阅读说明：本技术 一种基于偏置十字轴铰接的七自由度柔性机械臂 (Seven-degree-of-freedom flexible mechanical arm based on offset cross shaft hinge joint ) 是由 王旭浩 李明宇 吴孟丽 李德祚 林玉飞 吕东洋 陈莫 唐杰 张军 于 2021-10-19 设计创作，主要内容包括：一种基于偏置十字轴铰接的七自由度柔性机械臂。其包括驱动机构、臂段机构、第一连杆和第一导轨；臂段机构包括第一至第三关节单元；每个关节单元具有两个弯曲自由度,整个机构具有一个移动自由度和六个弯曲自由度。本发明优点：本发明采用偏置十字关节轴实现各个关节连杆间连接,加强了机械臂抗扭转刚度,提高了运动精度,同时外径尺寸较小,使得该机械臂可很好地适应各种狭窄空间的检测和操作任务。采用力传感器连接驱动绳索,通过感知预紧力的大小,从而改变驱动绳索的伸长量,由此来控制柔性机械臂的弯曲程度。一个驱动电机驱动两根对称的驱动绳索实现该机械臂的一个弯曲自由度,减少了驱动电机的数量,使得该柔性机械臂更加小型化。(A seven-degree-of-freedom flexible mechanical arm based on offset cross shaft hinge joint. The device comprises a driving mechanism, an arm section mechanism, a first connecting rod and a first guide rail; the arm section mechanism includes first to third joint units; each joint unit has two degrees of freedom in bending, and the entire mechanism has one degree of freedom in movement and six degrees of freedom in bending. The invention has the advantages that: the invention adopts the offset cross joint shaft to realize the connection among all the joint connecting rods, strengthens the torsion-resistant rigidity of the mechanical arm, improves the motion precision, and simultaneously has smaller outer diameter size, so that the mechanical arm can be well suitable for the detection and operation tasks of various narrow spaces. The force sensor is connected with the driving rope, and the extension amount of the driving rope is changed by sensing the pretightening force, so that the bending degree of the flexible mechanical arm is controlled. A driving motor drives two symmetrical driving ropes to realize a bending degree of freedom of the mechanical arm, and the number of the driving motors is reduced, so that the flexible mechanical arm is more miniaturized.)

1. The utility model provides a seven degree of freedom flexible mechanical arms based on articulated biasing cross axle which characterized in that: the seven-degree-of-freedom flexible mechanical arm based on the offset cross shaft hinge joint comprises a driving mechanism (1), an arm section mechanism (2), a first guide rail (3) and a first connecting rod (4);

the first guide rail (3) comprises a slide rail (31), a first slide block (32), a second lead screw (311), a first driving motor (33), a second coupler (34) and a support frame (35); the first driving motor (33) is fixedly arranged at one end of the supporting frame (35), the output shaft is connected with one end of a second lead screw (311) through a second coupling (34), and the other end of the second lead screw (311) is arranged at the other end of the supporting frame (35) in a rotating mode; the sliding rail (31) is arranged on the supporting frame (35) in a mode of being parallel to the second lead screw (311); the first sliding block (32) is sleeved on the second lead screw (311) and the bottom surface of the first sliding block is installed on the sliding rail (31), so that the first sliding block can reciprocate along the sliding rail (31) under the driving of the first driving motor (33);

