CN114031023B

CN114031023B - Mechanical driver system

Info

Publication number: CN114031023B
Application number: CN202111286744.0A
Authority: CN
Inventors: 彭高亮; 刘世伟; 程枫; 孙瑜
Original assignee: Harbin Institute of Technology
Current assignee: Harbin Institute of Technology
Priority date: 2021-11-02
Filing date: 2021-11-02
Publication date: 2022-06-14
Anticipated expiration: 2041-11-02
Also published as: CN114031023A

Abstract

The invention relates to a mechanical driver system, which comprises a base and a support frame, wherein the support frame is hinged with the base at a first hinge point; the rocker is hinged with the base at a second hinge point; a driver hinged to the base at a third hinge point; the sliding piece can slide relative to the supporting frame; and one end of the rocker, which is far away from the second hinge point, and one end of the flexible driver, which is far away from the third hinge point, are both hinged with the sliding piece. Adopt the scheme of this application, compare in traditional widely used three hinge point actuating mechanism, with fixed articulated replacement for fourth hinge point, increased a rocker simultaneously and be used for guaranteeing that whole mechanism satisfies the designing requirement of 1 degree of freedom, realize the quick drive of action is erected and transferred to the rising of operation object.

Description

Mechanical driver system

Technical Field

The invention belongs to the field of transmission devices, and particularly relates to a mechanical driver system.

Background

Mechanical actuator systems, which enable the mechanical transmission of an object to be operated from a horizontal position to a tilted position or a vertical position, have found wide and important applications in military and civil applications. The existing mechanical driver system mostly adopts a three-hinge-point mechanical driver system to realize erecting and leveling of an operation object through position control, the erecting stroke of the method is long, a driving device is often realized by adopting a multi-stage hydraulic oil cylinder or a multi-stage electric cylinder, the erecting time cannot be effectively reduced, the stability performance requirement cannot be met if the driving speed is accelerated, and particularly the stability of the system needs to be further improved and improved under the action of multi-stage cylinder stage change or impact load.

The existing research is mostly carried out on the aspects of system optimization design, starting and erecting track planning, control strategy optimization and the like of a mechanical driver, although a certain effect can be achieved, the double requirements of rapidity and stability cannot be considered at the same time, and therefore a new thought needs to be adopted to solve the problems of rapidity and stability in the starting and erecting process.

Disclosure of Invention

It is an object of the present invention to overcome the above-mentioned drawbacks of the prior art by providing a mechanical drive system, characterized in that: comprises a base and a plurality of connecting rods, wherein,

the support frame is hinged with the base through a first hinge point;

the rocker is hinged with the base at a second hinge point;

a driver hinged to the base at a third hinge point;

the sliding piece can slide relative to the supporting frame;

and one end of the rocker, which is far away from the second hinge point, and one end of the flexible driver, which is far away from the third hinge point, are both hinged with the sliding piece.

In one embodiment, the support frame is provided with a first guide member, and the sliding member is provided with a second guide member slidably engaged with the guide rail.

In one embodiment, the other end of the rocker and the other end of the flexible drive are coaxially hinged with the slider.

In one embodiment, the actuator is a compliant actuator comprising a spring element and a damping element.

In one embodiment, the driver is a compliant driver, the compliant driver comprises a supporting seat and a compliant mechanism, the supporting seat comprises a sleeve, a first baffle plate arranged at one end of the sleeve, and a second baffle plate sleeved at the other end of the sleeve, and the distance between the second baffle plate and the first baffle plate is adjustable; the compliant mechanism comprises an interface board, a first spring group and a second spring group, wherein the first spring group and the second spring group are respectively arranged at two free ends of two sides of the interface board, the two free ends of the first spring group and the two free ends of the second spring group are respectively arranged at two sides of the interface board, the first spring group comprises a first inner spring and a first outer spring which are sleeved together, the second spring group comprises a second inner spring and a second outer spring which are sleeved together, and the free lengths of the first inner spring and the first outer spring are different; the free lengths of the second inner spring and the second outer spring are different, wherein the interface board is hinged with the base at a second hinge point.

In one embodiment, the compliant driver further comprises a driving mechanism and a linear actuator, the linear actuator comprises a ball screw and a nut, the ball screw is used for converting the rotary motion of the driving mechanism into linear motion and connecting with an external load, the nut is fixedly arranged on the frame, and part of the ball screw is arranged inside the sleeve.

In one embodiment, the first inner spring and the first outer spring are concentrically arranged, and the second inner spring and the second outer spring are concentrically arranged.

