A redundant servo system based on nested screw transmission

Abstract

The application discloses a kind of redundancy servo systems based on nested screw drive, comprising: control computer, first / second redundancy branch chain, differential mechanism, position feedback mechanism and external load;First / second redundancy branch chain includes: first / second control module, first / second servo controller, first / second power driver, first / second servo motor, first / second rotary transformer, first / second brake, first / second reducer and first / second screw drive mechanism;Differential mechanism is connected with external load, differential mechanism directly bears the load situation introduced by external load, environmental condition situation;Position feedback mechanism is connected with differential mechanism, and the motion displacement signal of differential mechanism is collected by position feedback mechanism, and motion displacement signal is simultaneously fed back to first / second servo controller, to realize first / second control module position loop closed-loop control further.This application is in the consideration of system structure, volume weight index requirement, and greatly improves the reliability of system.

Description

Technical Field

[0001] This invention belongs to the field of electromechanical servo system control technology, and particularly relates to a redundant servo system based on nested helical transmission. Background Technology

[0002] Launch vehicles and spacecraft, as delivery tools of the space transportation system, undertake payload delivery missions with extremely high mission value. As an important component of these high-value spacecraft, the electromechanical servo system is responsible for the attitude control of the spacecraft control system. Therefore, the reliability of the servo control system plays a crucial role in the success or failure of the spacecraft mission. Once a failure or performance degradation occurs, it will lead to fatal consequences.

[0003] Patents focusing on the three areas of "controller," "actuator," and "control method" include: Patent CN106200479A discloses a "triple-redundant servo controller for absorbing faults in a fault amplification unit," which mainly uses three parallel power amplification units to enable servo valve control even in the event of a first-degree fault in the power amplification unit, and provides some fault absorption functionality in the event of a second-degree fault in some functional circuits. Patent CN104238406A discloses a "triple-redundant digital servo controller," which mainly achieves redundancy in this part of the circuit by setting up three command input channel circuits, three command output channel circuits, three redundant power conversion circuits, and three redundant feedback channel circuits. Patent CN104595451A discloses a "dual-input channel differential electromechanical actuator," which mainly utilizes the differential output function of a planetary gear reducer to combine the power of two motors into a ball screw actuator through a differential, thus achieving power synthesis. Patent CN108536004B discloses "a redundancy switching method for a dual-redundant electromechanical servo mechanism". Based on the above differential setting, the unlocking time of the brake is controlled to make the unlocking time shorter than the locking time, and the fault isolation and switching function is realized when a certain channel fails.

[0004] Patents related to "fault-tolerant motors and control" include: Patent CN111030329A discloses a "multiphase permanent magnet fault-tolerant servo motor," which mainly includes a modular stator and a non-ferromagnetic rotor with an irregular array. The modular stator has Q slots for setting Q stator sub-modules, and the non-ferromagnetic rotor includes a shaft and a p-pole permanent magnet. Fault tolerance of the permanent magnet servo motor is achieved through multiphase operation. Patent CN110266246B discloses "a fault-tolerant brushless DC motor drive control method," which mainly adds a half-bridge to the three-phase bridge drive circuit of a brushless DC motor. The star connection point of the three-phase brushless DC motor is led out, and the lead-out line is connected to the output terminal of the added half-bridge to achieve fault-tolerant control of the brushless motor. Patent CN113794322A discloses "a series drive electric servo actuator", which includes a multi-phase fault-tolerant permanent magnet synchronous motor, a planetary gear reducer, a planetary roller screw, and a dual-redundant feedback potentiometer. By arranging the multi-phase fault-tolerant permanent magnet synchronous motor and the ball screw in series, the actuator achieves the design requirements of high rigidity and high power-to-weight ratio.

[0005] The above analysis shows that existing publicly available technologies for redundant electric servo systems mainly focus on the redundant design of components such as the "controller," "actuator," and "control method." While achieving redundancy in their own components, these technologies introduce other limiting factors to other components, leading to problems such as reduced power-to-weight ratio, bulky structure, and difficulties in coordinated control. Consequently, redundant electromechanical servo systems are difficult to implement in engineering and commercial applications. Existing publicly available technologies do not propose a technical framework for redundant servo systems, nor do they propose a redundant servo system based on nested helical drives. They do not address or solve the problem of achieving full redundancy of the servo mechanism within the overall servo system architecture, while simultaneously considering system structure, size, and weight requirements and significantly improving system reliability. Summary of the Invention

[0006] The technical problem solved by this invention is to overcome the shortcomings of existing technologies and provide a redundant servo system based on nested helical drives. This system utilizes the power superposition characteristics of two redundant branches to achieve high power density. In the helical drive mechanism, nested redundant helical kinematic pairs are adopted, significantly reducing space volume while improving reliability. The helical drive mechanisms of the two redundant branches are combined through a differential mechanism to achieve motion synthesis, enabling switching of the faulty branch in case of failure and achieving power output for a multi-input single-output system. Based on the overall servo system architecture, a fully redundant servo system design is achieved, significantly improving system reliability while considering system structure, size, and weight requirements.

