CN112606043A - Multi-axis manipulator scram distance and scram time testing method - Google Patents
Multi-axis manipulator scram distance and scram time testing method Download PDFInfo
- Publication number
- CN112606043A CN112606043A CN202011618689.6A CN202011618689A CN112606043A CN 112606043 A CN112606043 A CN 112606043A CN 202011618689 A CN202011618689 A CN 202011618689A CN 112606043 A CN112606043 A CN 112606043A
- Authority
- CN
- China
- Prior art keywords
- scram
- distance
- time
- axis
- axis manipulator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J19/00—Accessories fitted to manipulators, e.g. for monitoring, for viewing; Safety devices combined with or specially adapted for use in connection with manipulators
- B25J19/0095—Means or methods for testing manipulators
Landscapes
- Engineering & Computer Science (AREA)
- Robotics (AREA)
- Mechanical Engineering (AREA)
- Manipulator (AREA)
Abstract
The invention discloses a method for testing the emergency stop distance and the emergency stop time of a multi-axis manipulator, which is characterized in that 3 acceleration sensors are fixed at the tail end or the tested shaft end of the multi-axis manipulator, the 3 acceleration sensors are arranged and installed in a mutually vertical mode, the multi-axis manipulator runs normally or runs according to a planned test path, the emergency stop is pressed when the multi-axis manipulator moves normally, and the emergency stop distance and the emergency stop time are calculated by analyzing the data fed back by the acceleration when the multi-axis manipulator stops. The invention does not need to use external triggering of a photoelectric sensor and a laser tracker, is not limited by the precision of the laser tracker or delay introduced by a delay device, can meet the test requirement of the multi-axis manipulator, and is simple to operate.
Description
Technical Field
The invention relates to the technical field of industrial machinery test, in particular to a method for testing the emergency stop distance and the emergency stop time of a multi-shaft manipulator.
Background
The multi-axis manipulator is an industrial robot, can be taught manually, can also operate according to a preset program, and is a machine which realizes various functions by means of self power and control capacity. No matter in the stages of debugging, running, maintaining and the like of the robot body or in the system integration environment, collision danger can occur at any time, and the emergency stop function plays a key role in preventing further expansion of the danger. In the design and manufacture of industrial robots, the stop time and the stop distance of the sudden stop are part 1 of the mandatory standard for industrial robots GB 11291.1-2011 "safety requirements for robots for industrial environments: the important technical indexes required in the robot system and the integration are important design bases of maintenance devices such as safety fences, safety light curtains and the like in the system integration of the industrial robot.
With the progress of industrial technology, automation is trending, the application of the multi-axis manipulator is more and more extensive, and along with the soundness of the function of the manipulator, safety is also the key point of long-term attention. The emergency stop time and the emergency stop distance form one of the most important links of the safety of the manipulator. Some current manipulator manufacturers can give theoretical emergency stop distance and emergency stop time according to design data, but only can be used as reference; and the photoelectric sensor is used for external triggering, the laser tracker is used for measuring the emergency stop distance and the emergency stop time, so that the test effect is not ideal enough due to the limited precision of the laser tracker or the introduction of a time delay device, and the measurement is not convenient enough.
Through retrieval, the Chinese special for publication No. CN110281273A in 2019, 9 and 27 disclose a device and a method for testing the emergency stop time and stop distance of an industrial robot, wherein the device comprises an emergency stop trigger device for triggering the emergency stop of the industrial robot; the data acquisition external trigger part is used for triggering the laser tracker to acquire data; the external trigger self-locking device is used for converting a pulse signal formed by the photoelectric sensor shielded by the detected part of the industrial robot into a continuous level signal; and the photoelectric sensor is used for simultaneously transmitting the electric signal to the emergency stop trigger device, the data acquisition external trigger device and the external trigger self-locking device. When the photoelectric sensor senses that the industrial robot reaches the designated position, a signal is sent out to trigger the emergency stop trigger device to act so as to enable the robot to perform emergency stop and trigger the data acquisition external trigger device to act so as to enable the laser tracker to perform data acquisition, and the test of emergency stop time and stop distance is completed. This patent application utilizes the quick reaction of devices such as photoelectric sensor, external trigger self-lock device to realize automatic test, but as mentioned earlier, its measuring accuracy is restricted by the precision of laser tracker itself, and has the time precision not good problem that the delay device leads to.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a method for testing the emergency stop distance and the emergency stop time of the multi-axis manipulator.
