Serial double screw redundant control electromechanical servo mechanism

Abstract

The present application relates to a kind of serial double lead screw redundancy control electromechanical servo mechanism, using a kind of RVI planetary roller screw pair and a kind of RV planetary roller screw pair serial coaxial arrangement, two kinds of screw pair share a screw shaft, and set same load capacity and structural parameter thread, through the same hollow structure servo motor drive two kinds of screw pair switch to RV screw when RVI screw transmission fails, utilize motor rotation sensor and mechanism linear displacement monitoring sensor to the transmission failure comprehensive judgment, to realize the conversion of two kinds of screw pair in static connection bearing and dynamic engagement bearing, realize EMA transmission redundancy backup.

Description

Technical Field

[0001] This invention relates to an electromechanical servo mechanism, and more particularly to a serial dual-screw redundant control electromechanical servo mechanism. Background Technology

[0002] The reliability improvement of electromechanical servo mechanisms is mainly limited by the inability to achieve redundant design of transmission components. Currently, servo motors, control drivers, sensors, etc. can all achieve redundancy design or fault-tolerant design with minimal increase in volume and space, and have been applied in some applications. However, the redundancy design of transmission components is more complex. How to propose a mechanical redundancy (EMA) scheme with a high degree of integration and a relatively simple layout structure has become the focus of engineering design. Summary of the Invention

[0003] The technical problem to be solved by this invention is as follows: The serial dual-screw redundant control electromechanical servo mechanism proposed in this invention adopts a serial coaxial arrangement of an RVI planetary roller screw pair and an RV planetary roller screw pair. The two screw pairs share a single screw shaft and are equipped with threads of the same load-bearing capacity and structural parameters. The two screw pairs are driven by the same hollow structure servo motor. When the RVI screw transmission fails, the RV screw is switched to perform the replacement work. The transmission fault is comprehensively judged by the motor rotation sensor and the linear displacement monitoring sensor of the mechanism, thereby realizing the conversion between static connection load and dynamic meshing load of the two screw pairs and realizing EMA transmission redundancy backup.

[0004] The technical solution adopted in this invention is: a serial dual-screw redundant control electromechanical servo mechanism, comprising: a servo motor assembly, an RVI roller screw pair assembly, an electromagnetic clutch assembly, an RV roller screw pair assembly, a sensor assembly, and a connecting assembly;

[0005] The servo motor assembly is coaxially arranged with the RVI planetary roller screw assembly and the RV planetary roller screw assembly. The RVI planetary roller screw assembly and the RV planetary roller screw assembly are installed in series and share a common screw shaft. The servo motor assembly drives the RVI roller screw assembly or the RV roller screw assembly. The electromagnetic clutch assembly is located at the output end of the servo motor assembly and changes the motor power output path by engaging or disengaging the end face teeth. The sensor assembly is connected to the linear reciprocating moving end of the RV roller screw assembly and the fixed-axis rotary moving end of the RVI planetary roller screw assembly, respectively, to detect jamming or sticking faults in the RVI roller screw assembly. The connecting assembly connects the housing of the servo motor assembly and the moving end of the RV roller screw assembly to the outside.

[0006] Furthermore, the servo motor assembly includes a motor rotor, a motor stator, a motor housing, a motor front end cover, an actuator cylinder, and a clutch connecting sprocket; the surface of the motor rotor is covered with a permanent magnet and a stainless steel sleeve, and is integrated with the long nut of the RVI roller screw assembly. One end of the long nut is fixedly connected to the clutch connecting sprocket, one end of the motor housing is connected to one end of the motor front end cover, and the other end of the motor front end cover is connected to the actuator cylinder; the motor stator is installed in the inner cavity of the motor housing and cooperates with the motor rotor.