[0007] To address the aforementioned technical problems, this invention discloses a redundant servo system based on nested helical transmission, comprising: a control computer, a first redundant branch, a second redundant branch, a differential mechanism, a position feedback mechanism, and an external load; wherein, the first redundant branch includes: a first control module, a first servo controller, a first power driver, a first servo motor, a first rotary transformer, a first brake, a first reducer, and a first helical transmission mechanism; the second redundant branch includes: a second control module, a second servo controller, a second power driver, a second servo motor, a second rotary transformer, a second brake, a second reducer, and a second helical transmission mechanism;

[0008] The control computer is connected to the first servo controller and the second servo controller respectively; wherein, the control computer sends instructions to the first servo controller and the second servo controller, and according to the communication protocol, the first servo controller and the second servo controller upload their own status information to the control computer;

[0009] The first power driver receives the drive control signal from the first servo controller, processes it through the internal power drive circuit, and then drives the first servo motor to move; the first rotary transformer is powered by the first servo controller and sends the collected angular displacement information of the first servo motor to the first servo controller; the first brake is installed inside the first servo motor and is powered by the first servo controller, receiving the control signal from the first servo controller; the first servo motor is connected to the first reducer, and the first reducer is connected to the first helical transmission mechanism; the first helical transmission mechanism converts the rotational motion of the first reducer into linear motion, and drives the differential mechanism to move with the degree of freedom in the axial direction, but does not restrict the degree of freedom in the rotational direction of the first helical transmission mechanism;

[0010] The second power driver receives the drive control signal from the second servo controller, processes it through the internal power drive circuit, and then drives the second servo motor to move. The second rotary transformer is powered by the second servo controller and sends the collected angular displacement information of the second servo motor to the second servo controller. The second brake is installed inside the second servo motor and is powered by the second servo controller, receiving the control signal from the second servo controller. The second servo motor is connected to the second reducer, and the second reducer is connected to the second helical transmission mechanism. The second helical transmission mechanism converts the rotational motion of the second reducer into linear motion. The second helical transmission mechanism drives the differential mechanism to move with the degree of freedom in the axial direction, but does not restrict the degree of freedom in the rotational direction of the second helical transmission mechanism.

[0011] The differential mechanism is connected to the external load and directly bears the load and environmental conditions introduced by the external load.

[0012] The position feedback mechanism is connected to the differential mechanism. The position feedback mechanism collects the motion displacement signal of the differential mechanism and feeds the motion displacement signal back to the first servo controller and the second servo controller at the same time, thereby realizing the position loop closed-loop control of the first control module and the second control module.

[0013] In the aforementioned redundant servo system based on nested helical drives, the first servo controller includes:

[0014] The circuit comprises a first communication circuit, a first main control circuit, a first power conversion circuit, and a first sampling and conditioning circuit;

[0015] The first communication circuit communicates with the control computer and the first main control circuit, and sends the instructions issued by the control computer to the first main control circuit.

[0016] The first main control circuit is used to execute the operations indicated by the instructions, and to complete the position loop control, speed loop control, and current loop control of the first redundant branch. The first main control circuit is based on a first DSP processor and a first FPGA processor. The first DSP processor acts as the main processor, used to complete the position loop control and speed loop control of the first redundant branch. The first FPGA processor acts as a coprocessor, used to perform AD parsing and decoding on the feedback information A sent from the first sampling and conditioning circuit. The first DSP processor and the first FPGA processor interact with each other via a parallel bus.

[0017] 0. The first power conversion circuit is used to isolate the power circuit and control circuit into the secondary power supply required by each chip in the first redundant branch.

[0018] The first sampling and conditioning circuit is used to sample and condition the current information, voltage information, rotary transformer information and position feedback mechanism information required in the first redundant branch, and send the feedback information A obtained by sampling and conditioning to the first main control circuit.

[0019] 5. In the aforementioned redundant servo system based on nested helical drives, the first helical drive mechanism includes:

[0020] Screw drive shaft S1, screw drive nut S2, nested screw drive nut S3, screw drive shaft S4, and screw drive nut S5;

[0021] The first reducer directly drives the screw drive nut S2, and the rotational motion of the screw drive nut S2 drives the screw drive shaft S1 to move linearly; next:

[0022] On one hand, the helical drive nut S2 is rigidly connected to the nested helical drive nut S3. The helical drive nut S2 will drive the nested helical drive nut S3 to rotate around the axis. The helical drive nut S3 and the helical drive shaft S4 have a helical kinematic pair relationship. The helical drive nut S3 will drive the helical drive shaft S4 to move linearly. The helical drive shaft S4 also has a helical kinematic pair relationship with the helical drive nut S5.

[0023] The rotary drive shaft S4 will drive the screw drive nut S5 to rotate around the axis, and the screw drive nut S55 is connected to the differential mechanism.

[0024] On the other hand, the screw drive shaft S1 moves in a straight line. There is a screw kinematic pair relationship between the screw drive shaft S1 and the screw drive shaft S4. The screw drive shaft S1 will drive the screw drive shaft S4 to move in a screw motion. The other end of the screw drive shaft S4 will drive the screw drive nut S5 to rotate around the axis. The screw drive nut S5 is kinematically connected to the differential mechanism.

[0025] In the aforementioned redundant servo system based on nested helical transmission, helical transmission shafts S1 and S4 serve as the external threads of helical kinematic pairs. Helical transmission shaft S1 forms helical kinematic pairs with helical transmission nuts S2 and S4, respectively, with leads of P2 and P4, respectively. Helical transmission shaft S4 forms helical kinematic pairs with nested helical transmission nuts S3 and S5, respectively, with leads of P3 and P5, respectively. Among these, P4 is greater than P2, and P5 is greater than P3.

[0026] In the aforementioned redundant servo system based on nested helical transmission, the second servo controller includes: a second communication circuit, a second main control circuit, a second power conversion circuit, and a second sampling and conditioning circuit.

[0027] The second communication circuit communicates with the control computer and the second main control circuit, and sends the instructions issued by the control computer to the second main control circuit.

[0028] The second main control circuit is used to execute the operations indicated by the instructions, and to complete the position loop control, speed loop control, and current loop control of the second redundant branch. The second main control circuit is based on a second DSP processor and a second FPGA processor. The second DSP processor acts as the main processor, used to complete the position loop control and speed loop control of the second redundant branch. The second FPGA processor acts as a coprocessor, used to perform AD parsing and decoding of the feedback information B sent from the second sampling and conditioning circuit. The second DSP processor and the second FPGA processor interact with each other via a parallel bus.

