a3(ii) a The linear induction synchronizer is used for acquiring the position of the redundant slide block on the guide rail of the linear induction synchronizer; and the dead point monitoring processor is used for calculating the ratio of the speed of the movable platform to the speeds of the three telescopic rod groups, comparing the ratio with a dead point set value, judging whether the parallel mechanism is close to a dead point position, and controlling the telescopic of the three telescopic rod groups and the movement direction of the redundant slide block to avoid the dead point position according to the judgment result.
Further, the dead point monitoring processor comprises a data setting module, a data acquisition module, a speed processing module, a dead point approach judgment module and a motion control module;
the data setting module is used for setting a dead point set value S; and calculating the ratio of the stretching speed of each telescopic rod group of the parallel mechanism to the speed of the movable platform of the parallel mechanism near the dead point of the parallel mechanism (obtaining a distribution diagram of the ratio in a three-dimensional space through MATLAB simulation). And selecting a ratio as a dead point set value according to the distance from the expected early evasion dead point position to the dead point. A comparison with the set value input by this module is required to determine whether or not the dead point is approached at the time of the dead point approach determination.
The data acquisition module is used for receiving signals from the first tachogenerator 1, the second tachogenerator 2, the third tachogenerator 3, the first photoelectric encoder 11, the second photoelectric encoder 12, the third photoelectric encoder 13 and the linear induction synchronizer; receiving signals from the linear induction synchronizer to determine the position of the redundant slide block;
the speed processing module is used for respectively calculating the telescopic speed of each telescopic rod group according to the output rotating speed of the servo motor in each telescopic rod group measured by the tachogenerator and the transmission ratio in each telescopic rod group, and calculating the rod length according to the number of turns of the lead screw in each telescopic rod group measured by the photoelectric encoder and the lead; and obtaining the moving speed of the movable platform according to the telescopic speed and the rod length of each telescopic rod group.
The dead point approach judging module is used for calculating the ratio of the moving speed value of the moving platform to the telescopic speed value of each telescopic rod group, comparing the obtained ratio with a set value in the data setting module, and judging whether the mechanism approaches the dead point.
The motion control module is used for controlling the three telescopic rod groups to stretch and retract and controlling the redundant slide block moving direction to avoid the dead point position according to whether the mechanism is close to the dead point: if the slide rail is close to a dead point, the upper telescopic rod group and the lower telescopic rod group are fixed, the middle telescopic rod group can be freely stretched, and the redundant slide block moves along the forward direction or the direction of the slide rail according to the current position. If the mechanism is not close to the dead point, the redundant slide block does not move, data acquisition is carried out again, and whether the mechanism is close to the dead point or not is calculated and judged.
Furthermore, the speed processing module comprises a telescopic rod expansion speed calculating unit, a telescopic rod length calculating unit and a moving platform movement speed calculating unit;
the telescopic rod telescopic speed calculation unit respectively obtains the telescopic speed of each telescopic rod group according to the output rotating speed of the servo motor in each telescopic rod group and the transmission ratio in each telescopic rod group measured by the tachogenerator;
setting the transmission ratios of the rotating speed of the servo motor and the telescopic speed of the telescopic rods in the three telescopic rod groups as i1、i2、i3，
The telescopic speed of the upper telescopic rod group is as follows: v. of1＝n1·i1；
The telescopic speed of the middle telescopic rod group is as follows: v. of2＝n2·i2；
The telescopic speed of the lower telescopic rod group is as follows: v. of3＝n3·i3；
The telescopic rod length calculating unit is used for calculating the rod length according to the rotation number of turns and the lead of the lead screw in each telescopic rod group measured by the photoelectric encoder;
the lead of the lead screw in the three telescopic rod groups is respectively set to be L1、L2、L3；
The length of the upper telescopic rod group is as follows: l1＝a1·L1；
The rod length of the middle telescopic rod group is as follows: l2＝a2·L2；
The rod length of the lower telescopic rod group is as follows: l3＝a3·L3；
The moving platform moving speed calculating unit calculates the speed v of each telescopic rod group1、v2、v3And length of rod l1、l2、l3Then the moving speed v of the moving platform is calculated through a speed Jacobian matrixd. Speed v of each telescopic rod group1、v2、v3Deleting the speed of 0 in the middle, and obtaining the | v' by solving the modulus of the speed of the telescopic rod group and the speed of the movable platform which are not zero1|、|v2|、|v3|、|vdAnd if the speed of the telescopic rod group is not 0.
