Longitudinal Control Design Research Articles

Energy-Efficient Connected Cruise Control With Lean Penetration of Connected Vehicles

This paper focuses on energy-efficient longitudinal controller design for a connected automated truck that travels in mixed traffic consisting of connected and non-connected vehicles. The truck has access to information about connected vehicles beyond line of sight using vehicle-to-everything (V2X) communication. A novel connected cruise control design is proposed which incorporates additional delays into the control law when responding to distant connected vehicles to account for the finite propagation speed of traffic waves. The speeds of non-connected vehicles are modeled as stochastic processes. A fundamental theorem is proven which links the spectral properties of the motion signals to the average energy consumption. Controller synthesis for gain parameters is conducted over downstream traffic data and evaluated over a combination of synthetic and real cycles. It is demonstrated that even with lean penetration of connected vehicles, our controller can bring significant energy savings.

Design and Analysis of Longitudinal Controller for the Platoon With Time-Varying Delay

The communication topologies between vehicles in a platoon substantially impact the platoon’s stability. This study provides a distributed linear feedback control law that considers time-varying delay with guaranteed internal and string stability of the platoon system under various communication topologies. Firstly, the vehicle dynamics linearized model was derived using the precise feedback linearization technology. Different types of communication topologies, such as vehicle-to-vehicle communication and sensor-based communication, were described using directed graphs. Secondly, the linear feedback control law was designed to establish the stable zone of the linear controller gain under the effect of different communication topologies using directed graphs and the Routh-Hurwitz stability theorem. The Lyapunov-Razumikhin theorem determines the upper bound of the time-varying delay of various communication topologies. Additionally, the string stability of leader-predecessor following topology was studied, and the results were combined with the internal stability to determine the upper bound of time-varying delay. Finally, the results were verified by conducting two numerical simulations.

The effects of cannabis use on physical health: A co-twin control study

BackgroundResearch on the influence of cannabis use on anthropometrics, cardiovascular and pulmonary function, and other indicators of physical health has reported mixed results. We examined whether cannabis frequency is associated with physical health outcomes phenotypically and after controlling for shared genetic and environmental factors via a longitudinal co-twin control design. MethodsWe tested the phenotypic associations of adolescent, young adult, and adult cannabis frequency with adult physical health. Next, we ran multilevel models to test if significant phenotypic associations remained at the between-family and within-twin pair levels. Participants include 677 individual twins (308 twin pairs) aged 25–35. ResultsAt the phenotypic level, adolescent cannabis use was associated with less adult exercise engagement (b = − 0.846 min, p = .000). Adult cannabis use was associated with a lower resting heart rate (HR; b = − 0.170 bpm, p = .001) and more frequent appetite loss (b = 0.018, p = .000). Only between-family effects were significant for adolescent cannabis use and exercise engagement (b = − 1.147 min, p = .000) and adult cannabis use and appetite loss frequency (b = 0.041, p = .002). The total within-twin (b = − 0.184, p = .014), MZ only (b = − 0.304, p = .003), and between-family effects (b = − 0.164, p = .025) were significant between adult cannabis use and a lower resting HR, which persisted after controlling for familial confounds and other substance use. ConclusionsThe associations between cannabis use with exercise engagement and frequency of appetite loss are explained by familial confounding while the association between cannabis use and resting HR was not. These results do not support a causal association between cannabis use once a week and poorer physical health effects among adults aged 25–35.

Site-Specific Education Using Digital Media to Improve Patient Understanding of the Radiotherapy Trajectory: An Interventional Study

