In this study, a control scheme for the stand‐alone generation system based on brushless doubly‐fed machine (BDFM) is presented. The output voltage amplitude and frequency are kept constant under variable rotor speed and load by regulating the amplitude and frequency of the control winding (CW) current of BDFM appropriately. The control scheme utilises a CW current vector controller as the inner loop, and a power winding voltage amplitude controller and a frequency controller as the outer loop. The proposed control scheme has been implemented on a prototype BDFM designed for the variable‐speed stand‐alone ship shaft generation application. Moreover, the satisfactory dynamic performance and low total harmonic distortion of the output voltage in the proposed stand‐alone generation system is verified by experiments with two kinds of typical loads: three‐phase induction motor load and three‐phase RL inductive load.

In an independent power generation system, the amplitude and frequency of the power generation voltage are easily affected by the fluctuation of the external load and harmonic pollution. The power quality may also be reduced by relatively imprecise measurements. In this regard, a measuring and reconstruction algorithm based on an improved second‐order generalised integrator configured as a quadrature signal generator (SOGI‐QSG) and phase locked loop (PLL) for three‐phase alternating current signals has been proposed in this study. The amplitudes and direct current components of the measured signals are obtained from three SOGI‐QSGs. The inverse function of sine is introduced to optimise the phase error that has been used to quickly acquire fundamental frequency and phase of the measured signals. Moreover, the phase sequence of the measured signals is determined by the sign function. Compared with a traditional dual second order generalised integrator PLL, quick responses and reconstruction performances of the proposed algorithm are validated by experiments.

Laser triangulation sensors (LTS) are widely used to acquire depth information in industrial applications. However, the parameters of the components, e.g., the camera, of the off-the-shelf LTS are typically unknown. This makes it difficult to recalibrate the degenerated LTS devices during regular maintenance operations. In this paper, a novel one-dimensional target-based camera intrinsic matrix-free LTS calibration method is proposed. In contrast to conventional methods that calibrate the LTS based on the precise camera intrinsic matrix, we formulate the LTS calibration as an optimization problem taking all parameters of the LTS into account, simultaneously. In this way, many pairs of the camera intrinsic matrix and the equation of the laser plane can be solved and different pairs of parameters are equivalent for displacement measurement. A closed-form solution of the position of the one-dimensional target is proposed to make the parameters of the LTS optimizable. The results of simulations and experiments show that the proposed method can calibrate the LTS without knowing the camera intrinsic matrix. In addition, the proposed approach significantly improves the displacement measurement precision of the LTS after calibration. In conclusion, the proposed method proved that the precise camera intrinsic matrix is not the necessary condition for LTS displacement measurement.

Purpose: This paper aims to propose a novel robot kinematic calibration method based on the common perpendicular line (CPL) model to improve the absolute accuracy of industrial robots. Design/methodology/approach: The deviation between the nominal and actual twists is considered the CPL transformation, which includes the rotation about the CPL and the translation along the CPL. By using the invariance of the reciprocal product of the two spatial lines, the previous deviation was analyzed in the neighbor space of the base frame origin. In this space, the line vector of the CPL contained only four independent parameters: two orientation elements and two moment elements. Thus, the CPL model has four independent parameters for the revolute joint and two parameters for the prismatic joint. Findings: By simulations and experiment conducted on a SCARA robot and a 6-DOF PUMA robot, the effectiveness of the novel method for calibration of industrial robot is validated. Originality/value: The CPL model avoided the normalization and orthogonalization in the iterative identification procedure. Therefore, identifying the CPL model was not only simpler but also more accurate than that of the traditional model. In addition, the results of the CPL transformation strictly conformed to the constraints of the twist.

Register control systems are a necessary technical measure and an important means of large-scale roll-to-roll industrial printing production. They are effective in reducing the generation of unqualified printing products and improving the accuracy and stability of industrial printing production lines. In this paper, we propose a new register control algorithm that effectively improves the detection accuracy and compensation speed of printing register control systems. Firstly, according to the principle of register color mark detection, a new pulse-width subdivision detection algorithm is proposed, which can greatly improve the accuracy of register error detection without increasing the resolution of external encoder pulse signals. Then, the optimized error compensation method can adaptively adjust the corresponding system parameters, such as the output intensity, error filtering period and output period, according to the current register error size. The new output method greatly improves the error compensation speed without increasing error oscillation. Lastly, the experimental results of 0.01 mm show that the proposed control approach significantly improves the detection accuracy of register errors. Furthermore, the new control algorithm can be applied in the industrial field.

A novel online algorithm to identify the moment of inertia, viscous friction coefficient, and load torque of PMSM (Permanent Magnet Synchronous Motor) drives and a distinctive autotuning speed control scheme are presented. The proposed identification algorithm does not require motors run in a particular trajectory and only needs a short identification time. A Luenberger speed observer is introduced to eliminate noises which are generated by the detection of position signal and to improve the accuracy of identified parameters. Parameters of the speed controller are optimized by analyzing the mathematical model of the system and the formula of the PI controller. Compared to a standard recursive least squares method (RLSM) and traditional PI algorithm, the effectiveness of the proposed identification algorithm and autotuning speed control scheme are validated through simulations and experiments.