Practical Tracking Control Under Actuator Saturation for a Class of Flexible-Joint Robotic Manipulators Driven by DC Motors

This paper is devoted to the practical tracking control for a class of flexible-joint robotic manipulators driven by DC motors. Different from the related literature where control constraint is neglected and the disturbances are excluded or only exist in one subsystem, actuator saturation is considered in this paper while the disturbances are present in all the three subsystems. This leads to the incapability of the traditional schemes on this topic. For this, a novel control design scheme is proposed by skillfully incorporating adaptive dynamic compensation technique, constructive methods of command filters and an auxiliary system for the actuator saturation into the backstepping framework, and in turn to design a practical tracking controller which ensures that all the states of the resulting closed-loop system are bounded and the system output practically tracks the reference signal. It is worthwhile strengthening that a more wider class of reference signals can be tracked since they are only first order continuously differentiable but twice or more in the related literature. Finally, a numerical example is provided to validate the effectiveness of the proposed theoretical results.

Attitude Control of a Flexible Spacecraft via Fuzzy Optimal Variance Technique

This paper investigates the performance of a fuzzy optimal variance control technique for attitude stability and vibration attenuation with regard to a spacecraft made of a rigid platform and multiple flexible appendages that can be retargeted to the line of sight. The proposed technique addresses the problem of actuators’ amplitude and rate constraints. The fuzzy model of the spacecraft is developed based on the Takagi-Sugeno(T-S) fuzzy model with disturbances, and the control input is designed using the Parallel Distributed Compensation technique (PDC). The problem is presented as an optimization problem in the form of Linear Matrix Inequalities (LMIs). The performance and the stability of the proposed controller are investigated through numerical simulation.

Optimization of CC-Coil Design for Wireless Power Transfer System with Series-Series Magnetic Resonance Compensation Technique

This study aims to increase the coupling coefficient of the coils and power transfer efficiency (PTE) of the wireless power transfer (WPT) system. WPT system has a severe issue with the PTE as the transfer distance between the transmitter and receiver increases. Therefore, the transmitter and receiver of the single-circular coil (CC-coil) need to be optimized in geometry to maintain high coupling at an optimum distance. Ferrite and aluminum shielding are also crucial on CC-coil optimization. Implementing the series-series (S-S) magnetic resonance compensation technique can increase the PTE of the WPT system. Therefore, the CC-coil is optimized using Ansys Electronics Desktop and co-simulated with the magnetic resonance circuit using Ansys Twin Builder. The results show that the CC-coils' coupling coefficient increased by 21.38% with the shielding implementation. The maximum optimum transfer distance of 37 mm for horizontal misalignment and 30 mm for vertical misalignment. Implementing the S-S magnetic resonance compensation technique can improve the PTE and output power of the WPT system. The power transmitted also varied with the transfer distance, which caused the system's variation of input impedance. Hence, it is essential to consider the coil design and compensation circuit to achieve high PTE and output power at a higher transfer distance.

A Curvature Compensation Technique for Low-Voltage Bandgap Reference

Based on the standard 40 nm Complementary Metal Oxide Semiconductor (CMOS) process, a curvature compensation technique is proposed. Two low-voltage, low-power, high-precision bandgap voltage reference circuits are designed at a 1.2 V power supply. By adding IPTAT (positive temperature coefficient current) and ICTAT (negative temperature coefficient current) to the output resistance, the first-order compensation bandgap voltages can be obtained. Meanwhile, the third high-order compensation current is also superimposed on the same resistance. We make use of the collector current of the bipolar transistor to compensate for the nonlinear term of VBE. The simulation results show that TC (temperature coefficient) of the first circuit reference could be reduced from 29.1 × 10−6/°C to 5.71 × 10−6/°C over the temperature range of −25 to 125 °C after temperature compensation. The second one could be reduced from 17 × 10−6/°C to 5.22 × 10−6/°C.