Adaptive Pulse Width Control for Precise Positioning Under the Influence of Stiction and Coulomb Friction

1988 ◽  
Vol 110 (3) ◽  
pp. 221-227 ◽  
Author(s):  
Sangsik Yang ◽  
Masayoshi Tomizuka
Keyword(s):  
Pulse Width ◽  
Coulomb Friction ◽  
Sufficient Conditions ◽  
Control Object ◽  
Single Pulse ◽  
Static Friction ◽  
Adaptation Algorithm ◽  
Precise Positioning ◽  
Pulse Input ◽  
Point To Point

Conventional linear digital control fails to provide precise positioning of a control object under the influence of static friction, Coulomb friction, and backlash. This paper presents an adaptive pulse width control (PWC) scheme for a precise point-to-point positioning system. This scheme is developed based on the relationship between the displacement of a control object due to a single pulse input and the pulse width. The coefficient appearing in this relationship is estimated by a parameter adaptation algorithm. Sufficient conditions for asymptotic stability of this adaptive scheme are developed using Popov hyperstability theorem. This adaptive PWC is tested on a laboratory positioning table and is shown to be effective.

Pulse Width Control for Precise Positioning of Structurally Flexible Systems Subject to Stiction and Coulomb Friction

2004 ◽  
Vol 126 (1) ◽  
pp. 131-138 ◽  
Author(s):  
David B. Rathbun ◽  
Martin C. Berg ◽  
Keith W. Buffinton
Keyword(s):  
Limit Cycle ◽  
Pulse Width ◽  
Coulomb Friction ◽  
Closed Loop ◽  
Position Control ◽  
Industrial Robot ◽  
Sufficient Conditions ◽  
Position Error ◽  
Mass System ◽  
Precise Positioning

Pulse width control refers to the use of a control law to determine the duration of fixed-height force pulses for point-to-point position control of a plant that is subject to mechanical friction, including stiction. The use of constant-gain pulse width control laws for precise positioning of structurally flexible plants subject to stiction and Coulomb friction is analyzed. It is shown that when the plant is a simple two-mass system subject to stiction and Coulomb friction, a position error limit cycle can result. Sufficient conditions for stability and self-sustained oscillation of this closed-loop system are derived. The sufficient conditions for stability are used to determine conditions on the plant parameters and the control gain that guarantee closed-loop stability and thus limit-cycle-free operation and zero steady-state position error. The analysis methods that are introduced are demonstrated in applications to the control of the position of the end-effector of an industrial robot.

scholarly journals Effects of electrical stimulation on isolated rodent gastric smooth muscle cells evaluated via a joint computational simulation and experimental approach

2009 ◽  
Vol 297 (4) ◽  
pp. G672-G680 ◽  
Author(s):  
P. Du ◽  
S. Li ◽  
G. O'Grady ◽  
L. K. Cheng ◽  
A. J. Pullan ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Electrical Stimulation ◽  
Pulse Train ◽  
Pulse Width ◽  
Computational Simulation ◽  
Minimum Energy ◽  
Experimental Studies ◽  
Single Pulse ◽  
Plateau Phase ◽  
Wide Range

Gastric electrical stimulation (GES) involves the delivery of electrical impulses to the stomach for therapeutic purposes. New GES protocols are needed that are optimized for improved motility outcomes and energy efficiency. In this study, a biophysically based smooth muscle cell (SMC) model was modified on the basis of experimental data and employed in conjunction with experimental studies to define the effects of a large range of GES protocols on individual SMCs. For the validation studies, rat gastric SMCs were isolated and subjected to patch-clamp analysis during stimulation. Experimental results were in satisfactory agreement with simulation results. The results define the effects of a wide range of GES parameters (pulse width, amplitude, and pulse-train frequency) on isolated SMCs. The minimum pulse width required to invoke a supramechanical threshold response from SMCs (defined at −30 mV) was 65 ms (at 250-pA amplitude). The minimum amplitude required to invoke this threshold was 75 pA (at 1,000-ms pulse width). The amplitude of the invoked response beyond this threshold was proportional to the stimulation amplitude. A high-frequency train of stimuli (40 Hz; 10 ms, 150 pA) could invoke and maintain the SMC plateau phase while requiring 60% less power and accruing ∼30% less intracellular Ca2+ concentration during the plateau phase than a comparable single-pulse protocol could in a demonstrated example. Validated computational simulations are an effective strategy for efficiently identifying effective minimum-energy GES protocols, and pulse-train protocols may also help to reduce the power consumption of future GES devices.

