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robot with dart

Industrial robots require high levels of accuracy and repeatability. Repeatability is a measure of the ability of the robot to consistently reach a specified point. Accuracy is a measure of the error between the value of the point the robot is programmed to go to and value of the point the robot actually goes to. Repeatability and accuracy are interrelated.

To help understand these two concepts better, let’s say there is a robot which can place darts into a dartboard target.

  • If the darts are placed all over the board, but none are in the bullseye, the robot has poor accuracy and poor repeatability.
  • If a few of the darts are in the bullseye, but the rest are scattered around the target, the robot has some accuracy, but poor repeatability.
  • If all of the darts are grouped near the outside edge of the target, the robot has poor accuracy, but good repeatability.
  • If all the darts are grouped in the bullseye, the robot has good accuracy and good repeatability.

Accuracy and repeatability can be affected by the quality of the robotic equipment, environmental conditions (such as the difference between a dusty environment and a clean one), calibration issues, and machine wear.

It is important to determine the repeatability and accuracy of industrial robots when considering them for specific applications. For example a robot which is moving posts used for artificial teeth in dental implants needs to have a higher level of accuracy, than a robot handling posts for a highway guard rail system.