Further, the specific process of calculating the ratio of the moving speed value of the moving platform and the telescopic speed values of the telescopic rod groups by the dead point approach determination module is as follows:
setting the sliding direction of the redundant slide block along the guide rail as an X axis, setting the X coordinate of the position, which is in the middle of the guide rail, of the redundant slide block as 0, and determining the X coordinate of the redundant slide block in the machine tool coordinate as X according to the position of the redundant slide block on the guide rails。
The dead point approach judging module calculates the ratio of the moving speed value of the moving platform to the telescopic speed values of all the telescopic rod groups, and compares the calculated ratio with a dead point set value S in the data setting module. If any ratio is larger than a set value, the mechanism is close to a dead point; if the ratio is not larger than the set value, the mechanism is not close to the dead point. Namely:
if it is
The mechanism is not close to the dead point; otherwise, the mechanism approaches dead center.
The motion control module slides according to the redundancy if the mechanism approaches the dead point according to the judgment resultThe current position of the block determines how to control the redundant slide block servo motor to move, and then the servo motors of the upper telescopic rod group and the lower telescopic rod group are controlled to be locked, and the middle telescopic rod group can freely stretch; if the redundant slide block has X-axis coordinatesLess than zero (coordinate x)sIf the value is less than 0), a signal is sent to the servo motor to control the redundant slide block to move towards the positive direction of the X axis; vice versa (coordinate x)sNot less than 0), the signal is sent to a servo motor to control the redundant slide block to move towards the X-axis negative direction.
A method for redundantly driving a dead point avoidance system of a parallel machine tool comprises the following steps:
step 1, inputting a dead point set value S, wherein different set values can be input according to different requirements on the proximity degree of the dead point to avoid the position of the dead point;
step 2, obtaining the output rotating speed n of the servo motors in the upper telescopic rod group, the middle telescopic rod group and the lower telescopic rod group1、n2、n3(ii) a The number of turns a of the screw rod in the upper telescopic rod group, the middle telescopic rod group and the lower telescopic rod group1、a2、a3(ii) a The position of the redundant slide block on the guide rail of the redundant slide block is determined to determine the coordinate of the redundant slide block on the guide rail;
step 3, calculating the stretching speed v of the upper stretching rod group, the middle stretching rod group and the lower stretching rod group respectively1、v2、v3(ii) a Respectively calculating the rod lengths l of the upper telescopic rod group, the middle telescopic rod group and the lower telescopic rod group1、l2、l3；
Respectively obtaining the telescopic speed of each telescopic rod group according to the output rotating speed of the servo motor in each telescopic rod group and the transmission ratio in each telescopic rod group measured by the tachogenerator; calculating the rod length according to the rotation number of turns and the lead of the lead screw in each telescopic rod group measured by a photoelectric encoder;
3.1 calculating the telescoping velocity v of the upper, middle and lower telescoping rod sets1、v2、v3: the upper telescopic rod group has a telescopic speed v1＝n1·i1The extension speed of the middle extension rod group is v2＝n2·i2The extension speed of the lower telescopic rod group is v3＝n3·i3。
3.2 calculating the rod lengths l of the upper, middle and lower telescopic rod groups1、l2、l3: the length of the upper telescopic rod group is l1＝a1·L1The length of the middle telescopic rod group is l2＝a2·L2The length of the lower telescopic rod group is l3＝a3·L3。
Step 4, calculating the speed of the movable platform: the velocity v of each telescopic rod set is obtained1、v2、v3And length of rod l1、l2、l3Calculating the motion speed v of the movable platform through a speed Jacobian matrixd。
Speed v of each telescopic rod group1、v2、v3Deleting the speed of 0 in the middle, and obtaining the | v' by solving the modulus of the speed of the telescopic rod group and the speed of the movable platform which are not zero1|、|v2|、|v3|、|vdAnd if the speed of the telescopic rod group is not 0.
