This numerical study focuses on the assignment of poles to a planetary gear train to avoid resonance, which can cause the failure of the system. The control strategy is output feedback, which involves feeding back the displacement and velocity to achieve active stiffness and damping respectively. The reverse process was considered. This occurs when the predicted control gains were assigned by the actuators, which were placed on the translational directions of either the carrier or the sun gear bearing mounted on the shaft. In addition, the closed-loop poles were assigned in the case whereby the actuators were positioned in the translational directions of either the carrier or the sun gear. The active control was considered using both the fixed and rotating frames of reference at a carrier speed of 100 rpm. Numerical examples are presented using both reference frames with the sensors and actuators collocated. The results show that the poles of the modes with lower frequencies, which are predominantly translational modes, can be shifted while the poles of the higher modes, which are predominantly rotational remain unchanged.

Two-electrode (2E) configuration was successfully utilised in the electrochemical deposition of cadmium telluride (CdTe) on fluorine-doped tin oxide (FTO) substrate with the main emphasis on the electrolytic bath pH. The electrochemical deposition pH explored is within the range of (1.00 to 6.00)±0.02 for the aqueous electrolyte comprising of tellurium oxide (TeO2) and cadmium nitrate (Cd(NO3)2) which are the respective precursors of Te and Cd. The optical, structural, morphological, compositional, and electrical properties of the electroplated CdTe thin-films were respectively explored using UV-Vis spectrophotometry, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and photoelectrochemical (PEC) cell measurements. The optical characterisation show that the CdTe samples exhibit dissimilar absorbance depending on the growth pH for both the as-deposited layers and post-growth treated CdTe layers. A decrease in the absorption edge slope and dip in the bandgap was observed away from pH2. The bandgap of the post-growth treated CdTe layers showed enhancement as it leans towards 1.45 eV, with the trend retention of absorption edge slope, similar to the as-deposited CdTe layers. The electrodeposited CdTe thin-films show a dominant orientation along the cubic (111) CdTe plane, while both the the calculated crystallite size and the XRD peak intensity Pi decreases with the electroplating pH outside the (2.00 to 3.00)±0.02 range. The EDX analyses depicts an alteration in the ratio of Cd to Te atomic percentage relative to the pH of the electrolyte. Comparatively high Te atomic ratio was observed at lower pH values and vice versa with increase alkalinity of the electrolyte. The obtained morphology depicts that the underlying FTO layers are well covered with a gradual reduction in the grain size of the CdTe observable away from pH value (2.00 and 3.00). The photoelectrochemical cell study depicts that the conduction type of the CdTe layers can also be attributed to the CdTe-electrolytic bath pH value.

This paper presents analytical and numerical studies on the active assignment of poles to a planetary gear system for vibration control in order to avoid resonance. This involves feeding back the displacement and velocity to add active stiffness and damping, respectively. A rotating frame of reference has been adopted in order to describe the dynamics over a broad range of rotational speed. As an illustration, the closed loop poles were assigned to the translational directions of the sun gear first and thereafter the carrier. This can be achieved by placing the actuators on the outer race of their bearings mounted onto their shafts. The controller was designed such that the closed loop poles can be assigned considering the rotational speed. In this way, it is possible to apply a robust pole-placement that is insensitive to the rotational speed. Numerical examples, where sensors and actuators were collocated, are presented to demonstrate the feasibility of the method when applied to a physical system. The results shows that the active control force and power required for the system, when rotating, can be determined using a rotating frame of reference and transformed for practical implementation. In addition, the same conjugate poles were assigned to the carrier and sun gear and the optimal place to apply control forces was discovered. This depends upon the control power required to shift the poles from one location to another. The results show that more control power will be required to shift the poles of the system when poles were assigned to the sun gear, where higher active bearing stiffness was required. Therefore, the optimal place to assign poles in this case is the carrier due to lower control power required to shift the system poles.

The mesh stiffness of gear teeth is one of the major sources of excitation in gear systems. Many analytical and finite element methods have been proposed in order to determine the mesh stiffness of gears especially parallel axis spur gears. Most of these methods are not trivial because they involve complicated analyses which incorporate parameters like gear tooth error, gear spalling sizes and shapes, nonlinear contact stiffness and sliding friction before mesh stiffness can be determined. In this work, a method is proposed to determine the sun-planet and ring-planet mesh stiffnesses of a planetary gear system. This approach involves fitting a relationship between the measured natural frequencies from an experimental modal test and natural frequencies predicted using an analytical model of a planetary gear. This method is relatively easier compared to the existing methods which involve complicated analyses. For this study, the average mesh stiffness estimated is 12.5 MN/m.

The mesh stiffness of gear teeth is one of the major sources of excitation in gear systems. Many analytical and finite element methods have been proposed in order to determine the mesh stiffness of gears especially parallel axis spur gears. Most of these methods are not trivial because they involve complicated analyses which incorporate parameters like gear tooth error, gear spalling sizes and shapes, nonlinear contact stiffness and sliding friction before mesh stiffness can be determined. In this work, a method is proposed to determine the sun-planet and ring-planet mesh stiffnesses of a planetary gear system. This approach involves fitting a relationship between the measured natural frequencies from an experimental modal test and natural frequencies predicted using an analytical model of a planetary gear. This method is relatively easier compared to the existing methods which involve complicated analyses. For this study, the average mesh stiffness estimated is 12.5 MN/m.