CN114029998B - A flexible underactuated manipulator for precision assembly of irregular parts - Google Patents

Abstract

The invention discloses a flexible underactuated manipulator for precise assembly of abnormal parts, comprising a power drive assembly, a drive guide assembly and a grasping mechanism assembly; wherein the power drive assembly includes a mounting base, a voice coil motor magnet, and a voice coil motor coil ; The drive guide assembly includes a flexible guide member, an annular casing, and a flexible decoupling hinge. The flexible guide member is composed of three parts: the output end of the guide member, the flexible beam, and the support end; the grasping mechanism assembly includes a floating end, three combined flexible straight Beam, three grasping mechanisms, base, combined flexible straight beam contains two kinds of flexible hinges: circular flexible hinge and three-degree-of-freedom flexible hinge, grasping mechanism contains finger end and four semi-circular flexible hinges. The flexible under-actuated manipulator of the present invention is driven by a single motor, and through the self-adaptive grabbing mechanism, the manipulator can adapt to the shape change and position deviation of the parts within a certain range, and can be used for grabbing abnormal parts at the same time.

Description

A flexible underactuated manipulator for precision assembly of irregular parts

technical field

The invention relates to the technical field of precision assembly, and more particularly, to a flexible underactuated manipulator for precision assembly of abnormal parts.

Background technique

With the rapid development of science and technology, the automation level of precision manufacturing is getting higher and higher, which is mainly reflected in automatic grasping, assembly automation, improving productivity and reducing production costs. The assembly of tiny components has always been one of the important links in precision manufacturing, and the quality of its assembly operations has a crucial impact on the performance of the final product. Precision micro-assembly is a kind of micro-operation that requires very high precision in the assembly of tiny components. Due to the low efficiency of manual assembly operations, the precision is difficult to guarantee. At the same time, the relative backwardness of automated precision assembly also restricts the production efficiency and performance of tiny components. In the precision assembly process, the versatility and adaptability of grasping tiny parts is very important, so the design of the micromanipulator is the premise of the successful precision assembly.

Although the research on micromanipulators has made great progress, it is still far from meeting the requirements in terms of grasping range, compact structure, and task requirements for grasping abnormal parts. The existing micromanipulator has a complex structure, a small grasping range, and cannot stably grasp abnormal parts. At present, one of the difficulties of the micromanipulator is the driving problem. Although the manipulator can be made very small, the size of the driving device cannot be adapted to the structure; on the other hand, in terms of structural characteristics, the traditional manipulator is generally connected by rigid kinematic pairs, although its grasping range is large However, due to the gap and friction between the motion pairs, it is easy to cause poor motion precision and cannot be used for precision grasping. On the contrary, the connection between the components of the micromanipulator is through flexible hinges, which can be processed in one piece or assembled less. This structure has the characteristics of high precision, high stability, no gap and no friction, and the size is easy to control. In addition, when the flexible hinge moves with limited displacement in a specific direction, it can store a certain elastic potential energy. When the driving force and external force are eliminated, the mechanism can rely on the elastic force of the hinge to restore the original state. The Chinese patent "Miniaturized Flexible Micro-Clamp Based on Piezoelectric Ceramic Drive (Patent No.: CN201310231678.6)" adopts piezoelectric ceramics to drive the grasping mechanism composed of flexible hinges. The movements of the two fingers of this kind of micromanipulator are synchronized Movement, that is, the movement direction is always opposite and the displacement is the same, so they do not have adaptive grasping characteristics, and cannot adapt to the shape and position deviation of the part, resulting in this type of manipulator can only grasp "floating" tiny parts, unable to grasp "fixed" parts. ” parts, and most of the precision-assembled parts are placed on a special fixture, which ensures that the initial position and posture of the parts remain unchanged. Therefore, the existing micromanipulators cannot be used for precision assembly at present.

In view of the limited flexibility and adaptability of the existing micromanipulators due to their own structural characteristics, it is difficult to handle microscopic parts with different shapes, sizes and materials. Therefore, designing a flexible underactuated manipulator with self-adaptation and a large grasping range can not only realize the grasping of abnormally small parts, automatically eliminate the position error of the parts, but also automatically adapt to the shape and size of the parts, and The change of material properties is of great significance to promote the development of precision assembly.