[0007] Furthermore, the RVI roller screw assembly includes a screw pair long nut, a screw shaft, and planetary rollers; the two ends of the screw pair long nut are respectively mounted on bearing seats in the motor housing and the motor front end cover through a pair of angular contact ball bearings; one end of the screw shaft is provided with a short-stroke thread and the other end is provided with a long-stroke thread, the short-stroke thread meshes with the external thread of the planetary rollers, and the planetary rollers mesh with the inner surface thread of the screw pair long nut.

[0008] Furthermore, the RVI roller screw assembly also includes a first cage, with several planetary rollers arranged around the circumference of the screw shaft. The two ends of the several planetary rollers are constrained by the first cage, so that the planetary rollers and the first cage rotate together on the short-stroke thread and drive the screw shaft to move linearly.

[0009] Furthermore, the electromagnetic clutch assembly includes an external spline hollow shaft, a movable double-sided splined sprocket, an electromagnetic engagement coil, a return spring, a fixed end face sprocket, a bearing outer ring seat, and a bearing lock nut.

[0010] The hollow external spline shaft and the movable double-sided splined sprocket are coaxially mounted via internal and external spline teeth. The hollow external spline shaft and the movable double-sided splined sprocket can move relative to each other. A pair of deep groove ball bearings are mounted on the outer ring of the hollow external spline shaft. The inner ring of the deep groove ball bearings is fixed using a bearing lock nut. The deep groove ball bearings are also installed in the bearing outer ring seat hole and fixed using a retaining ring. The fixed end face sprocket is fitted onto the bearing outer ring seat. One end of the fixed end face sprocket has teeth that engage with the teeth of the movable double-sided splined sprocket. Several return springs are set around the circumference to reset the movable double-sided splined sprocket. An electromagnetic attraction coil is installed in a U-shaped hole at one end of the fixed end face sprocket to attract the movable double-sided splined sprocket. The fixed end face sprocket and the bearing outer ring seat are fixed on the stepped structure inside the front cover of the motor.

[0011] Furthermore, the RV roller screw assembly includes a nut, planetary rollers, and a second cage;

[0012] The long-stroke threaded section of the lead screw shaft is inserted into the actuator cylinder and nut; the two ends of the planetary rollers, under the constraint of the rotational motion of the second cage, engage with the long-stroke external thread of the lead screw shaft and with the internal thread of one end of the inner wall of the nut; the combination of nut, planetary rollers, and second cage reciprocates in the long threaded section of the lead screw shaft and stops at the zero position (-2L, +2L), acting as a static load-bearing connection to drive the connecting assembly to reciprocate. When the RVI roller lead screw assembly fails, it is activated and becomes a transmission component. L is half of the linear motion stroke of the planetary rollers in the inner cavity of the long nut of the lead screw pair.

[0013] Furthermore, the sensor assembly includes a brush, a linear displacement plate, countersunk screws, a resolver rotor, a resolver stator, and fixing screws. The brush is a compression spring structure, connected to the limiting protrusion on the outer ring of the large end of the nut via countersunk screws. The actuating cylinder sidewall has a longitudinally formed limiting groove that mates with the limiting protrusion on the outer ring of the large end of the nut. The linear displacement plate is disposed on the outer surface of the limiting groove and makes sliding contact with the brush to detect the linear position of the nut. The resolver rotor is installed in the other end port of the lead screw pair long nut, and the resolver stator is fixed to the other end of the motor housing by a set of fixing screws. The resolver rotor and the resolver stator obtain the rotation angle of the servo motor through mutual magnetic field induction. The brush and the linear displacement plate constitute a linear displacement sensor.

[0014] Furthermore, the connecting assembly includes a front support lug, a rear support lug, a long bolt, and a nut; the rear support lug is installed at the other end of the motor housing, and the front support lug is installed at the end of the nut extending from the actuator cylinder; both the front and rear support lugs are provided with connecting pin holes for installation and connection with external pin shafts, and the actuator cylinder is connected to the motor housing and the front end cover of the motor using the long bolt and nut.