[0029] The second power conversion circuit is used to isolate the power circuit and control circuit into the secondary power supply required by each chip in the second redundant branch.

[0030] The second sampling and conditioning circuit is used to sample and condition the current information, voltage information, rotary transformer information and position feedback mechanism information required in the second redundant branch, and send the feedback information B obtained by sampling and conditioning to the second main control circuit.

[0031] In the aforementioned redundant servo system based on nested helical transmission, the second helical transmission mechanism includes: a helical transmission shaft S6, a helical transmission nut S7, a nested helical transmission nut S8, a helical transmission shaft S9, and a helical transmission nut S10.

[0032] The second reducer 2 directly drives the screw drive nut S7. The rotational motion of the screw drive nut S7 drives the screw drive shaft S6 to move linearly. Next:

[0033] On one hand, the screw drive nut S7 is rigidly connected to the nested screw drive nut S8. The screw drive nut S7 will drive the nested screw drive nut S8 to rotate around the axis. The screw drive nut S8 and the screw drive shaft S9 have a helical kinematic pair relationship. The screw drive nut S8 will drive the screw drive shaft S9 to move linearly. The screw drive shaft S9 and the screw drive nut S10 have a helical kinematic pair relationship. The screw drive shaft S9 will drive the screw drive nut S10 to rotate around the axis. The screw drive nut S10 is kinematically connected to the differential mechanism.

[0034] On the other hand, the screw drive shaft S6 moves in a straight line. There is a screw kinematic pair relationship between the screw drive shaft S6 and the screw drive shaft S9. The screw drive shaft S6 will drive the screw drive shaft S9 to move in a screw motion. The other end of the screw drive shaft S9 will drive the screw drive nut S10 to rotate around the axis. The screw drive nut S10 is kinematically connected to the differential mechanism.

[0035] In the aforementioned redundant servo system based on nested helical transmission, the differential mechanism is jointly driven by the first helical transmission mechanism and the second helical transmission mechanism. The first and second helical transmission mechanisms, as helical motion components, have two degrees of freedom in the axial direction and the rotational direction around the axis. A single helical transmission mechanism drives the differential mechanism with the degree of freedom in the axial direction, but does not restrict the degree of freedom in the rotational direction around the axis. The first and second helical transmission mechanisms are sliding helical pairs or rolling helical pairs, specifically ball screw pairs or roller screw pairs. The selection of sliding helical pairs or rolling helical pairs for the first and second helical transmission mechanisms is based on the external load.

[0036] In the aforementioned redundant servo system based on nested helical drives, the degrees of freedom of the first helical drive mechanism include: rotational motion ω1 about the axis and linear motion β1 in the axial direction; the degrees of freedom of the second helical drive mechanism include: rotational motion ω2 about the axis and linear motion β2 in the axial direction; the degrees of freedom of the differential mechanism include: rotational motion ω1 about the axis and linear motion β2 in the axial direction. a linear motion β along the axis a ;

[0037] When the rotational motions ω1 and ω2 are in the same direction and their amplitudes satisfy ω1-ω2≤γ, the differential mechanism maintains the rotational motion ω a ≤δ, linear motion along the axis achieves output superposition, that is:

[0038] β a =β1+β2

[0039] When the rotational motions ω1 and ω2 are in the same direction and their amplitudes satisfy ω1-ω2>γ, the differential mechanism achieves the rotational motion ω a >δ, the differential mechanism eliminates the imbalance between rotational motion ω1 and rotational motion ω2 through its own rotational motion, and the linear motion in the axial direction achieves output superposition, that is:

[0040] β a =β1+β2

[0041] Where δ and γ are the control variables that are set;

[0042] When the rotational motions ω1 and ω2 are in opposite directions, the differential mechanism achieves rotational motion ω by controlling |ω1| and |ω2|. a =|ω1+ω2|, the linear motion β along the axis of the differential mechanism. a Achieve high-precision output.

[0043] In the aforementioned redundant servo system based on nested helical drives,

[0044] The first control module includes: a first position loop controller, a first speed loop controller, a first current loop controller, a first servo motor model, and a first screw transmission mechanism model. The first position loop controller and the first speed loop controller form position and speed closed-loop control based on angle feedback and speed calculation from the first rotary transformer. The first current loop controller collects current data from the current sensor within the first power driver to form a current closed-loop control. Furthermore, based on the first servo motor model and the first screw transmission mechanism model, the module controls the first servo motor through Park transformation and SVPWM modulation.

[0045] The second control module includes: a second position loop controller, a second speed loop controller, a second current loop controller, a second servo motor model, and a second helical transmission mechanism model. The second position loop controller and the second speed loop controller form a position and speed closed-loop control based on angle feedback and speed calculation from the second rotary transformer. The second current loop controller collects the current of the second servo motor from the current sensor within the second power driver, forming a current closed-loop control. Furthermore, based on the second servo motor model and the second helical transmission mechanism model, the second servo motor is controlled through Park transformation and SVPWM modulation.

[0046] In the aforementioned redundant servo system based on nested helical transmission, the redundant servo system includes at least the following operating modes: normal mode and fault mode; wherein, the normal mode includes: differential mode and high-precision control mode.

[0047] In differential mode, based on the design of the first control law in the first control module and the second control law in the second control module, the differential mechanism will realize the speed deviation of the first redundant branch and the second redundant branch.

[0048] In high-precision control mode, the input voltage u = [u1 u2] is controlled and distributed. T This causes the first and second helical transmission mechanisms to move in opposite directions, thereby enabling the differential mechanism to output high-precision displacement motion; where u1 represents the first redundant branch input voltage and u2 represents the second redundant branch input voltage.

