A behavioural test-bed using a dataglove input device

In many cases, traditional hand-drawn animation has been replaced by computer technology. Computer-supported approaches can essentially be characterised as two interface types: keyframing and coding. However, these two interface types offer limited editing ability for scene animation applications, which usually consist of a large testing space of similar behaviours. The testing cycle, using either predefined keyframe sequences or general coding interface, tends to be costly and time consuming. This paper reports work which uses the DataGlove device to support and test variable schooling behaviours of fish in a virtual marine world. This is put forward as a representative example of scene animation. The glove-based interface places the user as a participant in the behavioural simulation process. In the work, hand shapes and motions are recognised and used for either event triggering or role switching. The specific shapes and motions of the user's hand trigger control signals or commands through a menu-based interface. The hand can itself be used to simulate an object in the scene. The object, which can be either static or dynamic, participates in the control process. Using hand movements in this way allows the user to interactively specify the paths of moving objects in the scene, and also creates a diversity of dynamic situations which can be useful for testing variable scene behaviours. The application presented in this paper looks at examples of controlling fish behaviour in a limited pond environment controlled by glove-based interaction.     

Design and validation of a desk-free and posture-independent input device

This study investigates variations in performance, postures and strains on the hand-arm-shoulder musculature during the operation of a wireless mouse, trackpad and a new input device. The device is held between the flexed index and middle fingers with the palm facing sideways. The buttons and wheels are activated by flexion and/or rolling of the thumb. Eleven males and nine females participated in the study. All subjects performed an aiming task to test the pointing and dragging functions. The results of this study reveal that the new pointing device allowed users to adopt more ergonomic postures and has the advantage of reduced muscular loadings of the upper extremities. Mean (SD) muscular activities (%RVC) using the wireless mouse, the trackpad and the new input device were as follows: trapezius: 3.0 (1.7), 4.4 (2.9) and 1.4 (1.0), and extensor carpi ulnaris: 7.3 (4.4), 14.5 (8.4) and 5.6 (3.1), respectively. The device was used in a variety of hand positions, alternatively. The size of the working area was far greater when the new input device was used than when the two conventional analogues were used. Although reasonable performance was not achieved, the results support recommendations concerning the redesign of the device. The ergonomic efforts in the design of the input device are of heuristic value, providing a basis for future development.     

Stabilization of linear systems with distributed input delay and input saturation

This paper is concerned with stabilization of a linear system with distributed input delay and input saturation. Both constant and time-varying delays are considered. In the case that the input delay is constant, under the stabilizability assumption on an auxiliary system, it is shown that the system can be stabilized by state feedback for an arbitrarily large delay as long as the open-loop system is not exponentially unstable. In the case that the input delay is time-varying, but bounded, it is shown that the system can be stabilized by state feedback if the non-asymptotically stable poles of the open-loop system are all located at the origin. In both cases, stabilizing controllers are explicitly constructed by utilizing the parametric Lyapunov equation based low gain design approach we recently developed. It is also shown that in the presence of actuator saturation and under the same assumptions on the system, these controllers achieve semi-global stabilization. Some discussions on the assumptions we impose on the system are given. A numerical example illustrates the effectiveness of the proposed stabilization approach.     

Sliding mode control based on a modified linear control input

In this study, we explain and demonstrate a design method of sliding mode control based on a modified linear control input. In the proposed method, the optimal gain matrix is derived such that it does not depend on the plant parameters. We confirmed the robustness of the proposed method by applying input-side disturbances and plant parameter deviations to plants and the effectiveness of the proposed method by performing a DC motor position control experiment     

Suboptimal control of linear discrete stochastic systems with linear input constraints

Optimal control of linear discrete stochastic systems with linear input constraints is considered. A lower bound on the achievable minimum of the loss function is given. A suboptimal control strategy is derived by using a truncated Taylor series to approximate the expected future loss in the Bellman equation. The performance of the suboptimal controller is studied using Monte Carlo simulation and the obtained loss is compared with the lower bound.     

Gain effects on performance using a head-controlled computer input device.