the arm section mechanism (2) comprises a first joint unit (I), a second joint unit (II) and a third joint unit (III) which are identical in structure and are sequentially arranged; each joint unit comprises a head end connecting rod (21), a plurality of joint connecting rods (22), a plurality of offset cross joint shafts (23), an elastic supporting rod (25) and four driving ropes (24); the whole head end connecting rod (21) is of a cylindrical structure, a first central hole (212) is formed at the axis in a penetrating mode, two first connecting grooves (213) are formed in the position, on the outer side of the rear end face, of the rear end face in a radially symmetrical and concave mode, the axes of the two first connecting grooves (213) are located on the same straight line, and a plurality of first guide holes (211) which are symmetrically distributed are formed in the position, located on the outer side of the first central hole (212), of the first guide holes in a penetrating mode in the axial direction; the joint connecting rod (22) is of a cylindrical structure as a whole, a second central hole (222) is formed at the axis in a penetrating manner, two second connecting grooves (223) are symmetrically formed at the outer side parts of the two end faces in a recessed manner, the axes of the two second connecting grooves (223) are positioned on a straight line, and a plurality of symmetrically distributed second guide holes (221) are formed at the outer side parts of the second central hole (222) in a penetrating manner along the axial direction; an offset cross joint shaft (23) is arranged between the head end connecting rod (21) and the joint connecting rod (22) and between two adjacent joint connecting rods (22); each offset cross joint shaft (23) comprises an offset central shaft (232) and four joint shafts (231); a third central hole (233) is formed in the axis of the offset central shaft (232) in a penetrating manner, two joint shafts (231) are symmetrically arranged at the positions, located on the outer side of the third central hole (233), on the two end faces of the offset central shaft (232), the axes of the two joint shafts (231) are located in a straight line, and the axes of the joint shafts (231) on the two end faces are perpendicular to each other; the outer parts of the two joint shafts (231) on each end surface are respectively embedded into two first connecting grooves (213) on the head end connecting rod (21) or two second connecting grooves (223) on the same end surface of the joint connecting rod (22), so that the two joint connecting rods (22) or the head end connecting rod (21) and the joint connecting rod (22) are connected with each other by using an offset cross joint shaft (23) to form two first rotating pairs (26) with mutually vertical axes, the third central hole (233) is aligned with the first central hole (212) on the head end connecting rod (21) and the second central hole (222) on the joint connecting rod (22), and simultaneously, each first guide hole (211) on the head end connecting rod (21) is aligned with one second guide hole (221) on all the joint connecting rods (22); the elastic support rod (25) penetrates through a first center hole (212) of the head end connecting rod (21), a second center hole (222) of each joint connecting rod (22) and a third center hole (233) of the offset cross joint shaft (23); one ends of four driving ropes (24) are connected to the head end connecting rod (21) at equal intervals, two opposite driving ropes (24) form a pair, and the other ends of the driving ropes penetrate through the joint unit and all guide holes in the same position on all joint units on the rear side of the joint unit and then are connected to the driving mechanism (1);

