CN103909526B - The two degrees of freedom parallel manipulator wrist that a kind of motor pattern is variable - Google Patents

Abstract

The invention discloses a two-degree-of-freedom parallel mechanical wrist with variable motion mode, which can realize the mode conversion between the two-degree-of-freedom rotation with the property of spherical pure rolling and the two-degree-of-freedom movement with the property of spherical translation; it includes a fixed base , motion platform and motion branch chain. The structure of the fixed base is the same as that of the motion platform, and the motion chain includes three different types of motion chains; the fixed base and the motion platform have two forms of space structure and planar structure; different types of motion chains and fixed bases, motion The platform can be composed of six parallel mechanisms that can convert two-dimensional rotation and two-dimensional movement modes, a two-degree-of-freedom parallel rotation mechanism with spherical pure rolling properties, and two two-degree-of-freedom parallel movement mechanisms with spherical translation properties. The invention has the advantages of variable motion mode, parallel mechanical wrists can be switched between two-dimensional rotation and two-dimensional translation under the same configuration, the mechanism has high rigidity, strong bearing capacity, and large space for moving the moving platform.

Description

A two-degree-of-freedom parallel mechanical wrist with variable motion modes

technical field

The invention relates to a two-degree-of-freedom parallel mechanical wrist with variable motion modes, which belongs to the field of robots and machinery manufacturing.

Background technique

Due to its high stiffness, fast response and high motion precision, the parallel mechanism is widely used in the fields of aircraft heavy-duty simulation equipment, robots, CNC machine tools, sensors and micro-operations. Among the applications of parallel mechanisms, parallel mechanisms with few degrees of freedom are the most widely used, especially in the fields of robot joints, space pointing and docking, load simulation, minimally invasive medical surgery, and human-computer interaction. For example: Clément Gosselin invented a spherical five-bar two-degree-of-freedom parallel pointing device, the publication number of which is US5966991, which can be used as a spherical cutter head for machine tools; Force feedback for abdominal surgery simulation environment; Publication No. US5893296 and Publication No. WO99/21070 disclose a four-branched two-degree-of-freedom parallel rotation mechanism, which has been successfully used in devices such as landscape fountains.

At present, although some achievements have been made in the research work of two-degree-of-freedom parallel mechanisms at home and abroad, there are still the following deficiencies: 1) The current two-degree-of-freedom parallel mechanisms can only realize a single motion mode, that is, the same parallel mechanism can only perform two-degree-of-freedom Two-degree-of-freedom rotation or two-degree-of-freedom movement, and it is impossible to switch motion modes between two-degree-of-freedom rotation and movement; 2) It is difficult to realize the virtual center of rotation in the current two-degree-of-freedom parallel rotation mechanism.

Contents of the invention

The purpose of the present invention is to propose a two-degree-of-freedom parallel mechanical wrist with variable motion mode, which can realize two-degree-of-freedom rotation or two-degree-of-freedom movement, and switch between the two modes when certain conditions are met.

A two-degree-of-freedom parallel mechanical wrist with variable motion modes is characterized in that it includes a fixed base, a motion platform and three motion branch chains.

The fixed base is composed of three fixed shafts, the axes of the three fixed shafts intersect at a point N, and the angles between the axes of adjacent fixed shafts are equal; The branches are connected to form a revolving pair.

The motion platform is composed of three moving shafts, the axes of the three moving shafts intersect at a point M, and the included angles between the axes of adjacent moving shafts are equal; connected to form a revolving pair.

Among them, the fixed base and the moving platform are located at the upper and lower positions respectively, and are connected by three moving branch chains uniformly distributed in the axial direction.

In the fixed base and the moving platform, the angles between the three fixed axes and the three moving axes and the line segment MN are all θ, and when 0<θ<90°, the three fixed axes are all inclined downward; The moving axes are all inclined upward; at this time, the fixed base and the moving platform are both spatial structures; when θ=90°, the three fixed axes are on the same plane; the three moving axes are on the same plane; at this time, Both the fixed base and the moving platform are planar structures.

