Calibration Concept

According to the National Standard, calibration is the process of comparing a measuring device with a standard, determining the amount of deviation from that standard, and adjusting the calibration if necessary to meet the relevant standards. In other words, calibration refers to the process of aligning the amount of movement of an axis with a specific standard unit or value. Common units used in industrial devices include millimeters, centimeters, meters, inches, feet, degrees, etc., and they can be used according to the requirement. Therefore, the concept of calibration, for example in the millimeter unit, can be defined as follows: aligning the amount of axis movement with the millimeter unit—meaning that in measurements using measuring tools, the amount of axis movement matches the value measured in millimeters.

In the Radonix controller, each axis can be calibrated individually, and axes can even be calibrated using different units. The variable that represents the calibration coefficient in this controller is the Step variable. To access this variable, open the Radonix software, then go to the Setting window, navigate to the System section and then to the Axis{n} subsection ({n} represents a number between 1 and 6, identifying the axis number). The Step variable can be found under these subsections, and each axis has its own unique Step variable. (For more details, please refer to System.)

Mathematical Concept of Calibration

The unit of this coefficient is defined as the number of pulses per unit of movement, and it can be simply described as the amount of axis movement in the desired unit for each pulse sent to the motor. For instance, if a user wants to calibrate an axis in millimeters, they must measure the amount of movement in millimeters per motor pulse to calculate the calibration coefficient or step value. Since this movement is usually very small, a large number of pulses is used for accurate measurement. The total movement is then divided by the number of pulses to find the amount of movement per pulse. For example, the movement is measured over 500,000 pulses, and the resulting value is divided by 500,000.

These calculated values also represent the numerical precision of the device. The smaller the number, the higher the numerical precision of the movement. However, this precision does not represent the final precision of the device. In reality, the final and true precision of the device is determined by a combination of numerical precision, the motion precision of the motors, and the mechanical precision of the device.

In the Radonix controller, values obtained for the movement step or calibration coefficient generally range from 10⁻² to 10⁻⁵, and can be calculated or measured with up to 12 significant digits. However, it is important to remember that the number of significant digits is limited by the precision of the measurement tools used.