A dynamic braking device and method for a multi-degree-of-freedom motion simulation platform

Abstract

The application relates to a dynamic braking device and method for a multi-degree-of-freedom motion simulation platform, which comprises a PLC motion controller, an uninterrupted power supply (UPS) and a plurality of first contactors corresponding to a plurality of motion execution mechanisms; the UPS supplies power to the PLC motion controller; the first contactors are connected between UVW ends of a servo driver and a servo motor; the PLC motion controller is connected with control ends of the first contactors, used for cutting off the connection between the UVW ends of the servo driver and the servo motor and connecting the UVW ends of the servo motor in parallel to form a reverse connection braking circuit, and dynamically braking the servo motor when the motion simulation platform is stopped due to a fault. The application has the advantages of simple process, high automation degree, no recycling limitation, no loss, low cost and high suitability for braking technology of a platform system above 3 tons.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of multi-degree-of-freedom motion simulation platform development, in particular to a dynamic braking device and method for a multi-degree-of-freedom motion simulation platform. BACKGROUND

[0002] With the development of science and technology, the application field of multi-degree-of-freedom motion simulation platform is wider and wider, and the load tonnage is larger and larger, from several dozen kilograms to several dozen tons, which is the best development and application platform for scientific research and teaching.

[0003] In order to protect the safety of equipment and personnel, the motor of the servo electric cylinder driving the multi-degree-of-freedom motion simulation platform has a brake, when the system fails or is powered off, the motor brake starts quickly, and the electric cylinder is immediately locked, so that the platform can stop moving immediately and be kept at the current position. Figure 1 Because the platform does not continue to move due to its own inertia and the inertia of the cabin, the traditional brake is designed and formed integrally with the servo motor, occupying 30% of the total length of the motor, and is a friction brake, which can only be used when the motor is enabled or the shaft is not subjected to external force. If the motor brake is used too much in the case of motor rotation and large inertia, the friction coefficient of the brake inner friction plate will be reduced, and the safety will be reduced. The braking technology of the motion simulation platform has been the biggest obstacle to safety in large tonnage, and is the last guarantee for the safety of the load equipment or personnel.

[0004] At the same time, since the multi-degree-of-freedom motion simulation platform is a high-precision motion platform developed based on servo devices, its motion complexity may cause it to fail and be stuck in any attitude. If there is no safe homing system, the motion simulation platform may be stuck in an inconvenient attitude for personnel evacuation or troubleshooting. SUMMARY

[0005] The present application provides a dynamic braking device and method for a multi-degree-of-freedom motion simulation platform, which solves the problem that the existing traditional braking technology cannot be used in dynamic state and can only be used in static state, and solves the problems of large motor volume, serious brake wear, high failure rate, poor safety, large load center of gravity deviation leading to inability to fall to a horizontal state, etc.

[0006] The technical solution of the present application to solve the above technical problems is as follows:

[0007] A dynamic braking device for a multi-degree-of-freedom motion simulation platform, the multi-degree-of-freedom motion simulation platform is supported and driven by a plurality of motion execution mechanisms to move the platform, the motion execution mechanism is composed of a servo driver and a servo motor, comprising: a PLC motion controller, an uninterruptible power supply (UPS), and a plurality of first contactors corresponding to the plurality of motion execution mechanisms.

[0008] The UPS supplies power to the PLC motion controller;

[0009] The first contactor is connected between the servo driver and the UVW end of the servo motor;

[0010] The PLC motion controller is connected to the control end of the first contactor, and when the motion simulation platform is shut down due to a fault, the connection between the servo driver and the UVW end of the servo motor is cut off, and the UVW end of the servo motor is connected in parallel to form a reverse braking circuit, and the servo motor is dynamically braked.

[0011] Further, the dynamic braking device further comprises a frequency converter and a second contactor corresponding to a plurality of motion execution mechanisms;

[0012] The UPS supplies power to the frequency converter, and the control end of the second contactor is connected to the PLC motion controller;

[0013] The UPS, the frequency converter, the second contactor, and the corresponding servo motor form a frequency converter control loop, which is used to drive the servo motor to retract the electric cylinder according to the preset speed;

[0014] The UPS, the servo driver, and the servo motor form a driver auxiliary control loop, which is used to collect servo motor position data;

[0015] The PLC motion controller is respectively connected in communication with the servo driver and the frequency converter, and is used to receive the servo motor position data collected by the servo driver and control the frequency converter to work.

