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ABSTRACT: The limiting possibilities of the protection of the human head from impacts by means of helmets are analyzed. The shell (base)
of the helmet is assumed to decelerate after an impact against an obstacle with constant acceleration during a given time
interval. The minimum of the peak magnitude of the displacement of the head (the object to be protected) relative to the helmet
shell is determined, provided that the injury risk index does not exceed a prescribed tolerable value, as well as the corresponding
time history of the absolute acceleration of the head. The injury risk index is defined by the HIC functional. This functional
is adopted as a standard measure for the head injury risk in crash tests of vehicles, as well as in the tests of shock protection
equipment for industries and sports. The time history of the motion of the head and the peak magnitude of the displacement
of the head relative to the helmet shell are studied as functions of the shock pulse duration (the deceleration time of the
helmet shell). The case of the instantaneous shock, when the shell comes to an instantaneous stop after hitting the obstacle,
was considered in [1].
Journal of Computer and Systems Sciences International 05/2012; 47(1):93-102. · 0.17 Impact Factor
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ABSTRACT: A limiting performance of shock isolation is studied for an object modeled by two rigid bodies connected by a viscoelastic
element with a linear characteristic. The object is attached to a movable base by means of a shock isolator, which is regarded
as a device that produces a control force between the base and the object. The base and the object move along the same straight
line. The base is subject to an external shock excitation that is characterized by the time history of the acceleration of
the base. A control law is defined for the shock isolator to minimize the maximum magnitude of the displacement of the object
relative to the base, provided that the force of interaction between the components of the object does not exceed a prescribed
value. An algorithm for constructing the exact solution of the problem under certain assumptions is presented. A technique
for constructing an approximate solution for an object having high stiffness is described. The optimal control is shown to
have impulse components. Examples are given. The two-component model considered in the paper is known to have been utilized
to describe the mechanical response of a human body to a shock load along the spine or from thorax to back. Therefore, the
problem under consideration can be regarded as a benchmark optimal control problem for a system that protects from injuries
cased by shock loads. Solution of such problems is highly topical for development of safety systems for vehicles.
Journal of Computer and Systems Sciences International 04/2012; 48(2):206-219. · 0.17 Impact Factor
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ABSTRACT: The optimal control of the deceleration of a particle moving along a straight line after an impact against a surface covered with an impact isolation coating is considered. The force applied to the particle by the surface is treated as the control variable, that is, the control force replaces the coating. The deceleration distance is minimized under the constrained value of the HIC functional - an integral criterion that is utilized in engineering biomechanics to evaluate the expected severity of impact-induced head injury of a human being. The solution indicates the limiting capabilities of the prevention from the head injuries in the case of traffic accidents, falling, or other occurrences by means of an appropriate coating of the surface against which impacts can occur.
Physics and Control, 2005. Proceedings. 2005 International Conference; 09/2005
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ABSTRACT: A review of recent research on the limiting performance analysis of impact isolation systems for injury prevention is presented. A limiting performance analysis establishes the absolute optimum for a performance index measuring the quality of an isolation system by solving an optimal control problem. Problems related to the optimal design of a crashworthy helicopter seat, automobile seatbelts, and sporting helmets are discussed.
