So, what are the important technical parameters for selecting a collaborative robot? Let's take a look:
1. Payload
Payload is the weight a robot can carry. Collaborative robots typically have a payload capacity between 3 and 20 kg. All robots have a specified payload capacity, excluding the weight of end effectors (such as grippers) or auxiliary tools. This means that the actual payload a robot can carry must be the weight of the end effectors (such as grippers) subtracted from its nominal payload. If a thorough analysis of the robot's application is conducted, considering practical application requirements (such as acceleration) and physical parameters (such as the coefficient of friction), it may be necessary to appropriately reduce the robot's maximum payload. Similar to general motion control systems, reducing the load mass is beneficial for improving the system's dynamic characteristics (acceleration).
2. Weight
The weight of a robot determines whether it can be easily moved and repositioned, or whether a forklift or forklift AGV (Automated Guided Vehicle) is needed to perform the task. In some workshops, robots need to constantly change jobs to complete various production tasks. If the robot is too heavy, more manpower and time are required to move and fix it in place.
3. Repeatability
Often, people ask about the accuracy or precision of a robot's movements. But in the world of collaborative robots, this metric is actually quite meaningless. What we really need to know is repeatability. Since collaborative robots are typically programmed and planned through manual trial-and-error teaching/manual instruction, the ability of a robot to replicate and execute exactly the same movements, and to locate xyz coordinates with millimeter-level precision, is far more valuable. Currently, the maximum repeatability values for most collaborative robots are listed in their specifications. Therefore, when we test and use robots, we typically obtain repeatability values that are lower than their nominal values.
4. Security
Safety is paramount for collaborative robots due to their need for human-robot integration. While safety is a highly complex issue, many robot manufacturers still calibrate their products to appropriate safety levels, and most obtain safety certifications from third parties. Currently, the most stringent machine safety approval process is tÜV. This organization has approved safety certifications for numerous robots. However, there are many different variables involved in a robot's "safety" certification. The only point to clarify is that a robot's certification as safe does not necessarily mean that its application is safe.
5. Ease of use
Collaborative robots often require human cooperation. They frequently switch between different tasks, and the ease of programming and configuration directly determines the production and operational efficiency of the equipment. However, this metric is actually difficult to quantify because it heavily relies on people's operating and usage habits. The same interface or method of use may be easy for some but difficult for others. Therefore, this metric is always subjective.
6. Arm span
A robot's arm span refers to the maximum (farthest) distance that the robot's wrist can reach. This distance is usually measured from the bottom of the robot. There are many methods to measure the span of a robot's arm. In most cases, we choose the maximum distance that the robot's wrist can reach as a reference. Typically, the arm length of a collaborative robot is equal to the length of a human arm.
The key differences between collaborative robots and traditional industrial robots are readily apparent from their technical specifications. These key technical parameters also determine the different application areas for collaborative robots and industrial robots.