SUMMARY OF THE INVENTION

In view of this, the present invention proposes a flexible underactuated manipulator for precision assembly of abnormal parts, mainly in order to deal with the problems of complex structure, poor adaptability and single grasping object of the existing micromanipulator manipulator, and its specific technical scheme is as follows:

A flexible underactuated manipulator for precision assembly of irregular parts, comprising a power drive assembly, a drive guide assembly, and a grasping mechanism assembly;

The power drive assembly includes a mounting base and a voice coil motor, the voice coil motor includes a voice coil motor magnet and a voice coil motor coil, and the voice coil motor magnet is mounted on the mounting base;

The drive guide assembly includes a flexible guide member, an annular casing, and a flexible decoupling hinge, and the mounting base and the annular casing are connected by screws; the flexible guide member is supported by an output end of the guide member, a flexible beam, and a support. The flexible beam is composed of three groups, and the flexible beams are 120° symmetrical and distributed horizontally on the outer circumference of the output end of the guide member; the support end is located at the end of the flexible beam away from the output end of the guide member; The voice coil motor coil, the output end of the guide member, and the end of the flexible decoupling hinge close to the output end of the guide member are fixed together by screws; the three support ends are connected to the The annular housing is connected; the flexible decoupling hinge has at least two rotational degrees of freedom;

The grasping mechanism assembly includes a floating end, three combined flexible straight beams, three grasping mechanisms, and a base, and one end of the flexible decoupling hinge away from the output end of the guide member is connected to the floating end; three The combined flexible straight beam is symmetrically installed on the floating end at 120° and forms a floating platform; the combined flexible straight beam and the grabbing mechanism are connected by screws, and the three grabbing mechanisms are the same Installed on the base in a 120° symmetry; the combined flexible straight beam includes two flexible hinges: a circular flexible hinge and a three-degree-of-freedom flexible hinge; the gripping mechanism includes finger ends and four semicircular Flexible hinge, four semi-circular flexible hinges form a flexible parallel four-bar mechanism, so that the finger end can move in translation; both the circular flexible hinge and the semi-circular flexible hinge are single-degree-of-freedom rotating hinges .

By adopting the above technical solutions, the present invention proposes a flexible underactuated manipulator for precision assembly of abnormal parts, which is driven by a voice coil motor and is a new type of adaptive flexible grasping mechanism coordinated by a variety of flexible hinges. The flexible parallel four-bar grasping mechanism composed of four semi-circular flexible hinges can realize the translation of three fingers, and the two-degree-of-freedom floating platform in the middle can ensure that the manipulator can automatically adapt to the shape change and position deviation of the parts within a certain range , and can be used for grabbing abnormal parts.

Preferably, each group of the flexible beams is composed of two identical parallel beams.

Preferably, the finger end is designed as an arc structure.

Preferably, the grasping mechanism further includes a strain-type displacement sensor for detecting the displacement of the finger end and a strain-type force sensor for detecting the grasping force of the finger end.

The flexible under-actuated manipulator of the present invention is driven by a single motor, and through the self-adaptive grabbing mechanism, the manipulator can adapt to the shape change and position deviation of the parts within a certain range, and can be used for grabbing abnormal parts at the same time. Compared with the existing micro-manipulation manipulator, the manipulator of the invention has the advantages of simple structure, strong self-adaptation, high grasping precision and low cost, can be mass-produced, and is widely used in the precise assembly of tiny parts.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to the provided drawings without creative work.

Figure 1 is an assembly diagram of a flexible underactuated manipulator.

Figure 2 is an exploded view of the assembly of the flexible underactuated manipulator.

FIG. 3 is a schematic structural diagram of a flexible guide member.

FIG. 4 is a schematic structural diagram of a grasping mechanism assembly.

Figure 5 shows the first configuration of the flexible decoupling hinge—a three-degree-of-freedom rotating hinge.

Figure 6 shows the second configuration of the flexible decoupling hinge - a compact two-degree-of-freedom rotating hinge.

Figure 7 shows the configuration three of the flexible decoupling hinge—a large-scale two-degree-of-freedom rotating hinge.

FIG. 8 is a schematic structural diagram of a combined flexible straight beam and a grabbing mechanism.

Fig. 9 is a schematic diagram of a manipulator grabbing a fixed symmetrical part when there is a lateral deviation.

Fig. 10 is a schematic diagram of a manipulator grabbing a fixed symmetrical part when there is an inclination deviation.

Fig. 11 is a schematic diagram of a manipulator grabbing an abnormally-shaped fixed part.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example:

As shown in FIG. 1 , the present invention is a flexible underactuated manipulator for precision assembly of irregular parts, including a power drive assembly 1 , a drive guide assembly 2 , and a grasping mechanism assembly 3 .