PurposeThe study assessed the effectiveness of a site-specific video educational material in improving patient understanding and confidence regarding radiation therapy trajectory. Methods and MaterialsA quasi experimental longitudinal pretest posttest study was conducted at a referral radiation therapy center from May 2020 to September 2020. It included 52 adult patients admitted for a first course radical radiation therapy. One generic and 6 site-specific (breast, pelvis, head and neck, brain, chest and abdomen, and bladder) animated cartoon videos were developed in house to provide concise overview of the overall patient's trajectory in radiation therapy, with full visual description of the procedures and specific preparation measures. A 14-item questionnaire was designed to assess pre- and postintervention levels of understanding and confidence of patients, with calculation of and an understanding and confidence score (UCS), range 0-14. ResultsThe mean (standard deviation) UCS in pre- and postintervention was 9.36 (2.48) and 11.92 (1.34) out of 14, respectively, indicating a mean increase of 2.57 subsequent to the intervention (P < .001). The effect size was large with a Cohen's d = 1.01. Of the 14 dimensions explored, 8 were observed to have remarkable improvement, notably understanding the purpose of the tattoo mark, reason of daily or weekly imaging, and what to expect with radiation therapy. Participants with poor reading ability had greater increase in UCS (ΔUCS = 4.25 vs ≤2.33) and in 5 out of 8 dimensions with remarkable improvement. ConclusionsThe use of digital educational material in radiation oncology meets the urgent need for providing patients with concise and site-specific information, while sparing extra hospital visits to meet education coordinators during the COVID-19 crisis. Additional studies are warranted to assess both the clinical and long-term effectiveness of the educational material, using a longitudinal controlled design.

Site-Specific Education Using Digital Media to Improve Patients’ Understanding of the Radiotherapy Trajectory: An Interventional Study

<h3>Purpose/Objective(s)</h3> To assess the effectiveness of a site-specific video educational material in improving patients' understanding and confidence regarding radiotherapy trajectory <h3>Materials/Methods</h3> A quasi-experimental longitudinal pre-test post-test study was conducted at a referral radiotherapy center, from May 2020 to September 2020. It included 52 adult patients admitted for a first course radical radiotherapy. One generic and 6 site-specific (breast, pelvis, head and neck, brain, chest and abdomen and bladder) inhouse production, animated cartoon videos were developed to provide concise overview of the overall patient's trajectory in radiotherapy, with full visual description of the procedures and specific preparation measures. A 14-item questionnaire was designed to assess pre- and post-intervention levels of understanding and confidence of patients, with calculation of and an understanding and confidence score (UCS, range 0-14). <h3>Results</h3> The mean (SD) UCS in pre- and post-intervention was 9.36 (2.48) and 11.92 (1.34) out of 14, respectively, indicating a mean increase of 2.57 subsequent to the intervention (<i>P</i> < 0.001). The effect size was large with a Cohen's <i>d</i> = 1.01. Of the 14 dimensions explored, 8 were observed to have remarkable improvement, notably understanding the purpose of the tattoo mark, reason of daily or weekly imaging, and what to expect with radiotherapy. Participants with poor reading ability had greater increase in UCS (ΔUCS = 4.25 vs ≤2.33) and in 5 out of 8 dimensions with remarkable improvement <h3>Conclusion</h3> The use of digital educational material in radiation oncology meets the urgent need for providing patients with concise and site-specific information, while sparing extra hospital visits to meet education coordinators during the COVID-19 crisis. Further studies are warranted to assess both the clinical and long-term effectiveness of the educational material, using a longitudinal controlled design.

Effects of bariatric surgery on functional connectivity of the reward and default mode network: A pre-registered analysis.

Obesity imposes serious health risks and involves alterations in resting‐state functional connectivity of brain networks involved in eating behavior. Bariatric surgery is an effective treatment, but its effects on functional connectivity are still under debate. In this pre‐registered study, we aimed to determine the effects of bariatric surgery on major resting‐state brain networks (reward and default mode network) in a longitudinal controlled design. Thirty‐three bariatric surgery patients and 15 obese waiting‐list control patients underwent magnetic resonance imaging at baseline, after 6 and 12 months. We conducted a pre‐registered whole‐brain time‐by‐group interaction analysis, and a time‐by‐group interaction analysis on within‐network connectivity. In exploratory analyses, we investigated the effects of weight loss and head motion. Bariatric surgery compared to waiting did not significantly affect functional connectivity of the reward network and the default mode network (FWE‐corrected p > .05), neither whole‐brain nor within‐network. In exploratory analyses, surgery‐related BMI decrease (FWE‐corrected p = .041) and higher average head motion (FWE‐corrected p = .021) resulted in significantly stronger connectivity of the reward network with medial posterior frontal regions. This pre‐registered well‐controlled study did not support a strong effect of bariatric surgery, compared to waiting, on major resting‐state brain networks after 6 months. Exploratory analyses indicated that head motion might have confounded the effects. Data pooling and more rigorous control of within‐scanner head motion during data acquisition are needed to substantiate effects of bariatric surgery on brain organization.

