Anti-Jackknifing Control of Tractor-Trailer Vehicles via Intrinsically Stable MPC

It is common knowledge that tractor-trailer vehicles are affected by jackknifing, a phenomenon that consists in the divergence of the trailer hitch angle and ultimately causes the vehicle to fold up. For the case of backwards motion, in which jackknifing can also occur at low speeds, we present a control method that drives the vehicle along a reference Cartesian trajectory while avoiding the divergence of the hitch angle. In particular, a feedback control law is obtained by combining two actions: a tracking term, computed using input-output linearization, and a corrective term, generated via IS-MPC, an intrinsically stable MPC scheme which is effective for stable inversion of nonminimum-phase systems. The proposed method has been verified in simulation and experimentally validated on a purposely built prototype

The VPN problems with concave costs

Only recently Goyal, Olver and Shepherd (Proc. STOC, 2008) proved that the symmetric Virtual Private Network Design (sVPN) problem has the tree routing property, namely, that there always exists an optimal solution to the problem whose support is a tree. Combining this with previous results by Fingerhut, Suri and Turner (J. Alg., 1997) and Gupta, Kleinberg, Kumar, Rastogi and Yener (Proc. STOC, 2001), sVPN can be solved in polynomial time. In this paper we investigate an APX-hard generalization of sVPN, where the contribution of each edge to the total cost is proportional to some non-negative, concave and non-decreasing function of the capacity reservation. We show that the tree routing property extends to the new problem, and give a constant-factor approximation algorithm for it. We also show that the undirected uncapacitated single-source minimum concave-cost flow problem has the tree routing property when the cost function has some property of symmetry

Bayesian neural network modeling and hierarchical MPC for a tendon-driven surgical robot with uncertainty minimization

In order to guarantee precision and safety in robotic surgery, accurate models of the robot and proper control strategies are needed. Bayesian Neural Networks (BNN) are capable of learning complex models and provide information about the uncertainties of the learned system. Model Predictive Control (MPC) is a reliable control strategy to ensure optimality and satisfaction of safety constraints. In this work we propose the use of BNN to build the highly nonlinear kinematic and dynamic models of a tendon-driven surgical robot, and exploit the information about the epistemic uncertainties by means of a Hierarchical MPC (Hi-MPC) control strategy. Simulation and real world experiments show that the method is capable of ensuring accurate tip positioning, while satisfying imposed safety bounds on the kinematics and dynamics of the robot

A behavior-based framework for safe deployment of humanoid robots

We present a complete framework for the safe deployment of humanoid robots in environments containing humans. Proceeding from some general guidelines, we propose several safety behaviors, classified in three categories, i.e., override, temporary override, and proactive. Activation and deactivation of these behaviors is triggered by information coming from the robot sensors and is handled by a state machine. The implementation of our safety framework is discussed with respect to a reference control architecture. In particular, it is shown that an MPC-based gait generator is ideal for realizing all behaviors related to locomotion. Simulation and experimental results on the HRP-4 and NAO humanoids, respectively, are presented to confirm the effectiveness of the proposed method

ZMP Constraint Restriction for Robust Gait Generation in Humanoids

We present an extension of our previously proposed IS-MPC method for humanoid gait generation aimed at obtaining robust performance in the presence of disturbances. The considered disturbance signals vary in a range of known amplitude around a mid-range value that can change at each sampling time, but whose current value is assumed to be available. The method consists in modifying the stability constraint that is at the core of IS-MPC by incorporating the current mid-range disturbance, and performing an appropriate restriction of the ZMP constraint in the control horizon on the basis of the range amplitude of the disturbance. We derive explicit conditions for recursive feasibility and internal stability of the IS-MPC method with constraint modification. Finally, we illustrate its superior performance with respect to the nominal version by performing dynamic simulations on the NAO robot

An all-endo Approach to Complete Ureteral Duplications Complicated by Ureterocele and/or Vesicoureteral Reflux: Feasibility, Limitations, and Results

Purpose. Totally endoscopic management (all-endo) of patients with a duplicated renal system (DS) associated with severe vesicoureteral reflux (VUR) or obstructive ureterocele (UC) is an attractive alternative to traditional open procedures. The authors discuss feasibility and results of an all-endo approach on a consecutive series of patients. Methods. From 1999 to 2009, all patients with a complete DS associated with UC and/or VUR were proposed for primary all-endo approach. UC puncture was performed using a 3 Fr Bugbee electrode. Deflux (dextranomer/hyaluronic acid copolymer) injection was administered for VUR. The need for secondary surgery was evaluated on followup. Results. Of the 62 patients recruited, 46 were treated using a primary all-endo approach and 16 patients received no treatment. Of the 46 treated patients with 56 affected renal units, 32 (97%) UCs collapsed following puncture and 29 (63%) VURs were resolved or downgraded. Secondary VUR occurred in 13 (39%) renal units. Secondary surgery was performed on 23 (41%) renal units. Conclusion. The all-endo approach for VUR in DS is an effective therapeutic option. UC collapse was achieved by puncture in most of the patients; secondary VUR was the main complication in a small group of extravesical UC