The invention is realized by the following technical scheme:
a multi-axis manipulator scram distance and scram time testing method comprises the following steps:
fixedly mounting 3 acceleration sensors at the tail end or the shaft end of the multi-shaft manipulator, wherein the 3 acceleration sensors are arranged vertically;
pressing down to stop suddenly when the multi-axis manipulator runs normally and the speed is stable;
and analyzing data fed back by the acceleration sensor, and calculating the emergency stop distance and the emergency stop time.
As a further technical scheme, 3 acceleration sensors are respectively arranged on an X axis, a Y axis and a Z axis of the multi-axis manipulator.
Among the above-mentioned technical scheme, fix 3 acceleration sensor at the multiaxis manipulator end or the axle head of surveying, 3 acceleration sensor mutually perpendicular arrange the installation, let multiaxis manipulator normal operating or according to the operation of planned test path, press scram when treating that multiaxis manipulator is in normal motion, treat that multiaxis manipulator stops, the data of analysis acceleration feedback calculates scram distance and scram time. According to the technical scheme, external triggering of a photoelectric sensor and the laser tracker are not needed, the method is not limited by the precision of the laser tracker or delay introduced by a delay device, the test requirement of the multi-axis manipulator can be met, and the method is simple to operate.
As a further technical scheme, the motion process of the multi-axis manipulator to the target point comprises three stages: an acceleration stage, a speed stabilization stage and a deceleration stage; and the emergency stop distance and the emergency stop time in the acceleration stage and the deceleration stage are both smaller than those in the speed stabilization stage. The existing multi-axis manipulator has a safer motion planning mode for rapidly reaching a target point: the manipulator reaches a target according to a preset program, generally accelerates firstly, and the acceleration time is short; the operation is stable after the speed is accelerated to the rated speed, and the time for stabilizing the speed is longer; and (5) decelerating for the first time after approaching the target area, continuing to move, and decelerating again when approaching the target. In the planned movement process, the multi-axis manipulator suddenly stops at the uniform speed stage, the sudden stop time and the sudden stop distance of the multi-axis manipulator are the longest, and the sudden stop time and the sudden stop distance of the uniform speed stage can represent the sudden stop performance of the multi-axis manipulator as a whole.
As a further technical solution, after the sudden stop is pressed, the sudden stop distance of the multi-axis manipulator in any direction is equal to the idle running distance + the braking distance.
As a further technical solution, the idle distance is the rated speed of the speed stabilization phase and the idle time, wherein the idle time is the time difference between the press scram time and the deceleration start time; the braking distance is the integral result of the rated speed in the speed stabilizing stage in the deceleration stage, wherein the deceleration stage refers to the stage of the multi-axis manipulator reducing the speed from the rated speed to zero.
Specifically, after acceleration data fed back by the acceleration sensor is obtained, for any one direction of the three directions of the multi-axis manipulator, the acceleration is subjected to integral calculation to obtain the speed, and the speed is further subjected to integral calculation to obtain the sudden stop distance in the direction.
As a further technical solution, the rated speed in the speed stabilization phase is a time integral of the acceleration in the acceleration phase, wherein the acceleration phase refers to a phase in which the multi-axis manipulator increases from zero speed to the rated speed.
As a further technical scheme, the scram distance of the multi-axis manipulator is the vector sum of the scram distances of the multi-axis manipulator in three directions.
As a further technical scheme, the scram time of the multi-axis manipulator is the time difference between the scram stop time of the multi-axis manipulator and the press scram time.
Specifically, data output by the three acceleration sensors are acceleration values corresponding to time points, wherein the time points are 1000 points/second, and the precision requirement is met.
Compared with the prior art, the invention has the beneficial effects that: according to the invention, 3 acceleration sensors are fixed at the tail end or the measured shaft end of the multi-axis manipulator, the 3 acceleration sensors are arranged and installed in a mutually perpendicular mode, the multi-axis manipulator runs normally or runs according to a planned test path, when the multi-axis manipulator is in normal motion, the multi-axis manipulator is pressed down to stop suddenly, when the multi-axis manipulator stops, the data fed back by the acceleration is analyzed, and the sudden stop distance and the sudden stop time are calculated. The invention does not need to use external triggering of a photoelectric sensor and a laser tracker, is not limited by the precision of the laser tracker or delay introduced by a delay device, can meet the test requirement of the multi-axis manipulator, and is simple to operate.