The kinematic branch chain includes an upper link, a middle link and a lower link; wherein, the upper link and the lower link are both arc-shaped bars, and both ends are provided with rotating pair connection holes that run through the inner and outer sides of the bar. And the axis of the connecting hole of the rotating pair on the upper link and the lower link intersects and is perpendicular to the axes of the upper link and the lower link respectively; the outer sides of the two ends of the middle link are designed with a connecting shaft, and the axis of the connecting shaft is perpendicular to the middle link and parallel to each other; the connecting hole of the rotating pair at one end of the lower connecting rod and the connecting shaft at the other end of the middle connecting rod form a rotating pair; The connecting hole of the rotating pair at the other end of the connecting rod is connected with the connecting shaft at the other end of the middle connecting rod to form a rotating pair; the connecting hole of the rotating pair at one end of the upper connecting rod is connected with the connecting end of the moving shaft of the motion platform to form a rotating pair; The auxiliary connecting hole is connected with the connecting shaft at one end of the middle connecting rod to form a rotating pair.

The kinematic branches of the above structure can have three configurations, specifically:

Configuration A: the upper link and the lower link are located on the same side of the middle link;

Configuration B: The upper link is located on the left side of the middle link, and the lower link is located on the right side of the middle link;

Configuration C: The upper link is on the right side of the middle link, and the lower link is on the left side of the middle link.

The above-mentioned fixed base and the motion platform adopt a spatial structure or a planar structure at the same time, are located in the upper and lower positions respectively, and are connected by the above-mentioned three configurations of motion branch chains; and must meet:

a. The rotation axis of the rotary joint between the lower link and the fixed base is perpendicular to the rotation axis of the rotary joint between the lower link and the middle link at point B;

b. The rotational axis of the rotary joint between the upper link and the motion platform is perpendicular to the rotational axis of the rotary joint between the upper link and the middle link at point A;

c. The rotational axis of the rotary joint between the upper link and the middle link is parallel to the rotational axis of the rotary joint between the lower link and the middle link;

d. After the three motion branch chains are connected to the fixed base and the motion platform, point B coincides with the center point of the fixed base, and point A coincides with the center point of the motion platform.

The advantages of the present invention are:

1. The two-degree-of-freedom parallel mechanical wrist with variable motion mode of the present invention can realize two motion modes of two-degree-of-freedom rotation and two-degree-of-freedom translation at the same time, and can realize flexible switching of motion modes in some configurations;

2. The two-degree-of-freedom parallel mechanical wrist with variable motion mode of the present invention uses the same branch chain and adopts different installation forms to produce different mechanism configurations to meet different needs;

3. The two-degree-of-freedom parallel mechanical wrist with variable motion mode of the present invention can realize the two-degree-of-freedom spherical pure rolling of the motion platform around a point on the fixed base in the two-degree-of-freedom rotation mode;

4. The two-degree-of-freedom parallel mechanical wrist with variable motion mode of the present invention can realize the two-degree-of-freedom spherical translation of the motion platform around a point on the fixed base in the two-degree-of-freedom movement mode;

5. The two-degree-of-freedom parallel mechanical wrist with variable motion mode of the present invention uses three motion branch chains, and the motion platform has a large motion space;

6. The two-degree-of-freedom parallel mechanical wrist with variable motion mode of the present invention only contains rotating pairs, and has a simple structure and is easy to manufacture;

7. The space between the motion platform and the fixed base of the two-degree-of-freedom parallel mechanical wrist with variable motion modes of the present invention can be installed with cables or sensors.

Description of drawings

Fig. 1 is a schematic diagram of the spatial structure of the fixed base in the two-degree-of-freedom parallel mechanical wrist of the present invention;

Fig. 2 is a schematic diagram of the spatial structure of the fixed base in the two-degree-of-freedom parallel mechanical wrist of the present invention;

3 is a schematic plan view of the fixed base in the two-degree-of-freedom parallel mechanical wrist of the present invention;

4 is a schematic plan view of the motion platform in the two-degree-of-freedom parallel mechanical wrist of the present invention;

Fig. 5 is a schematic structural diagram of the kinematic branch chain of configuration A in the two-degree-of-freedom parallel mechanical wrist of the present invention;

Fig. 6 is a schematic structural view of the configuration B kinematic branch chain in the two-degree-of-freedom parallel mechanical wrist of the present invention;