In one embodiment, the driver further comprises a damping unit disposed inside the sleeve, and an end of the ball screw, which is remote from the load, is connected to the damping unit.

In one embodiment, the interface board includes a connector member provided with an outer peripheral surface for connection with an external device.

In one embodiment, the interface plate includes annular protruding structures disposed on both sides, and the outer diameter of the protruding structures is adapted to the outer spring.

Adopt the scheme of this application, compare in traditional widely used three hinge point mechanical driver system, replace fixed hinge for fourth hinge point A, increased a rocker simultaneously and be used for guaranteeing that whole mechanism satisfies the designing requirement of 1 degree of freedom, realize the quick drive of action is erected and is transferred to operation object's rising. The support frame 10 is used for bearing and supporting an operation object, and can be designed adaptively according to the geometric form and the weight boundary of the object.

Drawings

FIG. 1 is a block diagram of a drive system of the present invention.

FIG. 2 is a schematic diagram of the operation of the driver system of the present invention.

Fig. 3 is a kinematic diagram of the actuator system of the present invention.

Fig. 4 is a kinematic diagram of a conventional three-pivot drive system.

FIG. 5 is a block diagram of another embodiment of the drive system of the present invention.

FIG. 6 is a schematic diagram of the compliant drive of the present invention.

FIG. 7 is a control block diagram of a compliant driver system of the present invention.

FIG. 8 is a control schematic of the compliant actuator system of the present invention.

FIG. 9 is a graph of the time domain response of the step excitation of the driver system of the present invention.

FIG. 10 is a graph of the time domain response of a sinusoidal excitation of the driver system of the present invention.

FIG. 11 is a block diagram of another embodiment of the drive system of the present invention.

FIG. 12 is a cross-sectional view of a compliant drive mechanism of the present invention.

Fig. 13 is a diagram of an interface board structure of the present invention.

FIG. 14 is a schematic diagram of the variable stiffness of a compliance of the present invention.

FIG. 15 is a graph comparing the driving forces of a compliant drive system and a rigid drive system of the present invention.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments.

Referring to fig. 1, the drive 30 system of the present invention includes a base 00, and,

the support frame 10 is hinged to the base 00 at a first hinge point O;

A rocker 20, wherein the rocker 20 is hinged with the base 00 at a second hinge point C;

a driver 30, said driver 30 being hinged to said base 00 at a third hinge point B;

a sliding part 40, wherein the sliding part 40 can slide relative to the supporting frame 10;

the end of the rocker 20 far away from the second hinge point C and the end of the flexible driver 30 far away from the third hinge point B are both hinged to the sliding member 40.

In one embodiment, the other end of the rocker 20 and the other end of the flexible actuator 30 are hinged to the slider 40 at a hinge point. For example, at the fourth hinge point a, and more specifically, by means of a hinge shaft 04.

The first hinge point, the second hinge point and the third hinge point are respectively supported by a first support 01, a second support 02 and a third support 03 which are arranged on the base 00.

Adopt the scheme of this application, compare in traditional widely used three hinge point driver system, replace fixed hinge for fourth hinge point A, increased a rocker 20 simultaneously and be used for guaranteeing that whole mechanism satisfies the designing requirement of 1 degree of freedom, realize the action of erectting and transferring of operation object 50. The support frame 10 is used for bearing and supporting the operation object 50, and can be designed according to the geometric form and the weight boundary of the object.

Referring to fig. 2, the present invention is shown in an initial state position and a terminal state position based on a drive 30 system. Because the length of the rocker 20 is constant, it is easy to determine that the motion trajectory of the fourth hinge point a is a circular arc curve CL taking the second hinge point B as the center of a circle and the length p of the rocker 20 as the radius. The fourth hinge point a moves on the support frame 10 by a distance range of AA'. In contrast to the conventional three-pivot actuator system, the pivot point pair is fixed at the position (a') of the support frame 10, and the actuating cylinder extends along with the rotation of the support frame 10. The stroke of the driving cylinder is reduced, so that the erecting time can be effectively reduced; meanwhile, the design of the driving cylinder can be optimized, the stage number of the driving cylinder can be reduced through reasonable design, the influence of stage-changing impact of the driving cylinder can be reduced, and the stability of the system in the erecting process is enhanced to a certain extent.

In one embodiment, a first guide member is provided on the support frame 10, and a second guide member slidably engaged with the guide rail is provided on the sliding member 40. The first guide member is for example a guide rail and the second guide member is for example a runner, but the reverse is of course possible.