[0049] In fault mode, when any component in the first redundant branch fails, the first control law in the first control module sends a command to the first brake, causing the first brake to brake the first servo motor, thereby braking the first redundant branch. The non-faulty redundant branches will continue to drive the differential mechanism. When any component in the second redundant branch fails, the second control law in the second control module sends a command to the second brake, causing the second brake to brake the second servo motor, thereby braking the second redundant branch. The non-faulty redundant branches will continue to drive the differential mechanism.

[0050] The present invention has the following advantages:

[0051] (1) This invention discloses a redundant servo system based on nested helical transmission. By utilizing the power superposition characteristics of two sets of redundant branches, the high power density characteristics of the redundant servo system are realized. This invention combines the first helical transmission mechanism of the first redundant branch and the second helical transmission mechanism of the second redundant branch with a differential mechanism to achieve motion synthesis. This can realize the switching of the faulty branch in case of failure and the power output of the multi-input single-output system.

[0052] (2) This invention discloses a redundant servo system based on nested helical transmission. It covers the entire field of control, drive, transmission and sensing. In terms of control, it is divided into single redundant branch control and double redundant branch high-precision collaborative control. The single redundant branch control is divided into position loop, speed loop and current loop control. In terms of drive, redundant design of power driver and servo controller is adopted. In terms of transmission, redundant design of helical transmission mechanism is adopted to realize that two sets of helical transmission mechanisms drive the differential mechanism at the same time. Therefore, based on the overall architecture of the servo system, this invention realizes the full redundancy design of servo mechanism, which greatly improves the reliability of the system while taking into account the requirements of system structure, volume and weight indicators.

[0053] (3) This invention discloses a redundant servo system based on nested helical transmission. On the basis of two sets of redundant branches driving the differential mechanism at the same time, a redundant nested helical transmission method is proposed for the key component helical transmission mechanism. By utilizing the two degrees of freedom of the helical transmission in the direction of rotation around the axis and the linear motion along the axis, a redundant design is designed for each degree of freedom. Through different nesting relationships, the transmission ratio is amplified in a limited space, ensuring that the failure of any point of the helical transmission mechanism will not cause functional loss of the system.

[0054] (4) This invention discloses a redundant servo system based on nested helical transmission. Compared with the existing disclosed technical solutions, this invention uses two sets of redundant branches to achieve the speed superposition output of the servo system. At the same time, the torque fluctuation of the servo motor of the redundant branch (including the PWM output fluctuation of the power driver) will inevitably affect the redundant branch at the other end. This invention uses a differential mechanism to eliminate this servo motor torque fluctuation, thus avoiding the impact on the other redundant branch.

[0055] (5) This invention discloses a redundant servo system based on nested helical transmission, which has multiple working modes such as differential mode, high-precision control mode, and fault mode, and features high-precision output, power superposition, and elimination of nonlinear links.

[0056] (6) This invention discloses a redundant servo system based on nested helical transmission, which has wide applicability. The redundant servo system based on nested helical transmission can meet the redundancy requirements of electromechanical servo systems for high-value aircraft (typically represented by launch vehicles and aerospace vehicles). Attached Figure Description

[0057] Figure 1 This is a schematic diagram of the structural composition of a redundant servo system based on nested helical transmission in an embodiment of the present invention;

[0058] Figure 2 This is a schematic diagram of the structural composition of a screw transmission mechanism according to an embodiment of the present invention;

[0059] Figure 3 This is a three-dimensional schematic diagram of a screw drive shaft according to an embodiment of the present invention;

[0060] Figure 4 This is a control principle diagram of a redundant servo system based on nested helical transmission in an embodiment of the present invention. Detailed Implementation

[0061] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments disclosed in the present invention will be described in further detail below with reference to the accompanying drawings.

[0062] like Figure 1 In this embodiment, the redundant servo system based on nested helical transmission includes: a control computer, a first redundant branch, a second redundant branch, a differential mechanism, a position feedback mechanism, and an external load. Specifically, the first redundant branch may include: a first control module, a first servo controller, a first power driver, a first servo motor, a first rotary transformer, a first brake, a first reducer, and a first helical transmission mechanism. The second redundant branch may specifically include: a second control module, a second servo controller, a second power driver, a second servo motor, a second rotary transformer, a second brake, a second reducer, and a second helical transmission mechanism.

[0063] The control computer is connected to the first servo controller and the second servo controller, communicating via RS422, CAN, and 1553B communication protocols. The control computer sends commands to the first and second servo controllers, and according to the communication protocols, the first and second servo controllers upload their own status information to the control computer. The first power driver receives the drive control signals from the first servo controller, processes them through its internal power drive circuit, and then drives the first servo motor. The first rotary transformer is powered by the first servo controller and sends the collected angular displacement information of the first servo motor to the first servo controller. The first brake is installed inside the first servo motor, powered by the first servo controller, and receives control signals from the first servo controller. The first servo motor is connected to the first reducer, and the first reducer is connected to the first helical transmission mechanism. The first helical transmission mechanism converts the rotational motion of the first reducer into linear motion. The first helical transmission mechanism drives the differential mechanism with a degree of freedom in the axial direction, but does not restrict the rotational direction degree of freedom of the first helical transmission mechanism. The second power driver receives the drive control signal from the second servo controller, processes it through its internal power drive circuit, and then drives the second servo motor. The second rotary transformer is powered by the second servo controller and sends the collected angular displacement information of the second servo motor to the second servo controller. The second brake is installed inside the second servo motor and is powered by the second servo controller, receiving control signals from the second servo controller. The second servo motor is connected to the second reducer, and the second reducer is connected to the second helical transmission mechanism. The second helical transmission mechanism converts the rotational motion of the second reducer into linear motion. The second helical transmission mechanism drives the differential mechanism with a degree of freedom in the axial direction, but does not restrict the degree of freedom in the rotational direction of the second helical transmission mechanism. The differential mechanism is connected to the external load and directly bears the load and environmental conditions introduced by the external load. The position feedback mechanism is connected to the differential mechanism, collects the motion displacement signal of the differential mechanism, and feeds the motion displacement signal back to both the first and second servo controllers, thereby realizing the closed-loop position control of the first and second control modules.