Discussion on the Polarity Effect of EDM

2010 ◽  
Vol 154-155 ◽  
pp. 429-432 ◽  
Author(s):  
Wei Zhao
Keyword(s):  
Electric Discharge ◽  
Pulse Width ◽  
Single Pulse ◽  
Electric Discharge Machining ◽  
Polarity Effect ◽  
Large Pulse ◽  
Positive Ion

the problem of polarity effect in EDM is researched in this paper. In order to find out the deterioration of the anode and the cathode, the experiment with single pulse is taken in kerosene oil. We find the deterioration of the anode is larger than that of the cathode even in the condition of large pulse width. But this result is contradictory with that gotten in electric discharge machining with continue pulses. Through analyzing the movement of the electron and positive ion in plasma canal, we explain the phenomenon above rationally.

scholarly journals Synthesis of Guaranteed Stability Regions of a Nonstationary Nonlinear System with a Fuzzy Controller

2019 ◽  
Vol 5 (1) ◽  
pp. 107 ◽  
Author(s):  
Vasiliy Berdnikov ◽  
Valeriy Lokhin
Keyword(s):  
Lyapunov Functions ◽  
Pid Controller ◽  
Sufficient Conditions ◽  
Control Object ◽  
Fuzzy Pid ◽  
Nonlinear Characteristics ◽  
Stability Regions ◽  
Fuzzy Pid Controller ◽  
Quadratic Lyapunov Functions ◽  
Conditions Of Stability

The paper proposes a method for constructing guaranteed regions of stability of nonstationary nonlinear systems on the plane of parameters of a fuzzy PID controller. It is shown that this method allows to determine the full stability areas, which are significantly larger than the areas determined by classical methods (frequency circle criterion, quadratic Lyapunov functions). This improvement is achieved by using the algorithm for constructing spline Lyapunov functions. This type of Lyapunov functions is based on the necessary and sufficient conditions of stability, while the classical methods are only sufficient conditions of stability. In this regard, on the basis of the proposed method, it is possible to calculate the maximum sizes of the sectors in which the nonlinear characteristics in the channels of the fuzzy PID controller should be located. Examples of the synthesis of fuzzy P, PI, PID controllers for a nonstationary control object of the third order are given. Numerical experiments show that the expansion of the boundaries of nonlinear characteristics allows to improve the accuracy in the steady state, and also to almost double the speed of the automatic control system with a nonstationary object. The advantages over linear controllers are demonstrated. The proposed method guarantees the stability inside the calculated stability regions for any character of the change in the nonstationary parameter, as well as for any character of the change in the nonlinear characteristics in the corresponding sectors.

The Influence of the Skin Effect on the Amplitude of Single Pulse Gamma Detected NMR on Oriented Nuclei Signals

1990 ◽  
Vol 45 (1) ◽  
pp. 43-49
Author(s):  
D. J. Isbister ◽  
D. H. Chaplin
Keyword(s):  
Pulse Width ◽  
Skin Effect ◽  
Single Pulse ◽  
Skin Depth ◽  
Excitation Pulse ◽  
Field Amplitude ◽  
Broad Line ◽  
Experimental Conditions ◽  
Turn Angle ◽  
Pulse Nuclear Magnetic Resonance

AbstractThe effects of skin depth on gamma detected single pulse Nuclear Magnetic Resonance on Oriented Nuclei (NMRON) signals are theoretically explored for narrow, intermediate and broad line metallic samples, using the density matrix approach describing a pure Zeeman system. It is shown that the skin effect distortion of the signal can dominate over intermediate to broadline distortions for that range of experimental conditions generally applicable to ferromagnetic hosts. In particular, the skin effect distortions of the first maximum, obtained when the excitation pulse width is lengthened, are significant and can determine the accuracy of calibration of the radiofrequency "(rf)" field amplitude at the resonating nuclei when assigning an average turn angle to this maximum.

