CN111800054A

CN111800054A - Multipoint position comparison system and method based on real-time Ethernet

Info

Publication number: CN111800054A
Application number: CN202010739074.2A
Authority: CN
Inventors: 邹爽; 周莹; 苏爱林; 沈武; 周维; 李健
Original assignee: Leetro Automation Co ltd
Current assignee: Leetro Automation Co ltd
Priority date: 2020-07-28
Filing date: 2020-07-28
Publication date: 2020-10-20
Anticipated expiration: 2040-07-28
Also published as: CN111800054B

Abstract

The invention provides a multipoint position comparison system and method based on real-time Ethernet, which is characterized in that a master station controls a DEV bus processor quickly in real time through the extremely short period control of an EtherCAT bus, periodically receives an instruction, controls the motion of a motor, compares the instruction position with the feedback position of an encoder, sets a comparison value in real time by the master station, outputs the comparison value to a multipoint position comparison output port to control a processing shaft when the comparison position is reached, and meanwhile, the comparison position can be a single-shaft position or a multi-shaft synthesized vector shaft position. The invention realizes flexible multi-point real-time comparison and correction through the operation, occupies less resources and can compare the vector position.

Description

Multipoint position comparison system and method based on real-time Ethernet

Technical Field

The invention belongs to the technical field of motion control, and particularly relates to a multipoint position comparison power system and method based on real-time Ethernet.

Background

In motion control, precise position control is required in many occasions, such as on-off valve control, photographing control and the like in a dispensing system.

The existing position comparison output is generally implemented in an integrated use device, compares preset position points of an upper computer, and outputs pulses or levels with set widths on a high-speed output port when a motion command or a feedback position reaches a preset position.

However, the prior art has the following defects:

(1) the method can only be a preset mode before movement, namely position comparison points are planned before the movement look ahead, the comparison state cannot be corrected in real-time movement, and the flexibility is poor;

(2) for the condition of a large number of points, a large memory resource needs to be reserved in the equipment, and the resource occupation is large;

(3) the position to be compared is only the pulse instruction or feedback position of the current shaft, the vector position cannot be compared, and the functionality is not strong.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a multi-point position comparison system and method based on real-time Ethernet, the master station controls a DEV bus processor quickly in real time through the characteristic of extremely short period control of an EtherCAT bus, receives instructions periodically, controls the motion of a motor, compares the instruction position with the feedback position of an encoder, sets a comparison value in real time by the master station, outputs the comparison value to a multi-point position comparison output port to control a processing shaft when the comparison position is reached, and meanwhile, the comparison position can be a single-shaft position or a multi-shaft synthesized vector shaft position. The invention realizes flexible multi-point real-time comparison and correction through the operation, occupies less resources and can compare the vector position.

The invention has the following implementation contents:

a multipoint position comparison system based on real-time Ethernet is connected with a multipoint position comparison result receiving system and comprises a master station, a servo slave station, a servo axis, a DEV bus processor, a stepping driver, a stepping X axis and a stepping Y axis;

the master station is connected with the servo slave station through an ErtherCAT bus;

the servo slave station is connected with the DEV bus processor through an ErtherCAT bus; the servo slave station is also connected with a servo shaft; the servo shaft is connected with the DEV bus processor through an encoder and transmits an encoder feedback signal;

the DEV bus processor is connected with the stepping driver;

the stepping driver is respectively connected with a stepping X shaft and a stepping Y shaft for processing; the step driver is a follow-up shaft step driver generated according to the servo shaft backup parameters;

the DEV bus processor is also connected with a multipoint position comparison result receiving system and sends an output result of multipoint position comparison to the multipoint position comparison result receiving system.

