Search results for "Motor control"
showing 10 items of 164 documents
An Online Observer for Minimization of Pulsating Torque in SMPM Motors.
2015
A persistent problem of surface mounted permanent magnet (SMPM) motors is the non-uniformity of the developed torque. Either the motor design or the motor control needs to be improved in order to minimize the periodic disturbances. This paper proposes a new control technique for reducing periodic disturbances in permanent magnet (PM) electro-mechanical actuators, by advancing a new observer/estimator paradigm. A recursive estimation algorithm is implemented for online control. The compensating signal is identified and added as feedback to the control signal of the servo motor. Compensation is evaluated for different values of the input signal, to show robustness of the proposed method.
How is gravity integrated into motor planning : behavioural and fMRI approaches
2016
Gravity is immutable, ubiquitous and affects the dynamic of our daily movements. The gravitational attraction (9.81 m / s2) which varies less than 1% of the earth's surface, is an actress of the evolution of all living species. Thanks to an efficient sensorimotor system, the dynamical consequences of the effects of gravity on our movements are stored as internal representations. To circumvent the time delays of the afferent signals coming from the sensorimotor system (too long to plan quick movements), the Central Nervous System (CNS) acts in a proactive fashion by using suitable internal models developed during our past experiences. These models are mainly used during the motor planning to…
Effects of muscle action type on corticospinal excitability and triceps surae muscle-tendon mechanics
2014
The present study was designed to investigate corticospinal excitability modulation during maximum isometric and eccentric muscle actions with two different velocities. Moreover, the study aimed to clarify the effect of muscle action type on muscle-tendon mechanical behavior in order to shed light into the possible role of sensory information in modulating corticospinal excitability during different muscle actions. We compared motor evoked potentials (MEPs) to transcranial magnetic stimulation and Hoffman reflexes (H-reflex) in soleus muscle during isometric, slow eccentric (25 deg/s) and fast eccentric (100 deg/s) muscle actions. Concomitantly, ultrasonography was utilized to access soleus…
Theta power and theta-gamma coupling during formation of novel representations in the infant brain
2021
Item does not contain fulltext Building object representations is crucial for understanding the visual world, but it is not yet understood how infants start to form these representations. In adults, theta power is higher during presentation of stimuli that were later remembered, compared to those later forgotten (Friese et al., 2013), and the coupling between theta phase and gamma amplitude has been shown to be responsible for binding perceptual features to form representations. Theta-gamma coupling has been observed, for example, during the formation of visual associations (Köster, Finger, Graetz, Kater & Gruber, 2018), and was again higher for remembered than forgotten stimuli. Theta-gamm…
Energy-related optimal control accounts for gravitational load: comparing shoulder, elbow, and wrist rotations.
2013
International audience; Gaveau J, Berret B, Demougeot L, Fadiga L, Pozzo T, Papaxanthis C. Energy-related optimal control accounts for gravitational load: comparing shoulder, elbow, and wrist rotations. J Neurophysiol 111: 4-16, 2014. First published October 16, 2013; doi: 10.1152/jn.01029.2012.-We permanently deal with gravity force. Experimental evidences revealed that moving against gravity strongly differs from moving along the gravity vector. This directional asymmetry has been attributed to an optimal planning process that optimizes gravity force effects to minimize energy. Yet, only few studies have considered the case of vertical movements in the context of optimal control. What kin…
Age-related operator deficits in a realistic instrument-control task: Assessment of possssible motor, cognitive and mental causes
2017
Abstract With advancing age, motor and mental functions gradually change. As these changes have been revealed by standardized laboratory tests, it remains unclear how much they affect older persons' performance in industrial workplace tasks. The present study therefore compared young and older participants in a task modeled after a complex, realistic industrial workplace scenario, and additionally assessed motor, cognitive and mental variables that might have an impact on overall task efficiency. 25 participants (13 young, mean age 25 years; 12 older participants, mean age 65 years) sat in front of a panel with multiple displays - indicating the momentary state of a simulated nuclear power …
Descriptor-type Robust Kalman Filter and Neural Adaptive Speed Estimation Scheme for Sensorless Control of Induction Motor Drive Systems
2012
Abstract This paper deals with robust estimation of speed and rotor flux for sensorless control of motion control systems which use induction motors as actuators. Due to the observability lack of five and six order Extended Kalman Filters, speed is here estimated by means of a Total Least Square algorithm with Neural Adaptive mechanism. This allows the use of a fourth-order Kalman Filter for estimating rotor flux and to filter stator currents. To cope with motor-load parameter variations, a descriptor-type robust Kalman Filter is designed taking explicitly into account these variations. The descriptor-type structure allows direct translation of parameter variations into variations of the co…
Adiabatic invariants drive rhythmic human motion in variable gravity.
2019
Voluntary human movements are stereotyped. When modeled in the framework of classical mechanics they are expected to minimize cost functions that may include energy, a natural candidate from a physiological point of view also. In time-changing environments, however, energy is no longer conserved---regardless of frictional energy dissipation---and it is therefore not the preferred candidate for any cost function able to describe the subsequent changes in motor strategies. Adiabatic invariants are known to be relevant observables in such systems, although they still need to be investigated in human motor control. We fill this gap and show that the theory of adiabatic invariants provides an ac…
The sensorimotor and cognitive integration of gravity.
1998
In order to demonstrate that gravity is not only a load acting locally and continuously on the body limbs, but is also used by higher levels of the nervous system as a dynamic orienting reference for the elaboration of the motor act, a review of several experiments conducted both in 1 g and 0 g are presented. During various locomotor tasks, the strategy that consists of stabilizing the head with respect to gravity illustrates one of the solutions used by the CNS to optimize the control of dynamic equilibrium. A question which remains to be solved when considering experimental results obtained in weightlessness concerns, however, the maintenance of motor schema that has evolved under normal …
Grip Force Adjustments Reflect Prediction of Dynamic Consequences in Varying Gravitoinertial Fields
2018
International audience; Humans have a remarkable ability to adjust the way they manipulate tools through a genuine regulation of grip force according to the task. However, rapid changes in the dynamical context may challenge this skill, as shown in many experimental approaches. Most experiments adopt perturbation paradigms that affect only one sensory modality. We hypothesize that very fast adaptation can occur if coherent information from multiple sensory modalities is provided to the central nervous system. Here, we test whether participants can switch between different and never experienced dynamical environments induced by centrifugation of the body. Seven participants lifted an object …