The industrial robot family has many members and a large number of branches. According to different application fields, many types of robots can be extended, such as welding robots, bending robots, AGV, Parallel robots, etc. They have formed a diverse world of intelligent manufacturing industry in the modern industrial sector.
On some modern industrial production lines, there is a robot with a round and rolling body resembling a spider, paired with several slender "feet", which attracts people's curious gaze. They are working in an inverted position, sorting and packaging quickly and accurately, and are capable operators of the production line. These spider-like things are members of the industrial robot family-parallel robots.
This article will provide a detailed explanation of some knowledge about parallel robots and their application fields. A parallel robot is a type of robot structure in which two or more robotic arms are connected by sharing one or more common fixed points (commonly referred to as "bases" or "end platforms"). Each robotic arm can move within its degrees of freedom, and these robotic arms can work together simultaneously. In contrast, a serial robot is a continuous chain formed by connecting one robotic arm to the end of another robotic arm.
*01 Development Process
The structural design of parallel robots can be traced back to 1965. Its development process is summarized as follows:
In 1965, British scholar Stewart proposed the 6-degree-of-freedom flight simulator, also known as the Stewart platform mechanism, in his article "A Platform with Six Degrees of Freedom."
In 1978, Australian scholar Hunt first introduced the Stewart platform mechanism into robots.
In 1985, Clavel from the Swiss Federal Institute of Technology in Lausanne (EPFL) invented a parallel robot with 3-degree-of-freedom spatial translation as shown in Figure (a) and named it the Delta robot. Delta robots generally adopt a suspended layout, with a base placed on top and the wrist supported by three parallel connecting rods evenly distributed in space. The robot can be controlled by the swing angle of the connecting rods shown in Figure (b) to position the wrist within a certain spatial cylinder.
*02 Structure and Working Principle of Parallel Robots
The structure of parallel robots typically includes multiple actuators (usually joints or linear actuators) and one or more platforms. These actuators are connected to the platform through connecting rods or chains, forming a complex parallel structure. This structure endows parallel robots with unique motion performance and capabilities.
The working principle of parallel robots originates from the collaborative action of multiple actuators, which enables robots to perform movements in a more complex and precise manner. Unlike traditional serial robots, where each joint is cascaded, parallel robots' actuators can simultaneously act on the same end platform, achieving faster and more precise movements. Specifically, by simultaneously adjusting the length, angle, or position of each actuator, the robot can achieve highly flexible motion, including various motion modes such as translation, rotation, and tilt.
*03 Characteristics of Parallel Robots
1. High rigidity and precision: Due to the shared base of each robotic arm in parallel robots, their connection structures are usually very rigid, which helps to provide high-precision motion control.
2. High load capacity: Parallel robots are usually able to withstand large loads because their structure allows the load to be distributed across multiple robotic arms.
3. Parallel Motion: The robotic arms of parallel robots can simultaneously coordinate motion, allowing them to achieve parallel motion and potentially be more efficient in specific applications.
4. Rapid movement: Due to the ability of multiple robotic arms to move simultaneously, parallel robots can complete tasks more quickly in certain situations.
5. Wide applicability: Parallel robots are suitable for many fields, including industrial manufacturing, medical surgery, flight simulation, aerospace, etc.
6. Complex motion planning: Although parallel robots have high flexibility, motion planning and control may also be more challenging due to their complex structure.
7. Workplace constraints: Due to the fact that the robotic arm is connected through a shared base, the workspace of parallel robots may be subject to certain constraints.
*04 Application Fields
In the industrial field, parallel robots provide valuable solutions for many application scenarios due to their high precision, high speed, and complex motion control capabilities.
1. Assembly and assembly: Parallel robots are crucial in the assembly production line and can efficiently complete fine assembly tasks. They can quickly and accurately locate and assemble parts, thereby improving product quality and production efficiency.
2. Parts handling and sorting: During the parts handling and sorting process in the factory, parallel robots can quickly and accurately grasp, handle, and sort various parts, reducing labor costs and improving production efficiency.
3. Part inspection and quality control: Parallel robots play a key role in part inspection and quality control. They can use sensors to detect the size, shape, and quality of parts, and respond promptly to detect and correct production problems in advance.
4. Robot-assisted manufacturing: In some industrial manufacturing processes, robots can serve as an extension of manual operations, expanding human work capabilities. For example, robots can handle difficult-to-reach positions or spaces when manufacturing complex structures, thereby improving production efficiency and quality.
Overall, due to the characteristics of high precision, high speed, and multiple degrees of freedom in the industrial field, parallel robots have a wide range of applications. From traditional manufacturing to modern smart factories, they all play an important role in improving production efficiency, enhancing product quality, and reducing costs.