In order to better implement the invention, further, the DEV bus processor comprises an ARM EtherCAT protocol chip and an FPGA motion processing chip which are connected with each other through an SPI interface;

the system also comprises two Ethernet PHY chips; the ErtherCAT bus connected between the ARM EtherCAT protocol chip and the servo slave station comprises an ErtherCAT uplink bus and an ErtherCAT downlink bus; the ARM EtherCAT protocol chip is respectively connected with an ErtherCAT uplink bus and an ErtherCAT downlink bus through two Ethernet PHY chips;

the FPGA motion processing chip is provided with 8 paths of latch input interfaces, 2 paths of encoder input interfaces, 4 paths of multipoint position comparison output interfaces and 2 paths of axial pulse direction output interfaces;

the FPGA motion processing chip is connected with the servo shaft through an encoder input interface, connected with the stepping driver through a shaft pulse direction output interface, and connected with a multipoint position comparison result receiving system through a multipoint position comparison output interface.

In order to better realize the invention, the invention further comprises a first clock circuit, a first reset circuit, a first JTAG interface circuit and a UART debugging interface circuit; the ARM EtherCAT protocol chip is respectively connected with the first clock circuit, the first reset circuit, the first JTAG interface circuit and the UART debugging interface circuit.

In order to better realize the invention, the invention further comprises a second clock circuit, a second reset circuit and a second JTAG interface circuit; the FPGA motion processing chip is respectively connected with the second clock circuit, the second reset circuit and the second JTAG interface circuit.

In order to better implement the present invention, further, the FPGA motion processing chip includes a bus unit, a backup axis data unit, an expected position unit FIFO2 of a motion point at a position to be compared, a position unit FIFO1 to be compared, a multi-point position comparison mode configuration unit, an internal logic control unit, a multi-point position comparison output unit, an encoder acquisition and synthesis unit, an axis processing unit, a multi-point position comparison information unit, and an axis current state data unit;

the bus unit is connected with the ARM EtherCAT protocol chip through an SPI interface; the bus unit is connected with the internal logic control unit through the backup shaft data unit, the expected position unit FIFO2 of a moving point at the position to be compared, the position unit FIFO1 to be compared and the multipoint position comparison mode configuration unit after being respectively connected with the backup shaft data unit, the expected position unit FIFO2 of a moving point at the position to be compared, the position unit FIFO1 to be compared and the multipoint position comparison mode configuration unit;

the internal logic control unit is also respectively connected with a multipoint position comparison output unit, an encoder acquisition and synthesis unit, a shaft processing unit, a multipoint position comparison information unit and a shaft current state data unit;

the multipoint position comparison output unit is connected with a multipoint position comparison result receiving system through a multipoint position comparison output interface;

the encoder acquisition and synthesis unit is connected with the servo shaft through an encoder input interface and is also connected with the multi-point position comparison output unit;

the shaft processing unit is connected with the stepping driver through a shaft pulse direction output interface; the shaft processing unit and the shaft current state data unit are also respectively connected with the backup shaft data unit;

the multipoint position comparison information unit is also connected with a multipoint position comparison output unit; the multipoint position comparison information unit and the shaft current state data unit are also connected with the bus unit.

The invention also provides a multipoint position comparison method based on the real-time Ethernet, which comprises the steps of setting a communication cycle, and carrying out data interaction for multipoint position comparison of the servo slave station and the master station according to the communication cycle; the master station and the servo slave station are interrupted regularly according to the set communication period, and the period starting point of the communication period of the current motion segment is the period ending point of the communication period of the previous motion segment;

setting the speed and the target position of the current motion segment of the DEV bus processor through a master station at the beginning of the communication period of the current motion segment;

at the end of the communication period of the current motion segment, the number of pulses sent by the DEV bus processor reaches the set target position;

the DEV bus processor is then used to calculate the actual position of the current motion segment from the velocity of the current motion segment and compare the actual position to the position to be compared.

In order to better implement the present invention, further, the set target position is an instruction backup position of the step driving shaft, the DEV bus processor maintains the speed in one communication cycle to be a constant speed and to be consistent with the actual moving speed, and simultaneously the DEV bus processor acquires the current timely position in real time for triggering the position comparison.