Fig. 7 is a schematic structural diagram of the kinematic branch chain of configuration C in the two-degree-of-freedom parallel mechanical wrist of the present invention;

Fig. 8 is a schematic structural diagram of Embodiment 1 of a two-degree-of-freedom parallel mechanical wrist with variable motion modes of the present invention;

Fig. 9 is a schematic structural diagram of Embodiment 2 of a two-degree-of-freedom parallel mechanical wrist with variable motion modes of the present invention;

Fig. 10 is a schematic structural diagram of Embodiment 3 of a two-degree-of-freedom parallel mechanical wrist with variable motion modes of the present invention;

Fig. 11 is a schematic structural diagram of Embodiment 4 of a two-degree-of-freedom parallel mechanical wrist with variable motion modes of the present invention;

Fig. 12 is a schematic structural diagram of Embodiment 5 of a two-degree-of-freedom parallel mechanical wrist with variable motion modes according to the present invention;

Fig. 13 is a schematic structural diagram of Embodiment 6 of a two-degree-of-freedom parallel mechanical wrist with variable motion modes of the present invention;

Fig. 14 is a schematic structural diagram of Embodiment 7 of a two-degree-of-freedom parallel mechanical wrist with variable motion modes of the present invention;

Fig. 15 is a schematic structural diagram of Embodiment 8 of a two-degree-of-freedom parallel mechanical wrist with variable motion modes in the present invention;

Fig. 16 is a schematic structural diagram of Embodiment 9 of a two-degree-of-freedom parallel mechanical wrist with variable motion modes according to the present invention.

In the picture:

1-fixed base 2-moving platform 3-moving branch chain

101-fixed shaft 201-moving shaft 301-upper link

302-middle link 303-lower link

detailed description

The present invention will be further described in detail with reference to the accompanying drawings and embodiments.

A two-degree-of-freedom parallel mechanical wrist with variable motion modes in the present invention includes a fixed base, a motion platform, and three motion branch chains; wherein, the fixed base and the motion platform are located at the upper and lower positions respectively, and are passed through three motion chains uniformly distributed in the circumferential direction. chain connected.

As shown in FIG. 1 , the fixed base 1 is a whole composed of three fixed shafts 101 , the axes of the three fixed shafts 101 intersect at a point N, and the included angles between the axes of adjacent fixed shafts 101 are equal. The other ends of the three fixed shafts 101 are rotating ends, which are respectively connected with the three kinematic branch chains 3 to form a rotating pair.

As shown in Figure 2, the moving platform 2 is the same as the fixed base 1, and is a whole composed of three moving shafts 201, the axes of the three moving shafts 201 intersect at a point M, and the distance between the axes of adjacent moving shafts 201 The included angles are equal. The other ends of the three moving shafts 201 are rotating ends, which are respectively connected with three moving branch chains 3 to form a rotating pair.

In the fixed base 1 and the moving platform 2, the angles between the three fixed axes 101 and the three moving axes 201 and the line segment MN are all θ, and when 0<θ<90°, the three fixed axes 101 all face It is inclined downward, as shown in Figure 1; the three moving shafts 201 are all inclined upward, as shown in Figure 2; at this time, both the fixed base 1 and the moving platform 2 are spatial structures. When θ=90°, the three fixed axes 101 are on the same plane, as shown in Figure 3; the three moving axes 201 are on the same plane, as shown in Figure 4; at this time, the fixed base 1 and the moving platform 2 All are planar structures.

The kinematic branch chain 3 includes an upper link 301 , a middle link 302 and a lower link 303 , as shown in FIG. 5 . Wherein, the upper connecting rod 301 and the lower connecting rod 303 are both arc rods, and both ends are provided with rotating pair connecting holes that run through the inner and outer sides of the rod, and the rotating pair connecting holes on the upper connecting rod 301 and the lower connecting rod 303 The axes intersect and are perpendicular to the axes of the upper link 301 and the lower link 303 respectively. The two ends of the middle connecting rod 302 are designed with connecting shafts, the axes of which are perpendicular to the middle connecting rod 302 and parallel to each other. The connecting hole at one end of the lower link 303 and the connecting shaft at the other end of the middle link 302 form a rotary pair. The connecting hole of one end of the lower connecting rod 303 is connected with the rotating pair of the fixed shaft 101 in the fixed base 1 to form a rotating pair; the connecting hole of the other end of the lower connecting rod 303 is connected with the connecting shaft at the other end of the middle connecting rod 302 to form a revolving pair. The connecting hole of the rotating pair at one end of the upper connecting rod 301 is connected with the connecting end of the moving shaft 201 of the motion platform 2 to form a rotating pair; the rotating pair connecting hole at the other end of the upper connecting rod 301 is connected with the connecting shaft at one end of the middle connecting rod 302 to form a rotating pair;