Sexually Unexperienced Adolescents Benefit the Most From a Sexual Education Program for Adolescents: A Longitudinal Cluster Randomized Controlled Study.

Using a longitudinal cluster-randomized controlled design, we examined whether the effects of Competencies for Adolescents with a Healthy Sexuality (COMPAS), an evidence-based sexual health promotion intervention, differ by adolescents' sexual experience. Participants were 699 students aged 14-16, 45.9% were sexually experienced, and assessed in the baseline, posttest, and 12- and 24-month follow-ups. All were recruited from 10 schools that were randomly assigned to the COMPAS program and waiting-list groups (WLG). Using an intent-to-treat analyses, longitudinal changes in psychosocial and behavioral outcomes were explored using generalized estimating equations. Compared to the WLG, COMPAS had a positive impact on six of the seven psychological and behavioral outcomes. Non-sexually experienced reported more favorable HIV-related attitudes, higher condom use intention, lower number of sexual partners, and higher condom use than those sexually experienced. Findings support the importance of implementing sex education actions before adolescents get involved in their first intimate relationships in order to achieve greater impact.

Energetic Impacts Evaluation of Eco-Driving on Mixed Traffic With Driver Behavioral Diversity

This study presents a fuel-economical driving strategy for connected and automated vehicles (CAVs) and investigates its impacts on human-driven platoon’s fuel efficiency, considering driver behavioral diversity. In mixed traffic where a limited number of CAVs and many human-driven vehicles share the road, the Eco-Driving strategy of CAVs, accomplished through vehicle connectivity and longitudinal dynamics control, can significantly reduce fuel consumption of CAVs, particularly during transient traffic conditions, by avoiding unnecessary braking and acceleration maneuvers which lead to excessive fuel consumption. This is implemented and validated by a vehicle longitudinal dynamic control design with an instantaneous power-based fuel rate estimation model. Moreover, such an Eco-Driving strategy will also help most of the following human-driven vehicles to improve fuel performance despite a highly diverse and uncertain driving characteristics spectrum. The car-following behaviors of a human-driven platoon are described by a microscopic traffic model with dedicated representations of the individual drivers’ preferences. A comprehensive statistical investigation shows the fuel-saving benefits for a human-driven platoon by adopting the proposed Eco-Driving strategy for CAVs. Some special cases are discussed, as well. The results collectively demonstrate the positive impacts of CAVs, even with a low penetration rate, could potentially have on the energy efficiency of the transportation sector within the foreseeable future.

Longitudinal and lateral control of autonomous vehicles in multi‐vehicle driving environments

Lane changes in multi-vehicle driving environments are one of the most challenging manoeuvres for autonomous vehicles. The key innovation of this study is to develop an integrated longitudinal and lateral trajectory planning and tracking control algorithm under vehicle-to-vehicle communication. This algorithm includes two levels: trajectory planning and path-following control. In the upper level, considering riding comfort, a collision-free lane-changing trajectory cluster is generated under different lane change durations. Then, the most appropriate trajectory from this cluster is provided by selecting the optimal lane change duration considering vehicle dynamics safety, collision avoidance of surrounding vehicles and driver preference. At the bottom level, a multiple-input multiple-output triple-step non-linear approach is proposed in the longitudinal and lateral path-following controller design. The stability of the closed-loop system is rigorously proven based on the Lyapunov function. Finally, the effectiveness of the proposed algorithm is verified with a high-fidelity and full-car model on the veDYNA platform.

Design of Longitudinal Controller for Automated Driving Bus

This paper describes the design of a longitudinal controller for an automated driving bus, which is expected to be a transportation method of the future. A linear longitudinal model is presented by approximating an aerodynamic drag force and rolling resistance force in a low speed range. Then, the feedback gains of a proportional integral (PI) controller for considering the longitudinal grade of the road are determined using a root locus method, with a constraint derived from the Chien–Hrones–Reswick method. A traffic light is predicted by the vehicle, so as to pass a signalized intersection smoothly. Further, a novel adaptive cruise control method is proposed for the automated driving bus, to reduce the acceleration of the vehicle. The performance of the controller is validated through pilot tests on public roads.