By adopting the scheme, the top end of the rocker 20 and the top end of the driver 30 are coaxially arranged, the rotation center and the receiving center of the sliding block are the same, and the whole driver system works more stably.

In one embodiment, the abscissa of the second hinge point C is located between the abscissa of the first hinge point O and the abscissa of the third hinge point D, and the ordinate of the second hinge point C is located between the ordinate of the first hinge point O and the ordinate of the third hinge point D. In one embodiment, the longitudinal coordinate value of the fourth hinge point a is located between the longitudinal coordinate value of the first hinge point O and the longitudinal coordinate value of the second hinge point C when the support frame 10 is in a horizontal state.

Experiments show that by adopting the scheme, when the driving device acts, the force bearing capacity of the rocker 20 and the driver 30 is stronger, the mechanism is more stable, and the mutual interference or dead position state is avoided.

Fig. 3 shows a fast vertical kinematic model of the driver 30 according to the present invention, in which a coordinate system is first established at the O point. Since the length p of the rocker 20 (which is equal to AC in the initial position) is constant, it is easy to determine that the motion trajectory of the fourth hinge point a is a circular arc curve CL with the center point C as the center and the length p of the rocker 20 as the radius. Wherein theta is a vertical angle theta ₁Is the angle of the driver 30 with respect to the horizontal axis, θ₂Is the angle of the rocker 20 to the horizontal axis.

The coordinates of the first hinge point O are (0,0), and the coordinates of the second hinge point C are (x)₂,y₂) The third hinge point B has the coordinate of (x)₁,y₁) The fourth hinge point A has the coordinate of (x)_a,y_a) The corner point D of the supporting frame 10 has coordinates of (x)_d,y_d) The barycentric G coordinate of the operation target 50 is (x)_G,y_G)。

The real-time distance between the fourth hinge point a and the third hinge point B is l.

The origin of coordinates O is at a distance h from the support foot 10.

Combining the definition of the vertical angle, firstly, the coordinate of the fourth hinge point A is solved according to the geometric relationship

The following equation is obtained

Wherein, beta is the first order coefficient of the quadratic equation, and gamma is the constant term coefficient of the quadratic equation, and can be calculated according to the following formula

Therefore, the coordinates of the point A can be obtained according to the quadratic equation of one unit. Due to x₂，y₂P and h are fixed values, and the coordinate of the fourth hinge point A is known to be a univariate function about the erecting angle theta, which is consistent with the single degree of freedom of the driver system.

The length of the driving device can be expressed by the coordinate of the fourth hinge point A

The fourth hinge point A is at a distance from the support frame 10

Note that l and d are both univariate functions with respect to theta. The lengths of the driving device in the horizontal state and the vertical state are respectively recorded as l _inAnd l_enThe stroke of the drive means available can be expressed as

L＝l_en-l_in

Similarly, let AD initial length and final length be d respectively_inAnd d_enThe movement stroke of the fourth hinge point A is

D＝d_en-d_in

The advantage of the designed actuator system in reducing the stroke of the actuator is illustrated by way of a specific example.

When h is 64mm, p is 421.5mm, the coordinate of each point is x₁＝230mm，y₁＝-130mm，x₂＝100mm，y₂＝-100mm，x_G＝3201mm，y_G＝17mm。

By calculation, it can be found that, for the designed driver system, the length of the driving device is 297.4mm in the initial horizontal state; in the vertical position, the length of the drive is 479.3 mm.

According to the design specification of the driving cylinder, the following empirical formula holds

l_en＝(1+nK)l_in

Wherein n is the number of the driving cylinders, and K is the expansion ratio of the driving cylinders, and is generally 0.7-0.8.

The number of drive cylinder stages can be determined by

For a designed actuator system, the stroke L can be calculated_m181.9mm, and n_mThe function can be realized by adopting a single-stage cylinder as 1.

Referring to fig. 4, for the conventional three-hinge-point actuator system, the determination principle of the lower hinge point position of the actuating cylinder is as follows: the stroke is reduced as far as possible on the premise of ensuring the minimum stage number of the driving cylinder. Meanwhile, considering the stability of the erecting process, according to engineering experience, in the erecting-to-vertical state, the inclination angle of the driver and the horizontal plane is not more than 75 degrees, and in the erecting initial state, the position of the driver is not lower than the position of the rocker 20. The design range of the hinge point position of the three-hinge-point erecting scheme is a polygon MAB ₁B₂And N is added. The optimization problem is a convex optimization problem, so that the optimal value of the convex optimization problem is required to be reached at a certain vertex of the convex set if the optimal value exists, and the solution of the optimal value is converted into the solution of the vertex. Easy to calculate to obtain the peak of the convex set of the problem as B₁(173.8，-89.8)、B₂(184.6, -130). For hinge point B₁The lengths of the corresponding driving cylinders are respectively l_in1＝148.4mm，l_en1424.2mm, n can be obtained according to the driving cylinder series formula₁＝3，L₁275.8 mm; for hinge point B₂In the same way, calculate l_in2＝150.6mm，l_en2＝465.8mm，n₂＝3，L₂＝315.2mm。