In order to better implement the method, when the position to be compared is an interpolation position, the main station configures the setting value of the interpolation position to the actual position of the longest axis in the stepping X axis and the stepping Y axis of the current motion segment according to the interpolation relation so as to improve the precision.

In order to better implement the present invention, further, in a communication cycle, the operation flow of the master station is as follows: the master station sequentially performs timing interruption, data processing and sending the periodic data to the servo slave station and receiving the periodic data of the servo slave station; and the servo slave station is matched with the master station to sequentially perform event interruption, sending the periodic data to the master station and receiving the last periodic data of the master station and processing the data.

In order to better implement the present invention, further, in one communication cycle, the operation flow of the slave station is as follows: sequentially performing local synchronous interruption, sending uplink frame data, receiving downlink frame data, performing data interaction of an FPGA motion processing chip, setting a comparison position, setting a comparison mode, synchronizing data of the FPGA motion processing chip, synchronously calculating a comparison point by the FPGA motion processing chip, performing position comparison, outputting multi-point position comparison information, and entering the next period; when the FPGA motion processing chip synchronously calculates the comparison points and compares the positions, the FPGA motion processing chip is required to synchronously encode data and synchronously generate pulse signals.

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

(1) the invention is based on EtherCAT bus form, because EtherCAT has high-speed response, the characteristic of the extremely short cycle control itself, can insert the opportunity of the preset position in the course of moving, and does not need to concentrate and write into before moving, so can raise and set up efficiency and control flexibility;

(2) with the current written position to be compared being triggered in the movement process, the next position multiplexing can be carried out, so that the device does not need to reserve too large space, and the comparison function of a large number of position points can be realized only by a moderate FIFO space;

(3) the encoder feedback signal has strong functionality by comparing the single-axis feedback position and the vector position.

Drawings

FIG. 1 is a schematic diagram of a system framework of the present invention;

FIG. 2 is a diagram of a DEV bus processor architecture according to the present invention;

FIG. 3 is a schematic diagram of the FPGA motion processing chip of the present invention;

FIG. 4 is a schematic of a velocity versus time plot of a position comparison of the present invention;

FIG. 5 is a schematic illustration of a position versus time plot of the present invention compared to the corresponding position of FIG. 4;

FIG. 6 is a schematic diagram of a periodic communication mechanism and a location comparison point according to the present invention;

FIG. 7 is a schematic diagram of the system when a step axis scenario is employed;

FIG. 8 is a schematic diagram of the system when a servo axis scenario is employed;

FIG. 9 is a schematic view of vector velocity decomposition for position comparison;

FIG. 10 is a schematic view of the encoder feedback position synthesis;

FIG. 11 is a schematic flow chart of the operation of the Master station;

FIG. 12 is a schematic diagram of the operation of a slave station in cooperation with a master station;

FIG. 13 is a flow chart illustrating operation of a slave station;

FIG. 14 is a schematic diagram of the comparative output of the internal pulse source;

FIG. 15 is a schematic diagram of the encoder composite position comparison output.

Detailed Description

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and therefore should not be considered as a limitation to the scope of protection. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Example 1:

the embodiment provides a multipoint position comparison system based on real-time ethernet, as shown in fig. 1, fig. 2, fig. 3, fig. 7 and fig. 8, which is connected to a multipoint position comparison result receiving system, and includes a master station, a slave station, a servo axis, a DEV bus processor, a step driver, a step X axis and a step Y axis;

the DEV bus processor is connected with the stepping driver;

The working principle is as follows: the invention is based on the EtherCAT bus form, because EtherCAT has the characteristics of high-speed response and extremely short cycle control, the timing of the preset position can be inserted in the motion process, and the centralized writing before the motion is not needed, thereby improving the setting efficiency and the control flexibility. Meanwhile, the position to be compared which is written currently in the motion process is triggered, and next position multiplexing can be carried out, so that a large space does not need to be reserved in the equipment, and the comparison function of a large number of position points can be realized only by a moderate FIFO space. In addition, the encoder feedback signal has strong functionality by comparing the single-axis feedback position and the vector position.