A Review of Automatic Vehicle Following Systems

There has been considerable interest recently in the development of connected and autonomous vehicles (CAVs). Automatic vehicle following capability is central for CAVs; in this article, we provide a review of the critical issues in the longitudinal control design for automatic vehicle following systems (AVFS) employed by CAVs. This expository review differs from others in providing a review of underlying methodologies for design of AVFS and the impact of AVFS on traffic mobility and safety.

The impact of three types of writing intervention on students' writing quality.

Students’ writing constitutes a topic of major concern due to its importance in school and in daily life. To mitigate students’ writing problems, school-based interventions have been implemented in the past, but there is still a need to examine the effectiveness of different types of writing interventions that use robust design methodologies. Hence, the present study followed a longitudinal cluster-randomized controlled design using a multilevel modeling analysis with 370 fourth-grade students (nested in 20 classes). The classes were randomly assigned to four conditions: one comparison group and three writing types of writing interventions (i.e., week-journals, Self-Regulation Strategy Development (SRSD) instruction and SRSD plus Self-Regulated Learning (SRL) program using a story-tool), with five classes participating in each condition. Data supports our hypothesis by showing differences between the treatment groups in students’ writing quality over time. Globally, the improvement of students’ writing quality throughout time is related to the level of specialization of the writing interventions implemented. This is an important finding with strong implications for educational practice. Week-journals and writing activities can be easily implemented in classrooms and provides an opportunity to promote students’ writing quality. Still, students who participated in the instructional programs (i.e., SRSD and SRSD plus story-tool) exhibited higher writing quality than the students who wrote week-journals. Current data did not find statistical significant differences between results from the two instructional writing tools.

Mathematical modeling of hybrid intelligent system to longitudinal landing control design

Mathematical modeling of hybrid intelligent system to longitudinal landing control design

An adaptive modified fuzzy-sliding mode longitudinal control design and simulation for vehicles equipped with ABS system

An adaptive modified fuzzy-sliding mode longitudinal control design and simulation for vehicles equipped with ABS system

Hybrid model reference adaptive second order sliding mode controller for automatic train operation

This study presents a non-linear longitudinal dynamic model of high speed trains by considering the rolling stock, train formations, rolling resistance, track environment, etc., and longitudinal controller design for Automatic Train Operation (ATO) as well. For a controller design, a novel hybrid model reference based adaptive super twisting sliding mode control scheme is proposed. The control law comprises a non-linear model reference adaptive control (MRAC) and an adaptive second order sliding mode control (SMC) in order to make the control signal continuous and to alleviate the chattering phenomenon. The adaptive gains of the proposed control law are derived based on Lyapunov approach that ensures global stability with exact tracking in finite time. A linear stable reference model is developed with the ideal train-track parameters to generate the reference trajectory. The effectiveness of the presented concept is demonstrated by introducing load variation, model uncertainties and external disturbances in the non-linear model of the train and its performance is compared with the non-linear MRAC and the second order sliding mode controller.

Writing week-journals to improve the writing quality of fourth-graders’ compositions

Students’ writing problems are a global educational concern and is in need of particular attention. This study aims to examine the impact of providing extra writing opportunities (i.e., writing journals) on the quality of writing compositions. A longitudinal cluster-randomized controlled design using a multilevel modeling analysis with 182 fourth grade students was conducted. We examined whether students’ writing quality differed when writing journals on a weekly basis for 12 weeks, compared with a control group. Three covariates were analyzed, namely: (i) the students’ attitudes towards writing; (ii) their self-efficacy in writing; (iii) and their use of self-regulation (SRL) strategies while writing. Findings have shown that students who wrote week-journals significantly improved the writing quality of their compositions and reported a higher use of SRL strategies in writing. Nevertheless, self-efficacy and attitude towards writing were found to not be related to the quality of the compositions. Moreover, data indicated that the writing quality of compositions improved along with the writing quality of the week-journals. Findings suggest the use of week-journals in class to promote writing.

Does assessing suicidality frequently and repeatedly cause harm? A randomized control study.