Drawings
Fig. 1 is a qualitative analysis diagram of acceleration/velocity/displacement of a robot to automatically achieve a predetermined target.
Fig. 2 is a schematic view of an installation of an acceleration sensor according to an embodiment of the present invention.
Fig. 3 is a schematic diagram of quantitative analysis of a multi-axis robot scram distance and scram time testing method according to an embodiment of the invention.
Detailed Description
The technical solutions of the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings, and it is to be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without any inventive step, are within the scope of the present invention.
The terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the invention, the motion planning mode of the multi-axis manipulator for rapidly reaching a target point is as follows: the manipulator reaches a target according to a preset program, the acceleration is carried out firstly, and the acceleration time is short; the operation is stable after the speed is accelerated to the rated speed, and the time for stabilizing the speed is longer; and (5) decelerating for the first time after approaching the target area, continuing to move, and decelerating again when approaching the target.
Specifically, as shown in fig. 1, the multi-axis manipulator starts to accelerate from t1 to t2, and then reaches a rated speed V1; the multi-axis manipulator normally moves at a speed V1, and the speed is stable at the moment; when the multi-axis manipulator approaches the target area, namely at the time t3, starting first deceleration and continuing for first deceleration time to reach the rated speed V2, and ending the first deceleration; and the multi-axis manipulator runs at the rated speed V2 for a period of time until the multi-axis manipulator approaches the target, starts to decelerate for the second time and continues for the second deceleration time until the speed is reduced to zero, and the multi-axis manipulator stops moving. Wherein t1 → t2 is the acceleration phase; t2 → t3 is a speed stabilization phase (uniform speed phase); t3 → t4 is the deceleration stage.
As described above, the sudden stop time and the sudden stop distance of the constant speed stage (speed stabilization stage) in the three time periods are the longest, the sudden stop time and the sudden stop distance of the constant speed stage can represent the sudden stop performance of the multi-axis manipulator as a whole, and the sudden stop time and the sudden stop distance of other time periods are shorter than those of the constant speed stage.
The invention provides a method for testing the emergency stop distance and the emergency stop time of a multi-axis manipulator, which is characterized in that 3 acceleration sensors are fixed at the tail end or the tested shaft end of the multi-axis manipulator, the 3 acceleration sensors are arranged and installed in a mutually vertical mode, the multi-axis manipulator runs normally or runs according to a planned test path, the emergency stop is pressed when the multi-axis manipulator runs normally, and the data fed back by the acceleration is analyzed to calculate the emergency stop distance and the emergency stop time when the multi-axis manipulator stops.
After the sudden stop is pressed down, the sudden stop distance of the multi-axis manipulator in any direction is equal to the idle running distance plus the braking distance.
Further, the idling distance is the rated speed of the speed stabilization stage and the idling time, wherein the idling time is the time difference between the press scram time and the deceleration starting time; the braking distance is the integral result of the rated speed in the speed stabilizing stage in the deceleration stage, wherein the deceleration stage refers to the stage of the multi-axis manipulator reducing the speed from the rated speed to zero. After acceleration data fed back by the acceleration sensor is obtained, for any direction of the multi-axis manipulator in three directions, the acceleration is subjected to integral calculation to obtain the speed, and the speed is further subjected to integral calculation to obtain the sudden stop distance in the direction. The rated speed of the speed stabilization stage is the time integral of the acceleration in the acceleration stage, wherein the acceleration stage refers to the stage of the multi-axis manipulator increasing from zero speed to the rated speed.
Finally, the scram distance of the multi-axis manipulator is the vector sum of the scram distances of the multi-axis manipulator in three directions. The scram time of the multi-axis manipulator is the time difference between the scram stop time of the multi-axis manipulator and the press scram time.
Examples
In the method for testing the scram distance and the scram time of the multi-axis manipulator, 3 acceleration sensors are fixed at the tail end or the measured shaft end of the multi-axis manipulator, and as shown in fig. 2, the 3 acceleration sensors are respectively arranged on the X axis, the Y axis and the Z axis of the multi-axis manipulator. For the convenience of calculation, one axis of the multi-axis manipulator is consistent with the axial direction of the multi-axis manipulator. The output data of the acceleration sensor is an acceleration value corresponding to a time point (1000 points/second, with sufficient accuracy).