[0064] In this embodiment, the first servo controller may specifically include: a first communication circuit, a first main control circuit, a first power conversion circuit, and a first sampling and conditioning circuit. The first communication circuit communicates with the control computer and the first main control circuit, sending instructions from the control computer to the first main control circuit. The first main control circuit executes the operations indicated by the instructions, completing the position loop control, speed loop control, and current loop control of the first redundant branch. The first main control circuit is based on a first DSP processor and a first FPGA processor architecture. The first DSP processor acts as the main processor, completing the position loop control and speed loop control of the first redundant branch. The first FPGA processor acts as a coprocessor, performing AD parsing and decoding on the feedback information A sent by the first sampling and conditioning circuit. The first DSP processor and the first FPGA processor interact via a parallel bus. The first power conversion circuit isolates the power supply and control power supply into the secondary power supplies required by each chip in the first redundant branch. The first sampling and conditioning circuit samples and conditions the current information, voltage information, resolver information, and position feedback mechanism information required in the first redundant branch, and sends the sampled and conditioned feedback information A to the first main control circuit.

[0065] Furthermore, such as Figure 2 As shown, the first screw drive mechanism may specifically include: a screw drive shaft S1, a screw drive nut S2, a nested screw drive nut S3, and a screw drive shaft S4 (e.g., Figure 3 (as shown) and screw drive nut S5.

[0066] Preferably, the first reducer directly drives the helical transmission nut S2, and the rotational motion of the helical transmission nut S2 causes the helical transmission shaft S1 to move linearly. Next: On one hand, the helical transmission nut S2 is rigidly connected to the nested helical transmission nut S3, and the helical transmission nut S2 drives the nested helical transmission nut S3 to rotate around its axis. The helical transmission nut S3 and the helical transmission shaft S4 have a helical kinematic pair relationship, and the helical transmission nut S3 drives the helical transmission shaft S4 to move linearly. Simultaneously, the helical transmission shaft S4 and the helical transmission nut S5 have a helical kinematic pair relationship, and the helical transmission shaft S4 drives the helical transmission nut S5 to rotate around its axis. The helical transmission nut S5 is kinematically connected to the differential mechanism. On the other hand, the helical transmission shaft S1 moves linearly, and the helical transmission shaft S1 and the helical transmission shaft S4 have a helical kinematic pair relationship. The helical transmission shaft S1 drives the helical transmission shaft S4 to move helically, and the other end of the helical transmission shaft S4 drives the helical transmission nut S5 to rotate around its axis. The helical transmission nut S5 is kinematically connected to the differential mechanism.

[0067] Furthermore, the screw drive shafts S1 and S4 serve as external threads of the helical kinematic pairs. The screw drive shaft S1 forms a helical kinematic pair relationship with the screw drive nut S2 and the screw drive shaft S4, respectively, with the leads of the corresponding helical kinematic pairs being P2 and P4, respectively. The screw drive shaft S4 forms a helical kinematic pair relationship with the nested screw drive nut S3 and the screw drive nut S5, respectively, with the leads of the corresponding helical kinematic pairs being P3 and P5, respectively. Among these, P4 is greater than P2, and P5 is greater than P3.

[0068] In this embodiment, the second servo controller may specifically include: a second communication circuit, a second main control circuit, a second power conversion circuit, and a second sampling and conditioning circuit. The second communication circuit communicates with the control computer and the second main control circuit, sending instructions from the control computer to the second main control circuit. The second main control circuit executes the operations indicated by the instructions, completing the position loop control, speed loop control, and current loop control of the second redundant branch. The second main control circuit is based on a second DSP processor and a second FPGA processor architecture. The second DSP processor acts as the main processor, completing the position loop control and speed loop control of the second redundant branch. The second FPGA processor acts as a coprocessor, performing AD parsing and decoding on the feedback information B sent by the second sampling and conditioning circuit. The second DSP processor and the second FPGA processor interact via a parallel bus. The second power conversion circuit isolates the power and control circuits into secondary power supplies required by each chip in the second redundant branch. The second sampling and conditioning circuit samples and conditions the current information, voltage information, resolver information, and position feedback mechanism information required in the second redundant branch, and sends the sampled and conditioned feedback information B to the second main control circuit.

[0069] Furthermore, such as Figure 2 As shown, the second helical transmission mechanism specifically includes: a helical transmission shaft S6, a helical transmission nut S7, a nested helical transmission nut S8, a helical transmission shaft S9, and a helical transmission nut S10.

[0070] Preferably, the second reducer 2 directly drives the helical drive nut S7. The rotational motion of the helical drive nut S7 causes the helical drive shaft S6 to move linearly. Next: On one hand, the helical drive nut S7 is rigidly connected to the nested helical drive nut S8, causing the nested helical drive nut S8 to rotate around its axis. The helical drive nut S8 and the helical drive shaft S9 have a helical kinematic pair relationship, causing the helical drive nut S8 to move linearly. Simultaneously, the helical drive shaft S9 and the helical drive nut S10 have a helical kinematic pair relationship, causing the helical drive nut S10 to rotate around its axis. The helical drive nut S10 is kinematically connected to the differential mechanism. On the other hand, the helical drive shaft S6 moves linearly. The helical drive shaft S6 and the helical drive shaft S9 have a helical kinematic pair relationship, causing the helical drive shaft S9 to move helically. The other end of the helical drive shaft S9 causes the helical drive nut S10 to rotate around its axis, and the helical drive nut S10 is kinematically connected to the differential mechanism.