The purpose of this study was to use a Fitts' task to (1) determine how control-display gain influences performance using a head-controlled computer input device; (2) compare relative sensitivity to gain and optimal gain between head control and hand/arm control; and (3) investigate control-display gain interactions with other task factors including target width, movement amplitude and direction. The task was a discrete target acquisition task using circular targets of 2.9 mm, 8.1 mm, and 23.5 mm, movement amplitudes of 24.3 mm and 61.7 mm, and eight radial directions including 0 degrees, 45 degrees, 90 degrees, 135 degrees, 180 degrees, 225 degrees, 270 degrees, and 315 degrees. Each device was operated at four gain levels. Ten subjects participated. The results indicated that gain had a significant effect on movement time for both types of pointing devices and exhibited local minimums. Discrete target acquisition at all gains was aptly described using Fitts' Law for both input devices. The mouse gain resulting in minimum movement time and RMS cursor deviation was between 1.0 and 2.0. The minimum movement time and RMS cursor deviation for the head-controlled pointer occurred at a gain between 0.3 and 0.6. Average movement time at the optimal head-controlled pointer gain had a slope of 169 ms/bit and was more than 76% greater than at the optimal mouse gain with a slope of 135 ms/bit. In addition, average RMS displacement was more than 27% greater for the head-controlled pointer at its optimal gain setting than for the mouse. Gain had the greatest effect for small target widths and long movement amplitudes using the head-controlled pointer. Average movement time increased 37% when increasing the head-controlled pointer gain from 0.6 to 1.2 for the small target width, but only increased 0.3% when increasing gain for the large target width. Average movement time also increased 12% when decreasing the head-controlled pointer gain from 0.3 to 0.15 for the long movement amplitude, but decreased 0.3% when decreasing gain for the short movement amplitude.     

Development of non-keyboard input device checklists through assessments

An assessment of non-keyboard input devices (NKID) was conducted to identify factors for good design in relation to operation, performance and comfort. Twenty-seven NKID users, working in health and safety, evaluated eight devices that included mice, trackballs and a joystick mouse. The factors considered important for good design were: (1) comfortable hand and finger position, (2) adequate control, (3) intuitive and easy to use, (4) ease of device, button and trackball movement, (5) good interaction with software, (6) provision of suitable accessories. Mice were rated more favourably than trackballs or the joystick mouse. The design of the standard 2-button mouse (D4) was considered most desirable to use; the 3-button mouse (D1) and 3-button curved mouse (D8) were also favoured. Assessment data and comments were drawn together with previously published research to produce useful tools for NKID purchasing (i.e. Device Purchasing Checklist) and assessment (i.e. Device Assessment Checklist).     

Canonical forms for single input linear systems

In this paper, we obtain a canonical form for single input n-dimensional linear systems over and, in general, over a Bezout domain. We also give an algorithm to obtain that canonical form.     

A new input device: comparison to three commercially available mouses

This study was conducted to simultaneously compare the postural demands and performance of a new human-centred computer input device to three devices currently on the market. It was hypothesized that the new device would perform as well as the commercial devices while requiring less postural strain. A total of 24 experienced computer users performed a series of modified Steering and Fitts' Law Tests while their postural behaviour was captured using an opto-electric system. Analysis of the postural data revealed strong similarities between the new device and the commercially available devices, including some similarities that are not suggested in the literature. Analysis of the performance data reveals no significant difference between the new device and most commercial devices and suggests further examination of the difference between familiarity and mastery. This study has shown that it is possible to use the new device in a relaxed posture and yet achieve the same accuracy as commercial devices at no more postural risk than when the traditional mouse is used at a customized, ergonomic workstation.     

A new input device: comparison to three commercially available mouses

This study was conducted to simultaneously compare the postural demands and performance of a new human-centred computer input device to three devices currently on the market. It was hypothesized that the new device would perform as well as the commercial devices while requiring less postural strain. A total of 24 experienced computer users performed a series of modified Steering and Fitts' Law Tests while their postural behaviour was captured using an opto-electric system. Analysis of the postural data revealed strong similarities between the new device and the commercially available devices, including some similarities that are not suggested in the literature. Analysis of the performance data reveals no significant difference between the new device and most commercial devices and suggests further examination of the difference between familiarity and mastery. This study has shown that it is possible to use the new device in a relaxed posture and yet achieve the same accuracy as commercial devices at no more postural risk than when the traditional mouse is used at a customized, ergonomic workstation.     