[0016] Further, the PLC motion controller is used for:

[0017] By comparing the position data of the corresponding servo motor collected by each servo driver, if the stroke difference of the adjacent servo motor is greater than a preset threshold, the servo motor with the larger stroke is taken as a target servo motor, the PLC motion controller controls the second contactor between the target servo motor and the frequency converter to close, and the first contactor corresponding to the target servo motor is disconnected, and the frequency converter is controlled to drive the target servo motor to retract the electric cylinder according to the preset speed.

[0018] Further, after the PLC motion controller controls the second contactor between the larger stroke servo motor and the frequency converter to close, and the first contactor corresponding to the larger stroke servo motor is disconnected, the frequency converter is started after a preset time interval, and the frequency converter is controlled to drive the larger stroke servo motor to retract the electric cylinder according to the preset speed.

[0019] Further, the PLC motion controller is further used for:

[0020] When the stroke difference between the target servo motor and its adjacent servo motor is less than a preset threshold, the second contactor corresponding to the target servo motor is disconnected, and the first contactor is closed.

[0021] Further, the design capacity of the UPS is a servo motor unit capacity.

[0022] Based on the above-mentioned dynamic braking device, the application further provides a dynamic braking method for a multi-degree-of-freedom motion simulation platform, comprising the following steps:

[0023] S1, when the motion simulation platform is shut down due to a fault, the PLC motion controller cuts off the connection between the servo driver and the UVW end of the servo motor and connects the UVW end of the servo motor in reverse, forming a reverse braking circuit;

[0024] S2, the UPS supplies power to each servo driver, and the servo driver acquires the position data of the servo motor encoder in real time and sends it to the PLC motion controller;

[0025] S3, the PLC motion controller compares the position data of the corresponding servo motor collected by each servo driver, and if the stroke difference between the adjacent servo motors is greater than a preset threshold, the servo motor with the larger stroke is taken as the target servo motor, the PLC motion controller controls the second contactor between the target servo motor and the frequency converter to be closed, and the first contactor corresponding to the target servo motor to be disconnected, controls the frequency converter to drive the target servo motor to retract the electric cylinder at a preset speed, until the stroke difference between the target servo motor and its adjacent servo motor is less than the preset threshold, then step S4 is executed;

[0026] S4, the PLC motion controller disconnects the second contactor corresponding to the target servo motor, closes the first contactor, and jumps to step S2 until the motion simulation platform is stationary.

[0027] The beneficial effects of the application are: 1. The brake originally installed on the servo motor is cancelled, the motor length is saved, and the relative redundant length is added to the stroke of the electric cylinder, which can increase the platform motion performance parameters.

[0028] 2. The brake originally installed on the servo motor is cancelled, the cost is saved, which is about 10-40% of the actual price of the servo motor, the larger the power of the servo motor, the larger the proportion; the RTH dynamic braking technology is used instead of the motor brake, only two contactors need to be added, only one PLC needs to be added on a platform system, and the frequency converter and UPS of one motor capacity are equivalent, which has the largest economic benefit for a six-degree-of-freedom platform of more than 3 tons.

[0029] 3. The brake originally installed on the servo motor is cancelled, the risk is avoided, the brake originally on the motor is only suitable for static use, and the use of the brake in the dynamic state will cause the friction plate inside the brake to wear, especially when the high-inertia motion of the high-power motor is performed, the wear is particularly prominent, which greatly reduces the service life of the brake, and the artificial unobservable wear use condition is caused, the more the use times are, the greater the safety risk is, the shorter the use cycle is, and the higher the replacement cost is; the dynamic braking technology is used to replace the motor brake, since the electric energy braking is adopted, the physical friction braking is avoided, the dynamic braking device can be used for a long time, the safety is high, and there is no maintenance and replacement cost. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 It is a traditional motor braking principle diagram;

[0031] Figure 2 It is a dynamic braking device structure principle diagram for a multi-degree-of-freedom motion simulation platform provided by the embodiment of the application. DETAILED DESCRIPTION

[0032] The principles and characteristics of the application are described below in combination with the drawings, and the examples are only used to explain the application and are not used to limit the range of the application.

