Unveiling the Implementation of the Host Computer Software for High-Speed Centrifugal Machine Dynamic Balancing Systems

　　 High-speed centrifuge Thanks to their versatility and high speed, these centrifuges are widely used in various laboratories. In response to market demand, centrifuge manufacturers have further developed high-speed centrifuges that integrate vacuum, high-speed operation, and cooling functions into a single unit. These advanced centrifuges enable rapid separation of large quantities of cells, subcellular organelles, bacteria, and viruses, thereby facilitating the isolation of nucleic acids, proteins, cells, and nanomaterials. They can meet the experimental needs of researchers in fields such as animal science, food science, and life sciences.

　　The advantage of using the influence coefficient method for dynamic balancing in high-speed centrifuges lies in the fact that it ultimately reduces the dynamic balancing problem to solving a system of linear equations. This method is remarkably simple and highly conducive to numerical computation by computers. Since the shaft system of a centrifuge employing air bearings exhibits very high stiffness—approaching rigidity—testing the vibration response of the shaft system reveals that the vibration responses measured by micrometers on the upper and lower test surfaces are linearly related to the unbalance amounts on the corresponding upper and lower correction planes. The coefficient of this linear relationship is precisely what is known as the influence coefficient. The influence coefficient method involves applying a well-defined excitation—a supplementary unbalance—to the dynamic balancing system, measuring the resulting vibration response, and then identifying the influence coefficients of the dynamic balancing system based on the observed relationship between the excitation and the response. Finally, using these influence coefficients, the original unbalance amounts can be calculated.

　　High-speed centrifuge centrifugation technology has been established and developed based on the behavior of tiny particles in a centrifugal force field. The rotor of a centrifuge rotates in a circular motion at a stable angular velocity, thereby generating a powerful centrifugal force field that radiates outward. This force imparts a centrifugal acceleration to any object placed within the field, subjecting it to an outward centrifugal force. The centrifugal force field G generated by the centrifuge can be calculated using the following formula:

　　G = ω²r ω — angular velocity of the rotor r — radius of rotation (the distance from the position of a material particle to the center of rotation)

　　The centrifugal force field of high-speed centrifuges is commonly expressed in terms of relative centrifugal force (RCF). The magnitude of the relative centrifugal force is indicated as a multiple of Earth's gravitational acceleration (g), namely:

　　RCF = ω²r/g × g = (2πn)²r/60²g × g = 1.119 × 10⁻⁵ × n²r × g N—rotor speed, rpm/min; g—acceleration due to gravity, 980.6 cm/s²; Sedimentation velocity refers to the distance traveled by particles along the radial direction per unit time under the influence of strong centrifugal force.

　　When the particles (or macromolecules) of the substance to be separated rotate together with the rotor in a centrifuge tube, they are subjected to a direct centrifugal force Fc acting along the radial direction. Fc = Mω²r, where M is the mass of the particle(s) being separated.

　　The settling velocity v of a high-speed centrifuge is given by: v = 6.092 × 10⁻⁴ × D² (ρ - ρm) n² r / ηm where: D — particle diameter, cm; ρ and ρm are the densities of the particle and the medium, respectively, in g/cm³; ηm — viscosity of the medium, in units of Pascal-seconds (Pa·s).

　　The host computer software for the dynamic balancing system primarily uses the influence coefficient method or the comprehensive solution algorithm to calculate the imbalance magnitude and direction, ultimately determining the size and orientation of the rotor's unbalance. The software’s main functions include:

　　Implementation of the Host Computer Software for the High-Speed Centrifugal Machine Dynamic Balancing System:

　　1. Communicate with the spindle controller, wait for the spindle to reach a constant rotational speed, receive micrometer and angle data, and record the data in a file.

　　2. Perform a fast Fourier transform on the data collected from the micrometer to isolate the first harmonic, which is closely related to the unbalance magnitude, and then display the data and log it in a log file.

　　3. Initial out-of-roundness compensation, frequency response compensation, and initial phase compensation. The imbalance amounts are solved separately using the influence coefficient method and the comprehensive solution algorithm, yielding both the magnitude and direction of the imbalance, which are then displayed.

　　4. Communicate with the unloading system to convert force sensor data, display it on LEDs, and log it in a file.

　　The high-speed centrifuge dynamic balancing system consists of data acquisition, data analysis and processing, unbalance magnitude calculation, and an actuation component. To ensure the accuracy of system balancing, a high-performance capacitive displacement sensor is selected as the vibration measurement transducer. Through data processing of the vibration signals, the primary harmonic component responsible for generating unbalanced vibrations is isolated. The unbalance magnitude is then calculated using the influence coefficient method. Finally, a PLC controls a stepper motor to drive the balancing slider on the centrifuge’s adjusting surface, thereby completing the dynamic balancing of the high-speed centrifuge.