the driving mechanism (1) comprises three driving units respectively connected with a joint unit, a first connecting disc (102), a second connecting disc (104), a third connecting disc (109), a circular table (110), a second connecting rod (113), a fourth connecting disc (114), a connecting part (117) and a central connecting part (118); the first connecting disc (102), the second connecting disc (104) and the third connecting disc (109) are arranged in parallel at intervals, and the middle parts of the first connecting disc, the second connecting disc and the third connecting disc are connected with each other by a central connecting piece (118); the bottom surface of the circular truncated cone (110) is arranged in the middle of the top surface of the third connecting disc (109), and the top surface of the circular truncated cone (110) is connected with a fourth connecting disc (114) through a plurality of second connecting rods (113); one end of the connecting part (117) is connected to the side surface of the central connecting part (118), and the other end of the connecting part extends to the outer side of the driving mechanism (1) and is fixedly connected with the first sliding block (32) on the first guide rail (3); each driving unit comprises two second driving motors (101), two first couplers (103), four first pulleys (115), two first lead screws (105), at least two guide rods (106), two first force sensors (107), two second force sensors (108), two second sliding blocks (116), four second pulleys (111) and four third pulleys (112); two second driving motors (101) are symmetrically arranged at the edge part of the bottom surface of the first connecting disc (102), and output shafts penetrate through the first connecting disc (102); the first coupling (103) is positioned between the first connecting disc (102) and the second connecting disc (104); the two first lead screws (105) are symmetrically arranged, one end of each first lead screw (105) is rotatably arranged at the outer side part of the third connecting disc (109), and the other end of each first lead screw penetrates through the second connecting disc (104) and is connected with the output end of a second driving motor (101) through a first coupler (103); at least one guide rod (106) is arranged near each first lead screw (105), and two ends of each guide rod (106) are respectively arranged on the second connecting disc (104) and the third connecting disc (109); each second sliding block (116) is simultaneously sleeved on a first lead screw (105) and at least one guide rod (106) nearby, so that the second sliding blocks can reciprocate along the guide rods (106); each of the first force sensor (107) and the second force sensor (108) is mounted on both the bottom surface and the top surface of a second slider (116); four first pulleys (115) are symmetrically arranged on the central connecting piece (118) at the position between the first connecting disc (102) and the second connecting disc (104); the four second pulleys (111) are symmetrically arranged on the circumferential surface of the circular truncated cone (110); four third pulleys (112) are symmetrically arranged on the edge of the top surface of the circular truncated cone (110), and each first pulley (115) is respectively aligned with the mounting positions of one second pulley (111) and one third pulley (112) up and down; one driving rope (24) of each pair of driving ropes (24) on each joint unit in the arm segment mechanism (2) firstly passes through the fourth connecting disc (114), then passes around a third pulley (112) and a second pulley (111), then passes through the third connecting disc (109) and is connected to a second force sensor (108) of one driving unit, and the other driving rope (24) firstly passes through the fourth connecting disc (114), then passes around a third pulley (112) and a second pulley (111), then sequentially passes through the third connecting disc (109) and the second connecting disc (104), then passes around a first pulley (115) and transversely passes through the central connecting piece (118), and finally passes around another first pulley (115) which is symmetrically arranged and is connected to the first force sensor (107);

one end of the first connecting rod (4) is connected to the middle of the top surface of the fourth connecting disc (114) in the driving mechanism (1), and the other end of the first connecting rod is connected to the rear end surface of a joint connecting rod (22) at the rear end of the first joint unit (I) in the arm section mechanism (2).

2. The seven-degree-of-freedom flexible mechanical arm based on the offset cross-shaft hinge joint as claimed in claim 1, wherein: the first connecting rod (4) is a slender hollow rod piece.

3. The seven-degree-of-freedom flexible mechanical arm based on the offset cross-shaft hinge joint as claimed in claim 1, wherein: two symmetrical U-shaped grooves (214) are formed on the circumferential surface of the middle part of the head end connecting rod (21) in an inwards recessed mode, and meanwhile a plurality of first lightening holes (215) are formed in the position, located between the first center hole (212) and the first guide hole (211), in an axially penetrating mode, so that the overall weight of the head end connecting rod (21) is reduced.

4. The seven-degree-of-freedom flexible mechanical arm based on the offset cross-shaft hinge joint as claimed in claim 1, wherein: and a plurality of second lightening holes (224) are formed in the joint connecting rod (22) between the second central hole (222) and the second guide hole (221) in a penetrating manner along the axial direction, and the middle parts of the two end faces are formed in an inwards concave manner, so that the overall weight of the joint connecting rod (22) is reduced.

5. The seven-degree-of-freedom flexible mechanical arm based on the offset cross-shaft hinge joint as claimed in claim 1, wherein: the central connecting piece (118) is of a hollow cylindrical structure.

Technical Field

The invention belongs to the technical field of robots, and particularly relates to a seven-degree-of-freedom flexible mechanical arm based on an offset cross shaft hinge.

Background

The flexible mechanical arm is different from the traditional rigid joint mechanical arm, is generally formed by connecting a plurality of flexible joints in series, has the advantages of multiple degrees of freedom, flexible movement and the like, and is particularly suitable for being applied in narrow space environments, such as pipeline detection, detection in a complex box body, wing detection and maintenance of an aircraft engine and the like.