It can be seen that if a conventional triple-pivot drive system is used, three stages of cylinders are required to meet the erection function, and the stroke is 1.5 times that of the rapid erection scheme of the present invention.

Therefore, the driver system can effectively reduce the stroke of the driving cylinder and the number of stages, further has the advantages of reducing the production cost, facilitating the spatial arrangement of the mechanism, effectively reducing the erecting time and the like in the practical engineering, and embodies great practical reference value.

As shown in FIG. 5, in one embodiment, the actuator 30 is a compliant actuator 30. Preferably, the compliant actuator 30 includes a spring element and a damping element. For example, a schematic of a compliant actuator 30 is shown in FIG. 6. The compliance actuator 30 includes a driving cylinder, an elastic element and a damping element, and a compliance link composed of the elastic element and the damping element is connected in series to the driving cylinder.

As shown in fig. 7, it is a structure diagram of a compliant drive control system of the actuator 30, wherein the control system performs control according to the pre-designed input command and the information fed back by the sensing device; the actuating element is generally a servo motor or a hydraulic cylinder; the transmission of motion and force is realized through a transmission device; the sensing device is used for detecting stress information and feeding the stress information back to the control system.

Fig. 8 shows a schematic control diagram of a compliant drive based actuator system. The control strategy adopts a force-position hybrid control scheme that force control is used as an inner ring and position control is used as an outer ring, so that flexible driving of a rapid driver system is realized. For the erecting mechanism, the erecting function of the mass load is finally realized, and therefore the erecting angle is used as a system expected signal.

The relation between the vertical angle theta and the driving force F is established, and the ideal driving force F can be obtained by converting the vertical angle theta and the driving force F_desThe actual output force F can be calculated by the force control law_o. Then the actual vertical angle theta of the driver system can be obtained by the conversion of theta (F)_oThe starting vertical angle is controlled by a position control law. The environmental collision link in the erecting process can be rotatedFor the influence on the driving force of the compliance driving device, the influence of external interference can be effectively reduced by reasonably designing a force control law, and the compliance control of the driver system can be realized.

The actuator 30 system of the present invention includes a damping element and a spring element. After certain interference is added to a control object and measurement noise is added to a feedback link, a rigid driver system and a compliant driver system are excited by a step signal and a sine signal respectively. In the simulation analysis, because the measurement noise generated by the feedback system sensor always exists, Gaussian white noise is added in a feedback link to simulate the measurement noise; the external disturbance is random, so adding a disturbance signal of constant amplitude at 5s simulates the compliance driver 30 experiencing the disturbance. The time domain response curves of the resulting system are shown in fig. 9 and fig. 10, respectively.

In the case of a rigid drive, the system bandwidth is broadened and the response is extremely fast due to infinite stiffness, but with the disadvantage of being very sensitive to both interference and noise. It can be found from both the response curves of step response and sinusoidal excitation that under the condition of rigid drive, the system has no obvious inhibition effect on external interference, has no filtering effect on measurement noise, always keeps oscillation, and cannot tend to be stable.

Compared with a pure rigid drive, the system can achieve better suppression effect on external interference and measurement noise in the case of an elastic drive, especially in terms of noise attenuation. However, as can be seen from the response curve, although the system can finally stabilize, the presence of external large disturbance causes the system output to have a large steady-state error, and the presence of measurement noise causes the system output to have a certain degree of oscillation. Although the spring drive is a good improvement over the prior rigid drive, further optimization of the control algorithm is necessary to achieve better results.

In one embodiment, as shown in fig. 11-14, another compliant drive is employed, and in particular, the compliant drive includes a frame 100, and a drive mechanism 200, a linear actuator 300, and a compliant mechanism 400 disposed on the frame 100.

The rack 100 includes a support base, the support base includes a sleeve 111, a first baffle 112 disposed at one end of the sleeve 111, and a second baffle 113 sleeved at the other end of the sleeve 111, and a distance between the second baffle 113 and the first baffle 112 is adjustable.