As shown in fig. 3, t1 is an acceleration start time, t2 is an acceleration end time, t0 is a press down sudden stop time, t3 is a deceleration start time, t4 is a deceleration end time, S1 is a free distance, S2 is a braking distance, S is a sudden stop distance, and V is a rated speed. Wherein t1-t2 is an acceleration stage, t2-t3 is a constant speed stage, and t3-t4 is a deceleration stage.
The calculation for a single direction includes:
S1＝V(t3-t0)
Si＝S1+S2(i＝X/Y/Z)
T＝t4-t0
according to the formula, the sudden stop time T and the sudden stop distance S in a single direction of the manipulator are obtainediAnd obtaining the final displacement of the manipulator through three-way vector synthesis, namely the scram distance of the manipulator is as follows:
Sscram distance＝SX+SY+SZ
In the description herein, references to the description of the terms "one embodiment," "certain embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention.
Claims (8)
1. A multi-axis manipulator scram distance and scram time testing method is characterized by comprising the following steps:
fixedly mounting 3 acceleration sensors at the tail end or the shaft end of the multi-shaft manipulator, wherein the 3 acceleration sensors are arranged vertically;
pressing down to stop suddenly when the multi-axis manipulator runs normally and the speed is stable;
and analyzing data fed back by the acceleration sensor, and calculating the emergency stop distance and the emergency stop time.
2. The multi-axis robot scram distance and scram time testing method as set forth in claim 1, wherein 3 acceleration sensors are respectively arranged on an X-axis, a Y-axis and a Z-axis of the multi-axis robot.
3. The multi-axis manipulator scram distance and scram time testing method as claimed in claim 1 or 2, wherein the motion process of the multi-axis manipulator to reach the target point comprises three stages: an acceleration stage, a speed stabilization stage and a deceleration stage; and the emergency stop distance and the emergency stop time in the acceleration stage and the deceleration stage are both smaller than those in the speed stabilization stage.
4. The multi-axis manipulator scram distance and scram time testing method as claimed in claim 3, wherein after the scram is pressed, the scram distance of the multi-axis manipulator in any direction is equal to the idle running distance + the braking distance.
5. The multi-axis manipulator scram distance and scram time testing method according to claim 4, wherein the idle distance is a rated speed of a speed stabilization phase and the idle time is a time difference between a press scram time and a deceleration start time; the braking distance is the integral result of the rated speed in the speed stabilizing stage in the deceleration stage, wherein the deceleration stage refers to the stage of the multi-axis manipulator reducing the speed from the rated speed to zero.
6. The multi-axis manipulator scram distance and scram time testing method as claimed in claim 5, wherein the rated speed of the speed stabilization phase is a time integral of acceleration in an acceleration phase, wherein the acceleration phase refers to a phase in which the multi-axis manipulator rises from zero speed to the rated speed.
7. The multi-axis robot scram distance and scram time testing method as recited in any one of claims 4 to 6, wherein the scram distance of the multi-axis robot is a vector sum of scram distances of the multi-axis robot in three directions.
8. The multi-axis robot scram distance and scram time testing method as set forth in claim 1, wherein the scram time of the multi-axis robot is a time difference between a time of scram stop of the multi-axis robot and a time of pressing down the scram stop.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011618689.6A CN112606043A (en) | 2020-12-30 | 2020-12-30 | Multi-axis manipulator scram distance and scram time testing method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011618689.6A CN112606043A (en) | 2020-12-30 | 2020-12-30 | Multi-axis manipulator scram distance and scram time testing method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN112606043A true CN112606043A (en) | 2021-04-06 |
Family
ID=75249504
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011618689.6A Pending CN112606043A (en) | 2020-12-30 | 2020-12-30 | Multi-axis manipulator scram distance and scram time testing method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112606043A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113352351A (en) * | 2021-06-01 | 2021-09-07 | 武汉联影智融医疗科技有限公司 | Method and system for measuring end emergency stop distance of medical surgical robot |