The motion branch chain 3 of the above-mentioned structure can have three configurations, specifically:

Configuration A: the upper link 301 and the lower link 303 are located on the same side of the middle link 302, as shown in Figure 5;

Configuration B: the upper link 301 is located on the left side of the middle link, and the lower link 303 is located on the right side of the middle link 302, as shown in Figure 6;

Configuration C: The upper link 301 is located on the right side of the middle link, and the lower link 303 is located on the left side of the middle link 302, as shown in FIG. 7 .

When the fixed base 1 and the motion platform 2 in the two-degree-of-freedom parallel mechanical wrist with variable motion mode of the present invention adopt a spatial structure and are set in reverse, if the three motion branch chains all adopt the configuration A of the above three configurations, At this time, the motion of the motion platform 2 is a two-degree-of-freedom rotation around the center point of the fixed base 1 (rotation mode), which can keep the motion platform 2 level and the fixed point on it moves on a spherical surface. If the three motion branch chains adopt configuration B or configuration C in the above three configurations, the movement of the motion platform 2 is a two-degree-of-freedom translation (translation mode) around the center point of the fixed base 1, and the movement can be realized The two-degree-of-freedom rotation of the platform around the fixed point on the fixed base is similar to the pure rolling of two equal-diameter spherical surfaces.

When the fixed base 1 and the motion platform 2 in the two-degree-of-freedom parallel mechanical wrist with variable motion modes of the present invention adopt a planar structure, the two-degree-freedom parallel mechanical wrist can be realized by using the following motion branch chain 3 for connection. The conversion between translation mode and rotation mode, specifically:

Ⅰ. The three kinematic branch chains 3 all adopt configuration A, and the upper link 301 and the lower link 303 are installed in the same direction (that is, the upper link 301 and the lower link 303 in the three kinematic branch chains 3 of configuration A are all installed in the same direction. located on the same side of the middle link 302);

II. All three motion branch chains 3 adopt configuration A, wherein, the upper link 301 and the lower link 303 in the two motion branch chains 3 are installed in the same direction, and the upper link 301 and the lower link 303 in the other motion branch chain 3 are installed in the same direction. The connecting rods 303 are installed in reverse (that is, the upper connecting rod 301 and the lower connecting rod 303 in the two configuration A kinematic branch chains 3 are located on the same side of the middle connecting rod 302, and the other configuration A kinematic branch chain 3 Both the upper link 301 and the lower link 303 are located on the other side of the middle link 302);

Ⅲ. All three kinematic branch chains adopt configuration B;

Ⅳ. All three kinematic branch chains adopt configuration C;

Ⅴ. Two of the three kinematic branch chains 3 adopt configuration B, and one adopts configuration C;

VI. One of the three kinematic branch chains 3 adopts configuration B, and two adopts configuration C.

In the two-degree-of-freedom parallel mechanical wrist with the above structure, the planes where the upper links 301 of the three kinematic branch chains 3 are located are respectively perpendicular to the planes where the axes of the two connecting shafts of the middle link 302 of the three kinematic branch chains 3 are located; and the three kinematic branch chains When the plane where the lower connecting rod 303 of 3 is located is perpendicular to the plane where the two connecting shaft axes of the middle connecting rod 302 of the three motion branch chains are located, the position of the motion platform 2 is the origin. When the plane of the upper link 301 and the plane of the lower link 303 in the three motion branch chains 3 are always parallel, the motion of the motion platform 2 is a two-degree-of-freedom translation around the center point of the fixed base 1 . When the angle between the plane where the upper link 301 is located and the plane where the axes of the two connecting shafts of the middle link 302 are located in the three motion branch chains 3, and the plane where the lower link 303 is located and the plane where the axes of the two connecting shafts of the middle link 302 are located When the included angles are complementary, the movement of the moving platform 2 is a two-degree-of-freedom rotation around the center point on the fixed base 1. The conversion position of the two-degree-of-freedom parallel mechanical wrist between the translation mode and the rotation mode is that the motion platform 2 is at the origin.

