Dynamic neural network-based robust observers for uncertain nonlinear systems.

A dynamic neural network (DNN) based robust observer for uncertain nonlinear systems is developed. The observer structure consists of a DNN to estimate the system dynamics on-line, a dynamic filter to estimate the unmeasurable state and a sliding mode feedback term to account for modeling errors and exogenous disturbances. The observed states are proven to asymptotically converge to the system states of high-order uncertain nonlinear systems through Lyapunov-based analysis. Simulations and experiments on a two-link robot manipulator are performed to show the effectiveness of the proposed method in comparison to several other state estimation methods.

Body rate decoupling using haltere mid-stroke measurements for inertial flight stabilization in Diptera.

Halteres, the modified rear wings of Diptera, have long been recognized as sensory organs necessary for basic flight stability. These organs, which act as vibrating structure gyroscopes, are known to sense strains proportional to Coriolis accelerations. While compensatory responses have been demonstrated that indicate the ability of insects to distinguish all components of the body rate vector, the specific mechanism by which the halteres are able to decouple the body rates has not been clearly understood. The research documented in this report describes a potential mechanism, using averaged strain and strain rate at the center of the haltere stroke, to decouple the inertial rate components. Through dynamic simulation of a nonlinear model of the haltere 3-dimensional trajectory, this straightforward method was demonstrated to provide an accurate means of generating signals that are proportional to three orthogonal body rate components. Errors associated with residual nonlinearity and rate-coupling were quantified for a bilaterally reconstructed body rate vector over a full range of pitch and yaw rates and two roll rate conditions. Models that are compatible with insect physiology are proposed for performing necessary signal averaging and bilateral processing.

Urinary symptoms and quality of life in women following urogenital fistula repair: a long-term follow-up study.

Using the Bristol Female Lower Urinary Tract Symptom questionnaire, we have investigated urinary and sexual symptoms and quality of life in a group of 31 women 50 months (median) after successful repair of urogenital fistula. All had undergone urodynamic investigation prior to their repair surgery, and only 36% had normal findings. Almost all women reported one or more symptoms, and for 65%, these caused at least 'a bit of a problem', although 87% said that their urinary symptoms had little or no impact on their quality of life. Symptoms were similar in urethrovaginal and vesicovaginal fistulae and were not significantly associated with prior functional abnormality.

Experimental demonstration of an actuated exercise machine.

Experimental results are obtained for a single degree of freedom prototype next generation exercise machine that aims to maximize the user's power output and ensure passivity with the user. In an effort to optimize the user's power expenditure, the desired velocity trajectory is developed that seeks the unknown user-dependent optimal velocity setpoint. A numerical extremum-seeking algorithm is utilized to seek the optimal velocity setpoint while ensuring the trajectory is sufficiently differentiable. To track the reference trajectory and to ensure passivity, a nonlinear controller is utilized.

Repetitive learning control: a Lyapunov-based approach.

In this paper, a learning-based feedforward term is developed to solve a general control problem in the presence of unknown nonlinear dynamics with a known period. Since the learning-based feedforward term is generated from a straightforward Lyapunov-like stability analysis, the control designer can utilize other Lyapunov-based design techniques to develop hybrid control schemes that utilize learning-based feedforward terms to compensate for periodic dynamics and other Lyapunov-based approaches (e.g., adaptive-based feedforward terms) to compensate for nonperiodic dynamics. To illustrate this point, a hybrid adaptive/learning control scheme is utilized to achieve global asymptotic link position tracking for a robot manipulator.

Adaptive tracking control of a wheeled mobile robot via an uncalibrated camera system.

This paper considers the problem of position/orientation tracking control of wheeled mobile robots via visual servoing in the presence of parametric uncertainty associated with the mechanical dynamics and the camera system. Specifically, we design an adaptive controller that compensates for uncertain camera and mechanical parameters and ensures global asymptotic position/orientation tracking. Simulation and experimental results are included to illustrate the performance of the control law.

Global exponential tracking control of a mobile robot system via a PE condition.

This paper presents the design of a differentiable, kinematic control law that achieves global asymptotic tracking. In addition, we also illustrate how the proposed kinematic controller provides global exponential tracking provided the reference trajectory satisfies a mild persistency of excitation (PE) condition. We also illustrate how the proposed kinematic controller can be slightly modified to provide for global asymptotic regulation of both the position and orientation of the mobile robot. Finally, we embed the differentiable kinematic controller inside of an adaptive controller that fosters global asymptotic tracking despite parametric uncertainty associated with the dynamic model. Experimental results are also provided to illustrate the performance of the proposed adaptive tracking controller.

Heredity and environment in phoneme articulation: hereditary and environmental contributions to articulation proficiency.

Large twin samples and recent applications of multiple regression techniques to behavioral genetics methodology makes possible evaluation of genetic and environmental contributions to the articulation proficiency of individual phonemes. Factor analysis of the articulation scores from 256 MZ and DZ twins and 124 of their non-twin siblings (all children ranged from 2; 11 to 9; 8 years) were conducted to reduce a 50-item articulation test to a more manageable set of five articulation factors. The twins' factor scores were then analyzed using multiple regression procedures to determine the extent to which the individual factors resulted from genetic and/or environmental influences. The /r/ and /[symbol: see text], t[symbol: see text], d[symbol: see text]/ factors were found to have strong genetic components, while the /l, j, w/ factor was found to be strongly influenced by environmental sources of variation.

The factor structure of the Rorschach for adolescent inpatients.

The factor structure of the Rorschach inkblot test was examined using a sample of 268 adolescent inpatients (including 105 with conduct disorders and 105 with depressive disorders). An initial analysis found a four-factor solution for both the conduct-disordered and depressive-disordered groups. However, examination of the factor patterns suggested that these groups did not yield significantly different factor structures. Thus, for the final analysis all inpatients were combined, and a single three-factor solution was found. These factors were substantively similar to the initial analysis and were interpreted as consisting of (a) struggles with affective expression, (b) general psychological health, and (c) perceptual organization.

Measuring symbolic play style in infancy: a methodological approach.

Researchers have examined symbolic play style as a qualitative variable distinguishing two groups of children: patterners and dramatists. We have conceptualized style not as a typology of children but as reflecting dimensions of difference between children which are amenable to quantitative analysis. For the construct of style to be invoked, it must be measurable by many variables, it must be observable over time, and it ought to be demonstrably independent of general developmental level. Fifteen boys and 15 girls were each seen twice, once at 21 months of age and again 6 weeks later. The Session 2 pattern of correlations among hypothesized dramatist measures was not entirely consistent with that observed at Session 1; however, three measures, narrative vocalizations, spontaneous play, and elicited-appropriate play were primary dramatist measures at both sessions.