Fig. 7 shows a scenario in which the DEV acts as a bus processor to give the pulse signals required by the stepper driver, and the stepper shaft is used to move the motor, as shown in fig. 7. At this time, the position information to be compared is written into DEV through bus, when using internal pulse source to make comparison, since DEV always produces pulse signal, the actual position information can be discriminated at any time, so as to trigger multipoint position comparison, and the multipoint position output is sent to the interface of valve switch. When the encoder feedback is used as single-axis comparison or as composite position comparison, the encoder feedback data of the stepping axis is directly used as source data;

as shown in fig. 8, fig. 8 is the case of servo driving controlled by EtherCAT bus, because there is no multi-point position comparison function in DEV inside the servo driver, because the bus servo driver is also reading data periodically, it is impossible to judge a certain position in the period accurately, which requires an external DEV for collecting encoder signal of the servo axis and synchronizing its actual pulse. The bus data backup of the servo driver is added into the DEV, the DEV generates actual pulses according to actual movement speed and movement acceleration, and the pulses can acquire accurate actual values at any time to judge position comparison points and synchronize to a stepping shaft so as to realize the follow-up of the stepping shaft and the servo shaft.

Example 2:

the embodiment also provides a multipoint position comparison method based on real-time ethernet, as shown in fig. 6, 11, 12 and 13, a communication cycle is set, and data interaction for multipoint position comparison of the slave station and the master station is performed according to the communication cycle; the master station and the servo slave station are interrupted regularly according to the set communication period, and the period starting point of the communication period of the current motion segment is the period ending point of the communication period of the previous motion segment;

the DEV bus processor is then used to calculate the actual position of the current motion segment from the velocity of the current motion segment and compare the actual position to the position to be compared. There are two types of actual positions: 1 is the position fed back by the encoder, and 2 is the position calculated by the shaft processing unit from the velocity. Different values are adopted according to different comparison modes. The two conditions correspond to the arrangement of a stepping driver, when a driving shaft and a slave station are arranged for processing, the stepping driver of a follow-up shaft is adopted, and when the slave station is not arranged, the driving stepping driver is adopted for directly controlling the driving of an X shaft and a Y shaft.

In order to better implement the present invention, further, the set target position is an instruction backup position of the step driving shaft, the DEV bus processor maintains the speed in one communication cycle to be a constant speed and to be consistent with the actual moving speed, and simultaneously the DEV bus processor acquires the current timely position in real time for triggering the position comparison. The concept of constant speed here is that in a communication period, the speed is set from the beginning of the communication period, so that in the period, the speed is constant, that is, the width and duty ratio of the pulse are the same, which is called constant speed. If the plurality of periods are all such same pulse width and duty cycle, then the constant speed is maintained. The actual movement speed here refers to the theoretical speed of the servo. Since the servo position is compared, but the servo can only obtain its actual position at the periodic nodes, which is discontinuous, we use a backup axis to simulate generating the motion, which is uniform in the period, but we can know every position. The current in-time position refers to the servo actual position fed back by the encoder. This position is asynchronous to the pulses we have sent, and is related to the servo motor stiffness and other parameters.

Example 3:

in this embodiment, on the basis of the above embodiment 2, as shown in fig. 4 and 5, the pulse speed and the target position actually sent by the bus-type control card are stepped, that is, the command is set at the beginning of the communication cycle, and the command of the next cycle is sent at the end of the communication cycle; thus the actual speed can only be kept constant within the communication period; the target position is due to the relation of communication cycles, the master control can only obtain the actual position at the end of each cycle, at the dotted line in the figure, the master and slave on the bus can interact once, the slave station feeds back the current position to the master station, and a real-time position value, namely a black line of a displacement curve cannot be obtained, so that the position comparison cannot be controlled by the master station in the position comparison. Thus, an axis unit is provided in the DEV to simulate the generation of an actual position in a unit cycle, so that a current position can be obtained in real time to be used as a comparison position of a command pattern; the axis unit processes the target position.