[0015] During normal operation, the RVI roller screw assembly, driven by the servo motor assembly, has its screw shaft and planetary rollers reciprocating together within the screw pair's long nut. When the electromagnetic clutch assembly is de-energized, it is not in operation, and its moving double-sided splined chuck is separated from the clutch connecting chuck of the servo motor assembly. Since the RVI roller screw assembly and the RV roller screw assembly share a single screw shaft, when the screw shaft is not rotating, the planetary rollers of the RV roller screw assembly remain at the zero position (-2L, +2L), acting as a static load-bearing connection to drive the connecting assembly to reciprocate.

[0016] When a fault occurs, the electromagnetic clutch assembly is energized, and the electromagnetic engagement coil causes the moving double-sided splined sprocket to overcome the spring force and engage with the clutch connecting sprocket. This causes the screw nut, screw shaft, and planetary rollers of the RVI roller screw assembly to rotate simultaneously, transforming it into a static load-bearing connection. The screw shaft transforms the RV roller screw assembly into a transmission component. The system calculates and restores the location of the RVI roller screw assembly jamming / sticking fault, ultimately satisfying the rated working stroke (-L, +L) of the servo mechanism as a whole, achieving EMA transmission redundancy backup.

[0017] The advantages of this invention compared to the prior art are:

[0018] (1) The serial dual lead screw redundancy control electromechanical servo mechanism proposed in this invention uses a servo motor and an electromagnetic clutch to realize the conversion of static load connection and transmission of two types of lead screws.

[0019] (2) The serial dual-screw redundant control electromechanical servo mechanism proposed in this invention has a reserved 2L stroke and zero position setting for the RV planetary roller screw. It can perform a zero return operation and restore normal load-bearing and motion functions when the RVI planetary roller screw is jammed or stuck at any position.

[0020] (3) The serial dual-screw redundant control electromechanical servo mechanism proposed in this invention is suitable for radial or flat installation spaces, and adaptable to situations with a large axial zero length, and is suitable for the application of deformable actuators. Attached Figure Description

[0021] Figure 1 This is a diagram showing the internal components of the serial dual-screw redundant control electromechanical servo mechanism of the present invention.

[0022] Figure 2 This is a schematic diagram of the external shape of the serial dual-screw redundant control electromechanical servo mechanism of the present invention. Detailed Implementation

[0023] The present invention will be described in conjunction with the accompanying drawings.

[0024] like Figure 1 , Figure 2 As shown, a serial dual-screw redundant control electromechanical servo mechanism includes: a servo motor assembly, an RVI roller screw pair assembly, an electromagnetic clutch assembly, an RV roller screw pair assembly, a sensor assembly, and a connecting assembly.

[0025] The servo motor assembly is coaxially arranged with the RVI planetary roller screw assembly and the RV planetary roller screw assembly. The RVI planetary roller screw assembly and the RV planetary roller screw assembly are installed in series and share a common screw shaft. After the rotor of the servo motor assembly is integrated with the long nut of the RVI roller screw assembly, it can independently drive the RVI roller screw assembly or drive the RV roller screw assembly. The electromagnetic clutch assembly is located at the right output end of the servo motor assembly, and realizes the change of motor power output path through the engagement / disengagement of the end face teeth. The sensor assembly is connected to the linear reciprocating moving end of the RV roller screw assembly and the fixed-axis rotary moving end of the RVI planetary roller screw assembly, respectively, and can perform comprehensive detection of jamming / sticking faults. The connecting assembly reliably connects the housing of the motor assembly and the moving end of the RV roller screw assembly to the outside.

[0026] During normal operation, the RVI roller screw assembly, driven by the servo motor assembly, has the screw shaft 2b and planetary rollers 2c reciprocating together within the screw pair long nut 2a. The electromagnetic clutch assembly is de-energized and does not operate, and its moving double-sided splined toothed plate 3b is separated from the clutch connecting toothed plate 1f of the servo motor assembly. Since the RVI roller screw assembly and the RV roller screw assembly share a screw shaft 2b, when the screw shaft 2b does not rotate, the planetary rollers 4b of the RV roller screw assembly remain at the zero position (-2L, +2L), acting as a static load-bearing connection to drive the connecting assembly to reciprocate. L is half of the linear travel of the planetary rollers 2c within the screw pair long nut 2a.

