Introduction: Generally, the arm of a Cartesian coordinate industrial robot can move vertically up and down (Z-axis direction) and can move horizontally in two-dimensional planes (X and Y directions) along guide rails on the carriage and crossbeam. Clearly, a Cartesian coordinate industrial robot has three translational joints, or three degrees of freedom.
1. Cartesian coordinate type industrial robot
The positional changes of the arm are achieved by moving along three mutually perpendicular axes, commonly used in loading and unloading of production equipment and high-precision assembly and inspection operations. Generally, the arm of a Cartesian coordinate industrial robot can move vertically up and down (Z-axis direction) and can move horizontally in two dimensions (X and Y directions) along guide rails on the carriage and crossbeam. Clearly, a Cartesian coordinate industrial robot has three translational joints, or three degrees of freedom.
advantage:
• Simple structure;
Programming is easy; it allows for movement in the X, Y, and Z directions.
The motion is uncoupled, which facilitates the design of control systems;
• High linear motion speed, high positioning accuracy, and good obstacle avoidance performance;
Disadvantages and problems:
• Limited range of motion and poor flexibility;
• The guide rail structure is relatively complex and difficult to maintain. The exposed surface of the guide rail is large, and its sealing performance is not as good as that of the rotary joint.
• The structure is large in size and occupies a large area;
The large inertia of the moving parts increases the requirements for drive performance;
GND@ZLA4_LDBYHDCY（（BEKH
2. Cylindrical coordinate industrial robot
The schematic diagram of the cylindrical coordinate industrial robot is shown in the figure. It has two translational joints and one rotational joint. The pose of the mounting axis of the end effector is represented by the (z, r, θ) coordinates. Its main body has three degrees of freedom: waist rotation, lifting motion, and arm extension and retraction motion.
advantage:
• High control precision, simple control, and compact structure;
• Compared with the rectangular coordinate form, the two reciprocating motions in the vertical and longitudinal directions can adopt a simple telescopic sleeve structure. When the waist rotates, the arm can be retracted, thereby reducing the moment of inertia and improving the mechanical load.
• It has a small spatial size, a large working range, and the end effector can achieve a high movement speed.
Disadvantages and problems:
Due to the structure of the robot body, the arm cannot reach the bottom. The farther the end effector is from the z-axis, the smaller the robot's working range, and the lower the resolution of its tangential linear displacement.
3. Spherical coordinate industrial robots
A spherical coordinate industrial robot has two rotary joints and one translating joint. The pose of the end effector's mounting axis is represented by (θ, φ, r) coordinates. The robot can extend and retract, swing in the vertical plane, and move around its base in the horizontal plane because the robot's workspace forms part of a sphere.
Features:
It has a small footprint, a compact structure, and acceptable positioning accuracy.
• Poor shielding performance and balance issues;
4. Articulated coordinate industrial robots
It mainly consists of a base, an upper arm, and a forearm. The rotational joint between the upper arm and forearm is called the elbow joint, and the rotational joint between the upper arm and the base is called the shoulder joint. The base can rotate around a vertical axis, which is called the waist joint. It is a widely used anthropomorphic robot.
advantage:
• Compact structure and small footprint;
• Good flexibility, good hand positioning, and good performance.
Its shielding performance;
• No moving joints, good joint sealing performance, and low friction.
Small, small inertia;
• Low joint driving force and low energy consumption;
Disadvantages and problems:
• Balance issues exist during movement, and control is coupled;
• The robot's structural rigidity is good when the upper and lower arms are fully extended.
5. Parallel industrial robots
A parallel mechanism is a closed-loop mechanism in which the moving platform and the fixed platform are connected by at least two independent kinematic chains, the mechanism has two or more degrees of freedom, and is driven in parallel.
Disclaimer: This article is a reprint. If there are any copyright issues, please contact us promptly for deletion (QQ: 2737591964). We apologize for any inconvenience.
