The local disturbance decoupling problem with stability for nonlinear systems

In this paper the Disturbance Decoupling Problem with Stability (DDPS) for nonlinear systems is considered. The DDPS is the problem of finding a feedback such that after applying this feedback the disturbances do not influence the output anymore and x = 0 is an exponentially stable equilibrium point of the feedback system. For systems that can be decoupled by static state feedback it is possible to define (under fairly mild assumptions) a distribution Δs* which is the nonlinear analogue of the linear V*s, the largest stabilizable controlled invariant subspace in the kernel of the output mapping, and to prove that the DDPS is locally solvable if and only if the disturbance vector fields are contained in Δs*

Designing and assessing a course on prioritization and importance assessment in strategic non-routine requirements engineering processes

In this contribution, we present a course for making stakeholders in requirements engineering (RE) processes aware of the relevance of importance assessment (the thinking process that they go through while assessing requirement weights) and giving them some experience with specific aspects of the importance assessment process. We also analyze the experiences of the participants in five pilot sessions. In RE instruments, elicitation of requirement weights receives much attention. However, the processes that individual stakeholders go through while assessing weights are largely ignored or seen as a ‘black box’. In the course, participants gain experience with some common issues and pitfalls in assessing weights. Issues covered are: completeness and interdependence of requirements, causal relationships and the common denominator, handling ‘irrational’ requirements, and the meaning of ‘importance’ (priority). The course was given in various large organizations in the aerospace sector, and data on participants’ experiences were gathered by means of a standardized questionnaire. The extent to which the participants claimed they learned about the relevance of importance assessment and about how to perform it were, respectively, 2.89 and 2.72 on a scale from 1 to 5. The relevance of the various assignments was rated between 3.74 and 4.00 on a 1–5 scale. Our study indicates that the course, or elements of it, should be embedded in an organization’s work practices in order to achieve lasting effect

Fuzzy group decision making in a competitive situation

In this paper a group decision making problem in a competitive situation with two opponents is considered. Uncertainty in the score assessment for both opponents of any individual of the group as well as between group members is taken into account by means of fuzzy sets. The individual scores can be obtained either direct or via pairwise comparisons of alternatives. The group scores are then mapped into a fuzzy set of preference orderings using the extension principle. By extending metaga7mes to a fuzzy metagame analysis the possible stable symmetric metaequilibria can be found as well as fuzzy ratings for each of the stable metaequilibria. The highest ranking stable metaequilibrium is then obtained by a fuzzy ranking procedure

Fuzzy group decision making in a competetive situation

In this paper a group decision making problem in a competitive situation with two opponents is considered. Uncertainty in the score assessment for both opponents of any individual of the group as well as between group members is taken into account by means of fuzzy sets. The individual scores can be obtained either direct or via pairwise comparisons of alternatives. The group scores are then mapped into a fuzzy set of preference orderings using the extension principle. By extending metagames to a fuzzy metagame analysis the possible stable symmetric metaequilibria can be found as well as fuzzy ratings for each of the stable metaequilibria. The highest ranking stable metaequilibrium is then obtained by a fuzzy ranking procedure

The Cortical Response Evoked by Robotic Wrist Perturbations Reflects Level of Proprioceptive Impairment After Stroke

Background: Proprioception is important for regaining motor function in the paretic upper extremity after stroke. However, clinical assessments of proprioception are subjective and require verbal responses from the patient to applied proprioceptive stimuli. Cortical responses evoked by robotic wrist perturbations and measured by electroencephalography (EEG) may be an objective method to support current clinical assessments of proprioception. Objective: To establish whether evoked cortical responses reflect proprioceptive deficits as assessed by clinical scales and whether they predict upper extremity motor function at 26 weeks after stroke. Methods: Thirty-one patients with stroke were included. In week 1, 3, 5, 12, and 26 after stroke, the upper extremity sections of the Erasmus modified Nottingham Sensory Assessment (EmNSA-UE) and the Fugl-Meyer Motor Assessment (FM-UE) and the EEG responses (64 channels) to robotic wrist perturbations were measured. The extent to which proprioceptive input was conveyed to the affected hemisphere was estimated by the signal-to-noise ratio (SNR) of the evoked response. The relationships between SNR and EmNSA-UE as well as SNR and time after stroke were investigated using linear regression. Receiver-operating-characteristic curves were used to compare the predictive values of SNR and EmNSA-UE for predicting whether patients regained some selective motor control (FM-UE > 22) or whether they could only move their paretic upper extremity within basic limb synergies (FM-UE ≤ 22) at 26 weeks after stroke. Results: Patients (N = 7) with impaired proprioception (EmNSA-UE proprioception score < 8) had significantly smaller SNR than patients with unimpaired proprioception (N = 24) [EmNSA-UE proprioception score = 8, t(29) = 2.36, p = 0.03]. No significant effect of time after stroke on SNR was observed. Furthermore, there was no significant difference in the predictive value between EmNSA-UE and SNR for predicting motor function at 26 weeks after stroke. Conclusion: The SNR of the evoked cortical response does not significantly change as a function of time after stroke and differs between patients with clinically assessed impaired and unimpaired proprioception, suggesting that SNR reflects persistent damage to proprioceptive pathways. A similar predictive value with respect to EmNSA-UE suggests that SNR may be used as an objective predictor next to clinical sensory assessments for predicting motor function at 26 weeks after stroke.Biomechatronics & Human-Machine Contro