Step 5, judging whether the mechanism is close to the dead point position: calculating the ratio of the motion speed value of the movable platform to the telescopic speed values of all telescopic rod groups, and comparing the obtained ratio with a dead point set value S in the data setting module; if any ratio is larger than a set value, the mechanism is close to a dead point; if the ratio is not larger than the set value, the mechanism is not close to the dead point.
Namely:
if it is
The mechanism is not close to the dead point; otherwise, the mechanism approaches dead center.
Step 6, controlling each telescopic rod group and each redundant slide block to move, and avoiding dead point positions:
if the mechanism is close to a dead point, determining how to control the redundant slide block servo motor to move according to the current position of the redundant slide block, then controlling the servo motors of the upper telescopic rod group and the lower telescopic rod group to be locked, and enabling the middle telescopic rod group to freely stretch and retract; if the redundant slide block has a coordinate X in the X-axis coordinatesIf it is less than zero, thenSignals are sent to a servo motor to control the redundant slide block to move towards the positive direction of the X axis; otherwise, a signal is sent to the servo motor to control the redundant slide block to move towards the X-axis negative direction.
The sliding direction of the redundant slide block along the guide rail is an X axis, the X coordinate of the position, located in the middle of the guide rail, of the redundant slide block is 0, and the X coordinate of the redundant slide block in the machine tool coordinate is determined to be X according to the position, located on the guide rail, of the redundant slide blocks。
The connecting structure of the invention is simplified as figure 4, according to the mechanism principle of the parallel machine tool parallel mechanism, when the rod lengths of the upper and lower telescopic rods are both determined values, the upper and lower branched chains can determine a circle at the moment, and the intersection point of the middle branched chain and the circle is the position of the tail end of the mechanism. If the middle branch is in fixed position with both branches (C)1C2Line) where the drive angle is zero and the mechanism reaches a dead-center position. As can be seen from the mechanical positional relationship, when the rod lengths of the upper and lower telescopic rod groups are determined, the rod length increment of the intermediate telescopic rod group is nonlinear with the end moving distance, and the end moving distance increases as the rod length of the intermediate telescopic rod group is increased by the same increment, the closer to the dead point position. Therefore, the invention only needs to measure the speed of the telescopic rod group and the speed of the tail end of the mechanism in real time, and can determine whether the parallel mechanism is close to the dead point position or not according to the comparison between the ratio of the two speeds and the set value.
The data required to be acquired is easy to acquire, and the acquisition mode is simple and reliable; in the aspect of data processing, the algorithm is simple and easy to realize, and the judgment result is reliable; the data required by the dead point approach judgment are less, the calculation is simple, the calculation speed is high, the response is sensitive, and the high requirement of a machine tool on the real-time performance can be met; and a data setting module is also adopted, so that a user can input different dead point set values according to the researched structural parameters of the parallel mechanism and the requirement on the close degree of the dead points, and the parallel mechanism avoids the dead points in advance.
Claims (8)
1. A redundant drive parallel machine tool dead point avoidance system is characterized by comprising three tachogenerators respectively connected with servo motors of an upper telescopic rod group, a middle telescopic rod group and a lower telescopic rod group, three photoelectric encoders respectively connected with lead screws of the upper telescopic rod group, the middle telescopic rod group and the lower telescopic rod group, a linear induction synchronizer connected with a redundant slide block and a dead point monitoring processor;
the three speed measuring generators are respectively used for acquiring the output rotating speeds of the servo motors in the upper telescopic rod group, the middle telescopic rod group and the lower telescopic rod group; the three photoelectric encoders are respectively used for collecting the number of turns of the screw rod in the upper telescopic rod group, the middle telescopic rod group and the lower telescopic rod group; the linear induction synchronizer is used for acquiring the position of the redundant slide block on the guide rail of the linear induction synchronizer; and the dead point monitoring processor is used for calculating the ratio of the speed of the movable platform to the speeds of the three telescopic rod groups, comparing the ratio with a dead point set value, judging whether the parallel mechanism is close to a dead point position, and controlling the telescopic of the three telescopic rod groups and the movement direction of the redundant slide block to avoid the dead point position according to the judgment result.
