Robot joints are the basic units that make up the mechanical structure of a robot. By combining joints, various movements of the robot can be achieved. The following is a detailed introduction to several common types of robot joints and their connection methods.
1. Revolute Joint
Definition: A joint that allows rotation along an axis, similar to the wrist or elbow in the human body.
Features:
• Single degree of freedom: Allows rotation only around one axis.
• Rotation angle: It can be a finite range of angles or an infinite rotation (continuous rotation).
application:
• Industrial robots: Used to achieve the rotational movement of an arm.
• Service robots: Used for head or arm rotation.
Connection method:
• Direct connection: The joint rotation is directly driven by the motor.
• Gear reducer connection: Use a gear reducer to reduce the motor speed and increase torque.
2. Prismatic Joint
Definition: A joint that allows linear movement along an axis, similar to the extension and retraction of a human arm.
Features:
• Single degree of freedom: Allows only linear movement along one axis.
• Linear displacement: can be a finite range of displacement or a large displacement distance.
application:
• Gantry robot: Used to achieve linear motion along the X and Y axes.
• Stacking robots: Used for moving goods up and down.
Connection method:
• Lead screw connection: Linear motion is achieved through the cooperation of a lead screw and a nut.
• Linear guide connection: Achieve smooth linear motion using linear guides and sliders.
3. Fixed Joint
Definition: A joint that does not allow any relative movement and is mainly used to fix two parts.
Features:
• Zero degrees of freedom: No degrees of freedom of movement are provided.
• Rigid connection: Ensures that there is no relative movement between the two parts.
application:
• Robot base: The basic structure used to secure the robot.
• Fixed part of the robotic arm: The fixed section used to connect different joints.
Connection method:
• Welding: Permanently fix two parts together.
• Screw connection: It can be disassembled by fastening with screws.
4. Composite Joint
Definition: A joint that combines rotation and translation functions, enabling more complex movements.
Features:
• Multiple degrees of freedom: It can simultaneously achieve rotation and translation.
• High flexibility: Suitable for occasions requiring multiple degrees of freedom of movement.
application:
• Dual-arm collaborative robots: used to achieve complex arm movements.
• Bionic robots: robots that mimic the complex movement patterns of living organisms.
Connection method:
• Integrated motor: The rotation and translation functions are integrated into a single motor.
• Multi-joint combination: Achieve multi-degree-of-freedom motion by combining multiple single-degree-of-freedom joints.
5. Spherical Joint
Definition: Allows rotational movement along three mutually perpendicular axes, similar to the human shoulder joint.
Features:
• Three degrees of freedom: It can rotate in three directions.
• High flexibility: Suitable for applications requiring a wide range of motion.
application:
• Six-axis industrial robots: used to achieve a wide range of arm movements.
• Service robots: Used for multi-directional rotation of the head or arms.
Connection method:
• Spherical bearings: Rotation in three directions is achieved through spherical bearings.
• Multi-axis motor: Uses multiple motors to drive rotation in different directions.
Summary of connection methods
Different connection methods determine the performance and applicability of robot joints:
1. Direct connection: Suitable for small, lightly loaded robot joints, directly driven by motors.
2. Reducer connection: Suitable for robot joints that require large torque, the reducer reduces the speed and increases the torque.
3. Lead screw connection: Suitable for joints that require linear motion, achieved through the cooperation of a lead screw and a nut.
4. Linear guide rail connection: Suitable for joints that require smooth linear motion, achieved through linear guide rails and sliders.
5. Welding: Suitable for components that require permanent fixation, achieving rigid connections through welding.
6. Screw connection: Suitable for components that require detachable connection, achieved by fastening with screws.
Summarize
The selection and connection method of robot joints depend on specific application requirements, including range of motion, load capacity, and accuracy requirements. Through proper design and selection, efficient and flexible robot movement can be achieved. Different joint types and connection methods can be combined to meet the needs of various scenarios.