[0033] Figure 2 It is a dynamic braking device structure principle diagram for a multi-degree-of-freedom motion simulation platform provided by the embodiment of the application.

[0034] The multi-degree-of-freedom motion simulation platform in the embodiment generally comprises a foundation, an upper platform, a power source (i.e., a motion execution mechanism), and a transmission mechanism, the foundation is used to support the power source and the transmission mechanism; the power source is used to provide power for the upper platform and is connected with the upper platform and the foundation through the transmission mechanism; the two ends of the transmission mechanism are connected with the upper platform and the foundation respectively; the upper platform is used to carry a carrier and realize various spatial motions with the carrier. The motion execution mechanism is composed of a servo driver and a servo motor.

[0035] As shown in the figure, Figure 2 The dynamic braking device provided by the embodiment of the application comprises a PLC motion controller, an uninterrupted power supply (UPS), a frequency converter, and a plurality of first contactors and second contactors corresponding to a plurality of motion execution mechanisms;

[0036] The UPS is used to supply power for the PLC motion controller and the frequency converter;

[0037] The first contactor is connected between the UVW end of the servo driver and the servo motor;

[0038] The PLC motion controller is connected with the control end of the first contactor, and is used for cutting off the connection between the servo driver and the UVW end of the servo motor and connecting the UVW end of the servo motor in parallel when the motion simulation platform is shut down due to failure, forming a reverse braking circuit, and dynamically braking the servo motor;

[0039] The frequency converter is connected with the control end of the second contactor and the PLC motion controller;

[0040] The UPS, the frequency converter, the second contactor and the corresponding servo motor form a frequency converter control circuit, which is used for driving the servo motor to retract the electric cylinder according to the preset speed.

[0041] The UPS, the servo driver and the servo motor form a driver auxiliary control circuit, which is used for collecting the position data of the servo motor.

[0042] The PLC motion controller is respectively connected with the servo driver and the frequency converter in communication, is used for receiving the position data of the servo motor collected by the servo driver, and is used for controlling the frequency converter.

[0043] Further, the PLC motion controller is used for:

[0044] Comparing the position data of the corresponding servo motor collected by each servo driver, if the stroke difference of the electric cylinder of the adjacent servo motor is greater than a preset threshold, the servo motor with the larger stroke is taken as a target servo motor, the PLC motion controller controls the second contactor between the target servo motor and the frequency converter to be closed, and controls the first contactor corresponding to the target servo motor to be disconnected, and controls the frequency converter to drive the target servo motor to retract the electric cylinder according to the preset speed. In this embodiment, the preset threshold is 15% of the maximum stroke.

[0045] Further, after the PLC motion controller controls the second contactor between the servo motor with the larger stroke and the frequency converter to be closed, and controls the first contactor corresponding to the servo motor with the larger stroke to be disconnected, the frequency converter is started after a preset time, and the frequency converter is controlled to drive the servo motor with the larger stroke to retract the electric cylinder according to the preset speed. In this embodiment, the preset time is 50ms.

[0046] Further, the PLC motion controller is further used for:

[0047] When the stroke difference of the electric cylinder of the target servo motor and its adjacent servo motor is less than a preset threshold, the second contactor corresponding to the target servo motor is disconnected, and the first contactor corresponding to the target servo motor is closed.

[0048] Further, the design capacity of the UPS is one servo motor unit capacity.

[0049] Based on the dynamic braking device, the application further provides a dynamic braking method for a multi-degree-of-freedom motion simulation platform, comprising the following steps.

[0050] S1, when the motion simulation platform is shut down due to a fault (including abnormal external power supply, servo system error and abnormal external associated logic signal), the PLC motion controller cuts off the connection between the servo driver and the UVW end of the servo motor and connects the UVW end of the servo motor in reverse, thereby forming a reverse braking circuit.