At present, a cross universal hinge, a spherical hinge structure or a pure flexible material supporting structure is commonly adopted in joints of a flexible mechanical arm, and the problems of complex joint structure, large outer diameter size, low torsional rigidity and the like exist, so that the application range of the flexible mechanical arm is greatly limited. In addition, the flexible mechanical arm driven by the rope generally adopts one driving motor to drive one rope, so that a plurality of driving motors are needed, and a driving mechanism is complex.

Disclosure of Invention

In order to solve the above problems, the present invention aims to provide a seven-degree-of-freedom flexible mechanical arm based on an offset cross-axle hinge.

In order to achieve the aim, the seven-degree-of-freedom flexible mechanical arm based on the offset cross shaft hinge joint comprises a driving mechanism, an arm section mechanism, a first guide rail and a first connecting rod;

the first guide rail comprises a slide rail, a first slide block, a second lead screw, a first driving motor, a second coupler and a support frame; the first driving motor is fixedly arranged at one end of the support frame, the output shaft is connected with one end of a second lead screw through a second coupler, and the other end of the second lead screw is rotatably arranged at the other end of the support frame; the sliding rail is arranged on the supporting frame in a mode of being parallel to the second lead screw; the first sliding block is sleeved on the second lead screw, and the bottom surface of the first sliding block is arranged on the sliding rail, so that the first sliding block can reciprocate along the sliding rail under the driving of the first driving motor;

the arm section mechanism comprises a first joint unit, a second joint unit and a third joint unit which have the same structure and are sequentially arranged; each joint unit comprises a head end connecting rod, a plurality of joint connecting rods, a plurality of offset cross joint shafts, an elastic supporting rod and four driving ropes; the whole head end connecting rod is of a cylindrical structure, a first central hole is formed in the axis of the head end connecting rod in a penetrating mode, two first connecting grooves are formed in the outer side portion of the rear end face in a radially symmetrical and concave mode, the axes of the two first connecting grooves are located on the same straight line, and a plurality of first guide holes which are symmetrically distributed are formed in the position, located on the outer side of the first central hole, in a penetrating mode in the axial direction; the whole joint connecting rod is of a cylindrical structure, a second central hole is formed in the axis of the joint connecting rod in a penetrating mode, two second connecting grooves are formed in the positions, on the outer sides of two end faces, of the two second connecting grooves in a symmetrically-recessed mode, the axes of the two second connecting grooves are located on the same straight line, and a plurality of second guide holes which are symmetrically distributed are formed in the positions, on the outer sides of the second central holes, of the two second connecting grooves in a penetrating mode in the axial direction; an offset cross joint shaft is arranged between the head end connecting rod and the joint connecting rod as well as between two adjacent joint connecting rods; each offset cross joint shaft comprises an offset central shaft and four joint shafts; a third central hole is formed at the axis of the offset central shaft in a penetrating way, two joint shafts are symmetrically arranged at the positions, which are positioned at the outer side of the third central hole, on the two end surfaces of the offset central shaft, the axes of the two joint shafts are positioned on a straight line, and the axes of the joint shafts on the two end surfaces are mutually vertical; the outer side parts of the two joint shafts on each end surface are respectively embedded into two first connecting grooves on the head end connecting rod or two second connecting grooves on the same end surface of the joint connecting rod, so that the two joint connecting rods or the head end connecting rod and the joint connecting rod are connected with each other by utilizing an offset cross joint shaft to form two first rotating pairs with mutually vertical axes, the third central hole is aligned with the first central hole on the head end connecting rod and the second central holes on the joint connecting rods, and simultaneously, each first guide hole on the head end connecting rod is aligned with one second guide hole on all the joint connecting rods; the elastic supporting rod is arranged in a first center hole of the head end connecting rod, a second center hole of each joint connecting rod and a third center hole of the offset cross joint shaft in a penetrating manner; one ends of the four driving ropes are connected to the head end connecting rod at equal intervals, the two opposite driving ropes are a pair, and the other ends of the four driving ropes penetrate through the joint unit and all the guide holes in the same position on all the joint units positioned at the rear side of the joint unit and then are connected to the driving mechanism;