2. The dead point avoidance system of the redundant drive parallel machine tool according to claim 1, wherein the dead point monitoring processor comprises a data setting module, a data acquisition module, a speed processing module, a dead point approach determination module, and a motion control module;
the data setting module is used for setting a set dead point value;
the data acquisition module is used for receiving signals of the three encoders and the three photoelectric sensor linear induction synchronizers;
the speed processing module is used for respectively calculating the telescopic speed of each telescopic rod group according to the output rotating speed of the servo motor in each telescopic rod group measured by the tachogenerator and the transmission ratio in each telescopic rod group, and calculating the rod length according to the number of turns of the lead screw in each telescopic rod group measured by the photoelectric encoder and the lead; obtaining the moving speed of the movable platform according to the telescopic speed and the rod length of each telescopic rod group;
the dead point approach judging module is used for calculating the ratio of the motion speed value of the movable platform to the telescopic speed value of each telescopic rod group, comparing the obtained ratio with a set value in the data setting module and judging whether the mechanism approaches the dead point or not;
and the motion control module is used for controlling the three telescopic rod groups to stretch and retract and controlling the movement direction of the redundant slide block to avoid the position of the dead point according to whether the mechanism is close to the dead point.
3. The redundant driving parallel machine tool dead point avoidance system according to claim 2, wherein the speed processing module comprises a telescopic rod expansion and contraction speed calculation unit, a telescopic rod length calculation unit and a moving platform movement speed calculation unit;
the telescopic rod telescopic speed calculation unit respectively obtains the telescopic speed of each telescopic rod group according to the output rotating speed of the servo motor in each telescopic rod group and the transmission ratio in each telescopic rod group measured by the tachogenerator;
the telescopic rod length calculating unit is used for calculating the rod length according to the rotation number of turns and the lead of the lead screw in each telescopic rod group measured by the photoelectric encoder;
the moving speed calculation unit of the moving platform calculates the moving speed of the moving platform through the speed and the rod length of each telescopic rod group and a speed Jacobian matrix; speed v of each telescopic rod group1、v2、v3And deleting the speed of 0, and solving the modulus of the speed of the telescopic rod group and the speed of the movable platform which are not zero.
4. The dead point avoidance system of the redundant drive parallel machine tool according to claim 2, wherein the specific process of calculating the ratio of the motion speed value of the movable platform and the telescopic speed value of each telescopic rod group by the dead point approach determination module is as follows:
calculating the ratio of the motion speed value of the movable platform to the telescopic speed values of all telescopic rod groups, and comparing the obtained ratio with a dead point set value S in the data setting module; if any ratio is larger than a set value, the mechanism is close to a dead point; if the ratio is not larger than the set value, the mechanism is not close to the dead point.
5. The dead point avoiding system of the redundant driving parallel machine tool as claimed in claim 4, wherein the motion control module controls the servo motors of the upper and lower telescopic rod sets to be locked if the mechanism approaches the dead point according to the judgment result, and the middle telescopic rod set can be freely stretched and contracted:
if the coordinate of the redundant slide block on the X axis is less than zero, the redundant slide block is controlled to move towards the positive direction of the X axis;
and otherwise, controlling the redundant slide block to move towards the X-axis negative direction.