[0051] The reverse braking is to use the UVW of the stator coil of the servo motor when the UVW is disconnected from the external driver, adopt star connection, that is, the UVW are connected together, at this time, when the rotor of the servo motor is passively rotated due to external mechanical transmission, a rotating magnetic field is generated and cuts the stator coil to generate electric energy, and then the UVW are reversely connected to form a reverse braking system.

[0052] According to the law of conservation of energy, the mechanical kinetic energy of the rotor is converted into stator electric energy, motor heat energy and overflow magnetic field energy, and theoretically, the motor can almost be prohibited from moving, because the stator electric energy generated by the motor will be consumed by the heat generated by the internal resistance of the stator coil, so the electric energy generated after reverse connection is smaller than the mechanical kinetic energy of the rotor, so the motor and the electric cylinder will passively drop at a very small speed V1, thereby slowly falling in the case that the platform and the load are not powered and have no brake.

[0053] The entire system first enters reverse braking in the abnormal condition or power-off condition, so that all servo motors enter the internal consumption process in the condition of no external power supply, and the servo motor passively rotates at a certain speed.

[0054] Taking six degrees of freedom as an example, at this time, all servo motors are executing reverse braking and are subjected to the vertical gravity of the six degrees of freedom, and the motor passively rotates slowly, because the load center on the platform is offset and changes, the forces on the six shaft motors are different, the descending speeds of the motors are inconsistent, which will cause the load center to be offset more and more, and finally stop in a large-angle inclined state and cannot return to the horizontal safe bottom position; therefore, the frequency converter needs to be started to intervene, when the reverse braking is connected, the motor encoder data is quickly collected, the longest shaft is judged, the first shaft is put into the frequency converter, and the shaft is actively operated downward at a speed faster than the reverse braking speed to the bottom position. The other shaft motors are sequentially judged and put in, so that the load center can be quickly corrected, and the load center is finally lowered to the horizontal safe bottom position.

[0055] S2, the UPS supplies power to each servo driver, the servo driver acquires the position data of the servo motor encoder in real time and sends the position data to the PLC motion controller.

[0056] When the system is powered off (the platform can be in any angle state), the servo driver under the power supply of the UPS continues to have power, continues to keep the servo motor encoder position data, and communicates to the PLC motion controller for judgment.

[0057] S3, the PLC motion controller compares the position data of the corresponding servo motor collected by each servo driver, if the stroke difference of the adjacent servo motor is greater than the preset threshold, the servo motor with the larger stroke is taken as the target servo motor, the PLC motion controller controls the second contactor between the target servo motor and the frequency converter to be closed, and the first contactor corresponding to the target servo motor to be disconnected, controls the frequency converter to drive the target servo motor to retract the electric cylinder at a preset speed V2, until the stroke difference of the target servo motor and its adjacent servo motor is less than the preset threshold, then step S4 is executed.

[0058] The first contactor and the second contactor (KMn1 and KMn2 in the figure) are output by the PLC, cut into the frequency converter control loop, and the start of the frequency converter needs to be delayed by 50 ms, so as to avoid simultaneous or advanced start of the frequency converter, which causes the frequency converter to identify output missing and stop working, according to the actual load center of gravity on the platform, the action frequency of the output of the frequency converter to the motor is adjusted (generally 2Hz~5Hz), and the speed V2 of the frequency converter is greater than the speed V1 in the reverse connection braking, so that the platform can be adjusted to a horizontal degree while slowly descending, and the electric cylinder is not subjected to upward tension due to the high center of gravity, large deviation of the load and the mechanism, and finally stops in a large-angle inclined state when the platform slowly descends, if the fault cannot be eliminated in a short time, the platform returns to the original position, and the platform structure is at risk of deformation under the force of a large angle.

[0059] S4, the PLC motion controller disconnects the second contactor corresponding to the target servo motor, closes the corresponding first contactor, and jumps to step S2, until the motion simulation platform presents a horizontal state and slowly falls to the safest position.

[0060] The dynamic braking technology provided by the application has the advantages of simple process, high automation degree, no cycle use limitation, no loss, low cost, and is very suitable for braking technology of a platform system above 3 tons.

[0061] Although the preferred embodiments of the application have been described, those skilled in the art can make further changes and modifications to the embodiments once they know the basic inventive concept. Therefore, the appended claims are intended to be interpreted as including all changes and modifications falling within the scope of the application.

