This paper investigates a class of Lagrangian control systems with n degrees-offreedom (DOF) and n − 1 actuators, assuming that n − 1 virtual holonomic constraints have been enforced via feedback, and a basic regularity condition holds. The reduced dynamics of such systems are described by a second-order unforced differential equation. We present necessary and sufficient conditions under which ...

Conducting polymer actuators are biocompatible with a small footprint, and operate in air or liquid media under low actuation voltages. This makes them excellent actuators for macroand micro-manipulation devices, however, their positioning ability or accuracy is adversely affected by their hysteresis non-linearity under open-loop control strategies. In this paper, we establish a hysteresis mode...

My research focuses primarily on optimal control of systems in domains with contacts, equipped with variable impedance actuators. The control of such robots is non-trivial due to the the discontinuity in the dynamics which is introduced by mechanical contact with the environment. The traditional optimal control approach is designed to handle smooth continuous system dynamics for tasks over a pr...

Hysteretic dynamical systems are challenging to control due to their hard nonlinearity and difficulty in modeling. One type of systemwith hysteretic dynamics that is gaining use in aerospace systems is the shape-memory alloy-based actuator. These actuators provide aircraft and spacecraft systems with the ability to achieve component-level or vehicle-level geometry or shape changes. Characteriza...

The passive dynamic walker (PDW) has an interesting characteristic that it realizes cyclic locomotion without planning joint trajectories. On the other hand, the walking behavior cannot be controlled because it is dominated by the fixed body dynamics. Observing the human cyclic locomotion that is activated by elastic muscles, we adopt a compliant hip joint on PDW, and we propose the ”phasic dyn...

The piezo tutorial "Actuators for dynamic applications" or Actuator 2 describes dynamic applications, where dynamics (acceleration, damping) can be neglected. However, in many applications, dynamics play an important role and have to be taken into account in the design process. The tutorial gives an introduction to dynamic applications. Also the Mason model used to model, analyze and estimate t...

In this paper, we derive a sensor-based nonlinear dynamic inversion (NDI) control law for system with first-order linear actuators, and compare it to incremental (INDI), which has gained popularity in recent years. It is shown that, actuator dynamics, INDI approximates the corresponding NDI arbitrarily well under condition of sufficiently fast actuators. If bandwidth low compared changes states...

This paper is concerned with tracking control of series elastic actuators unmatched disturbances based on sliding mode control. The state- and disturbance-observers are constructed to estimate the states mismatched actuators, respectively. Using argument differential flatness, desired generated modified by estimation disturbances. Then, a linear surface in terms errors designed, dynamics transf...