6. A method for redundantly driving a dead point avoidance system of a parallel machine tool is characterized by comprising the following steps:
step 1, obtaining output rotating speed n of servo motors in an upper telescopic rod group, a middle telescopic rod group and a lower telescopic rod group1、n2、n3(ii) a The number of turns a of the screw rod in the upper telescopic rod group, the middle telescopic rod group and the lower telescopic rod group1、a2、a3(ii) a The position of the redundant slide block on the guide rail of the redundant slide block is determined to determine the coordinate of the redundant slide block on the guide rail;
step 2, calculating the stretching speed v of the upper stretching rod group, the middle stretching rod group and the lower stretching rod group respectively1、v2、v3(ii) a The rod lengths l of the upper telescopic rod group, the middle telescopic rod group and the lower telescopic rod group are respectively calculated1、l2、l3；
Step 3, calculating the speed of the moving platform: the velocity v of each telescopic rod set is obtained1、v2、v3And length of rod l1、l2、l3Calculating the motion speed v of the movable platform through a speed Jacobian matrixd(ii) a Calculating the modulus of the speed of the telescopic rod group and the speed of the movable platform which are not zero;
step 4, judging whether the mechanism is close to the dead point position: calculating the ratio of the motion speed value of the movable platform to the telescopic speed values of all telescopic rod groups, and comparing the obtained ratio with a dead point set value S in the data setting module; if any ratio is larger than a set value, the mechanism is close to a dead point; if the ratio is not greater than the set value, the mechanism is not close to the dead point;
and 5, controlling the telescopic rod groups and the redundant slide blocks to move to avoid dead point positions.
7. The method for redundantly driving the parallel machine tool dead point avoidance system according to claim 6, wherein the step 2 is used for calculating the speed and the length of the telescopic rod group, and specifically comprises the following steps:
2.1 calculating the telescoping speed v of the upper, middle and lower telescoping rod sets1、v2、v3: the upper telescopic rod group has a telescopic speed v1＝n1·i1The extension speed of the middle extension rod group is v2＝n2·i2The extension speed of the lower telescopic rod group is v3＝n3·i3；
2.2 rod lengths l of the upper, middle and lower telescopic rod groups1、l2、l3: the length of the upper telescopic rod group is l1＝a1·L1The length of the middle telescopic rod group is l2＝a2·L2The length of the lower telescopic rod group is l3＝a3·L3；
Wherein i1、i2、i3The transmission ratios of the upper telescopic rod group, the middle telescopic rod group and the lower telescopic rod group are respectively set; l is1、L2、L3Respectively the lead screw leads of the upper telescopic rod group, the middle telescopic rod group and the lower telescopic rod group.
8. The method for avoiding the dead point of the redundant driving parallel machine tool according to claim 6, wherein the step 5 is characterized in that the method for avoiding the dead point comprises the following steps:
if the mechanism is close to a dead point, the servo motors of the upper and lower telescopic rod groups are controlled to be locked, and the middle telescopic rod group can be freely stretched:
if the coordinate of the redundant slide block on the X axis is less than zero, the redundant slide block is controlled to move towards the positive direction of the X axis;
and otherwise, controlling the redundant slide block to move towards the X-axis negative direction.
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| CN115139224B (en) * | 2022-06-17 | 2024-06-11 | 中国第一汽车股份有限公司 | Four-axis tool control method based on simulink |
| CN115284298B (en) * | 2022-08-31 | 2024-07-02 | 深圳前海瑞集科技有限公司 | Robot singular avoidance method, device, terminal and medium |
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| JP3806273B2 (en) * | 1999-09-17 | 2006-08-09 | 株式会社ジェイテクト | 4-DOF parallel robot |
| CN101543858B (en) * | 2009-05-08 | 2010-09-29 | 南京理工大学 | High-speed fine press |
| CN101745820A (en) * | 2009-12-14 | 2010-06-23 | 北京航空航天大学 | Three-degree-of-freedom parallel mechanism type dual head for five-axis machine tools and control method |
| CN102025116B (en) * | 2010-12-17 | 2012-11-14 | 安徽鑫龙电器股份有限公司 | Interlocking device of high-tension switch gear |
| CN102645335B (en) * | 2012-05-11 | 2014-08-20 | 天津工业大学 | Method for locating top dead center of six cylinder engine |
| CN104148976B (en) * | 2014-07-24 | 2016-05-25 | 深圳市领略数控设备有限公司 | A kind of accurate digital control rotating shaft system |
| CN106426092B (en) * | 2016-10-10 | 2019-03-22 | 燕山大学 | Motion redundancy series parallel robot in five degrees of freedom |
| CN106736634B (en) * | 2016-12-23 | 2018-09-25 | 南京理工大学 | A kind of three translation parallel lathe of big working space of additional redundancy Circular Sliding |
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