Impact of COVID-19 pandemic lockdown on narcolepsy type 1 management

Study Objectives: Narcolepsy type 1 (NT1) is a chronic rare hypersomnia of central origin requiring a combination of behavioral and pharmacological treatments. During the coronavirus disease 2019 (COVID-19) pandemic, in Italy the population was forced into a lockdown. With this study, we aimed to describe the lockdown impact on NT1 symptom management, according to different patients' working schedule. Methods: In the period between 10 April and 15 May 2020, we performed routine follow-up visits by telephone (as recommended during the COVID-19 emergency) to 50 patients >18 years old (40% males) under stable long-term treatment. We divided patients into three groups: unchanged working schedule, forced working/studying at home, and those who lost their job (“lost occupation”). Current sleep–wake habit and symptom severity were compared with prelockdown assessment (six months before) in the three patient groups. Results: At assessment, 20, 22, and eight patients belonged to the unchanged, working/studying at home, and lost occupation groups, respectively. While in the lost occupation group, there were no significant differences compared with prepandemic assessment, the patients with unchanged schedules reported more nocturnal awakenings, and NT1 patients working/studying at home showed an extension of nocturnal sleep time, more frequent daytime napping, improvement of daytime sleepiness, and a significant increase in their body mass index. Sleep-related paralysis/hallucinations, automatic behaviors, cataplexy, and disturbed nocturnal sleep did not differ. Conclusions: Narcolepsy type 1 patients working/studying at home intensified behavioral interventions (increased nocturnal sleep time and daytime napping) and ameliorated daytime sleepiness despite presenting with a slight, but significant, increase of weight

Habitats Directive in northern Italy: a series of proposals for habitat definition improvement

Habitats Directive (92/43/EEC) is the cornerstone of nature conservation in Europe and is at the core of the EU Biodiversity Strategy for 2030. There is room, however, for its improvement, at least for northern Italy, where ambiguities in the definition of habitat types of Annex I of the Habitats Directive are not novel and interpretation difficulties have been highlighted. Sharpening the characterization of habitat types represents an opportunity for lowering classification uncertainties and improving conservation success. With the aim to refine the definitions of habitat types and associated typical species of the Habitats Directive, a group of vegetation scientists of the Italian Society of Vegetation Science based in northern Italy made the exercise of finding viable proposals for those habitat types having a problematic interpretation in the Alpine biogeographical region of Italy. Such proposals arise from group discussions among scientists, and professionals, thus offering a shared view. We prepared 9 habitat proposals important for this geographic area. They include new habitat types at the European level, new subtypes within pre-existing habitat types, including some adjustments of the recently proposed subtypes with respect to northern Italy, and recognition of priority criteria for a pre-existing habitat type. With a vision of tailored conservation, our proposals represent a starting point in view of a future update of Annex I. Furthermore, the list of typical species could be useful for preparing expert systems for automatic classification. Irrespective of legally binding solutions in place, we caution these proposals represent relevant baseline conservation indications that local and regional administrations of the Alpine Arch should consider

Uso de la analgesia acupuntural quirúrgica en la herniorrafía inguinal. The use of surgical acupunctural analysis in inguinal herniarhaphy

Por la importancia que ha alcanzado en nuestro país la aplicación de la medicina natural y tradicional y dentro de ésta la acupuntura, no sólo en el orden clínico sino con fines quirúrgicos, se realizó un estudio descriptivo y retrospectivo de 40 pacientes operados por hernia inguinal en el Hospital General Docente "Abel Santamaría Cuadrado" de Pinar del Río durante el período comprendido de enero a julio del año 2003, con el objetivo de evaluar la efectividad de la analgesia quirúrgica acupuntural en este tipo de cirugía. Se conformaron dos grupos (control y estudio). Al control se le aplicó anestesia espinal y al de estudio, analgesia quirúrgica acupuntural. Se comparó grado de analgesia transoperatoria y postoperatoria, así como las complicaciones. Se determinó el grado de satisfacción de los pacientes, para lo cual fue aplicada una escala analógica visual, siendo buena en un 90% de los pacientes, a los cuales se les aplicó la analgesia acupuntural. Este proceder es inocuo, de fácil aplicación, bien aceptado por el paciente, y representa un ahorro económico considerable, ya que disminuye los costos hospitalarios, por lo que recomendamos su empleo de forma sistemática. En todos los pacientes se aplicó la cirugía mayor ambulatoria. Palabras clave: ACUPUNTURA, ANALGESIA, HERNIA INGUINAL, MEDICINA TRADICIONAL. ABSTRACT By the importance the application of the traditional and natural medicine has gotten in our country, specially acupuncture, not only clinically but also with surgical purposes, a descriptive and retrospective study was performed with 40 patients operated on for inguinal hernia at "Abel Santamaría Cuadrado" Teaching University Hospital in Pinar del Río, from January to July 2003, with the purpose of assessing the effectiveness of the surgical acupunctural analgesia in this type of surgery. Two groups were formed (control and study). The control group was applied spinal anesthesia, and the study group was applied surgical acupunctural analgesia. The degree of transoperative and post-operative analgesia was compared, as well as the complications. The degree of the patient's satisfaction was registered, for which a visual analogical scale was applied, being good in 90% patients who underwent acupunctural analgesia. This procedure is harmless, easily applicable, well accepted by the patient, and represents a significant economical saving since it diminishes hospital costs. This is why its systematic use is recommended. All patients underwent major ambulatory surgery. Key words: ACUPUNCTURE, ANALGESIA, INGUINAL HERNIA, TRADITIONAL MEDICINE