Partial unknown input reconstruction for linear systems

The problem of partial unknown input (UI) reconstruction is addressed. It is considered that a linear functional of the UI vector has to be reconstructed using output information only. Necessary and sufficient conditions are given allowing for the reconstruction in finite time of the required UI’s; analogous conditions are obtained for the asymptotic reconstruction of the required UI’s. The solution of the problem under consideration provides a means to solve the problem of fault detection and isolation for disturbed linear systems.     

Stochastic linear quadratic regulation for discrete-time linear systems with input delay

This paper considers the stochastic LQR problem for systems with input delay and stochastic parameter uncertainties in the state and input matrices. The problem is known to be difficult due to the presence of interactions among the delayed input channels and the stochastic parameter uncertainties in the channels. The key to our approach is to convert the LQR control problem into an optimization one in a Hilbert space for an associated backward stochastic model and then obtain the optimal solution to the stochastic LQR problem by exploiting the dynamic programming approach. Our solution is given in terms of two generalized Riccati difference equations (RDEs) of the same dimension as that of the plant.     

Interval statement of the input word recognition problem for a linear machine

A method is proposed to solve the recognition problem for the input word of a linear machine in the interval statement reduced to solving linear systems of equations with an exact matrix and interval right-hand side.     

A camera-based input device for large interactive displays

The Digital Vision Touch (DViT) system uses smart cameras to determine where a person touches a large display, thereby allowing intuitive human-computer interaction. The cameras process the collected images in such a way as to recognize various object attributes, such as location relative to the display in 3D space. The system can then use this information in feedback to the computer generating the display, enabling touch control of the application. When we touch-enable large displays, multiuser collaboration and the ability to detect pen or finger contact are desirable functions. DViT is a touch-enabling technology with this capability and facilitates human-computer interaction in a natural way. The system we created works with a variety of display sizes - both large and wall-sized formats - and accommodates multiple users simultaneously.     

Periodic input estimation for linear periodic systems: Automotive engine applications

In this paper, we consider periodic linear systems driven by T₀-periodic signals that we desire to reconstruct. The systems under consideration are of the form , y=C(t)x, x∈Rⁿ, w∈R^m, y∈R^p, (m?p?n) where A(t), A₀(t), and C(t) are T₀-periodic matrices. The period T₀ is known. The T₀-periodic input signal w(t) is unknown but is assumed to admit a finite dimensional Fourier decomposition. Our contribution is a technique to estimate w from the measurements y. In both full state measurement and partial state measurement cases, we propose an efficient observer for the coefficients of the Fourier decomposition of w(t). The proposed techniques are particularly attractive for automotive engine applications where sampling time is short. In this situation, standard estimation techniques based on Kalman filters are often discarded (because of their relative high computational burden). Relevance of our approach is supported by two practical cases of application. Detailed convergence analysis is also provided. Under standard observability conditions, we prove asymptotic convergence when the tuning parameters are chosen sufficiently small.     

Nonlinear regulation in constrained input discrete-time linear systems

The use of composite linear and non-linear feedback laws for the control of constrained input discrete-time linear systems is re-examined. By making use of the delta operator formulation of a discrete-time system, an apparent restriction on the magnitude of the non-linear control law is removed, and the similarities between the continuous and discrete-time solutions to the problem are elucidated. In order to develop the results, unconstrained systems are treated initially, but it is shown that, locally, the sufficient conditions for the stabilization of such systems are actually equivalent to those for the stabilization of the corresponding constrained systems.     

Adaptive weighted suboptimal control for linear dynamic systems having a polynomial input

Introducing a cost term on the highest power of the nonlinear polynomial, we derive a simple direct adaptive control weighted suboptimal control algorithm which is very useful for the control of all stable nonminimum-phase and some unstable nonminimum-phase linear systems having a polynomial input. Both stochastic and deterministic situations are considered and the global convergence of the proposed algorithm has been established.     

Semi-global stabilizability of linear null controllable systemswith input nonlinearities

An H_∞-based Lyapunov proof is provided for a result established by Lin and Saberi (1993): if a linear system is asymptotically null controllable with bounded controls then, when subject to input saturation, it is semi-globally stabilizable by linear state feedback. A new result is that if the system is also detectable then it is semi-global stabilizable by completely linear output feedback. Further, an extension which relaxes the requirements on the input characteristic is obtained