Dual-joint multi-degree-of-freedom mechanical arm and driving method thereof

A dual joint multi-degree-of-freedom mechanical arm, comprising a base (1), a driving mechanism, a big arm module and a small arm module;

• wherein the driving mechanism comprises three bidirectional driving components (2) mounted on the base (1);
• each of the three bidirectional driving components (2) is capable of outputting a rotary motion and an axial stretching motion;
• the big arm module comprises three big arm push rods (3), a big arm central rod (4) and an elbow joint universal plate (5);
• and the elbow joint universal plate (5) is provided with a first central ball socket (5-1) and three ellipse-shaped ball sockets (5-2) surrounding the first central ball socket (5-1);
• an inner end of the big arm central rod (4) is fixed with the base (1);
• a first central sphere (4-1) is fixed at an outer end of the big arm central rod (4);
• the first central sphere (4-1) and the first central ball socket (5-1) on the elbow joint universal plate (5) form a spherical joint;
• inner ends of the three big arm push rods (3) are respectively fixed with output shafts of the three bidirectional driving components (2);
• three connecting balls (3-2) are respectively fixed at outer ends of the three big arm push rods (3);
• and the three connecting balls (3-2) are respectively constrained in the three ellipse-shaped ball sockets (5-2);
• the small arm module comprises a universal joint coupler (12), a small arm central rod (13), three small arm stretching rods and a wrist joint universal plate (10);
• the wrist joint universal plate (10) is provided with a second central ball socket (10-1);
• an inner end of the small arm central rod (13) is fixed with the elbow joint universal plate (5);
• an outer end of the small arm central rod (13) is fixed with a second central ball (13-1);
• and the second central ball (13-1) and the second central ball socket on the wrist joint universal plate (10) form a spherical joint;
• and
• each of the three small arm stretching rods comprises a first connecting rod (8) and a second connecting rod (9);
• an outer end of the first connecting rod (8) and an inner end of the second connecting rod (9) form a screw mechanism;
• an inner end of the first connecting rod (8) of each of the three small arm stretching rods is in transmission connection with a corresponding one of the three connecting balls through the universal joint coupler (12);
• and an outer end of the second connecting rod (9) of each of the three small arm stretching rods and a corresponding one of three different positions on the wrist joint universal plate (10) form a rotating joint.