Physics and Control, 2003. Proceedings. 2003 International Conference; 09/2003
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ABSTRACT: An effective method for damping elastic vibration of load-carrying
structures by means of a dynamic absorber is suggested. The control law
is defined as a linear feedback with respect to the absolute
displacement and velocity of the load and the displacement and velocity
of the absorber body relative to the load. Two methods of adjusting the
feedback gains are compared. One method is based on the maximization of
the system degree of stability. It provides a rapid damping but can lead
to unacceptably large displacement of the absorber body if its mass is
small compared with that of the load. In the second method, the feedback
with respect to the variables of motion of the load is weaker, which
decreases the damping rate but reduced the maximum displacement of the
absorber body. An optimal combination of these two damping modes makes
it possible to provide an acceptable performance of the damping process
Control of Oscillations and Chaos, 2000. Proceedings. 2000 2nd International Conference; 02/2000
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ABSTRACT: For a simple vibroimpact system consisting of a particle moving on
a line segment between two rigid stops, a time-optimal feedback control
driving the particle from an arbitrary initial state to a prescribed
terminal position is constructed. The control variable is the force
applied to the particle, the magnitude of this force being constrained
by a given number
Control of Oscillations and Chaos, 2000. Proceedings. 2000 2nd International Conference; 02/2000
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ABSTRACT: The static interaction of a two-member linkage with a given surface is investigated. Dry friction acts at the point of contact
of the linkage with the surface. The linkage has two drives generating torques at its joints. The optimal distribution of
the joint torques is determined to maximize the friction force at the point of contact. The dependence of this maximal force
on the lengths of the links and on the linkage configuration is investigated. The results obtained can be applied to the analysis
and optimization of various robotic systems, in particular, manipulators interacting with rough surfaces and walking machines,
especially tube-crawling robots.
Archive of Applied Mechanics 07/1999; 69(7):429-442. · 0.95 Impact Factor
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ABSTRACT: The tube-crawling robot is an eight-legged walking machine that
moves inside pipe-lines and can be used for inspection, maintenance, and
repair. Optimization of structural parameters and possible gaits of the
robot is discussed. The results obtained by computer simulation show a
considerable sensitivity of operation characteristics of the robot with
respect to its geometrical and kinematic parameters
Robot Motion and Control, 1999. RoMoCo '99. Proceedings of the First Workshop on; 02/1999
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ABSTRACT: Optimal control methods present an efficient approach to construct controls of robotic manipulators. Much recent research has been devoted to different problems of optimal control for industrial robots. In this paper we give a brief survey of work done in this field and present some new results on optimization of robotic motions. Manipulation robots governed by electromechanical drives are considered. We obtain open-loop and feedback time-optimal controls for robotic motions using both analytical and numerical methods. The results show that optimal controls can lead to a considerable improvement in the time taken for transport operations performed by robots.
Optimal Control Applications and Methods 09/1989; 10(4):293 - 311. · 0.65 Impact Factor
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ABSTRACT: The controlled motion of a rigid inhomogeneous cylinder over a rough horizontal plane is considered. The control is provided by controlled motion of internal masses. Mathematical models are constructed that correspond to rolling without loss of contact or slippage. The conditions for the physical implementability of such a motion are derived. The case where the internal moving masses from a rigid flywheel the centre of inertia of which lies on the axis of the cylinder is investigated in detail. A near-time-optimal feedback control that enables the total energy to be changed in a required way is constructed on the basis of an asymptotic approach. The main operating modes are simulated, namely, swinging up of the cylinder to a large angular amplitude, rotation with a prescribed energy, deceleration of rolling to a complete stop, and oscillations and rotations in the neighbourhood of the separatrix.
Journal of Applied Mathematics and Mechanics.
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ABSTRACT: Plane rotational motions of an elastic rod loaded by a perfectly rigid body and acted upon by a controlling moment of forces, are considered. A system of integrodifferential equations with initial and boundary conditions is obtained. The problems of control are studied, which carried the system from some initial state to a given angular state with damping of elastic oscillations or to a state when the system rotates as a whole with fixed angular velocity. These formulations appear in the course of considering a whole series of practical problems of controlling the systems with elastic constraints such as robots and manipulators, weight lifting machines, etc. The asymptotic methods are used to obtain the solution of the control problems stated, close to the two limiting cases: 1) the case of weightless rod (quasistatic approximation) and 2) the case of high flexural rigidity. The problems of dynamics and control of oscillating systems with distributed parameters were studied in /1–11/ et al.
Journal of Applied Mathematics and Mechanics. 46(4):465-471.