When the two-degree-of-freedom parallel mechanical wrist with variable motion mode of the present invention is connected through the motion branch chains of the above three configurations, it must meet the following requirements:

a. The rotation axis of the rotation pair between the lower link 303 and the fixed base 1 is perpendicular to the rotation axis of the rotation pair between the lower link 303 and the middle link 302 at point B;

b. The rotation axis of the rotary pair between the upper link 301 and the motion platform 2 is perpendicular to the point A;

c. The rotation axis of the rotation pair between the upper link 301 and the middle link 302 is parallel to the rotation axis of the rotation pair between the lower link 303 and the middle link 302;

d. After the three motion branch chains are connected to the fixed base 1 and the motion platform 2, point B coincides with the center point of the fixed base 1, and point A coincides with the center point of the motion platform 2;

Example:

Each of the two-degree-of-freedom parallel manipulators with variable motion modes in each of the following embodiments can adopt a fixed base 1 and a moving platform 2 with a spatial structure, or a fixed base 1 and a moving platform 2 with a planar structure. Each motion branch chain 3 of the fixed base 1 and the motion platform 2 can adopt configuration A, configuration B or configuration C; thus, the present invention has the following nine typical implementation structures, specifically:

Implementation structure 1:

As shown in Figure 8, the two-degree-of-freedom parallel mechanical wrist includes a fixed base 1, a motion platform 2, and three configuration A motion branch chains 3. Both the fixed base 1 and the moving platform 2 are spatial structures, and they are arranged in reverse. Each fixed axis 101 of the fixed base 1 is connected with each moving axis 201 of the motion platform 2 through a configuration A motion branch chain 3 . At this time, the motion platform 1 can realize two-degree-of-freedom translational motion on the spherical surface.

Implement Structure 2:

As shown in FIG. 9 , the two-degree-of-freedom parallel mechanical wrist includes a fixed base 1 , a motion platform 2 and three configuration B motion branch chains 3 . Both the fixed base 1 and the moving platform 2 are spatial structures, and they are arranged in reverse. Each fixed axis 101 of the fixed base 1 is connected with each moving axis 201 of the motion platform 2 through a configuration B motion branch chain 3 . At this time, the motion platform 2 can realize two-degree-of-freedom translational motion on the spherical surface.

Implementation Structure 3:

As shown in Figure 10, the two-degree-of-freedom parallel mechanical wrist includes a fixed base 1, a motion platform 2, and three configuration C motion branch chains 3. Both the fixed base 1 and the moving platform 2 are spatial structures, and they are arranged in reverse. Each fixed shaft 101 of the fixed base 1 is connected with each moving shaft 201 of the motion platform 2 through a configuration C motion branch chain 3 . At this time, the motion platform 2 can realize two-degree-of-freedom translational motion on the spherical surface.

Implement structure 4:

As shown in Figure 11, the two-degree-of-freedom parallel mechanical wrist includes a fixed base 1, a motion platform 2, and three configuration A motion branch chains 3. Both the fixed base 1 and the moving platform 2 are planar structures, and are symmetrically arranged parallel to each other. Each fixed shaft 101 of the fixed base 1 is connected to each moving shaft 201 of the motion platform 2 through a motion branch chain 3 of configuration A, and the upper link 301 in the three configuration A motion branch chains 3 is connected to the The lower connecting rods 303 are all arranged in the same direction. When the motion platform 2 is at the origin and drives the two-degree-of-freedom parallel mechanical wrist to move, if the plane where the upper link 301 is located is always parallel to the plane where the lower link 303 is located, then the motion platform 2 can realize two-dimensional spherical translation at this time movement; if the angle between the plane where the upper link 301 is located and the plane where the two axes of the middle link 302 is located is complementary to the angle between the plane where the lower link 303 is located and the plane where the two axes of the middle link 302 are located, then this The time motion platform 2 can realize two-dimensional rotation, and the motion characteristic is spherical pure rolling. The two-degree-of-freedom parallel mechanical wrist with variable motion mode performs mode transformation at the origin.

