Abstract-In this paper, a learning nonlinear proportional integral derivative (PID) controller is developed for vaguely modeled nonlinear systems under the influence of significant disturbance and noise. The control scheme is generic in nature, but it is applied specifically to the micropositioning of linear-piezoelectric motors in this paper. The design of the control scheme does not require a full mathematical model of the nonlinear system. Simulation and experimental results are provided to highlight the good motion control performance achieved from the control scheme.

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3D printing has emerged as one of the modern tissue engineering techniques that could potentially form scaffolds (with or without cells), which is useful in treating cardiovascular diseases. This technology has attracted extensive attention due to its possibility of curing disease in tissue engineering and organ regeneration. In this paper, we have developed a novel rotary forming device, prepared an alginate–gelatin solution for the fabrication of vessel-like structures, and further proposed a theoretical model to analyze the parameters of motion synchronization. Using this rotary forming device, we firstly establish a theoretical model to analyze the thickness under the different nozzle extrusion speeds, nozzle speeds, and servo motor speeds. Secondly, the experiments with alginate–gelatin solution are carried out to construct the vessel-like structures under all sorts of conditions. The experiment results show that the thickness cannot be adequately predicted by the theoretical model and the thickness can be controlled by changing the parameters. Finally, the optimized parameters of thickness have been adjusted to estimate the real thickness in 3D printing.

3D bioprinting is an emerging technology that drives us to construct the complicated tissues and organs consisting of various materials and cells, which has been in widespread use in tissue engineering and organ regeneration. However, the protection and accurate distribution of cells are the most urgent problems to achieve tissue and organ reconstruction. In this article, a multinozzle multichannel temperature deposition and manufacturing (MTDM) system is proposed to fabricate a blood vessel with heterogeneous materials and gradient hierarchical porous structures, which enables not only the reconstruction of a blood vessel with an accurate 3D model structure but also the capacity to distribute bioactive materials such as growth factors, nutrient substance, and so on. In addition, a coaxial focusing nozzle is proposed and designed to extrude the biomaterial and encapsulation material, which can protect the cell from damage. In the MTDM system, the tubular structure of a blood vessel was successfully fabricated with the different biomaterials, which proved that the MTDM system has a potential application prospect in tissue engineering and organ regeneration.

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Absfmcf-in this paper, the basic theory of repetitive control are summarized and modified repetitive controllers are introduced. The steady-state error and asymptotic stability condition are presented. A CNC precision lathe impiemented with repetitive control system for machining elliptical pistons are constructed by a precision linear servomechanism, computer itive controller and a machine-tool. driven directly by the linear servomechanism in radial direction of the piston tracks -section curve of the piston. Compared with the m a c h i~~~g results of a traditional piston CNC machinetools with a PID regular, the tracking error is reduced by 40 %. Keg words--noncircular manufacturing repetitive control linear servomechanism