[0027] During fault operation, an angle sensor is installed on the left end of the servo motor to measure its rotation angle, and a linear displacement sensor is installed on the outside of the nut of the RV roller screw assembly to measure its position. When the servo system sends the motor to rotate a certain angle, if the resolver feedback is normal, but the linear displacement sensor feedback value is less than the theoretical value and exceeds a certain range, the RVI roller screw assembly is determined to be stuck. When the servo system sends the motor to rotate a certain angle, if the resolver feedback is abnormal, and the servo motor current suddenly increases, and the linear displacement sensor feedback is abnormal, the RVI roller screw assembly is determined to be jammed. At this time, the electromagnetic clutch assembly is energized, and the electromagnetic engagement coil 3c is used to move the double-sided splined sprocket 3b to overcome the spring force. By extending a certain distance, the clutch connecting the crank 1f at the output end of the servo motor engages with the screw nut 2a, screw shaft 2b, planetary rollers 2c, and cage of the RVI roller screw assembly, causing them to rotate simultaneously, thus transforming into a static load-bearing connection and isolating any faults. The screw shaft 2b transforms the RV roller screw assembly into a transmission component and calculates and restores the location of jamming / sticking faults in the RVI roller screw assembly, ultimately satisfying the rated working stroke (-L, +L) of the entire servo mechanism and achieving redundant backup of the EMA transmission.

[0028] The servo motor assembly includes a motor rotor 1a, a motor stator 1b, a motor housing 1c, a motor front end cover 1d, an actuator cylinder 1e, and a clutch connecting sprocket 1f. The motor rotor 1a has a permanent magnet and a stainless steel sleeve attached to its surface and is integrated with the lead screw pair long nut 2a. One end of the lead screw pair long nut 2a is fixedly connected to the clutch connecting sprocket 1f. One end of the motor housing 1c is connected to one end of the motor front end cover 1d, and the other end of the motor front end cover 1d is connected to the actuator cylinder 1e. Both ends of the lead screw pair long nut 2a are mounted on bearing seats inside the motor housing 1c and the motor front end cover 1d respectively via a pair of angular contact ball bearings. The motor stator 1b is heat-fitted into the inner cavity of the motor housing 1c, and the outer ring of the bearing is connected to the seat hole of the motor front end cover 1d. The actuator cylinder 1e is connected to the motor housing 1c and the motor front end cover 1d using four sets of long bolts 6c and nuts 6d, thereby ensuring that the pair of angular contact ball bearings are in a preloaded state.

[0029] The RVI roller screw assembly includes a long nut 2a, a screw shaft 2b, planetary rollers 2c, and a first cage 2d. The left end of the screw shaft 2b has a short-stroke thread, and the right end has a long-stroke thread. The short-stroke thread at the left end meshes with the external thread of the planetary rollers 2c, and the planetary rollers 2c mesh with the inner thread of the long nut 2a. A number of planetary rollers 2c are arranged around the circumference of the screw shaft 2b, and their two ends are constrained by two first cages 2d, so that the planetary rollers 2c and the first cages 2d can only rotate on the left end with the short-stroke thread, thus driving the screw shaft 2b to move linearly.