| CN113650012A (en) * | 2021-08-06 | 2021-11-16 | 中科新松有限公司 | Method, device and system for testing braking performance of robot |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20110245970A1 (en) * | 2010-04-02 | 2011-10-06 | Gm Global Technology Operations, Inc. | Systems and Methods for Evaluating Braking Performance |
| CN102874665A (en) * | 2012-09-27 | 2013-01-16 | 杭州亿恒科技有限公司 | Method and device for accurately and quickly measuring escalator stopping distance |
| CN104071681A (en) * | 2014-06-19 | 2014-10-01 | 广州特种机电设备检测研究院 | Escalator brake parameter detecting method |
| CN106945042A (en) * | 2017-03-29 | 2017-07-14 | 浙江工业大学 | A kind of discrete S types curve speed control method of manipulator |
| CN110181507A (en) * | 2019-05-07 | 2019-08-30 | 成都卡诺普自动化控制技术有限公司 | A kind of emergency stop control method and system for robot |
| CN110281273A (en) * | 2019-06-27 | 2019-09-27 | 上海电器科学研究所（集团）有限公司 | Industrial robot emergency stop dwell time and stop distance test device and test method |
-
2020
- 2020-12-30 CN CN202011618689.6A patent/CN112606043A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20110245970A1 (en) * | 2010-04-02 | 2011-10-06 | Gm Global Technology Operations, Inc. | Systems and Methods for Evaluating Braking Performance |
| CN102874665A (en) * | 2012-09-27 | 2013-01-16 | 杭州亿恒科技有限公司 | Method and device for accurately and quickly measuring escalator stopping distance |
| CN104071681A (en) * | 2014-06-19 | 2014-10-01 | 广州特种机电设备检测研究院 | Escalator brake parameter detecting method |
| CN106945042A (en) * | 2017-03-29 | 2017-07-14 | 浙江工业大学 | A kind of discrete S types curve speed control method of manipulator |
| CN110181507A (en) * | 2019-05-07 | 2019-08-30 | 成都卡诺普自动化控制技术有限公司 | A kind of emergency stop control method and system for robot |
| CN110281273A (en) * | 2019-06-27 | 2019-09-27 | 上海电器科学研究所（集团）有限公司 | Industrial robot emergency stop dwell time and stop distance test device and test method |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113352351A (en) * | 2021-06-01 | 2021-09-07 | 武汉联影智融医疗科技有限公司 | Method and system for measuring end emergency stop distance of medical surgical robot |
| CN113650012A (en) * | 2021-08-06 | 2021-11-16 | 中科新松有限公司 | Method, device and system for testing braking performance of robot |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN112606043A (en) | Multi-axis manipulator scram distance and scram time testing method | |
| JP2840720B2 (en) | Mechanical calibration device and calibration method using the device | |
| CN111765844B (en) | Method for detecting dynamic error of grating ruler | |
| CN106289767A (en) | A kind of robot is with high-end speed reducer drive accuracy testing platform | |
| US20030201746A1 (en) | Positional control of a controlled object during movement initiation | |
| CN212300247U (en) | Detection system for dynamic error of grating ruler | |
| CN104697440A (en) | Multi-light-beam cascading staircase angle reflector laser interferometer and measurement method thereof | |
| CN114442556A (en) | Machine tool rapid compensation system based on laser interference principle and compensation method thereof | |
| CN205538092U (en) | On --spot calibrating device of measuring equipment that measured one's own ability in six minutes | |
| CN113280992A (en) | Wind tunnel virtual flight test system for lifting body model | |
| US4719578A (en) | Profiling control apparatus and control method thereof | |
| CN110281273B (en) | Industrial robot scram stop time and stop distance testing device and testing method | |
| CN214200176U (en) | Precision calibration device for eddy current displacement sensor in sealed environment | |
| CN215248905U (en) | Elevator operating speed real-time detection device | |
| CN114814424A (en) | Quality testing device of servo driver | |
| CN210500340U (en) | Industrial robot scram stop time and stopping distance testing arrangement | |
| CN113899575A (en) | Precision speed reducer testing platform and method | |
| CN113494890A (en) | Fiber bragg grating strain sensor precision measuring device and method based on FPI interferometer | |
| CN215297663U (en) | Vehicle-mounted laser radar testing device | |
| CN206756127U (en) | A kind of high-precision Self-resetting probe-type displacement measuring device | |
| CN115475013B (en) | Master-slave arm time delay measuring method for master-slave operation robot | |
| CN213904103U (en) | Linear servo motor dynamic data acquisition system based on Internet of things | |
| CN216133086U (en) | Accurate control high-speed motor driving device based on optical counting | |
| CN204495277U (en) | A kind of anti-interference ladder corner reflector laser interferometer | |
| CN110030922B (en) | Multipoint synchronous measurement method and system and storage medium |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20210406 |