Wherein the driving mechanism 200 is used for outputting a driving force.

The linear actuator 300 is used to convert the rotational motion of the driving mechanism 200 into a linear motion and is connected to an external load for providing motion and support to the load. The linear actuator 300 includes a ball screw 301 and a nut 302, the nut 302 is fixed on the frame 100, and the ball screw 301 is installed inside the sleeve 111. In one aspect, one end of the ball screw 301 is provided with a joint 303 for connecting with an external load, and the joint 303 is connected with the ball screw 301 through a thread, for example.

The compliant mechanism 400 comprises an interface board 401 sleeved outside the sleeve 111, and a first spring group and a second spring group, wherein the first spring group and the second spring group are sleeved outside the sleeve 111 and are respectively arranged at two free ends of two sides of the interface board 401, the first spring group comprises a first inner spring 412 and a first outer spring 411 which are sleeved together, the second spring group comprises a second inner spring 422 and a second outer spring 421 which are sleeved together, and the free lengths of the first inner spring 412 and the first outer spring 411 are different; the free lengths of the second inner spring 422 and the second outer spring 421 are different.

By adopting the scheme, the free lengths of the first inner spring 412 and the first outer spring 411 and the free lengths of the second inner spring 422 and the second outer spring 421 are set, the distance between the second baffle 113 and the first baffle 112 is adjusted, the relationship between the pre-tightening force of the springs and the spring gap is changed, and the variable stiffness is realized. According to the external load characteristics, the rigidity adjustment under the tension working condition and the compression working condition is realized.

In one embodiment, the first inner spring 412 and the first outer spring 411 are concentrically disposed, and the second inner spring 422 and the second outer spring 421 are concentrically disposed.

In one embodiment, the two springs, which are concentrically arranged, have opposite handedness. For example, the first inner spring 412 is a left-handed spring and the first outer spring 411 is a right-handed spring, or vice versa. The second spring set may be the same or opposite to the first spring set. The reverse arrangement can ensure that the inner spring and the outer spring are concentric and cannot be skewed.

In one embodiment, the free length of the outer spring 411/421 is greater than the free length of the inner spring 412/422.

In one embodiment, the spring free length and stiffness are set according to the stiffness change of the driver during operation, for example, when the compliance device is subjected to a pressure force greater than a tension force during operation, the stiffness of the springs on the right side of the interface board 401 is greater than the stiffness of the springs on the left side (the stiffness of the second outer spring 421 is greater than the stiffness of the first outer spring 411 and/or the stiffness of the second inner spring 422 is greater than the stiffness of the first inner spring 412). For example, when the working environment of the softener is subjected to a tensile force and a compressive force with asymmetric stiffness in a certain section, the free length difference of the first spring group is different from that of the second spring group.

In one embodiment, the free lengths of the first inner spring 412 and the second inner spring 422 are the same, the free lengths of the first outer spring 411 and the second outer spring 421 are the same, the stiffness of the first outer spring 411 and the stiffness of the second outer spring 421 are the same, and the stiffness of the first inner spring 412 and the stiffness of the second inner spring 422 are the same. By adopting the scheme of symmetrical arrangement, the rigidity characteristic curves when the driver bears the tensile force and the pressure are the same, the method is suitable for occasions when the driver bears the tensile force and the pressure, and can realize accurate control.

In one embodiment, the compliance mechanism 400 further comprises a guide device and a pre-tightening device, the guide device comprises a guide rod 431, the guide rod 431 passes through the interface board 401 and the second baffle 113, one end of the guide rod is connected with the first baffle 112, and the pre-tightening device is used for fixing the second baffle 113 at a preset position to achieve pre-tightening on the spring. The pre-tightening device is, for example, a pre-tightening nut 432, a thread is provided on the ball screw 301, and by adjusting the position of the pre-tightening nut 432 on the thread, the pre-tightening nut 432 pushes the second baffle 113 to move along the sleeve 111, thereby controlling the pre-tightening of the first outer spring 411 and the second outer spring 421. The pre-tightening force can be directly determined by calculation according to the thread pitch and the number of tightening turns of the pre-tightening nut 432.

In one embodiment, the guide apparatus further comprises a bearing block 402, the bearing block 402 is disposed on the interface plate 401, and the guide rod 431 is disposed through the bearing block 402. The bearing mount 402 is preferably disposed on the interface plate 401 in an interference fit.