Friction-Compensating Command Shaping for Vibration Reduction

2004 ◽  
Vol 127 (4) ◽  
pp. 307-314 ◽  
Author(s):  
Jason Lawrence ◽  
William Singhose ◽  
Keith Hekman
Keyword(s):  
Steady State ◽  
Coulomb Friction ◽  
Vibration Reduction ◽  
Input Shaping ◽  
Residual Vibration ◽  
Command Shaping ◽  
Point Motion ◽  
Common Operation ◽  
Point To Point ◽  
Theoretical Developments

Fast and accurate point-to-point motion is a common operation for industrial machines, but vibration will frequently corrupt such motion. This paper develops commands that can move machines without vibration, even in the presence of Coulomb friction. Previous studies have shown that input shaping can be used on linear systems to produce point-to-point motion with no residual vibration. This paper extends command-shaping theory to nonlinear systems, specifically systems with Coulomb friction. This idea is applied to a PD-controlled mass with Coulomb friction to ground. The theoretical developments are experimentally verified on a solder cell machine. The results show that the new commands allow the proportional gain to be increased, resulting in reduced rise time, settling time, and steady-state error.

Electronic Analogue Computer Study of Non-Linear Effects in a Class of Hydraulic Servomechanisms

1968 ◽  
Vol 10 (4) ◽  
pp. 346-359 ◽  
Author(s):  
J. Panjaby
Keyword(s):  
Coulomb Friction ◽  
Equations Of Motion ◽  
Control Valve ◽  
Static Friction ◽  
Analogue Computer ◽  
Prime Mover ◽  
Hydraulic Jack ◽  
Computer Study ◽  
Non Linear ◽  
Linear Effects

An electronic analogue is first described, of a system comprising a prime mover controlled by a non-linear flyweight governor using a non-linear hydraulic jack/valve servomechanism as a power amplifier to operate the prime mover energy supply control valve. The governor non-linearity is due to static and Coulomb friction. When dimensionless equations of motion are used for the various components in the system, the analogue is representative of a type of control system often encountered in mechanical engineering. It is shown that the presence of static friction in the governor, of magnitude greater than the Coulomb friction, has a de-stabilizing eifect and limit cycling of the system in the autonomous and non-autonomous conditions, caused by governor friction, is examined.

Passive Q-Switching with Graphene Saturable Absorber in Nd:YAG Operating at 1064nm

2011 ◽  
Vol 694 ◽  
pp. 700-703 ◽  
Author(s):  
Man Jiang ◽  
Zhao Yu Ren ◽  
Yu Ping Zhang ◽  
Bao Le Lu ◽  
Ren Jian Zhang ◽  
...  
Keyword(s):  
Mechanical Property ◽  
Polyvinyl Alcohol ◽  
Pulse Width ◽  
Mechanical Characteristics ◽  
Single Pulse ◽  
Single Pulse Energy ◽  
Excellent Mechanical Property ◽  
Q Switching ◽  
Graphene Saturable Absorber ◽  
Easy Operation

A graphene-PVA film is fabricated by using polyvinyl alcohol(PVA), which provides excellent mechanical property and easy operation. Based on the numerous advantages of graphene in optical and mechanical characteristics,Graphene was used as absorber with passively Q-switched Nd:YAG solid laser in our experiment. Furthermore, there are no changes in the structure and characteristics of graphene. Inserting our graphene-PVA SA mirror to the Nd: YAG laser, we ultimately get that the single pulse energy is about 7.68μJ, and that the shortest pulse width is about 640ns. The experiment results prove that our graphene-PVA SA mirror is feasible and suitable for Q-switched lasers.

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