Parallel robots are currently a very mature robot product, and also the fastest industrial robots. They are also known in the industry as spider-arm robots.
First, let's understand parallel robots and serial robots.
Serial robots, with their serial structure, form an open kinematic chain, where all moving links do not form a closed chain. Serial robots offer a large workspace, making motion analysis relatively easy and avoiding coupling effects between drive axes. However, each axis must be controlled independently, requiring encoders and sensors to improve the accuracy of the mechanism's movements.
Parallel robots and traditional serial industrial robots complement each other in application, forming a closed kinematic chain. Parallel robots are less prone to dynamic errors, exhibiting high accuracy with no error accumulation. Furthermore, their compact and stable structure, with most of the output shaft bearing axial force, results in high machine rigidity and large load-bearing capacity. However, solving the position problem for parallel robots using forward tracing is more difficult than using inverse kinematics.
II. Mechanism of Parallel Robots
1. Static Platform: Used to mount and secure servo motors and intermediate axes, ensuring stable operation in high-frequency, high-intensity working environments. The static platform is used to install and secure the top mechanism of the parallel robot, including all servo motors. This platform houses several drive axes, each with its own servo motor, including the intermediate axes.
2. Moving platform: Connected to the lower end of the driven boom, used for suspending loads and can operate within the boom's reach. The moving platform is the lowest platform where grippers or suction cups are mounted. Moving platforms generally have no drive mechanism; if other drive mechanisms are needed, they are usually pneumatic valves, etc., but these are typically installed later.
3. Driving arm and driven arm. Carbon fiber is used to effectively improve the strength ratio, connecting the servo motor and the driven arm. Many people ask why carbon fiber is used. The answer is simple: the delta speed is very high. If a load of 3-12 kg needs to be maintained, carbon fiber can meet the requirements of being lightweight, high-strength, and non-deformable, thus ensuring accuracy.
III. Characteristics of Parallel Robots
1. No cumulative error, high accuracy;
2. The drive unit can be placed on or near a fixed platform, which makes the moving parts lightweight, high-speed, and with good dynamic response;
3. Compact structure, high rigidity, and large load-bearing capacity;
4. Completely symmetrical parallel mechanisms have good isotropy;
5. The workspace is relatively small.