In one embodiment, the guide further includes a fixing device 433, such as a fixing nut, for preventing the guide rod 431 from falling off the second shutter 113. Specifically, the fixing device 433 is sleeved on the guide rod 431 and is installed on one side of the second baffle 113 far away from the pretension nut 432. The first blocking plate 112 limits the movement of the guide rod 431 to the left in the figure, and the fixing device 433 limits the movement of the guide rod 431 to the right in the figure. During assembly, the first baffle plate 112, the first spring set, the interface board 401, the second spring set, the guide rod 431 and the fixing nut 433 are installed (the nut is unscrewed leftwards in advance), then the second baffle plate 113 is installed, and then the second baffle plate is pre-tightened through the pre-tightening nut 432. After the pre-tightening is completed, the fixing nut 433 is screwed to the right end, and the guide rod is blocked by the nut and the second baffle 113, so that the guide rod is fixed. By adopting the scheme, the guide rod can be fixed, the installation and the disassembly are more convenient, the guide rod and the baffle are not required to be integrally arranged, and the processing cost is reduced.

In one embodiment, the guiding rods 431 are a plurality of guiding rods 431, preferably distributed in a regular polygon, for example, four guiding rods 431 are distributed in a square on the periphery of the protruding structure 403.

By adopting the scheme, the pre-tightening of the spring can be conveniently realized, and an accurate guiding function can be provided for the movement of the interface board 401.

In one embodiment, the driver further comprises a damping unit 500, the damping unit 500 is arranged inside the sleeve 111, and one end of the ball screw 301, which is far away from the load, is connected with the damping unit 500. In one embodiment, the ball screw 301 is connected to the damping unit 500 by a screw thread. Preferably, the end of the damping unit 500 away from the ball screw 301 is extended out of the sleeve 111, and is provided with a thread for cooperating with the pre-tightening nut 432.

By adopting the scheme, the driver can provide elastic force and damping force, and the damping unit 500 is added in the scheme, so that the conversion of energy is facilitated, and the designed driving device can obtain better environmental adaptability; through adding damping unit 500 to the sleeve 111 of back supporting seat, can accomplish damping unit 500's the arrangement under the condition that does not occupy extra space like this, can also provide the support of one end for ball 301 pair simultaneously, greatly reduced the bulk of integrated device for compact structure easily spatial arrangement.

In one embodiment, the interface plate 401 includes annular protruding structures 403 disposed on both sides, and the outer diameter of the protruding structures 403 is adapted to the outer springs 411/421. In one embodiment, the inner side of the protruding structure 403 includes a groove with sides that conform to the outer diameter of the inner spring 412/422.

With this arrangement, the annular protrusion 403 can position the inner spring 412/422 and the outer spring 411/412 when the springs are compressed, thereby increasing the stability of the springs.

In one embodiment, the interface board 401 further includes a connector 404 provided with an outer peripheral surface for connecting with an external device. In one aspect, the connector 404 is a stub shaft.

In one embodiment, the drive means comprises a motor 401 and a reduction mechanism 402, the reduction mechanism 402 preferably being a gear set.

In one embodiment, the frame 100 further comprises a second base 114, and the second base 114 is fixedly connected to the supporting base or is an integral structure. Specifically, the second base 114 is fixedly connected to the first baffle 112 or is an integrated mechanism.

In one embodiment, the driving means and the nut 302 cooperating with the ball screw 301 are provided on the second base 114. Specifically, the second base 114 is a box body having openings at both sides, and the motor 401 is fixed to the box body. The nut 302 is sleeved with a first shaft sleeve 121, and the first shaft sleeve 121 is fixed on the inner wall of the second pedestal 114 through a bearing 122. The gear shaft of the speed reducing mechanism 402 is fixed to the second bushing 123, and the second bushing 123 is fixed to the nut 302 and the first bushing 122 by bolts. The first shutter 112 closes one opening of the case, and the gear train blocks the other opening of the case.

The working principle of the compliant driver of the present application is described with reference to fig. 14 and a specific scheme, wherein two springs with different free lengths are arranged in parallel to form a spring set, and the change of stiffness is realized by the difference between the lengths of the two springs; two spring groups are arranged in parallel to realize elastic driving during pressure-tension conversion, and the combined spring can be designed into various rigidity combinations according to different pre-tightening pressures and spring length differences. Specifically, in the present embodiment, the free length of the first outer spring 411 is greater than the free length of the first inner spring 412, the free length of the second outer spring 421 is greater than the free length of the second inner spring 422, and the stiffness of the first outer spring 411 is the same as that of the second outer spring 421, both of which are k₁The stiffness of the first inner spring 412 is the same as the stiffness of the second inner spring 422, and both are k₂. As follows