the driving mechanism comprises three driving units, a first connecting disc, a second connecting disc, a third connecting disc, a circular table, a second connecting rod, a fourth connecting disc, a connecting part and a central connecting piece, wherein the three driving units, the first connecting disc, the second connecting disc, the third connecting disc, the circular table, the second connecting rod, the fourth connecting disc, the connecting part and the central connecting piece are respectively connected with one joint unit; the first connecting disc, the second connecting disc and the third connecting disc are arranged in parallel at intervals, and the middle parts of the first connecting disc, the second connecting disc and the third connecting disc are connected with each other by a central connecting piece; the bottom surface of the circular truncated cone is arranged in the middle of the top surface of the third connecting disc, and the top surface of the circular truncated cone is connected with the fourth connecting disc through a plurality of second connecting rods; one end of the connecting part is connected to the side face of the central connecting part, and the other end of the connecting part extends to the outer side of the driving mechanism and is fixedly connected with the first sliding block on the first guide rail; each driving unit comprises two second driving motors, two first couplers, four first pulleys, two first lead screws, at least two guide rods, two first force sensors, two second sliding blocks, four second pulleys and four third pulleys; the two second driving motors are symmetrically arranged at the edge part of the bottom surface of the first connecting disc, and the output shaft penetrates through the first connecting disc; the first coupling is positioned between the first connecting disc and the second connecting disc; the two first lead screws are symmetrically arranged, one end of each first lead screw is rotatably arranged at the outer side part of the third connecting disc, and the other end of each first lead screw penetrates through the second connecting disc and is connected with the output end of a second driving motor through a first coupler; at least one guide rod is arranged near each first lead screw, and two ends of each guide rod are respectively arranged on the second connecting disc and the third connecting disc; each second sliding block is sleeved on one first lead screw and at least one guide rod nearby at the same time, so that the second sliding blocks can move back and forth along the guide rods; each of the first force sensor and the second force sensor is installed on the bottom surface and the top surface of a second slide block; the four first pulleys are symmetrically arranged on the central connecting piece and positioned between the first connecting disc and the second connecting disc; the four second pulleys are symmetrically arranged on the circumferential surface of the circular truncated cone; the four third pulleys are symmetrically arranged on the edge of the top surface of the circular truncated cone, and each first pulley is vertically aligned with the mounting position of one second pulley and the mounting position of one third pulley respectively; one driving rope of each pair of driving ropes on each joint unit in the arm section mechanism firstly passes through the fourth connecting disc, then passes through the third pulley and the second pulley, then passes through the third connecting disc and then is connected to a second force sensor of one driving unit, and the other driving rope firstly passes through the fourth connecting disc, then passes through the third pulley and the second pulley, then sequentially passes through the third connecting disc and the second connecting disc, then passes through the first pulley, transversely penetrates through the central connecting piece, finally passes through the other symmetrically arranged first pulley and then is connected to the first force sensor;

one end of the first connecting rod is connected to the middle of the top surface of the fourth connecting disc in the driving mechanism, and the other end of the first connecting rod is connected to the rear end face of the joint connecting rod at the rear end of the first joint unit in the arm section mechanism.

The first connecting rod is a slender hollow rod piece.

Two symmetrical U-shaped grooves are formed on the circumferential surface of the middle part of the head end connecting rod in an inwards recessed mode, and meanwhile a plurality of first lightening holes are formed in the position, located between the first center hole and the first guide hole, in a penetrating mode along the axial direction, so that the overall weight of the head end connecting rod is reduced.

