Robot calibration is the process by which a robot’s movements and the timing of those movements are set to the proper values, usually relative to some default setting. It is a very important process, particularly in industries where many robots are coordinated to work on a task that often requires significant precision in timing and movement. If a robot is a few centimeters or a few seconds off in an industrial project, it could interrupt the entire process and result in a great deal of lost productivity. Proper robot calibration ensures that the programs that govern the robot’s motion are set to proper starting values and that all motion relative to those values is as it should be.
The process of calibrating a robot is by no means simple. There are many different variables that must be accounted for, even in the case of simple robots. The geometry of the robot, for example, and its surroundings must be taken into consideration in the programming. For a robot with many moving parts, this can be very difficult to organize. Robot calibration is done to ensure that the various functional parts of a robot do not interfere with each other and are not impeded by the environment.
There are two main aspects of robot calibration: kinematic calibration and dynamic calibration. Both kinematics and dynamics are concerned with the movement of the various parts of the robot. Kinematics is generally concerned with the motion of the parts of the robot without consideration for the mechanisms by which those parts move. Dynamic robot calibration is more concerned with the parts of the robot itself than with their precise positions in space. Dynamic calibration, for example, takes friction and mass into consideration while kinematic calibration is concerned with position in space.
Robot calibration normally involves a significant amount of external measurement to ensure that the robot and all of its parts are where they need to be. Lasers, rulers, triangulation, and other methods can all be used to ensure precise positioning. Precision in this area is very important, as measurement generally determines the values that direct the motion of the robot.
The programs that are used for robot calibration are generally based on the mathematical principles of optimization. The motions are optimized to be as efficient as possible—the shortest and fastest possible movements are used. In this manner, industrial processes that involve robots are allowed to proceed quickly and with minimal wasted time and energy.