The use of actuators with inherent compliance, such as series elastic actuators (SEAs), has become traditional for robotic systems working in close contact with humans. SEAs can reduce the energy consumption for a given task compared to rigid actuators, but this reduction is highly dependent on the design of the SEA's elastic element. This design is often based on natural dynamics or a paramete...

A new approach to manage actuator redundancy in the presence of faults is proposed based on reliability indicators and a reference governor. The aim is to preserve the health of the actuators and the availability of the system both in the nominal behavior and in the presence of actuator faults. The use of reference governor control allocation is a solution to distribute the control efforts amon...

Heritage space telescope mirror technology—i.e. large, monolithic glass primary mirrors—has reached an upper limit on allowable aperture diameter given launch vehicle volume and mass constraints. The next generation of space telescopes will feature lightweight, actively controlled, segmented primary mirrors in order to achieve the advances in angular resolution and sensitivity that larger apert...

This paper presents a method for determining smooth and time-optimal path-constrained trajectories for robotic manipulators. The desired smoothness of the trajectory is imposed through limits on the actuator jerks. The third derivative of the path parameter with respect to time, the pseudo-jerk, is the controlled input. The limits on the actuator torques translate into state-dependent limits on...

This paper presents a novel observer-based robust fault predictive control (OBRFPC) approach for wind turbine time-delay system subject to constraints, actuator/sensor faults, and external disturbances. The proposed is based on an augmented state-space representation that contains variables estimation errors. then used synthesize controller. In addition, observer developed estimate both state f...

Control barrier functions have been demonstrated to be a useful method of ensuring constraint satisfaction for wide class controllers. However, the existing results are mostly restricted continuous-time systems. Mechanical systems, including robots, typically second-order systems in which control occurs at force/torque level. These actuator, velocity, and position constraints (i.e., relative de...

This paper discusses design considerations for a water cooled high acceleration 3-phase air-cored brushless DC PM linear actuator used in a vacuum radiation environment. Radiation can cause damage to magnets, and the requirement for a vacuum chamber around the moving parts imposes additional constraints that further complicate the electromagnetic and mechanical design of the actuator. This pape...

In active sensing, actuators are used to impart user-defined energy into a structure from which resulting sensor responses may be mined for useful information regarding the structure’s health. Optimal actuator-sensor placement works to maximize the observability of this information given two primary constraints: the number of actuators and sensors available for the network and the power availab...

A major challenge faced in the design of large-scale cyber-physical systems, such as power systems, the Internet of Things or intelligent transportation systems, is that traditional distributed optimal control methods do not scale gracefully, neither in controller synthesis nor in controller implementation, to systems composed of millions, billions or even trillions of interacting subsystems. T...