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In this paper we use optimal control on a geared electric DC motor to compare the energetic efficiency of a simulation of conceptual monoped hoppers with either parallel elastic actuation (PEA) or series elastic actuation (SEA). The energy is measured using three cost functions: positive actuator work, electrical losses, and positive electrical work. For PEA, the presence of the motor inertia in the...
The development of variable impedance actuators (VIAs) has highlighted the need for proper control of passive impedance to attain suitable interaction performance. Until recently the regulation of the intrinsic impedance in VIAs is achieved in an open-loop model-based manner, mainly due to the lack of physical sensors capable of measuring impedance components such as stiffness and damping. Hence,...
Similar to combustion engines comprising multiple cylinders engaged with a crankshaft, multiple piezoelectric stack actuators (PSA) engaged with a common output rod can produce smooth, long stroke motion with desired properties. In particular, when equally spaced multiple units are arranged to push sinusoidal gear teeth on the output rod, the system exhibits unique collective behaviors thanks to “harmonic”...
This paper studies the dynamic performance of an electric machine integrated with the trans-rotary magnetic gear (MITROMAG) in a motoring mode of operation. MITROMAG is formed by mechanically coupling a rotary electric machine to the rotor of a trans-rotary magnetic gear (TROMAG). TROMAG is a magnetic device that converts low-torque, high-speed rotation of its rotor to a high-force, low-speed linear...
Using robots for very wide operating ranges, as in the case of concrete pumps, requires that elastic deformations of the links be taken into account. From a structural point of view a rigid design is impossible. In addition, these applications demand actuators with a significant power density, able to produce high forces with fast response which can be achieved profitably by the use of hydraulic actuators...
Large space structures often consist of truss elements which are connected by bolted joints. The dry friction energy dissipation in these junctions turns out to be a major source of damping. For vibration suppression, the joints are designed such that the normal force to a frictional interface is controlled which improves damping performance. The use of active control to vary the normal contact force...
This paper deals with single-wheel suspension car model. The benefits of controlled semi-active suspensions compared to passive ones are here emphasized. The contribution relies on robust analysis of a H∞ controller which improves comfort and road holding of the car under industrial specifications. Simulations on an exact nonlinear model of the suspension are performed for control validation.
The port-Hamiltonian formalism is a very powerful tool for describing dynamical systems and their interconnections and for designing control laws with specified energetic properties. In this paper, in particular, it is shown how a variable structure control can be designed in this general framework in order to achieve a passive systems with, additionally, the robust properties obtainable with variable...
In this paper, a new semiactive control approach is presented to stabilize a base isolated structure subjected to parametric uncertainties and unknown disturbances. In the controller design, the actuator dynamics (time delay and frictional effects) are taken into account. The ultimate boundedness is achieved in the closed-loop system. Numerical simulation is done for a 10 story base isolated building,...
This paper presents an investigation on the performance of algorithms in semi active suspension system. A validated full car model was used for this purpose. The semi active suspension system is using the magnetorheological (MR) damper as its variable damping damper element. The Skyhook and Modified Skyhook algorithms are used to control the operation of the MR damper model in the semi active suspension...
This paper proposes a conceptually simple Si-based shock-protection micro-platform to be integrated with MEMS devices. The micro-platform is able to generate a mitigated shock condition under impact via beam structures and air damping. This paper provides calculations of kinematic and mechanical parameters of the system, including stiffness coefficient and squeeze film damping coefficient, to offer...
Based on comprehensive theoretical analysis of all parts of digital hydraulic cylinder, a nonlinear mathematical model was deduced. The model includes the dynamics of spool and feedback mechanism, and also covers factors such as backlash, radial leakage, overlap and dynamic friction, which make it more reasonable and perfect. Based on the model, simulation experiments were carried out to investigate...
In this paper, a new control strategy is developed to improve comfort and roadholding of a ground vehicle equipped with an industrial damper. This damper can be controlled by means of a small servomechanism which adjusts the damping rate. The main controller is a linear parameter varying (LPV ) static state-feedback controller synthesized in the ℋ∞/LPV framework to compute the required damping force...
Magnetorheological (MR) dampers have received special attention as semi-active devices for mitigation of structural vibrations. Because of the inherent nonlinearity of these devices, it is difficult to obtain a reasonable mathematical inverse model. This paper is concerned with two related concepts. On one hand, it presents a new inverse model of MR dampers based on the normalized Bouc-Wen model....
In this article the modeling and control design aspects of an electrostatic microactuator (EmA) with squeezed thin film damping effects are presented. The modeling analysis of the squeezed film damping effect is investigated in the case of an EmA composed by a set of two plates. The bottom plate is clamped to the ground, while the moving plate is driven by an electrically induced force which is opposed...
A control system of a Magneto-Rheological (MR) damper force based on the Internal Model Control (IMC) strategy is proposed. Dynamic models of the MR damper were built exploiting Artificial Neural Networks (ANN). The control system was implemented with a controller based on an inverse ANN model of the MR damper and a forward model as internal nominal model. The feasibility of the control system was...
This paper applies the concept of the output frequency response function (OFRF) derived recently by the authors to analyse the effects of the nonlinear damping characteristic parameters in a MR damper on the output frequency response of a single degree of freedom (SDOF) vibrating system, where the MR damper is directly used to dissipate the vibration energy. The results gained from this work are of...
In mixed reality, real objects can be used to interact with virtual objects. However, unlike in the real world, real objects do not encounter any opposite reaction force when pushing against virtual objects. The lack of reaction force during manipulation prevents users from perceiving the mass of virtual objects. Although this could be addressed by equipping real objects with force-feedback devices,...
In this paper, a design method of frequency-domain damping(FDD) to improve stability is proposed. In recent days, haptics is one of major topics in robotics field. Especially tele-operation with haptic feedback has been studied for long years, but problem of time delay still exists. Time delay causes three problems : operational force, oscillating motion, and degrading of contact stability. To solve...
The acceleration based force control is very important component in motion control. Looking ahead the development of the robotics system in the future, realization with high accuracy of the force control is essential. Since it is controlled so as to follow the external environment, the control performance completely depends on an impedance of the contact object. In generally, the velocity feedback...
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