(1) In the initial state, namely, no pre-tightening load is applied, and all the springs keep the original length state;

(2) and in a pre-tightening state, the spring is pre-tightened and loaded. The second outer spring 421 is driven to move by the movement of the second baffle 113, so as to push the interface board 401 to move, so that the first outer spring 411 and the second outer spring 421 reach a pre-tightening state, the first inner spring 412 and the second inner spring 422 are still in a free state, and at this time, the length difference between the first outer spring 411 and the first inner spring 412 is L _dThe length difference between the second outer spring 421 and the second inner spring 422 is also L_d(hereinafter referred to as a gap L)_d). At this time, the inner spring is not active, and the stiffness of the combined spring is the parallel stiffness of the first outer spring 411 and the second outer spring 421, i.e., 2k 1;

(3) as the force applied to the driver increases, there are 3 cases to discuss:

the first method comprises the following steps: when the clearance L is_dWhen the size is small, the first baffle 112 or the second baffle 113 moves towards the interface board 401 under the action of external force, but the first outer spring 411 and the second outer spring 421 are still in a pre-tightening state, at this time, the interface board 401 contacts one of the first inner spring 412 and the second inner spring 422 and is compressed, and at this time, the overall stiffness of the combined spring is 2k1+ k 2;

and the second method comprises the following steps: when the clearance L is_dWhen the size is larger, the first baffle 112 or the second baffle 113 moves towards the interface board 401 under the action of external force, so that one of the first outer spring 411 and the second outer spring 421 is compressed, and the other one is separated from the pre-tightening state, at this time, the interface board 401 does not contact the first inner spring 412 or the second inner spring 422, namely, the two inner springs are still not contacted with the interface board 401 and keep a free state, and one outer spring is also separated from the pre-tightening state, only one outer spring is accepted, and at this time, the overall stiffness of the combined spring is k 1;

And the third is that: when the clearance L is_dWhen the external force is balanced, the first baffle 112 or the second baffle 113 moves to the interface board 401 by a gap L when the external force is moderate, but the first outer spring 411 and the second outer spring 421 are still in a pre-tightening state, and when the external force balances the pre-tightening force, the first baffle 112 or the second baffle 113 moves to the interface board 401 by exactly the gap L_dAt this time, although the inner spring contacts the upper interface board 401, it does not exert a strong force, and the overall stiffness of the combined spring is 2k 1;

(4) when the external force is continuously applied to the driver, the first baffle 112 or the second baffle 113 moves towards the interface board 401 under the action of the external force, the interface board 401 is in contact with the first inner spring 412 or the second inner spring 422 and is compressed, at this time, only the first outer spring 411 and the first inner spring 412 play a role, or only the second outer spring 421 and the second inner spring 422 play a role, at this time, the overall stiffness of the combined spring in a bearable range is k1+ k 2;

according to practical engineering experience, the ball screw 301 pair is often subjected to compression force when it is extended and tensile force when it is retracted. When the external load is pressure, since the interface board 401 is fixed as an external support position, the combined spring (the first spring group) on the left side in the figure is compressed; similarly, when the external load is a tensile force, the interface board 401 is fixed, and the right combination spring (the second spring set) is compressed.

In the embodiment, the first spring group and the second spring group are in a symmetrical state, so that the tension working condition and the compression working condition of the driver are symmetrical.

Wherein L is_d1First of the three cases, L_d2Second, L, showing the three conditions mentioned above_d3A third of the three cases is shown. The horizontal axis x represents the moving distance of the first shutter 112 or the second shutter 113 with respect to the interface board 401; f₀Is the balance point of the external force and the pretension.

As shown in fig. 15, a comparison graph of the driving force during the erecting process based on the compliant driver and the rigid driver is shown. The experimental procedure was as follows: after the maximum output torque value of the motor is set, when the maximum erecting weight of the flexible erecting system is added, the rigid erecting mechanism is found to be incapable of erecting smoothly. And applying manual assistance to enable the system to overcome the initial force, so that the rigid driving mechanism can be erected normally. And (5) simulating external pulse disturbance by using the rubber hammer to knock when the rigid driver is erected to the middle moment, and finally measuring the stress curve of the output end of the rigid driver.

It can be seen from the figure that when the motor is powered on, the output end force is gradually increased to the point of the maximum output capacity A, but the driving load is still insufficient to be erected. After artificial assistance is applied, the output end force is reduced to a point B, and the load can be erected to a certain angle. And (3) removing the manual assistance, enabling the rigid driver to normally drive the load to be erected at the moment, enabling the driving force to immediately rise to the point C, and enabling the system to realize stable output after being adjusted to the point D. The supporting frame 10 is knocked by a rubber hammer at the point E to simulate environmental collision, the output end force can tend to be stable after being increased rapidly, and the normal erection is kept.