And a plurality of second lightening holes are formed on the joint connecting rod between the second central hole and the second guide hole in a penetrating manner along the axial direction, and the middle parts of the two end surfaces are formed in a concave manner so as to reduce the whole weight of the joint connecting rod.

The central connecting piece is of a hollow cylindrical structure.

The seven-degree-of-freedom flexible mechanical arm based on the offset cross shaft hinge joint has the following advantages:

1. the connection between each joint connecting rod is realized by adopting the offset cross joint shaft, the anti-torsion rigidity of the flexible mechanical arm is enhanced, the movement precision of the flexible mechanical arm is improved, and meanwhile, the outer diameter of the flexible mechanical arm is smaller, so that the flexible mechanical arm can be well suitable for detection and operation tasks in various narrow spaces.

2. The force sensor is connected with the driving rope, and the extension amount of the driving rope is changed by sensing the pretightening force, so that the bending degree of the flexible mechanical arm is controlled.

3. A driving motor drives two symmetrical driving ropes to realize a bending degree of freedom of the mechanical arm, and the number of the driving motors is reduced, so that the flexible mechanical arm is more miniaturized.

Drawings

FIG. 1 is a schematic structural diagram of a seven-degree-of-freedom flexible mechanical arm based on an offset cross shaft hinge joint.

Fig. 2 is a schematic structural view of a joint unit of the arm segment mechanism of the present invention.

Fig. 3 is a schematic view of the head end link structure of the arm segment mechanism of the present invention.

Fig. 4 is a schematic view of the joint link structure of the arm segment mechanism of the present invention.

FIG. 5 is a schematic view of an offset cross-joint axis structure of the arm segment mechanism of the present invention.

Fig. 6 is a schematic structural view of a driving mechanism according to the present invention.

Fig. 7 is a schematic view of a first guide rail structure according to the present invention.

Fig. 8 is a longitudinal sectional view of the driving mechanism of the present invention.

Detailed Description

The invention provides a seven-degree-of-freedom flexible mechanical arm based on offset cross-axle hinge, which is described in detail in the following with reference to the attached drawings.

As shown in fig. 1-8, the seven-degree-of-freedom flexible mechanical arm based on the offset cross-axle hinge provided by the invention comprises a driving mechanism 1, an arm section mechanism 2, a first connecting rod 4 and a first guide rail 3;

the first guide rail 3 comprises a slide rail 31, a first slide block 32, a second lead screw 311, a first driving motor 33, a second coupler 34 and a support frame 35; the first driving motor 33 is fixedly installed at one end of the supporting frame 35, the output shaft is connected with one end of the second lead screw 311 through the second coupling 34, and the other end of the second lead screw 311 is installed at the other end of the supporting frame 35 in a rotating manner; the slide rail 31 is mounted on the support frame 35 in parallel with the second lead screw 311; the first slider 32 is sleeved on the second lead screw 311, and the bottom surface of the first slider is mounted on the slide rail 31, so that the first slider can reciprocate along the slide rail 31 under the driving of the first driving motor 33;