As shown in FIG. 2 , the power drive assembly 1 includes a mounting base 101 and a voice coil motor, the voice coil motor provides power for the manipulator, and the mounting base 101 protects and fixes the voice coil motor. The voice coil motor includes a voice coil motor magnet 102 and a voice coil motor coil 103 , wherein the voice coil motor magnet 102 is mounted on the mounting base 101 .

The drive guide assembly 2 includes a flexible guide member 21 , an annular housing 22 and a flexible decoupling hinge 23 , and the drive guide assembly 2 is used to linearly guide the voice coil motor coil 103 . The mounting base 101 and the annular housing 22 are connected by screws.

As shown in FIG. 3 , the flexible guide member 21 is composed of three parts: the output end 2101 of the guide member, the flexible beam 2102 and the support end 2103. The flexible beams 2102 are arranged in three groups, which are symmetrical at 120° and distributed horizontally at the output end 2101 of the guide member. The outer periphery of each group of flexible beams 2102 is composed of two identical parallel beams, and this structure has a good linear motion. The support end 2103 is located at the end of the flexible beam 2102 away from the output end 2101 of the guide member. The voice coil motor coil 103 , the output end 2101 of the guide member, and the end of the flexible decoupling hinge 23 close to the output end 2101 of the guide member are fastened together by screws. The three support ends 2103 in the flexible guide member 21 are connected with the annular housing 22 by screws.

As shown in FIG. 4 , the grasping mechanism assembly 3 mainly includes a floating end 31 , three combined flexible straight beams 32 , three grasping mechanisms 33 , and a base 34 . The flexible decoupling hinge 23 is away from the output end 2101 of the guide member. One end is connected to the floating end 31 . Among them, three combined flexible straight beams 32 are installed on the floating end 31 symmetrically at 120°, and form a floating platform. The combined flexible straight beam 32 and the grabbing mechanism 33 are connected by screws, and the three grabbing mechanisms 33 are also installed on the base 34 symmetrically at 120°. The gripping mechanism 33 includes finger tips 3301 thereon.

During the grabbing process, when the movement displacement or applied grabbing force of the finger ends 3301 of the three grabbing mechanisms 33 are different, the motion or force can be transmitted to the floating end 31 through the inclination of the three combined flexible straight beams 32, Therefore, the floating end 31 has two rotational degrees of freedom θ _x and θ _y along the x-axis and the y-axis in addition to the linear degree of freedom d _z provided by the voice coil motor. Since the flexible decoupling hinge 23 connects the guide member output end 2101 and the floating end 31, the guide member output end 2101 has one linear degree of freedom dz, and the floating end 31 has three degrees of freedom d _z , θ _x and θ _y , therefore, in order to To avoid motion interference between the two, the flexible decoupling hinge 23 should have at least two rotational degrees of freedom θ _x and θ _y . Figures 5-7 show three configurations of decoupling hinges. Figure 5 is a three-degree-of-freedom rotating hinge, and Figures 6 and 7 are two-degree-of-freedom rotating hinges. From the perspective of structural dimensions, Figure 6 is relatively compact, which All three hinges meet the required decoupling function.

As shown in FIG. 8 , the combined flexible straight beam 32 includes two types of flexible hinges: a circular flexible hinge 3201 and a three-degree-of-freedom flexible hinge 3202 . The grasping mechanism 33 includes four semicircular flexible hinges 3303 to form a flexible parallel four-bar mechanism, thereby ensuring the translational movement of the finger end 3301 thereof, making grasping more stable. Both the circular flexible hinge 3201 and the semicircular flexible hinge 3303 are single-degree-of-freedom rotating hinges.

Further, in this embodiment, the finger end 3301 is designed as an arc structure, mainly to increase the contact area between the manipulator and the grasped object.

At the same time, because the strain gauge has the advantages of small size, high sensitivity and low cost, the displacement of each finger end 3301 in the present invention is detected by the strain type displacement sensor 3304; similarly, the grasping force of each finger end 3301 adopts the strain type force Sensor 3302 detects.

The parallel four-bar mechanism in the grabbing mechanism 33 of the present invention adopts the semi-circular flexible hinge 3303 instead of the circular flexible hinge 3201, mainly because the former has a larger deformation than the latter, and a larger finger can be obtained under the premise of the same material End 3301 range of motion.

The grasping mechanism assembly 3 in the present invention has the characteristics of simple structure, compactness and strong adaptability, and is an important part of the flexible underactuated manipulator. Three combined flexible straight beams 32 and a floating end 31 form a two-degree-of-freedom floating platform, which ensures the self-adaptive function of the manipulator.

