Model Predictive Control for Vehicle Stabilization at the Limits of Handling

Recent developments in vehicle steering systems offer new opportunities to measure the steering torque and reliably estimate the vehicle sideslip and the tire-road friction coefficient. This paper presents an approach to vehicle stabilization that leverages these estimates to define state boundaries that exclude unstable vehicle dynamics and utilizes a model predictive envelope controller to bound the vehicle motion within this stable region of the state space. This approach provides a large operating region accessible by the driver and smooth interventions at the stability boundaries. Experimental results obtained with a steer-by-wire vehicle and a proof of envelope invariance demonstrate the efficacy of the envelope controller in controlling the vehicle at the limits of handling.

Must We Forgive?: Exploring the Limits and Possibilities of Forgiveness and Resentment

Conflict has marked civilization from Biblical times to the present day. Each of us, with our different and competing interests, and our desires to pursue those interests, have over time wronged another person. Not surprisingly then, forgiveness is a concern of individuals and groups¿communities, countries, religious groups, races¿yet it is a complex idea that philosophers, theologians, political scientists, and psychologists have grappled with. Some have argued that forgiveness is a therapeutic means for overcoming guilt, pain, and anger. Forgiveness is often portrayed as a coping mechanism¿how often we hear the phrase, ¿forgive and forget,¿ as an arrangement to help two parties surmount the complications of disagreement. But forgiveness is not simply a modus vivendi; the ability to forgive and conversely to ask for forgiveness, is counted as an admirable trait and virtue. This essay will explore the nature of forgiveness, which in Christian dogma is often posited as an unqualified virtue. The secular world has appropriated the Christian notion of forgiveness as such a virtue¿but are there instances wherein offering forgiveness is morally inappropriate or dangerous? I will consider the situations in which forgiveness, understood in this essay as the overcoming of resentment, may not be a virtue¿when perhaps maintaining resentment is as virtuous, if not more virtuous, than forgiving. I will explain the various ethical frameworks involved in understanding forgiveness as a virtue, and the relationship between them. I will argue that within Divine Command Theory forgiveness is a virtue¿and thus morally right¿because God commands it. This ethical system has established forgiveness as unconditional, an idea which has been adopted into popular culture. With virtue ethics in mind, which holds virtues to be those traits which benefit the person who possesses them, contributing to the good life, I will argue unqualified forgiveness is not always a virtue, as it will not always benefit the victim. Because there is no way to avoid wrongdoing, humans are confronted with the question of forgiveness with every indiscretion. Its limits, its possibilities, its relationship to one¿s character¿forgiveness is a concern of all people at some time if for no other reason than the plain fact that the past cannot be undone. I will be evaluating the idea of forgiveness as a virtue, in contrast to its counterpart, resentment. How can forgiveness be a response to evil, a way to renounce resentment, and a means of creating a positive self-narrative? And what happens when a sense of moral responsibility is impossible to reconcile with the Christian (and now, secularized imperative of) forgiveness? Is it ever not virtuous to forgive? In an attempt to answer that question I will argue that there are indeed times when forgiveness is not a virtue, specifically: when forgiveness compromises one¿s own self-respect; when it is not compatible with respect for the moral community; and when the offender is unapologetic. The kind of offense I have in mind is a dehumanizing one, one that intends to diminish another person¿s worth or humanity. These are moral injuries, to which I will argue resentment is a better response than forgiveness when the three qualifications cannot be met.

Experimental Evaluation of the Influence of Human-Structure Interaction for Vibration Serviceability

The effects of human-structure interaction on the dynamic performance of occupied structures have long been observed. The inclusion of the effects of human-structure interaction is important to ensure that the dynamic response of a structure is not overestimated. Previous observations, both in service and in the laboratory, have yielded results indicating that the effects are dependent on the natural frequency of the structure, the posture of the occupants, and the mass ratio of the occupants to the structure. These results are noteworthy, but are limited in their application,because the data are sparse and are only pertinent to a specific set of characteristics identified in a given study. To examine these characteristics simultaneously and consistently, an experimental test structure was designed with variable properties to replicate a variety of configurations within a controlled setting focusing on the effects of passive occupants. Experimental modal analysis techniques were employed to both the empty and occupied conditions of the structure and the dynamic properties associated with each condition were compared. Results similar to previous investigations were observed, including both an increase and a decrease in natural frequency of the occupied structure with respect to the empty structure, as well as the identification of a second mode of vibration. The damping of the combined system was higher for all configurations. Overall, this study provides a broad data set representing a wide array of configurations. The experimental results of this study were used to assess current recommendations for the dynamic properties of a crowd to analytically predict the effects of human-structure interaction. The experimental results were used to select a set of properties for passive, standing occupants and develop a new model that can more accurately represent the behavior of the human-structure system as experimentally measured in this study.