[0030] The electromagnetic clutch assembly includes an external spline hollow shaft 3a, a movable double-spline sprocket 3b, an electromagnetic engagement coil 3c, a return spring 3d, a fixed end face sprocket 3e, a bearing outer ring seat 3f, and a bearing lock nut 3g. The hollow external spline shaft 3a and the movable double-sided spline sprocket 3b are coaxially mounted via internal and external spline teeth, allowing relative movement between them. A pair of deep groove ball bearings are mounted on the outer ring of the hollow external spline shaft 3a, and the inner ring is fixed using a bearing locking nut 3g. The bearings are also installed in the holes of the bearing outer ring seat 3f and fixed using a retaining ring. The fixed end face sprocket 3e is fitted onto the bearing outer ring seat 3f. One end of the fixed end face sprocket 3e has teeth that can engage with the teeth of the movable double-sided spline sprocket 3b. Several return springs 3d are circumferentially set to reset the movable double-sided spline sprocket 3b. The electromagnetic attraction coil 3c is heat-fitted into the U-shaped hole at one end of the fixed end face sprocket 3e to attract the movable double-sided spline sprocket 3b. The fixed end face sprocket 3e and the bearing outer ring seat 3f are fixed on the stepped structure inside the front cover 1d of the motor.

[0031] The RV roller screw assembly includes a nut 4a, planetary rollers 4b, and a second cage 4c. The screw shaft 2b is the screw section of the RV roller screw assembly, with a long-stroke thread at the right end. Under the constraint of the rotational motion of the second cage 4c, the two ends of the planetary rollers 4b engage with the external thread of the screw shaft 2b and with the internal thread section at one end of the inner wall of the nut 4a. The assembly of the nut 4a, planetary rollers 4b, and second cage 4c reciprocates along the long thread of the screw shaft 2b, stopping at the zero position (-2L, +2L), acting as a static load-bearing connection to drive the connecting assembly to reciprocate. When the RV roller screw fails, it is activated and becomes a transmission component.

[0032] The sensor assembly includes a brush 5a, a linear displacement plate 5b, a countersunk screw 5c, a resolver rotor 5d, a resolver stator 5e, and fixing screws 5f. The brush 5a has a spring-like structure, with one end of its flat surface connected to the limiting protrusion of the nut 4a via the countersunk screw 5c. The linear displacement plate 5b is located above the brush 5a and makes sliding contact, detecting the linear position of the nut 4a. The linear displacement plate 5b is mounted on the outer surface of the actuator cylinder 1e using a set of fixing screws 5f. The brush 5a and the linear displacement plate 5b constitute a linear displacement sensor. The resolver rotor 5d is connected to the long nut 2a via an interference fit. The resolver stator 5e is mounted to the motor housing 1c via a set of fixing screws 5f. The resolver rotor and stator mutually induce a magnetic field to obtain the motor's rotation angle.

[0033] The connecting assembly includes a front support lug 6a, a rear support lug 6b, a long bolt 6c, and a nut 6d. The rear support lug 6b is installed at the other end of the motor housing 1c, and the front support lug 6a is installed at the end of the nut 4a that extends from the actuator cylinder 1e. Both the front support lug 6a and the rear support lug 6b are provided with connecting pin holes, which can be installed and connected with external pins. The long bolt 6c passes through the front support lug 6a, the motor housing 1c, the motor front end cover 1d, and the actuator cylinder 1e.

[0034] The parts of this invention not described in detail are well-known to those skilled in the art.

Claims

1. A serial double lead screw redundant control electromechanical actuator, characterized by, include: Servo motor assembly, RVI roller screw assembly, electromagnetic clutch assembly, RV roller screw assembly, sensor assembly, and connection assembly; The servo motor assembly is coaxially arranged with the RVI planetary roller screw assembly and the RV planetary roller screw assembly. The RVI planetary roller screw assembly and the RV planetary roller screw assembly are installed in series and share a common screw shaft. The servo motor assembly drives the RVI roller screw assembly or the RV roller screw assembly. The electromagnetic clutch assembly is located at the output end of the servo motor assembly and changes the motor power output path through the engagement or disengagement of the end face teeth. The sensor assembly is connected to the linear reciprocating moving end of the RV roller screw assembly and the fixed-axis rotary moving end of the RVI planetary roller screw assembly, respectively, to detect jamming or sticking faults in the RVI roller screw assembly. The connecting assembly connects the housing of the servo motor assembly and the moving end of the RV roller screw assembly to the outside. The RVI roller screw assembly includes a screw pair long nut (2a), a screw shaft (2b), and planetary rollers (2c). The two ends of the screw pair long nut (2a) are respectively mounted on bearing seats inside the motor housing (1c) and the motor front end cover (1d) through a pair of angular contact ball bearings. One end of the screw shaft (2b) is provided with a short-stroke thread, and the other end is provided with a long-stroke thread. The short-stroke thread meshes with the planetary rollers (2c) for external transmission, and the planetary rollers (2c) mesh with the inner surface thread of the screw pair long nut (2a) for transmission.