[0071] In this embodiment, the differential mechanism is jointly driven by a first helical transmission mechanism and a second helical transmission mechanism. The first and second helical transmission mechanisms, as helical motion components, have two degrees of freedom of motion: one in the axial direction and the other in the rotational direction around the axis. A single helical transmission mechanism drives the differential mechanism with the degree of freedom in the axial direction, but does not restrict the degree of freedom of rotation around the axis. The first and second helical transmission mechanisms are sliding helical pairs or rolling helical pairs, specifically ball screw pairs or roller screw pairs. The selection of sliding helical pairs or rolling helical pairs for the first and second helical transmission mechanisms is based on the external load.

[0072] In this embodiment, the degrees of freedom of the first screw drive mechanism include: rotational motion ω1 about the axis and linear motion β1 in the axial direction; the degrees of freedom of the second screw drive mechanism include: rotational motion ω2 about the axis and linear motion β2 in the axial direction; the degrees of freedom of the differential mechanism include: rotational motion ω1 about the axis and linear motion β2 in the axial direction. a linear motion β along the axis a The differential mechanism can differentially process the rotational motion ω1 and rotational motion ω2. A typical differential processing mode is as follows:

[0073] When the rotational motions ω1 and ω2 are in the same direction and their amplitudes satisfy ω1-ω2≤γ, the differential mechanism maintains the rotational motion ω a ≤δ, linear motion along the axis achieves output superposition, that is:

[0074] β a =β1+β2

[0075] When the rotational motions ω1 and ω2 are in the same direction and their amplitudes satisfy ω1-ω2>γ, the differential mechanism achieves the rotational motion ω a >δ, the differential mechanism eliminates the imbalance between rotational motion ω1 and rotational motion ω2 through its own rotational motion, and the linear motion in the axial direction achieves output superposition, that is:

[0076] β a =β1+β2

[0077] Where δ and γ are the control variables that are set.

[0078] When the rotational motions ω1 and ω2 are in opposite directions, the differential mechanism achieves rotational motion ω by controlling ω1 and ω2. a =ω1+ω2, the linear motion β along the axis of the differential mechanism a Achieve high-precision output.

[0079] In this embodiment, as Figure 4 The first control module specifically includes: a first position loop controller, a first speed loop controller, a first current loop controller, a first servo motor model, and a first helical transmission mechanism model. The first position loop controller and the first speed loop controller form position and speed closed-loop control based on angle feedback and speed calculation from the first rotary transformer; the first current loop controller collects the current of the first servo motor from the current sensor in the first power driver to form current closed-loop control; and then, based on the first servo motor model and the first helical transmission mechanism model, control of the first servo motor is achieved through Park transformation and SVPWM modulation. Furthermore, the second control module specifically includes: a second position loop controller, a second speed loop controller, a second current loop controller, a second servo motor model, and a second helical transmission mechanism model; the second position loop controller and the second speed loop controller form position and speed closed-loop control based on angle feedback and speed calculation from the second rotary transformer; the second current loop controller collects the current of the second servo motor from the current sensor in the second power driver to form current closed-loop control; and then, based on the second servo motor model and the second helical transmission mechanism model, control of the second servo motor is achieved through Park transformation and SVPWM modulation.

[0080] In this embodiment, the redundant servo system includes at least the following operating modes: normal mode and fault mode; wherein, the normal mode includes: differential mode and high-precision control mode. Specifically:

[0081] In differential mode, based on the first control law in the first control module and the second control law in the second control module, the differential mechanism will realize the speed deviation of the first redundant branch and the second redundant branch.

[0082] In high-precision control mode, the input voltage u = [u1 u2] is controlled and distributed. T This causes the first and second helical transmission mechanisms to move in opposite directions, thereby enabling the differential mechanism to output high-precision displacement motion; where u1 represents the first redundant branch input voltage and u2 represents the second redundant branch input voltage.

[0083] In fault mode, when any component in the first redundant branch fails, the first control law in the first control module sends a command to the first brake, causing the first brake to brake the first servo motor, thereby braking the first redundant branch. The non-faulty redundant branches will continue to drive the differential mechanism. When any component in the second redundant branch fails, the second control law in the second control module sends a command to the second brake, causing the second brake to brake the second servo motor, thereby braking the second redundant branch. The non-faulty redundant branches will continue to drive the differential mechanism.

[0084] In this embodiment, the design of the first and second control laws eliminates the linear synthesis terms of the redundant servo system, and realizes high-precision collaborative control of the dual-input single-input system of the first redundant branch and the second redundant branch.

