Jeff Pieper

Doubly Fed Induction Generator (DFIG) based wind turbinesare particularly sensitive to grid disturbances, which has implications for overall power system stability. Grid codes require continual operation of DFIGs despite certain system disturbances. During a three-phase voltage dip, the decay of a natural flux fixed to the stator of the machine induces large voltages in the rotor windings, leading to saturation of rotor converters and potential damage to the system. This work presents a novel dual-loop state-plane based architecture to solve the stator flux transient, allowing the system to regain standard operation and power reference tracking in a fast and effective manner. An outer loop geometric controller is proposed as a framework for achieving rapid and controllable transients in the decoupled state space, and various reference geometries are considered. The proposed control structure implements a unique continuous solution for both steady state and transient operating conditions and does not require any additional hardware, switching circuits, or fault detection mechanisms. Performance-based tuning is used to determine a controller that optimizes the performance index across a variety of grid fault levels, and the resultant controller is shown to achieve rapid transient response for all fault levels, with power reference tracking achieved in under one line cycle ($\text{20}\,\text{ms}$) for even the most extreme grid faults. The proposed controller is supported by detailed mathematical analysis and validated by simulation results.

The paper presents a novel method which generates hopping gaits for an articulated single leg. Inspired by human running, the flight phase is assumed to be nearly-passive. Consequently, the initial joint velocities of the flight phase can be solved by using a static optimization procedure, provided that the boundary joint angles have been picked in advance. The two hopping phases can then be dynamically optimized, with the velocity jumps of the joints predicted by a simple collision model. The direct single shooting method solves the nonlinear constrained optimization problem. Ground reaction forces and the zero-moment-point serve as constraints. Simulation results show that the proposed approach produces energy-efficient hopping gaits.

Mechatronics is inherently abstract. However, the concepts and applications can lead to practical issues as in control system implementation. The mechatronics program at the University of Calgary is aiming at the intersection of practical and abstract. In a yearlong experiential learning course involving a sequence of labs, students are asked to consider issues of control saturation, tuning, bias, operating range and linearity in design of combined mechanical and control systems. Graduates of the program are uniquely trained as mechatronics engineers, different from mechanical, manufacturing, electrical or instrumentation engineers. Success can be measured by both student satisfaction, via exit surveys and course evaluations, and from career opportunities found of graduates. The latter has shown to be successful in placements ranging from research to design