2. A serial double lead screw redundant control electromechanical actuator according to claim 1, characterized in that, The servo motor assembly includes a motor rotor (1a), a motor stator (1b), a motor housing (1c), a motor front end cover (1d), an actuator cylinder (1e), and a clutch connecting sprocket (1f). The surface of the motor rotor (1a) is covered with a permanent magnet and a stainless steel sleeve, and it is integrated with the lead screw pair long nut (2a) of the RVI roller lead screw pair assembly. One end of the lead screw pair long nut (2a) is fixedly connected to the clutch connecting sprocket (1f). One end of the motor housing (1c) is connected to one end of the motor front end cover (1d), and the other end of the motor front end cover (1d) is connected to the actuator cylinder (1e). The motor stator (1b) is installed in the inner cavity of the motor housing (1c) and cooperates with the motor rotor (1a).

3. A serial double lead screw redundant control electromechanical actuator according to claim 2, characterized in that, The RVI roller screw assembly also includes a first cage (2d), and several planetary rollers (2c) are arranged around the circumference of the screw shaft (2b). The two ends of the several planetary rollers (2c) are constrained by the first cage (2d), so that the planetary rollers (2c) and the first cage (2d) rotate together on the short-stroke thread and drive the screw shaft (2b) to move linearly.

4. A serial double lead screw redundant control electromechanical actuator according to claim 3, characterized in that, The electromagnetic clutch assembly includes an external spline hollow shaft (3a), a movable double-sided splined sprocket (3b), an electromagnetic engagement coil (3c), a return spring (3d), a fixed end face sprocket (3e), a bearing outer ring seat (3f), and a bearing lock nut (3g). The outer spline hollow shaft (3a) is coaxially installed with the moving double-sided spline tooth disc (3b) through inner and outer spline teeth, the outer spline hollow shaft (3a) and the moving double-sided spline tooth disc (3b) can be relatively moved, a pair of deep groove ball bearings are installed on the outer circle of the outer spline hollow shaft (3a), the inner circle of the deep groove ball bearing is fixed by using a bearing locking nut, the deep groove ball bearing is simultaneously installed in the hole of the bearing outer circle seat (3f) and is fixed by using a hole stopper; the fixed end face tooth disc (3e) is sleeved on the bearing outer circle seat (3f), one end of the fixed end face tooth disc (3e) is provided with teeth, which are matched with the teeth of the moving double-sided spline tooth disc (3b) and a plurality of reset springs (3d) are arranged around the circumference to reset the moving double-sided spline tooth disc (3b), the electromagnetic attraction coil (3c) is installed in the U-shaped hole at one end of the fixed end face tooth disc (3e) to attract the moving double-sided spline tooth disc (3b), and the fixed end face tooth disc (3e) and the bearing outer circle seat (3f) are fixed on the stepped structure in the motor front end cover (1d).