Implementation Structure 5:

As shown in Figure 12, the two-degree-of-freedom parallel mechanical wrist includes a fixed base 1, a motion platform 2, and three configuration A motion branch chains 3. Both the fixed base 1 and the moving platform 2 are planar structures, and are symmetrically arranged parallel to each other. Each fixed shaft 101 of the fixed base 1 is connected to each moving shaft 201 of the motion platform 2 through a configuration A motion branch chain 3, and all three motion branch chains 3 adopt configuration A, and two of them move The upper connecting rod 301 and the lower connecting rod 303 in the branch chain 3 are installed in the same direction, and the upper connecting rod 301 and the lower connecting rod 303 in the other moving branch chain 3 are installed in the opposite direction. When the moving platform 2 is at the origin, two degrees of freedom are driven When the parallel mechanical wrist moves, if the plane where the upper link 301 is located is always parallel to the plane where the lower link 303 is located, then the motion platform 2 can realize two-dimensional spherical translation at this time; if the plane where the upper link 301 is located is parallel to The angle between the two axes of the middle connecting rod 302 is complementary to the angle between the plane of the lower connecting rod 303 and the plane of the two axes of the middle connecting rod 302. At this time, the motion platform 2 can realize two-dimensional rotation, and the kinematic characteristics It is pure rolling on a spherical surface. The two-degree-of-freedom parallel mechanical wrist with variable motion mode performs mode transformation at the origin.

Implementation Structure 8:

As shown in Figure 13, the two-degree-of-freedom parallel mechanical wrist includes a fixed base 1, a motion platform 2, and three configuration B motion branch chains 3. Both the fixed base 1 and the moving platform 2 are planar structures, arranged parallel to each other, and the fixed axis 101 of the fixed base 1 is interlaced with the axis of the moving shaft of the moving platform 2 . Each fixed shaft 101 of the fixed base 1 is respectively connected with each moving shaft 201 of the motion platform 2 through a configuration B motion branch chain 3 . When the motion platform 2 is at the origin and drives the two-degree-of-freedom parallel mechanical wrist to move, if the plane where the upper link 301 is located is always parallel to the plane where the lower link 303 is located, then the motion platform 2 can realize two-dimensional spherical translation at this time movement; if the angle between the plane where the upper link 301 is located and the plane where the two axes of the middle link 302 is located is complementary to the angle between the plane where the lower link 303 is located and the plane where the two axes of the middle link 302 are located, then this The time motion platform 2 can realize two-dimensional rotation, and the motion characteristic is spherical pure rolling. The two-degree-of-freedom parallel mechanical wrist with variable motion mode performs mode transformation at the origin.

Implementation Structure 9:

As shown in FIG. 14 , the two-degree-of-freedom parallel robot wrist includes a fixed base 1 , a motion platform 2 , two kinematic branch chains 3 of configuration B and one kinematic branch chain 3 of configuration C. Both the fixed base 1 and the moving platform 2 are planar structures, arranged parallel to each other, and the fixed axis 101 of the fixed base 1 is interlaced with the axis of the moving shaft of the moving platform 2 . The two fixed shafts 101 of the fixed base 1 and the two moving shafts 201 of the moving platform 2 are respectively connected by a configuration B motion branch chain 3; the other fixed shaft 101 of the fixed base 1 is connected with the other The moving shafts 201 are connected by a motion branch chain 3 of configuration C; when the motion platform 2 is at the origin and the two-degree-of-freedom parallel mechanical wrist is driven to move, if the plane where the upper link 301 is located and the plane where the lower link 303 is located If they are always parallel, the motion platform 2 can realize two-dimensional spherical translational motion at this time; The angles between the planes where the two axes of the connecting rod 302 are complementary, the motion platform 2 can realize two-dimensional rotation at this time, and the motion characteristic is spherical pure rolling. The two-degree-of-freedom parallel mechanical wrist with variable motion mode performs mode transformation at the origin.

