Technical parameters are the technical data provided by robot manufacturers when supplying products. Different robots have different technical parameters, and the specific parameters provided by different manufacturers may not perfectly align with user requirements. However, the main technical parameters of a robot generally include: degrees of freedom, positioning accuracy and repeatability, working range, maximum working speed, and load capacity.
Degrees of Freedom
Degrees of freedom refer to the number of independent coordinate axes of motion a robot possesses, excluding the opening and closing degrees of freedom of the gripper (end-effector). Describing the pose of an object in three-dimensional space requires six degrees of freedom. However, a robot's degrees of freedom are designed according to its intended use; it may have fewer than six degrees of freedom or more. For example, the A4020 assembly robot has four degrees of freedom and can insert electronic components onto printed circuit boards; the PUMA562 robot has six degrees of freedom and can perform arc welding operations on complex spatial curved surfaces. From a kinematic perspective, a robot with extra degrees of freedom when performing a specific task is called a redundant degree-of-freedom robot, or simply a redundant robot. For example, when the PUMA562 robot performs the task of connecting electronic components on a printed circuit board, it becomes a redundant robot. Utilizing redundant degrees of freedom can increase a robot's flexibility, obstacle avoidance, and improve dynamic performance. The human arm (upper arm, forearm, wrist) has seven degrees of freedom, making it very dexterous; the hand can avoid obstacles and reach the same destination from different directions.
Most robots are generally open-chain mechanisms, but they may contain locally closed-loop mechanisms. Closed-loop mechanisms can increase rigidity but limit the range of motion of the joints, thus reducing the workspace.
Positioning Accuracy
Robot accuracy includes positioning accuracy and repeatability. Positioning accuracy refers to the difference between the actual position reached by the robot's hand and the target position. Repeatability refers to the robot's ability to repeatedly position its hand at the same target position, which can be represented by the standard deviation statistic. It measures the density of a series of error values, i.e., repeatability.
The positioning accuracy of a robot arm is determined by the usage requirements. The positioning accuracy that the robot arm can achieve depends on factors such as positioning method, movement speed, control method, arm stiffness, drive method, and buffering method.