The other parts of this embodiment are the same as those of embodiment 2, and thus are not described again.

Example 4:

this embodiment is based on any of the above embodiments 2-3, as shown in fig. 9, the master communication is sending data to our DEVs at fixed time intervals (e.g., 1 ms). In each communication cycle, the received speed is stable and can be decomposed according to the interpolation relation of two axes.

The DEV receives the single axis data after it has been decomposed, including the target velocity and target position for the cycle. Thus, when DEV processes a certain position to be compared on the vector displacement, the y-axis is necessarily in place when the decomposed x-axis is in place due to isochronism of the decomposed motion.

When the encoder position value fed back from the outside is needed to be used as comparison, the encoder unit is used for receiving the encoder value to obtain a real-time position;

if the position is a single axis, the comparison is simple and can be directly carried out by using the position;

if the positions of the vector axes are required to be compared, the positions of the two axes need to be synthesized.

Other parts of this embodiment are the same as any of embodiments 2 to 3, and thus are not described again.

Example 5:

this embodiment is based on any of embodiments 2 to 4 described above, and it is assumed that a comparison value needs to be triggered at a point (x1, y1) in the figure, as shown in fig. 10.

The actual positions of the x-axis and the y-axis are synthesized in the DEV, and due to the fact that the motion of the two axes is not uniform, delay parameters are different and the like, the synthesized real-time position cannot be exactly superposed with the point (x1, y1), and fluctuates up and down along the track, and at the moment, the synthesized actual position needs to be judged.

The master station communication contains comparison position information and last expected movement position information (x0, y0), and by the positions of the two points, a perpendicular bisector equation in the movement direction at the comparison point can be made:

y＝-(x1-x0)/(y1-y0)x+(y0+y1)/2+(x0-x1)(x0+x1)/(2y1-2y0)

the position of the synthesized vector is synthesized according to the rectangular coordinate system in fig. 9, and the synthesized position is compared with the position of the middle vertical line in real time, and when the motion direction is positive and the position is above the straight line, or the motion direction is negative and the position is below the straight line, the synthesized position is determined as the comparison position.

Other parts of this embodiment are the same as any of embodiments 2 to 4, and thus are not described again.

Example 6:

this embodiment is based on any of embodiments 2 to 5 described above, and as shown in fig. 14, the target speed on the x axis is 400KHz, the target speed on the y axis is 300KHz, and the comparison pulse width is 50 us.

The communication period is 1 ms.

Then: the x-axis runs 400 pulses per cycle and the y-axis runs 300 pulses per cycle.

At time t0(x0, y0), the target comparison position needs to be set to (x1, y1), the pseudo x1 is x0+80, and the y1 is y0+60, when the internal pulse source is used for comparison, the comparison position of the target is set to (x0+80, y0+60), and when the current period passes 80/400 to 0.2ms, a pulse width of 50us is output through calculation.

Other parts of this embodiment are the same as any of embodiments 2 to 5 described above, and therefore, description thereof is omitted.

Example 7:

this embodiment is based on any of embodiments 2 to 6 described above, and as shown in fig. 15, when an external encoder is used as a comparison source, the position of a comparison point and a theoretical previous position are set in advance. The following is analyzed in a simple micro-segment:

for example, the comparison point is p1(100 ), and the position on the comparison point is p0(99, 99).

And a perpendicular to the movement direction perpendicular to the perpendicular bisector is made according to the point position, and y is-x + 199.

The encoder position values obtained in real time hardly reach the (100 ) position accurately due to the difference in rigidity, delay, and the like of the encoder shaft feedback. Assuming that the y axis of the actually returned encoder is earlier than the x axis, the returned speed fluctuation is consistent, namely the returned position curve is y ═ x + 20;

then the calculation triggers a position comparison when x is 90, i.e. point a (90,110) is reached.

In practice, the difference between the encoders should be adjusted as much as possible so that the comparison point is as close to the set point as possible. The accuracy of the actual positioning is higher when the difference is smaller.