[0062] Obviously, many modifications and variations of the present application are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims and their equivalents, the application can be practiced otherwise than as specifically described.

Claims

1. A dynamic braking device for a multi-degree-of-freedom motion simulation platform, wherein the multi-degree-of-freedom motion simulation platform is supported and driven to move by multiple motion actuators, wherein the motion actuators are composed of servo drivers and servo motors, characterized in that, include: PLC motion controller, uninterruptible power supply (UPS) and multiple first contactors corresponding to multiple motion actuators; The UPS provides power to the PLC motion controller; The first contactor is connected between the servo driver and the UVW terminals of the servo motor. The PLC motion controller is connected to the control terminal of the first contactor and is used to disconnect the connection between the servo driver and the UVW terminal of the servo motor and connect the UVW terminal of the servo motor in parallel when the motion simulation platform stops due to a fault, thereby forming a reverse braking circuit to dynamically brake the servo motor. The dynamic braking device also includes a frequency converter and a second contactor corresponding to multiple motion actuators; The UPS supplies power to the frequency converter, and the control terminals of the frequency converter and the second contactor are connected to the PLC motion controller. The UPS, inverter, second contactor and its corresponding servo motor constitute the inverter control circuit, which is used to drive the servo motor to retract the electric cylinder at a preset speed. The UPS, servo driver, and servo motor constitute a driver auxiliary control loop for collecting servo motor position data. The PLC motion controller is communicatively connected to the servo driver and the frequency converter, respectively, and is used to receive servo motor position data collected by the servo driver and to control the operation of the frequency converter.

2. The dynamic braking device according to claim 1, characterized in that, The PLC motion controller is used for: By comparing the position data of the corresponding servo motors collected by each servo driver, if the difference in the electric cylinder stroke of adjacent servo motors is greater than a preset threshold, the servo motor with the larger stroke is selected as the target servo motor. The PLC motion controller controls the second contactor between the target servo motor and the frequency converter to close, and disconnects the first contactor corresponding to the target servo motor. The frequency converter then drives the target servo motor to retract the electric cylinder at a preset speed.

3. The dynamic braking device according to claim 2, characterized in that, After the PLC motion controller controls the second contactor between the long-stroke servo motor and the frequency converter to close and disconnect the first contactor corresponding to the long-stroke servo motor, the frequency converter is started after a preset time interval, and the frequency converter drives the long-stroke servo motor to retract the electric cylinder at a preset speed.

4. The dynamic braking device according to claim 2, characterized in that, The PLC motion controller is also used for: When the difference in electric cylinder stroke between the target servo motor and its adjacent servo motor is less than a preset threshold, the second contactor corresponding to the target servo motor is disconnected and the corresponding first contactor is closed.

5. The dynamic braking device according to claim 1, characterized in that, The UPS is designed to have the capacity of one servo motor unit.

6. A dynamic braking method for a multi-degree-of-freedom motion simulation platform, the method being implemented based on the dynamic braking device described in claim 2, characterized in that, Includes the following steps: S1, When the motion simulation platform stops due to a fault, the PLC motion controller disconnects the connection between the servo driver and the UVW terminal of the servo motor and connects the UVW terminal of the servo motor in parallel to form a reverse braking circuit. S2, the UPS supplies power to each servo drive, and the servo drive acquires the servo motor encoder position data in real time and sends it to the PLC motion controller; S3, the PLC motion controller compares the position data of the corresponding servo motors collected by each servo driver. If the difference in the electric cylinder stroke of adjacent servo motors is greater than a preset threshold, the servo motor with the larger stroke is taken as the target servo motor. The PLC motion controller controls the second contactor between the target servo motor and the inverter to close and disconnects the first contactor corresponding to the target servo motor. The inverter controls the target servo motor to retract the electric cylinder at a preset speed until the difference in the electric cylinder stroke between the target servo motor and its adjacent servo motors is less than the preset threshold. Then, step S4 is executed. S4, the PLC motion controller disconnects the second contactor corresponding to the target servo motor, closes the corresponding first contactor, and jumps to step S2 until the motion simulation platform comes to a stop.

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