[0085] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

[0086] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A redundant servo system based on nested helical transmission, characterized in that, include: The system comprises a control computer, a first redundant branch, a second redundant branch, a differential mechanism, a position feedback mechanism, and an external load. The first redundant branch includes: a first control module, a first servo controller, a first power driver, a first servo motor, a first rotary transformer, a first brake, a first reducer, and a first helical transmission mechanism. The second redundant branch includes: a second control module, a second servo controller, a second power driver, a second servo motor, a second rotary transformer, a second brake, a second reducer, and a second helical transmission mechanism. The control computer is connected to the first servo controller and the second servo controller respectively; wherein, the control computer sends instructions to the first servo controller and the second servo controller, and according to the communication protocol, the first servo controller and the second servo controller upload their own status information to the control computer; The first power driver receives the drive control signal from the first servo controller, processes it through the internal power drive circuit, and then drives the first servo motor to move; the first rotary transformer is powered by the first servo controller and sends the collected angular displacement information of the first servo motor to the first servo controller; the first brake is installed inside the first servo motor and is powered by the first servo controller, receiving the control signal from the first servo controller; the first servo motor is connected to the first reducer, and the first reducer is connected to the first helical transmission mechanism; the first helical transmission mechanism converts the rotational motion of the first reducer into linear motion, and drives the differential mechanism to move with the degree of freedom in the axial direction, but does not restrict the degree of freedom in the rotational direction of the first helical transmission mechanism; The second power driver receives the drive control signal from the second servo controller, processes it through the internal power drive circuit, and then drives the second servo motor to move. The second rotary transformer is powered by the second servo controller and sends the collected angular displacement information of the second servo motor to the second servo controller. The second brake is installed inside the second servo motor and is powered by the second servo controller, receiving the control signal from the second servo controller. The second servo motor is connected to the second reducer, and the second reducer is connected to the second helical transmission mechanism. The second helical transmission mechanism converts the rotational motion of the second reducer into linear motion. The second helical transmission mechanism drives the differential mechanism to move with the degree of freedom in the axial direction, but does not restrict the degree of freedom in the rotational direction of the second helical transmission mechanism. The differential mechanism is connected to the external load and directly bears the load and environmental conditions introduced by the external load. The position feedback mechanism is connected to the differential mechanism. The position feedback mechanism collects the motion displacement signal of the differential mechanism and feeds the motion displacement signal back to the first servo controller and the second servo controller at the same time, thereby realizing the position loop closed-loop control of the first control module and the second control module.

2. The redundant servo system based on nested helical transmission according to claim 1, characterized in that, The first servo controller includes: a first communication circuit, a first main control circuit, a first power conversion circuit, and a first sampling and conditioning circuit; The first communication circuit communicates with the control computer and the first main control circuit, and sends the instructions issued by the control computer to the first main control circuit. The first main control circuit is used to execute the operations indicated by the instructions, and to complete the position loop control, speed loop control and current loop control of the first redundant branch; wherein, the first main control circuit is based on a first DSP processor and a first FPGA processor; the first DSP processor acts as the main processor, and is used to complete the position loop control and speed loop control of the first redundant branch; the first FPGA processor acts as a coprocessor, and is used to perform AD parsing and decoding on the feedback information A sent by the first sampling and conditioning circuit; the first DSP processor and the first FPGA processor interact with each other through a parallel bus; The first power conversion circuit is used to isolate the power circuit and control circuit into the secondary power supply required by each chip in the first redundant branch. The first sampling and conditioning circuit is used to sample and condition the current information, voltage information, rotary transformer information and position feedback mechanism information required in the first redundant branch, and send the feedback information A obtained by sampling and conditioning to the first main control circuit.

3. The redundant servo system based on nested helical transmission according to claim 2, characterized in that, The first screw drive mechanism includes: a screw drive shaft S1, a screw drive nut S2, a nested screw drive nut S3, a screw drive shaft S4, and a screw drive nut S5. The first reducer directly drives the screw drive nut S2, and the rotational motion of the screw drive nut S2 drives the screw drive shaft S1 to move linearly; next: On one hand, the helical drive nut S2 is rigidly connected to the nested helical drive nut S3. The helical drive nut S2 will drive the nested helical drive nut S3 to rotate around the axis. The helical drive nut S3 and the helical drive shaft S4 have a helical kinematic pair relationship. The helical drive nut S3 will drive the helical drive shaft S4 to move linearly. The helical drive shaft S4 and the helical drive nut S5 have a helical kinematic pair relationship. The helical drive shaft S4 will drive the helical drive nut S5 to rotate around the axis. The helical drive nut S5 is kinematically connected to the differential mechanism. On the other hand, the screw drive shaft S1 moves in a straight line. There is a screw kinematic pair relationship between the screw drive shaft S1 and the screw drive shaft S4. The screw drive shaft S1 will drive the screw drive shaft S4 to move in a screw motion. The other end of the screw drive shaft S4 will drive the screw drive nut S5 to rotate around the axis. The screw drive nut S5 is kinematically connected to the differential mechanism.

4. The redundant servo system based on nested helical transmission according to claim 3, characterized in that, Screw drive shafts S1 and S4 are external threads of a helical kinematic pair. Screw drive shaft S1 forms a helical kinematic pair relationship with screw drive nuts S2 and S4 respectively, and the leads of the corresponding helical kinematic pairs are P2 and P4 respectively. Screw drive shaft S4 forms a helical kinematic pair relationship with nested screw drive nuts S3 and S5 respectively, and the leads of the corresponding helical kinematic pairs are P3 and P5 respectively. Among them, P4 is greater than P2 and P5 is greater than P3.

5. The redundant servo system based on nested helical transmission according to claim 1, characterized in that, The second servo controller includes: a second communication circuit, a second main control circuit, a second power conversion circuit, and a second sampling and conditioning circuit; The second communication circuit communicates with the control computer and the second main control circuit, and sends the instructions issued by the control computer to the second main control circuit. The second main control circuit is used to execute the operations indicated by the instructions, and to complete the position loop control, speed loop control, and current loop control of the second redundant branch. The second main control circuit is based on a second DSP processor and a second FPGA processor. The second DSP processor acts as the main processor, used to complete the position loop control and speed loop control of the second redundant branch. The second FPGA processor acts as a coprocessor, used to perform AD parsing and decoding of the feedback information B sent from the second sampling and conditioning circuit. The second DSP processor and the second FPGA processor interact with each other via a parallel bus. The second power conversion circuit is used to isolate the power and control circuits into the secondary power supplies required by each chip in the second redundant branch. The second sampling and conditioning circuit is used to sample and condition the current information, voltage information, rotary transformer information and position feedback mechanism information required in the second redundant branch, and send the feedback information B obtained by sampling and conditioning to the second main control circuit.