Assessing suicidality is common in mental health practice and is fundamental to suicide research. Although necessary, there is significant concern that such assessments have unintended harmful consequences. Using a longitudinal randomized control design, the authors evaluated whether repeated and frequent assessments of suicide-related thoughts and behaviors negatively affected individuals, including those at-risk for suicide-related outcomes. Adults (N = 282), including many diagnosed with borderline personality disorder (BPD), were recruited through psychiatric outpatient clinics and from the community at large, and were randomly assigned to assessment groups. A control assessment group responded to questions regarding negative psychological experiences several times each day during a 2-week main observation phase. During the same observation period, an intensive suicide assessment group responded to the same questions, along with questions regarding suicidal behavior and ideation. Negative psychological outcomes were measured during the main observation phase (for BPD symptoms unrelated to suicide and for BPD-relevant emotions) and/or at the end of each week during the main observation phase and monthly for 6 months thereafter (for all outcomes, including suicidal ideation and behavior). Results revealed little evidence that intensive suicide assessment triggered negative outcomes, including suicidal ideation or behavior, even among people with BPD. A handful of effects did reach or approach significance, though these were temporary and nonrobust. However, given the seriousness of some outcomes, the authors recommend that researchers or clinicians who implement experience sampling methods including suicide-related items carefully consider the benefits of asking about suicide and to inform participants about possible risks.

Design of Longitudinal Motion Controller of a Small Unmanned Aerial Vehicle

The need for autonomous Unmanned Aerial Vehicles (UAVs) is very interesting nowadays. Autonomous UAVs provide the possibility of performing tasks and missions that are currently hazardous or can cost humans or money, enable autonomous search, persistent combat intelligence, surveillance and reconnaissance (ISR), and many other applications. This paper presents an overview of autopilot design with a detailed design of longitudinal autopilot of a Small Unmanned Aerial Vehicle (SUAV). The designed autopilot is applied to an Ultrastick-25e fixed wing UAV depending on longitudinal linear model and analytic linear model with trimmed values of straight and leveling scenario. The longitudinal motion controller design is started with the design of most inner loop (pitch rate feedback) of the longitudinal system, then pitch tracker design with a Proportional Integral (PI)controller. The guidance and control system is related with the design of altitude hold controller with Pcontroller as an example of outer loop controller design. The performance of two classic controller approaches for the design of autopilot are compared and evaluated for both linear and non-linear models. The proposed controller is chosen for design due to its higher performance than the classic one. At last the climbing turn scenario is applied to the whole autopilot (longitudinal and lateral) for the evaluation process. The results show a good performance in both disturbance rejection and robustness against sensors noise.

Longitudinal control of an intelligent vehicle using particle swarm optimization based sliding mode control

This paper focuses on the design of longitudinal controller for an intelligent vehicle which was built at Asian Institute of Technology based on sliding mode control. The proposed controller uses particle swarm optimization (PSO) for optimal tuning of sliding surface and controller gain in the sliding mode controller (SMC). The longitudinal control is conducted via controlling of throttle value angle using PSO-based SMC on the simplified first-order linear model of the intelligent vehicle and controlling of brake force using fuzzy logic. In order to achieve the desired headway time, integration of throttle valve angle control and brake force control is required. To obtain the optimal parameters of SMC, two equations velocity updating and position updating are applied. Firstly, the performance of proposed controller is evaluated by using MATLAB simulation to compare with conventional PD controller. Finally, the experimental results show that the proposed PSO-based SMC can perform efficiently in longitudinal control of the intelligent vehicle.

Effect of a new longitudinal interprofessional geriatric medicine educational track on knowledge and attitude of medical students: a controlled cohort study.

A new interprofessional geriatric medicine curriculum was recently introduced at a large undergraduate Asian medical school. A longitudinal controlled interventional cohort study was conducted to evaluate the effect of the new curriculum on the knowledge and attitudes of medical students. The medical students under the new curriculum formed the intervention cohort, and those under the former curriculum formed the control cohort. To test knowledge, the University of California at Los Angeles (UCLA) geriatrics knowledge test (GKT) was used in Year 2 and the University of Michigan GKT in Year 5. Geriatrics attitudes were evaluated using the UCLA geriatrics attitudes test in Years 2 and 5. Not surprisingly, geriatrics knowledge at the end of Year 5 of medical school was enhanced to a greater degree in the intervention cohort than the control cohort, although improvements in geriatrics attitudes in each cohort were of similar magnitude by the end of Year 5, suggesting that factors other than a formal geriatrics curriculum influenced the improvements in geriatrics attitudes. This article is one of few published on the effectiveness of geriatrics curricular innovations using validated knowledge and attitude outcomes in a longitudinal controlled study design and will be useful to other medical institutions seeking to improve the geriatrics knowledge and attitudes of their students.