the arm section mechanism 2 comprises a first joint unit I, a second joint unit II and a third joint unit III which are identical in structure and are sequentially arranged; each joint unit comprises a head end connecting rod 21, a plurality of joint connecting rods 22, a plurality of offset cross joint shafts 23, an elastic supporting rod 25 and four driving ropes 24; the whole head end connecting rod 21 is of a cylindrical structure, a first central hole 212 is formed at the axis in a penetrating manner, two first connecting grooves 213 are formed at the outer side part of the rear end surface in a radially symmetrical and concave manner, the axes of the two first connecting grooves 213 are positioned on a straight line, and a plurality of first guide holes 211 which are symmetrically distributed are formed at the outer side part of the first central hole 212 in a penetrating manner along the axial direction; the joint connecting rod 22 is of a cylindrical structure as a whole, a second central hole 222 is formed at the axis in a penetrating manner, two second connecting grooves 223 are symmetrically formed at the outer side parts of the two end faces in a recessed manner, the axes of the two second connecting grooves 223 are positioned on a straight line, and a plurality of symmetrically distributed second guide holes 221 are formed at the outer side parts of the second central hole 222 in a penetrating manner along the axial direction; an offset cross joint shaft 23 is arranged between the head end connecting rod 21 and the joint connecting rod 22 and between two adjacent joint connecting rods 22; each offset cross joint shaft 23 includes an offset center shaft 232 and four joint shafts 231; a third central hole 233 is formed through the axis of the offset central shaft 232, two joint shafts 231 are symmetrically installed at the positions, located on the outer side of the third central hole 233, on the two end surfaces of the offset central shaft 232, the axes of the two joint shafts 231 are located on a straight line, and the axes of the joint shafts 231 on the two end surfaces are perpendicular to each other; the outer parts of the two joint shafts 231 on each end surface are respectively embedded in the two first connecting grooves 213 on the head end connecting rod 21 or the two second connecting grooves 223 on the same end surface of the joint connecting rod 22, so that the two joint connecting rods 22 or the head end connecting rod 21 and the joint connecting rod 22 are connected with each other by the offset cross joint shaft 23 to form two first rotating pairs 26 with mutually perpendicular axes, the third central hole 233 is aligned with the first central hole 212 on the head end connecting rod 21 and the second central holes 222 on the joint connecting rods 22, and simultaneously, each first guide hole 211 on the head end connecting rod 21 is aligned with one second guide hole 221 on all the joint connecting rods 22; the elastic support rod 25 is arranged in the first center hole 212 of the head end connecting rod 21, the second center hole 222 of each joint connecting rod 22 and the third center hole 233 of the offset cross joint shaft 23 in a penetrating way; one end of each of the four driving ropes 24 is connected to the head end connecting rod 21 at equal intervals, the two opposite driving ropes 24 form a pair, and the other end of each driving rope passes through the joint unit and all the guide holes at the same position on all the joint units at the rear side of the joint unit and then is connected to the driving mechanism 1;

the driving mechanism 1 comprises three driving units respectively connected with a joint unit, a first connecting disc 102, a second connecting disc 104, a third connecting disc 109, a circular table 110, a second connecting rod 113, a fourth connecting disc 114, a connecting part 117 and a central connecting part 118; the first connecting disc 102, the second connecting disc 104 and the third connecting disc 109 are arranged in parallel at intervals, and the middle parts of the first connecting disc, the second connecting disc and the third connecting disc are connected with each other by a central connecting piece 118; the bottom surface of the circular truncated cone 110 is arranged in the middle of the top surface of the third connecting disc 109, and the top surface of the circular truncated cone 110 is connected with a fourth connecting disc 114 through a plurality of second connecting rods 113; one end of the connecting part 117 is connected to the side surface of the central connecting part 118, and the other end extends to the outer side of the driving mechanism 1 and is fixedly connected with the first slide block 32 on the first guide rail 3; each driving unit comprises two second driving motors 101, two first couplers 103, four first pulleys 115, two first lead screws 105, at least two guide rods 106, two first force sensors 107, two second force sensors 108, two second sliders 116, four second pulleys 111 and four third pulleys 112; the two second driving motors 101 are symmetrically arranged at the edge of the bottom surface of the first connecting disc 102, and output shafts penetrate through the first connecting disc 102; the first coupling 103 is located between the first connection disc 102 and the second connection disc 104; two first lead screws 105 are symmetrically arranged, one end of each first lead screw 105 is rotatably arranged at the outer side part of the third connecting disc 109, and the other end of each first lead screw 105 penetrates through the second connecting disc 104 and is connected with the output end of a second driving motor 101 through a first coupler 103; at least one guide rod 106 is arranged near each first lead screw 105, and two ends of each guide rod 106 are respectively arranged on the second connecting disc 104 and the third connecting disc 109; each second slide block 116 is simultaneously sleeved on one first lead screw 105 and at least one adjacent guide rod 106, so that the second slide blocks can reciprocate along the guide rods 106; each of the first force sensor 107 and the second force sensor 108 is mounted on both the bottom surface and the top surface of one of the second sliders 116; four first pulleys 115 are symmetrically arranged on the central connecting piece 118 at the position between the first connecting disc 102 and the second connecting disc 104; four second pulleys 111 are symmetrically arranged on the circumferential surface of the circular truncated cone 110; four third pulleys 112 are symmetrically arranged on the edge of the top surface of the circular truncated cone 110, and each first pulley 115 is vertically aligned with the installation position of one second pulley 111 and one third pulley 112 respectively; one drive rope 24 of each pair of drive ropes 24 on each joint unit in the arm segment mechanism 2 passes through the fourth connecting disc 114, then passes around a third pulley 112 and a second pulley 111, then passes through the third connecting disc 109 and then is connected to a second force sensor 108 of one drive unit, and the other drive rope 24 passes through the fourth connecting disc 114, then passes around a third pulley 112 and a second pulley 111, then passes through the third connecting disc 109 and the second connecting disc 104 in sequence, passes around a first pulley 115 and then passes through the central connecting piece 118 in the transverse direction, and finally passes around another first pulley 115 which is symmetrically arranged and then is connected to the first force sensor 107;