6. The redundant servo system based on nested helical transmission according to claim 5, characterized in that, The second screw drive mechanism includes: a screw drive shaft S6, a screw drive nut S7, a nested screw drive nut S8, a screw drive shaft S9, and a screw drive nut S10. The second reducer directly drives the screw drive nut S7. The rotational motion of the screw drive nut S7 drives the screw drive shaft S6 to move linearly. Next: On one hand, the screw drive nut S7 is rigidly connected to the nested screw drive nut S8. The screw drive nut S7 will drive the nested screw drive nut S8 to rotate around the axis. The screw drive nut S8 and the screw drive shaft S9 have a helical kinematic pair relationship. The screw drive nut S8 will drive the screw drive shaft S9 to move linearly. The screw drive shaft S9 also has a helical kinematic pair relationship with the screw drive nut S10. The screw drive shaft S9 will drive the screw drive nut S10 to rotate around the axis. The screw drive nut S10 is kinematically connected to the differential mechanism. On the other hand, the screw drive shaft S6 moves in a straight line. There is a screw kinematic pair relationship between the screw drive shaft S6 and the screw drive shaft S9. The screw drive shaft S6 will drive the screw drive shaft S9 to move in a screw motion. The other end of the screw drive shaft S9 will drive the screw drive nut S10 to rotate around the axis. The screw drive nut S10 is kinematically connected to the differential mechanism.

7. The redundant servo system based on nested helical transmission according to claim 1, characterized in that, The differential mechanism is driven by both the first and second helical transmission mechanisms. As helical motion components, the first and second helical transmission mechanisms have two degrees of freedom: one in the axial direction and the other in the rotational direction around the axis. A single helical transmission mechanism drives the differential mechanism with the degree of freedom in the axial direction, but does not restrict the degree of freedom in the rotational direction around the axis. The first and second helical transmission mechanisms are sliding helical pairs or rolling helical pairs, specifically ball screw pairs or roller screw pairs. The selection of sliding or rolling helical pairs for the first and second helical transmission mechanisms is based on the external load.

8. The redundant servo system based on nested helical transmission according to claim 7, characterized in that, The degrees of freedom of motion of the first screw drive mechanism include: rotational motion ω1 about the axis and linear motion β1 in the axial direction; the degrees of freedom of motion of the second screw drive mechanism include: rotational motion ω2 about the axis and linear motion β2 in the axial direction; the degrees of freedom of motion of the differential mechanism include: rotational motion ω1 about the axis and linear motion β1 in the axial direction. a linear motion β along the axis a ; When the rotational motions ω1 and ω2 are in the same direction and their amplitudes satisfy ω1-ω2≤γ, the differential mechanism maintains the rotational motion ω a ≤δ, linear motion along the axis achieves output superposition, that is: β a ＝β1+β2 When the rotational motions ω1 and ω2 are in the same direction and their amplitudes satisfy ω1-ω2>γ, the differential mechanism achieves the rotational motion ω a >δ, the differential mechanism eliminates the imbalance between rotational motion ω1 and rotational motion ω2 through its own rotational motion, and the linear motion in the axial direction achieves output superposition, that is: β a ＝β1+β2 Where δ and γ are the control variables that are set; When the rotational motions ω1 and ω2 are in opposite directions, the differential mechanism achieves rotational motion ω by controlling ω1 and ω2. a =ω1+ω2, the linear motion β along the axis of the differential mechanism a Achieve high-precision output.

9. The redundant servo system based on nested helical transmission according to claim 1, characterized in that, The first control module includes: a first position loop controller, a first speed loop controller, a first current loop controller, a first servo motor model, and a first screw transmission mechanism model. The first position loop controller and the first speed loop controller form position and speed closed-loop control based on angle feedback and speed calculation from the first rotary transformer. The first current loop controller collects current data from the current sensor within the first power driver to form a current closed-loop control. Furthermore, based on the first servo motor model and the first screw transmission mechanism model, the module controls the first servo motor through Park transformation and SVPWM modulation. The second control module includes: a second position loop controller, a second speed loop controller, a second current loop controller, a second servo motor model, and a second helical transmission mechanism model. The second position loop controller and the second speed loop controller form a position and speed closed-loop control based on angle feedback and speed calculation from the second rotary transformer. The second current loop controller collects the current of the second servo motor from the current sensor within the second power driver, forming a current closed-loop control. Furthermore, based on the second servo motor model and the second helical transmission mechanism model, the second servo motor is controlled through Park transformation and SVPWM modulation.

10. The redundant servo system based on nested helical transmission according to claim 9, characterized in that, A redundant servo system includes at least the following operating modes: normal mode and fault mode; wherein, the normal mode includes: differential mode and high-precision control mode; In differential mode, based on the design of the first control law in the first control module and the second control law in the second control module, the differential mechanism will realize the speed deviation of the first redundant branch and the second redundant branch. In high-precision control mode, the input voltage u = [u1 u2] is controlled and distributed. T This causes the first and second helical transmission mechanisms to move in opposite directions, thereby enabling the differential mechanism to output high-precision displacement motion; where u1 represents the first redundant branch input voltage and u2 represents the second redundant branch input voltage. In fault mode, when any component in the first redundant branch fails, the first control law in the first control module sends a command to the first brake, causing the first brake to brake the first servo motor, thereby braking the first redundant branch. The non-faulty redundant branches will continue to drive the differential mechanism. When any component in the second redundant branch fails, the second control law in the second control module sends a command to the second brake, causing the second brake to brake the second servo motor, thereby braking the second redundant branch. The non-faulty redundant branches will continue to drive the differential mechanism.

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