Human operator modeling, joystick input notch filtering, and safety constraint enforcement for powered wheelchair operation under Parkinson’s tremor

This study considers use of a notch filter and enforcement of performance safety limits to mitigate the effects of Parkinson tremors on a battery powered wheelchair directed by a joystick. The wheelchair has regenerative braking to extend range of operation between charges. Regenerative braking transforms the wheelchair model into an autonomously switched hybrid system. The wheelchair is represented as a joystick controlled wheeled mobile robot having two modes of operation per drive wheel, propelling and regenerative braking. In this study, a Parkinson’s patient is directed to follow a path that includes moving from a stopped position to a trajectory along a wall that includes a 90˚ corner. A cognitive model of a human operator is incorporated for simulation of an operator with Parkinson’s tremor. The human operator model output provides the joystick with noisy velocity, orientation, and position commands. The article delineates a notch filter to remove the main Parkinson’s tremor from the joystick input followed by the application of velocity and acceleration performance safety limits. Results show significant feasible advantages for safe wheelchair operation by Parkinson’s patients with tremor

A TECHNICAL REPORT ON A POLYTOPIC SYSTEM APPROACH FOR THE HYBRID CONTROL OF A DIESEL ENGINE USING VGT/EGR

This paper develops a hybrid/gain scheduled control to move a diesel engine through a driving profile represented as a set of 12 operating points in the 7-dimensional state space of a 7th order nonlinear state model. The calculations for the control design are based on a 3rd order(reduced) model of the Diesel engine on which state space is projected the 12 operating points. About each operating point, we generate a 3rd order nonlinear error models of the Diesel engine. Using the error model for each operating point, a control design is set forth as a system of LMI\u27s. The solution of each system of LMI\u27s produces a norm bounded controller guaranteeing that x x i d i d - Æ 1 where xi d is the i-th desired operating point in the 3-dimensional state space. The control performance is then evaluated on the 7th order model

Perspectives and Results on the Stability and Stabilizability of Hybrid Systems

This paper introduces the concept of a hybrid system and some of the challenges associated with the stability of such systems, including the issues of guaranteeing stability of switched stable systems and finding conditions for the existence of switched controllers for stabilizing switched unstable systems. In this endeavor, this paper surveys the major results in the (Lyapunov) stability of finite-dimensional hybrid systems and then discusses the stronger, more specialized results of switched linear (stable and unstable) systems. A section detailing how some of the results can be formulated as linear matrix inequalities is given. Stability analyses on the regulation of the angle of attack of an aircraft and on the PI control of a vehicle with an automatic transmission are given. Other examples are included to illustrate various results in this paper

Sensitivity Analysis of a State Variable Model

This paper reports results of a sensitivity analysis of a state variable model of the Software Test Process (STP). Given a state model of the STP, a sensitivity matrix is calculated using tensor algebra. The sensitivity matrix allows computation of output variations to small perturbations in the model parameters. The results con rm that the model behaves in a manner very similar to what one might expect from a software test process. Results of this analysis also suggest changes and enhancements in the model to improve its accuracy in predicting the behavior of the software test process