5. A serial double lead screw redundant control electromechanical actuator according to claim 4, characterized in that, The RV roller screw pair assembly comprises a nut (4a), a planetary roller (4b) and a second retainer (4c); The long-stroke threaded section of the screw shaft (2b) is inserted into the actuating cylinder (1e) and the nut (4a); the planetary roller (4b) is in meshing transmission with the long-stroke external thread of the screw shaft (2b) and the internal thread at one end of the inner wall of the nut (4a) under the rotation and movement constraint of the second retainer (4c) at both ends of the planetary roller (4b); the combination of the nut (4a), the planetary roller (4b) and the second retainer (4c) reciprocates along the long-stroke threaded section of the screw shaft (2b) and stays at the zero position of (-2L, +2L) to drive the connecting assembly to realize reciprocating movement as a static bearing connection, and is used when the RV I roller screw pair assembly fails, and is changed into a transmission component, L being half of the linear motion stroke of the planetary roller (2c) in the inner cavity of the screw pair long nut (2a).

6. A serial double lead screw redundant control electromechanical actuator according to claim 5, characterized in that, The sensor assembly comprises a brush (5a), a linear displacement plate (5b), a countersunk screw (5c), a resolver rotor (5d), a resolver stator (5e) and a fixing screw (5f); the brush (5a) is a compression spring structure and is connected to the limiting protrusion on the large end outer circle of the nut (4a) through the countersunk screw (5c), the side wall of the actuating cylinder (1e) is longitudinally provided with a limiting groove matched with the limiting protrusion on the large end outer circle of the nut (4a), the linear displacement plate (5b) is arranged on the outer surface of the limiting groove and is in sliding contact with the brush (5a) to detect the linear position of the nut (4a); the resolver rotor (5d) is installed in the other end port of the screw pair long nut (2a), the resolver stator (5e) is fixed to the other end of the motor housing (1c) through a group of fixing screws (5f), and the rotation angle of the motor servo motor is obtained through mutual magnetic field induction between the resolver rotor (5d) and the resolver stator (5e); the brush (5a) and the linear displacement plate (5b) constitute a linear displacement sensor.

7. A serial double lead screw redundant control electromechanical actuator according to claim 6, characterized in that, The connecting assembly comprises a front lug (6a), a rear lug (6b), a long bolt (6c) and a nut (6d). The rear lug (6b) is installed at the other end of the motor housing (1c), and the front lug (6a) is installed at the end of the nut (4a) extending from the actuator cylinder (1e). The front lug (6a) and the rear lug (6b) are both provided with connecting pin holes and are installed and connected with external pin shafts. The actuator cylinder (1e) is connected with the motor housing (1c) and the motor front end cover (1d) by the long bolt (6c) and the nut (6d).

8. A serial double lead screw redundant control electromechanical actuator according to any one of claims 1 to 7, characterized in that, In normal operation, the RVI roller screw pair assembly moves reciprocatingly in the screw pair long nut (2a) together with the screw shaft (2b) and the planetary roller (2c) under the driving of the servo motor assembly. The electromagnetic clutch assembly is not working when power off, and the moving double-sided spline tooth disc (3b) is separated from the clutch connecting tooth disc (1f) of the servo motor assembly. Since the RVI roller screw pair assembly and the RV roller screw pair assembly share a screw shaft (2b), when the screw shaft (2b) does not rotate, the planetary roller (4b) of the RV roller screw pair assembly stays at the zero position of (-2L, +2L), which is used as a static bearing connection to drive the connecting assembly to move reciprocatingly.

9. A serial double lead screw redundant control electromechanical actuator according to any one of claims 1 to 7, characterized in that, In fault operation, the electromagnetic clutch assembly is powered on, and the moving double-sided spline tooth disc (3b) is pushed out against the spring force by the electromagnetic attraction coil (3c) to combine with the clutch connecting tooth disc (1f), so that the screw pair nut (2a), the screw shaft (2b) and the planetary roller (2c) of the RVI roller screw pair assembly rotate at the same time, which is converted into a static bearing connection. The screw shaft (2b) converts the RV roller screw pair assembly into a transmission component and calculates and recovers the position of the RVI roller screw pair assembly jamming / clogging fault, finally meets the rated working stroke of the whole servo mechanism (-L, +L), and realizes the EMA transmission redundancy backup.

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