Adaptive controllers and robustness analysis for curve tracking with unknown control gains

We study adaptive control and parameter identification for robotic curve tracking under unknown control gains. We build adaptive controllers that identify the unknown control gains and stabilize equilibria corresponding to a fixed constant distance to the curve and zero bearing. Our strict Lyapunov function method allows us to prove robust performance under actuator errors in terms of integral input-to-state stability under a bound on the disturbance that maintains forward invariance of a class of invariant hexagons. This extends existing curve tracking results to allow controller uncertainty and parameter identification. We demonstrate our work in simulations. © 2012 AACC American Automatic Control Council)

Empowering Migrant Workers and Labor NGOs in China: Creating a Law Searching Tool through a Design Science Approach

Labor NGOs in China has been utilizing various social media tools, such as WeChat for networking workers and promotion. In the year 2017 WeChat Mini Program was released, allowing developers to create “sub-application” within WeChat. This research evolves from a laws-searching WeChat Mini Program development project, which will adopt a design science approach, follow the design science research methodology (DSRM) process model, and measure the effect of the WeChat Mini Program with the concepts from information systems success model and post-adoption behaviors. We propose that the law-searching WeChat Mini Program can sever labor NGOs in terms of legal service and promotion

Stability and robustness analysis for human pointing motions with acceleration under feedback delays

Pointer acceleration is often used in computer mice and other interfaces to increase the range and speed of pointing motions without sacrificing precision during slow movements. However, the effects of pointer acceleration are not yet well understood. We use a system perspective and feedback control to analyze the effects of pointer acceleration. We use a new pointer acceleration model connected in feedback with the vector integration to endpoint model for pointing motions. When there are no feedback delays, we prove global asymptotic stability of the closed loop system for a general class of acceleration profiles. We also prove robustness under delays and perturbations by building Lyapunov–Krasovskii functionals for delay systems, and we find state performance bounds using robust forward invariance with maximal perturbation sets. The results are relevant to designing pointing interfaces, and our simulations illustrate the good performance of our control under realistic operating conditions. Copyright © 2016 John Wiley & Sons, Ltd

Adaptive planar curve tracking control and robustness analysis under state constraints and unknown curvature

We provide adaptive controllers for curve tracking in the plane, under unknown curvatures and control uncertainty, which is a central problem in robotics. The system dynamics include a nonlinear dependence on the curvature, and are coupled with an estimator for the unknown curvature, to form the augmented error dynamics. We prove input-to-state stability of the augmented error dynamics with respect to an input that is represented by additive uncertainty on the control, under polygonal state constraints and under suitable known bounds on the curvature and on the control uncertainty. When the uncertainty is zero, this gives tracking of the curve and convergence of the curvature estimate to the unknown curvature. Our curvature identification result is a significant improvement over earlier results, which do not ensure parameter identification, or which identify the control gain but not the curvature