Implementation Structure 6:

As shown in Figure 15, the two-degree-of-freedom parallel mechanical wrist includes a fixed base 1, a motion platform 2, and three configuration C motion branch chains 3. Both the fixed base 1 and the moving platform 2 are planar structures, arranged parallel to each other, and the fixed axis 101 of the fixed base 1 is interlaced with the moving axis of the moving platform 2 . Each fixed shaft 101 on the fixed base 1 is respectively connected with each moving shaft 201 of the motion platform 2 through a configuration C motion branch chain 3 . When the motion platform 2 is at the origin, if the plane where the upper link 401 is driven is always parallel to the plane where the lower link 403 is located, then the motion platform 2 can realize two-dimensional spherical translation at this time; if the drive makes the upper link 401 The angle between the plane where the plane is located and the two axes of the middle link 402 is complementary to the angle between the plane where the lower link 403 is located and the two axes of the middle link 402, then the motion platform 2 can realize Two-dimensional rotation, its motion characteristic is spherical pure rolling. The two-degree-of-freedom parallel mechanical wrist with variable motion mode performs mode transformation at the origin.

Implement structure 7:

As shown in FIG. 16 , it includes a fixed base 1 , a motion platform 2 , two configuration C motion branch chains 3 , and one configuration B motion branch chain 3 . Both the fixed base 1 and the moving platform 2 are planar structures, arranged parallel to each other, and the fixed axis 101 of the fixed base 1 is interlaced with the axis of the moving shaft of the moving platform 2 . The two fixed shafts 101 of the fixed base 1 and the two moving shafts 201 of the moving platform 2 are respectively connected by a configuration C motion branch chain 3; the other fixed shaft 101 of the fixed base 1 is connected with the other The moving shafts 201 are connected through a configuration B kinematic branch chain 3 . When the moving platform is at the origin, if it is driven so that the plane where the upper link 401 is located is always parallel to the plane where the lower link 403 is located, then the moving platform 2 can realize two-dimensional spherical translation at this time; The included angle between the plane of the lower link 403 and the two axes of the middle connecting rod 402 is complementary to the angle between the two axes of the lower connecting rod 403 and the two axes of the middle connecting rod 402. dimensional rotation, and its motion characteristic is spherical pure rolling. The two-degree-of-freedom parallel mechanical wrist with variable motion mode performs mode transformation at the origin.

The two-degree-of-freedom parallel mechanical wrist of the present invention can realize two motion modes, and has the advantages of high rigidity, strong bearing capacity, etc., and a large range of motion, and can be widely used in robot terminal wrists, medical surgical devices, and space pointing and alignment devices.

Claims (9)