It can be seen from the above figure that the driving force of the two driving modes approximately approaches to be consistent after the vertical movement reaches the point D. But compared with a rigid driver system, the stress curve of the output end of the flexible driver is integrally smooth, and the frequency and the amplitude of local oscillation are smaller. When knock disturbance is applied, the change amplitude of the compliant driver system is obviously smaller than that of the rigid driver system, and the oscillation time is longer. The reason is that after the elastic element is added, the bandwidth of the system is reduced, so that the response is slowed, and the impact adjusting time is prolonged; meanwhile, the small oscillation amplitude reflects that the flexible erecting system can effectively alleviate the influence of external impact.

The above embodiments are merely illustrative of the technical solutions of the present invention, and not restrictive, and those skilled in the art may make changes, substitutions, modifications, and simplifications in the spirit of the present invention and equivalent changes without departing from the spirit of the present invention, and shall fall within the protection scope of the claims of the present invention.

Claims

1. A mechanical drive system, characterized by: comprises a base and a plurality of connecting rods, wherein,

the support frame is hinged with the base at a first hinge point;

the rocker is hinged with the base at a second hinge point;

The compliant driver is hinged with the base at a third hinge point;

the sliding part can slide relative to the supporting frame;

one end of the rocker, which is far away from the second hinge point, and one end of the compliant driver, which is far away from the third hinge point, are both hinged with the sliding piece;

the flexible driver comprises a supporting seat and a flexible mechanism, the supporting seat comprises a sleeve, a first baffle plate arranged at one end of the sleeve and a second baffle plate sleeved at the other end of the sleeve, and the distance between the second baffle plate and the first baffle plate is adjustable; the compliant mechanism comprises an interface board, a first spring group and a second spring group, wherein the first spring group and the second spring group are respectively arranged at two free ends of two sides of the interface board, the two free ends of the first spring group and the two free ends of the second spring group are respectively arranged at two sides of the interface board, the first spring group comprises a first inner spring and a first outer spring which are sleeved together, the second spring group comprises a second inner spring and a second outer spring which are sleeved together, and the free lengths of the first inner spring and the first outer spring are different; the free lengths of the second inner spring and the second outer spring are different, wherein the interface board is hinged with the base at a second hinge point;

the free length of the first outer spring is greater than that of the first inner spring, the free length of the second outer spring is greater than that of the second inner spring, the stiffness of the first outer spring is the same as that of the second outer spring, k1 is achieved, and the stiffness of the first inner spring is the same as that of the second inner spring, k2 is achieved;

When the pressure borne by the flexible driver is greater than the pulling force in work, the rigidity of the second outer spring is greater than that of the first outer spring, the rigidity of the second inner spring is greater than that of the first inner spring, and the free length difference between the first inner spring and the first outer spring of the first spring set is different from that between the second inner spring and the second outer spring of the second spring set.

2. The mechanical drive system of claim 1, wherein: the support frame is provided with a first guide piece, and the sliding piece is provided with a second guide piece in sliding fit with the first guide piece.

3. The mechanical drive system of claim 1, wherein: the other end of the rocker and the other end of the compliant driver are coaxially hinged with the sliding piece.

4. The mechanical drive system of claim 1, wherein: the flexible driver further comprises a driving mechanism and a linear actuating mechanism, the linear actuating mechanism comprises a ball screw and a nut and is used for converting the rotary motion of the driving mechanism into linear motion and connecting the linear motion with an external load, the supporting seat is fixedly connected with a second base, the nut is fixedly arranged on the second base, and part of the ball screw is arranged inside the sleeve.

5. The mechanical drive system of claim 1, wherein: the first inner spring and the first outer spring are concentrically arranged, and the second inner spring and the second outer spring are concentrically arranged.

6. The mechanical drive system of claim 4, wherein: the compliant driver further comprises a damping unit, the damping unit is arranged inside the sleeve, and one end, far away from the load, of the ball screw is connected with the damping unit.

7. The mechanical drive system of claim 1, wherein: the interface board includes a connector provided with an outer peripheral surface for connection with an external device.

8. The mechanical drive system of claim 1, wherein: the interface board comprises annular protruding structures arranged on two sides, and the outer diameters of the protruding structures are matched with the first outer spring and the second outer spring.