CN104890005A - Spherical space based under-actuated robot wrist mechanism - Google Patents

Abstract

The invention relates to an underactuated robot wrist mechanism based on a spherical space. It includes an executive connection body and an arm frame. The executive connection body has a spherical cavity, and at the center of the spherical cavity, there are two adjustable circular plates fixedly connected to the arm frame through bolts; three power frames It can be fixed in different bolt holes in the adjustable circular plate according to the needs. The ends of the two power frames in the three power frames are respectively equipped with a power source, and the power source is connected to a roller shaft through a jaw clutch. Each roller shaft is equipped with a roller, and the roller is in rolling contact with the inner wall of the spherical cavity of the executive connector; the other end of the power frame is directly equipped with a roller and is in rolling contact with the inner wall of the spherical cavity of the executive connector. Because the underactuated robot wrist mechanism based on spherical space has pure rolling contact between the roller and the actuator, there is no gap between the roller and the actuator, so the error is small, there is no return error, and the precision is high.

Description

Underactuated Robot Wrist Mechanism Based on Spherical Space

technical field

The invention relates to an underactuated robot wrist mechanism based on a spherical space.

Background technique

Similar to humans, the functions of robots generally need to be realized through the operation of the mechanical arm, while the wrist is an important device connecting the arm and the gripper, and its design is one of the key technologies of the robot. For conventional robotic wrists, since one degree of freedom requires a power source (such as a motor, etc.), and the mass of the power source often accounts for the majority of the total mass of the joint, the obvious disadvantages of conventional robotic wrist devices are: the device adopts The way of full driving results in more complex mechanical mechanism, larger volume, larger quality and higher cost.

An underactuated mechanism refers to a mechanism whose power source is less than the degree of freedom of the system. An underactuated robot is a robot containing an underactuated mechanism. Due to its small size, light weight, low cost, low energy consumption, and high flexibility, Therefore, it has attracted extensive attention of scholars and has become a new hotspot in the field of robotics. It is against this background that the present invention proposes an underactuated robot wrist based on spherical space, which has a simple mechanism and light weight, and has good application prospects.

Contents of the invention

The invention directly adds an under-actuated mechanism inside the executive connection body, which saves an external complicated power source device, saves cost and quality, and improves precision at the same time. In order to achieve the above object, the present invention adopts the following technical scheme: a kind of underactuated robot wrist mechanism based on spherical space includes, an execution link and an arm frame, it is characterized in that: the execution link has a spherical cavity, in At the center of the spherical cavity, there are upper and lower adjustable circular plates fixedly connected to the arm frame through bolts; the three power frames can be fixed in different bolt holes in the adjustable circular plate according to needs, and two of the three power frames Each power frame end is equipped with a power source, the power source is connected to a roller shaft through a jaw clutch, and a roller is installed on each roller shaft, and the roller is in rolling contact with the inner wall of the spherical cavity of the executive connector; the other A roller is directly installed at the end of the power frame, and the roller is in rolling contact with the inner wall of the spherical cavity of the connecting body. As shown in Figure 1, the structures of A and B are exactly the same, and the structure of C has no motor relative to A and B. The axes of the three rollers and the center of the sphere of the executive connector must determine a plane D, and the three The rollers can adjust the angle between the rollers in the plane D by adjusting the fixed position of the power frame on the adjustable circular plate.

As shown in Figure 1, rollers 1 and 2 are driven by a power source, and their angular displacements are , then the angular velocities of rollers 1 and 2 are the first derivatives of the angular displacement , , roller 3 is a roller driven by no power source, and its angular displacement is , is the angular displacement of the connecting body, then is the angular velocity of the connecting body, r is the radius of the roller, R is the radius of the connecting body, is the institutional perspective, is the angle between the rotation axis of the executive connector and the line connecting the sphere center of the executive connector and the center of mass of the roller. In this mechanism, it is 120°. :

Find out that in the above formulas (1) and (2) because The angle is constantly changing, so it is not integrable,

That is, the constraint on velocity constitutes an underactuated moving mechanism. Formula (1) can be compared with formula (2):

Therefore, the β angle can be obtained, that is, the rotation axis of the connecting body can be determined, and it changes with the change of the input angular velocity of the driving roller.

Compared with the prior art, the present invention has the following obvious outstanding substantive features and significant progress: because the roller and the executive link of the underactuated robot wrist mechanism based on spherical space are pure rolling contact, between the roller and the executive link There is no gap, so the error is small, there is no return error, and the precision is high.

The underactuated robot wrist mechanism based on the spherical space can adjust the angle between the rollers by adjusting the fixed position of the power frame on the adjustable circular plate. When adjusting, the axis of the rollers must define a plane with the center of the sphere of the actuator to form an underactuated robot. Drive mechanism. When the underactuated robot wrist mechanism based on spherical space is applied to the robot wrist mechanism, the angular velocity of the two rollers at A and B can be adjusted through the power source, and the speed difference between the two rollers at A and B and the contact point of the executive connector can be adjusted. Drive the executive connector to move in three degrees of freedom in space, that is, the movement of the robot's wrist. For the underactuated robot wrist mechanism based on spherical space, the structure in which the axes of the three rollers and the center of the sphere of the actuating link are on the same plane is unique, because it cannot be realized in the mechanism when one roller or two rollers are used. .