one end of the first link 4 is connected to the middle of the top surface of the fourth connecting plate 114 in the driving mechanism 1, and the other end is connected to the rear end surface of the joint link 22 at the rear end of the first joint unit i in the arm section mechanism 2.

The first link 4 is an elongated hollow rod.

Two symmetrical U-shaped grooves 214 are formed on the circumferential surface of the middle part of the head end connecting rod 21 in an inward concave manner, and a plurality of first lightening holes 215 are formed at the position between the first center hole 212 and the first guide hole 211 in an axially penetrating manner so as to lighten the whole weight of the head end connecting rod 21.

A plurality of second lightening holes 224 are formed on the joint connecting rod 22 between the second central hole 222 and the second guide hole 221 in an axially penetrating manner, and the middle parts of the two end surfaces are formed in an inwards concave manner, so that the overall weight of the joint connecting rod 22 is reduced.

The central connector 118 is a hollow cylindrical structure.

The invention provides a seven-degree-of-freedom flexible mechanical arm based on offset cross shaft hinge joint, which has the working principle that: each second driving motor 101 on the driving mechanism 1 drives the first lead screw 105 to rotate through the first coupler 103, so that the second sliding block 116 moves back and forth along the guide rod 106, and the two symmetrical driving ropes 24 are driven to realize one bending degree of freedom of one joint unit; one drive rope 24 is connected at one end to the head end link 21 of the joint unit in the arm segment structure 2 and at the other end to the first force sensor 107 of the drive unit in the drive mechanism 1, and the other symmetrical drive rope 24 is connected at one end to the second force sensor 108 of the drive unit and at the other end to the head end link 21 of the joint unit in the arm segment structure 2; the pre-tightening force can be sensed through the force sensor, so that the extension of the driving rope 24 is changed to drive the bending degree of the flexible mechanical arm; each driving unit is driven by only two second driving motors 101, and finally six bending degrees of freedom of the arm section mechanism 2 are realized through six second driving motors 101, so that the purpose of controlling the tail end position of the flexible mechanical arm is achieved; in addition, the first driving motor 33 can drive the driving mechanism 1 and the arm section mechanism 2 to slide on the first guide rail 3, so that the moving freedom degree of the whole flexible mechanical arm can be realized; the flexible mechanical arm has six bending freedom degrees and one moving freedom degree in total, and has seven freedom degrees; the mechanical arm has the advantages of flexible movement, high flexibility, small outer diameter size, less required driving, high torsional rigidity and the like, and can be well adapted to detection and operation tasks in various narrow spaces.