1. A two-degree-of-freedom parallel mechanical wrist with variable motion modes, characterized in that: it includes a fixed base, a motion platform, and three motion branch chains; The fixed base is composed of three fixed shafts, the axes of the three fixed shafts intersect at a point N, and the angles between the axes of adjacent fixed shafts are equal; The branches are connected to form a rotating pair; The motion platform is composed of three moving shafts, the axes of the three moving shafts intersect at a point M, and the included angles between the axes of adjacent moving shafts are equal; connected to form a revolving pair; Among them, the fixed base and the motion platform are located at the upper and lower positions respectively, and are connected by three motion branch chains uniformly distributed in the axial direction; In the fixed base and the moving platform, the angles between the three fixed axes and the three moving axes and the line segment MN are all θ, and when 0<θ<90°, the three fixed axes are all inclined downward; The moving axes are all inclined upward; at this time, the fixed base and the moving platform are both spatial structures; when θ=90°, the three fixed axes are on the same plane; the three moving axes are on the same plane; at this time, Both the fixed base and the moving platform are planar structures; The kinematic branch chain includes an upper link, a middle link and a lower link; wherein, the upper link and the lower link are both arc-shaped bars, and both ends are provided with rotating pair connection holes that run through the inner and outer sides of the bar. And the axis of the connecting hole of the rotating pair on the upper link and the lower link intersects and is perpendicular to the axes of the upper link and the lower link respectively; the outer sides of the two ends of the middle link are designed with a connecting shaft, and the axis of the connecting shaft is perpendicular to the middle link and parallel to each other; the connecting hole of the rotating pair at one end of the lower connecting rod and the connecting shaft at the other end of the middle connecting rod form a rotating pair; The connecting hole of the rotating pair at the other end of the connecting rod is connected with the connecting shaft at the other end of the middle connecting rod to form a rotating pair; the connecting hole of the rotating pair at one end of the upper connecting rod is connected with the connecting end of the moving shaft of the motion platform to form a rotating pair; The auxiliary connecting hole is connected with the connecting shaft at one end of the middle connecting rod to form a rotating pair; The above-mentioned kinematic branch chain can have three configurations, specifically: Configuration A: the upper link and the lower link are located on the same side of the middle link; Configuration B: The upper link is located on the left side of the middle link, and the lower link is located on the right side of the middle link; Configuration C: The upper link is located on the right side of the middle link, and the lower link is located on the left side of the middle link; The above-mentioned fixed base and the motion platform adopt a spatial structure or a planar structure at the same time, are located in the upper and lower positions respectively, and are connected by the above-mentioned three configurations of motion branch chains; and must meet: a. The rotation axis of the rotary joint between the lower link and the fixed base is perpendicular to the rotation axis of the rotary joint between the lower link and the middle link at point B; b. The rotational axis of the rotary joint between the upper link and the motion platform is perpendicular to the rotational axis of the rotary joint between the upper link and the middle link at point A; c. The rotational axis of the rotary joint between the upper link and the middle link is parallel to the rotational axis of the rotary joint between the lower link and the middle link; d. After the three motion branch chains are connected to the fixed base and the motion platform, point B coincides with the center point of the fixed base, and point A coincides with the center point of the motion platform. 2. A two-degree-of-freedom parallel mechanical wrist with variable motion modes as claimed in claim 1, characterized in that: both the fixed base and the motion platform adopt a spatial structure, which are set in reverse, and the three motion branch chains all adopt In configuration A, the movement of the motion platform is a two-degree-of-freedom rotation around the center point of the fixed base. 3. A two-degree-of-freedom parallel mechanical wrist with variable motion modes as claimed in claim 1, characterized in that: both the fixed base and the motion platform adopt a spatial structure and are set in reverse, and the three motion branch chains all adopt In configuration B or configuration C, the movement of the motion platform is a two-degree-of-freedom translation around the center point of the fixed base. 4. A two-degree-of-freedom parallel mechanical wrist with variable motion modes as claimed in claim 1, characterized in that: the fixed base and the motion platform both adopt a planar structure, are arranged parallel and symmetrical to each other, and the three motion branch chains all adopt Configuration A: the upper link and the lower link of the three kinematic branch chains are installed in the same direction. 5. A two-degree-of-freedom parallel mechanical wrist with variable motion modes as claimed in claim 1, characterized in that: both the fixed base and the motion platform adopt a planar structure, are arranged parallel and symmetrical to each other, and the three motion branch chains all adopt Configuration A: wherein, the upper link and the lower link in the two kinematic branch chains are installed in the same direction, and the upper link and the lower link in the other kinematic branch chain are installed in opposite directions. 6. A two-degree-of-freedom parallel mechanical wrist with variable motion mode as claimed in claim 1, characterized in that: the fixed base and the motion platform both adopt a planar structure and are arranged in parallel, and the fixed axis of the fixed base and the The axes of the moving shafts of the motion platform are staggered, and the three motion branch chains all adopt configuration B. 7. A two-degree-of-freedom parallel mechanical wrist with variable motion mode as claimed in claim 1, characterized in that: the fixed base and the motion platform both adopt a planar structure and are arranged in parallel, and the fixed axis of the fixed base and the The axes of the moving shafts of the motion platform are staggered, and the three motion branch chains all adopt configuration C. 8. A two-degree-of-freedom parallel mechanical wrist with variable motion modes as claimed in claim 1, characterized in that: the fixed base and the motion platform are both planar structures, arranged parallel to each other, and the fixed axis of the fixed base Interlaced with the axis of the moving shaft of the motion platform, two of the three motion branch chains adopt configuration B, and one adopts configuration C. 9. A two-degree-of-freedom parallel mechanical wrist with variable motion modes as claimed in claim 1, characterized in that: the fixed base and the motion platform are both planar structures, arranged parallel to each other, and the fixed axis of the fixed base Interlaced with the axis of the moving shaft of the motion platform, two of the three motion branch chains adopt configuration C, and one adopts configuration B.