Description of drawings

Fig.1 Schematic diagram of underactuated robot wrist mechanism based on spherical space;

Fig. 2 Half-section view of underactuated robot wrist mechanism based on spherical space;

Fig. 3 Partial view of F direction in Fig. 2;

Figure 4 N-direction view of Figure 2;

Figure 5 Schematic diagram of the connection mechanism between the roller shaft and the power source, in which (a) is a longitudinal sectional view,

(b) is a cross-sectional view at E-E in Figure (a);

Figure 6 Schematic diagram of the structure of the adjustable circular plate, in the figure (a) is the main view, (b) is the

Sectional view at G-G.

Detailed ways

Preferred implementation cases of the present invention are described in detail as follows in conjunction with accompanying drawings:

Implementation case one:

See Figures 1-6, the spherical space-based underactuated robot wrist mechanism includes: an executive link (1) and an arm (8). It is characterized in that: the executive connecting body (1) has a spherical cavity, and at the center of the spherical cavity there are two adjustable circular plates (2) fixedly connected to the boom (8) by bolts; three power The frame (3) can be fixed in different bolt holes in the adjustable circular plate (2) as required, and two power frames (3) in the three power frames (3) are respectively equipped with a power source (4 ), the power source (4) is connected to a roller shaft (7) via a jaw clutch (5), and each roller shaft (7) is equipped with a roller (6), and the roller (6) is connected to the executive connection body (1 ) is in rolling contact with the inner wall of the spherical cavity; the end of the other power frame (3) is directly equipped with a roller (6), and the roller (6) is in rolling contact with the inner wall of the spherical cavity of the executive connector (1). The mechanisms at A and B are exactly the same, and the mechanism at C has no power source (4) relative to A and B. The axes of the three rollers (6) and the spherical center of the executive connector (1) must determine a plane D, And the three rollers (6) can adjust the angle between the rollers (6) in the plane D by adjusting the fixed position of the power frame (3) on the adjustable circular plate (2).

The power source (4) is used to drive the rollers (6) to rotate, the axes of the three rollers (6) and the spherical center of the executive connector (1) must define a plane D, and the three rollers (6) can be in the plane D The included angle between the rollers (6) is adjusted by adjusting the fixed position of the power frame (3) on the adjustable circular plate (2). Due to the mechanism characteristics of the underactuated robot wrist mechanism based on spherical space, the speed of the actuator connector (1) at the contact point between the roller (6) and the actuator connector (1) at A is equal to the speed of the roller (6), and the same The speed of the execution connector (1) at the point of contact between the roller (6) and the execution connector (1) at B is equal to the speed of the roller (6), and the relationship between the roller (6) and the execution connection at A and B can be obtained. The speed of the connecting body (1) at the contact point of the connecting body (1), because the axis of rotation of the connecting body (1) is constantly changing, that is, the axis of rotation of the connecting body (1) and the ball of the connecting body (1) The angle between the center and the center of mass line of the roller (6) is constantly changing, so an under-actuated moving mechanism is formed.

Because the roller (6) of the underactuated robot wrist mechanism based on the spherical space and the actuator connector (1) are in pure rolling contact, there is no gap between the roller (6) and the actuator connector (1), so the error is small and the There is no return error and high precision.

This underactuated robot wrist mechanism based on spherical space can adjust the angle between the rollers (6) by adjusting the fixed position of the power frame (3) on the adjustable circular plate (2), and the three power frames ( 3) The axis of the corresponding roller (6) is on the same plane D as the center of the sphere of the executive connecting body (1), so as to constitute an under-actuated moving mechanism. When the underactuated robot wrist mechanism based on spherical space is applied to the robot mechanism, the angular velocity of the two rollers (6) at A and B can be adjusted through the power source (4), and the two rollers (6) at A and B can be connected with the actuator The different speeds at the contact points of the connecting body (1) drive and execute the moving of the connecting body (1) in three degrees of freedom in space, that is, the movement of the robot wrist. At the same time, for the underactuated robot wrist mechanism based on spherical space, the axis of the three rollers (6) in this scheme is unique to the mechanism on the same plane as the center of the sphere of the executive connecting body (1), because one or two rollers are used When (6), it cannot be realized on the mechanism.

Claims (2)

1. the under-actuated robot wrist mechanism based on diameter of Spherical Volume, comprise, one performs connector (1) and a jib (8), it is characterized in that: described execution connector (1) has a spherical hollow space, have the adjustable plectane of upper and lower two panels (2) to be fixedly connected with jib (8) by bolt in this spherical hollow space center; Three power racks (3) can be fixed in bolts hole different in adjustable plectane (2) as required, a power source (4) is respectively equipped with in two power rack (3) ends in these three power racks (3), power source (4) connects a roller shaft (7) through a jaw clutch (5), roller shaft (7) is above each fills a roller (6), this roller (6) and the inwall Structure deformation performing connector (1) spherical hollow space; A roller (6) is directly equipped with and this roller (6) and the inwall Structure deformation performing connector (1) spherical hollow space in another power rack (3) end.

2. according to claim 1, this under-actuated robot wrist mechanism based on diameter of Spherical Volume can by regulating the angle between fixed position adjustment roller (6) of power rack (3) on adjustable plectane (2), the axis of the roller (3) that three power racks (3) three place is corresponding to be ensured during adjustment and perform the centre of sphere of connector (1) at grade, to form drive lacking travel mechanism.