Other parts of this embodiment are the same as any of embodiments 2 to 6, and thus are not described again.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and all simple modifications and equivalent variations of the above embodiments according to the technical spirit of the present invention are included in the scope of the present invention.

Claims

1. A multipoint position comparison system based on real-time Ethernet is connected with a multipoint position comparison result receiving system and is characterized by comprising a master station, a servo slave station, a servo axis, a DEV bus processor, a stepping driver, a stepping X axis and a stepping Y axis;

the DEV bus processor is connected with the stepping driver;

the stepping driver is respectively connected with a stepping X shaft and a stepping Y shaft for processing; the step driver is divided into a driving step driver or a follow-up shaft step driver according to the use condition;

2. The real-time ethernet based multipoint location comparison system of claim 1 wherein said DEV bus processor comprises an ARM EtherCAT protocol chip and an FPGA motion processing chip interconnected by an SPI interface;

3. The real-time ethernet based multipoint position comparing system according to claim 2, further comprising a first clock circuit, a first reset circuit, a first JTAG interface circuit, a UART debug interface circuit; the ARM EtherCAT protocol chip is respectively connected with the first clock circuit, the first reset circuit, the first JTAG interface circuit and the UART debugging interface circuit.

4. The real-time ethernet based multipoint position comparing system according to claim 2, further comprising a second clock circuit, a second reset circuit, a second JTAG interface circuit; the FPGA motion processing chip is respectively connected with the second clock circuit, the second reset circuit and the second JTAG interface circuit.

5. A real-time Ethernet based multipoint position comparison system as claimed in any one of claims 2-4 wherein said FPGA motion processing chip includes bus unit, backup axis data unit, expected position unit FIFO2 of a motion point at a position to be compared, position unit FIFO1 to be compared, multipoint position comparison mode configuration unit, internal logic control unit, multipoint position comparison output unit, encoder acquisition and synthesis unit, axis processing unit, multipoint position comparison information unit, axis current state data unit;

6. The multipoint position comparison method based on the real-time Ethernet as claimed in claim 5, wherein a communication cycle is set, and data interaction for multipoint position comparison of the slave station and the master station is performed according to the communication cycle; the master station and the servo slave station are interrupted regularly according to the set communication period, and the period starting point of the communication period of the current motion segment is the period ending point of the communication period of the previous motion segment;

7. The method as claimed in claim 6, wherein the target position is set as a command backup position of the step driving axis, the DEV bus processor maintains a constant speed in one communication cycle and keeps consistent with an actual moving speed, and the DEV bus processor acquires a current and timely position in real time for triggering the position comparison.

8. The method as claimed in claim 7, wherein when the position to be compared is an interpolation position, the master station configures the setting value of the interpolation position to the actual position of the longest axis of the step X axis and the step Y axis of the current motion segment according to the interpolation relationship, so as to improve the accuracy.

9. The multipoint position comparing method based on real time ethernet of claim 8, wherein in a communication cycle, the operation procedure of the master station is as follows: the master station sequentially performs timing interruption, data processing and sending the periodic data to the servo slave station and receiving the periodic data of the servo slave station; and the servo slave station is matched with the master station to sequentially perform event interruption, sending the periodic data to the master station and receiving the last periodic data of the master station and processing the data.

10. The real-time ethernet-based multipoint position comparing method according to claim 8, wherein in a communication cycle, the slave station is operated by: sequentially performing local synchronous interruption, sending uplink frame data, receiving downlink frame data, performing data interaction of an FPGA motion processing chip, setting a comparison position, setting a comparison mode, synchronizing data of the FPGA motion processing chip, synchronously calculating a comparison point by the FPGA motion processing chip, performing position comparison, outputting multi-point position comparison information, and entering the next period; when the FPGA motion processing chip synchronously calculates the comparison points and compares the positions, the FPGA motion processing chip is required to synchronously encode data and synchronously generate pulse signals.