With the rapid development of the robotics industry, industrial robots have been widely used in various industries, from material handling to machine maintenance, from welding to cutting, from assembly to spraying. We have found that these industrial robots have different shapes and functional performance. So what determines the flexibility and range of activity of industrial robots? This problem is quite complex, But there is a key factor that largely determines the flexibility and range of motion of robots, which is the degree of freedom of industrial robots, commonly known as the number of axes.
What are the degrees of freedom of industrial robots?
Usually used as a technical indicator for robots, it reflects the flexibility of robot actions and can be represented by the number of linear movements, swings, or rotations of the axis. The number of joints that a robot mechanism can independently move is called the degree of freedom of the robot mechanism, abbreviated as Degree of Freedom, which is abbreviated as DOF. The current control method used by industrial robots is to treat each joint on the robotic arm as a separate servo mechanism, that is, each axis corresponds to a server, and each server is controlled through a bus, which is controlled and coordinated by the controller.
IS08373 explains industrial robots as follows: "Robots have automatic control, reprogrammability, and multi-purpose functions. The robot operator has three or more programmable axes. In industrial automation applications, the robot's base can be fixed or movable. It can be seen that the number of axes of industrial robots is an important technical indicator.
The Application of Robots with Different Degrees of Freedom in Industry
The number of robot axes determines its degree of freedom. Is it better to have more degrees of freedom? The more degrees of freedom, the closer it is to the action function of the human hand, and the better its versatility; However, the more degrees of freedom, the more complex the structure, and the higher the overall requirements for robots, which is a contradiction in robot design. As the number of axes increases, the flexibility of the robot also increases. However, in current industrial applications, the most commonly used are three axis, four axis, five axis dual arm, and six axis industrial robots, and the selection of the number of axes usually depends on the specific application. This is because in some applications, high flexibility is not required, while three-axis and four-axis robots have higher cost-effectiveness, and three-axis and four-axis robots also have significant advantages in speed. If it is only for some simple applications, such as picking and placing parts between conveyor belts, then a four axis robot is sufficient. If the robot needs to work in a narrow space and the robotic arm needs to twist and reverse, a six axis or seven axis robot is the best choice.
Currently, six axis robots are the most widely used in the industrial field. An industrial robot with six joints is very similar to a human arm, with parts equivalent to the shoulders, elbows, and wrists. Its "shoulders" are usually installed on a fixed base structure. The function of a human arm is to move the hand to different positions, while the function of a six axis robot is to move the end effector and install various actuators suitable for specific application scenarios at the end of the robotic arm, such as grippers, spray lamps, drill bits, and sprayers, to complete different work tasks.
Recently, various robot manufacturers have released the latest human-machine collaborative robots, almost all of which use seven axis redundant degree of freedom industrial robots. Internationally renowned robot manufacturers have made efforts to launch new products for seven axis robots to seize the high-end new market. However, compared with traditional four axis and six axis industrial robots, the gap in product types and sales proportion is currently very significant.
The Development Trend of Redundant Degree of Freedom Robots
Six degrees of freedom are the minimum number of degrees of freedom that have the ability to complete spatial positioning. Robots with more than six axes are collectively referred to as redundant degrees of freedom robots. The research of robot kinematics aims to solve the movement or rotation of each joint when the end effector of the robot manipulator reaches a certain position in space, which is the cornerstone and key of the entire robotics. With the rapid development of human civilization, robots are required to complete tasks in many industrial, high-altitude, deep-sea, nuclear waste, and hazardous working environments. This places higher demands on the reliability, operability, and intelligence of robot motion control. In the future, as its accuracy continues to increase, redundant degree of freedom robots will have more advantages in obstacle avoidance, overcoming singular points, flexibility, and fault tolerance. In the face of complex working environments and ever-changing job demands, redundant degree of freedom industrial robots will have more places to use. I believe that in the near future, it will replace manual labor for more precise operations.