The manipulator of the present invention can automatically adapt to the positional deviation. Taking the grasping of symmetrical parts as an example, when there is only a lateral error, as shown in FIG. 9 , only two fingers are shown in the figure for the sake of clarity. 41 is the center line of the manipulator, 42 is the center line of the symmetrical part, and the deviation between the two is Δ. The symmetrical part 51 is fixed in the fixture 52. Before each finger touches the part, the three combined flexible straight beams 32 have the same inclination angle, and the three fingers move synchronously; The left finger continues to move under the drive of the voice coil motor until the end 3301 of the finger touches the part and stops moving. At this time, the inclination angles of the three combined flexible straight beams 32 are different, and the floating end 31 is deflected. . Therefore, the flexible underactuated manipulator proposed by the present invention can automatically adapt to the lateral error between the manipulator and the part. Similarly, as shown in Figure 10, when the manipulator grabs a symmetrical part, there is an inclination deviation, and the three fingers touch the object in sequence according to the positional relationship with the part, and finally achieve a stable grabbing of the three fingers.

When the manipulator grabs the abnormally-shaped fixed part, the positional relationship of each finger relative to the part is shown in Figure 11, O ₁ and O ₂ are the center position of the manipulator and the center position of the abnormal-shaped part, respectively. The adaptive characteristics, the coordinated movement of the three fingers, according to the difference of the shape of the parts, the relative position of the end of each finger finally satisfies d ₃ >d ₂ >d ₁ .

Therefore, the underactuated flexible manipulator designed in the present invention grabs fixed parts, and the manipulator can automatically adapt to a certain range of positional deviation (lateral deviation and inclination deviation), and can also be used for grabbing irregular parts.

The above description of the disclosed embodiments enables any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (4)

1. A flexible underactuated manipulator for precision assembly of abnormal parts, characterized in that it comprises a power drive assembly (1), a drive guide assembly (2), and a grasping mechanism assembly (3); The power drive assembly (1) includes a mounting base (101) and a voice coil motor, the voice coil motor includes a voice coil motor magnet (102) and a voice coil motor coil (103), and the voice coil motor magnet (102) is installed on the mounting base (101); The drive guide assembly (2) includes a flexible guide member (21), an annular housing (22), and a flexible decoupling hinge (23), and the mounting base (101) and the annular housing (22) pass through screw connection; the flexible guide member (21) is composed of three parts: the output end of the guide member (2101), the flexible beam (2102), and the support end (2103). ° symmetrical and horizontally distributed on the outer circumference of the output end of the guide member (2101); the support end (2103) is located at the end of the flexible beam (2102) away from the output end of the guide member (2101); the sound The motor coil (103), the output end of the guide member (2101) and the end of the flexible decoupling hinge (23) close to the output end of the guide member (2101) are fixed together by screws; three Each of the supporting ends (2103) is connected with the annular housing (22) by screws; the flexible decoupling hinge (23) has at least two rotational degrees of freedom; The grasping mechanism assembly (3) includes a floating end (31), three combined flexible straight beams (32), three grasping mechanisms (33), and a base (34), and the flexible decoupling hinge (23) ), the end away from the output end (2101) of the guide member is connected to the floating end (31); the three combined flexible straight beams (32) are mounted on the floating end (31) symmetrically at 120°, and form a floating platform; the combined flexible straight beam (32) and the grabbing mechanism (33) are connected by screws, and the three grabbing mechanisms (33) are also installed on the base in a 120° symmetry. (34); the combined flexible straight beam (32) includes two flexible hinges: a circular flexible hinge (3201) and a three-degree-of-freedom flexible hinge (3202); the grasping mechanism (33) includes a finger end ( 3301) and four semicircular flexible hinges (3303), the four semicircular flexible hinges (3303) constitute a flexible parallel four-bar mechanism, enabling the finger end (3301) to move in translation; the circular Both the flexible hinge (3201) and the semicircular flexible hinge (3303) are single-degree-of-freedom rotational hinges. 2 . The flexible underactuated manipulator for precision assembly of special-shaped parts according to claim 1 , wherein each group of the flexible beams ( 2102 ) is composed of two identical parallel beams. 3 . 3 . The flexible underactuated manipulator for precision assembly of irregular parts according to claim 1 , wherein the finger end ( 3301 ) is designed as an arc structure. 4 . 4. A flexible underactuated manipulator for precision assembly of irregular parts according to claim 1, wherein the grasping mechanism (33) further comprises a strain for detecting the displacement of the finger end (3301) A type displacement sensor (3304) and a strain type force sensor (3302) for detecting the grasping force of the finger end (3301).

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