A series elastic brake pedal for improving driving performance under regenerative braking

Electric and hybrid vehicles are favored to decrease the carbon footprint on the planet. The electric motor in these vehicles serves a dual purpose. The use of electric motor for deceleration, by converting the kinetic energy of the vehicle into electrical energy to be stored in the battery is called regenerative braking. Regenerative braking is commonly employed by electrical vehicles to signi cantly improve energy e ciency and to help to meet emission standards. When the regenerative and friction brakes are simultaneously activated by the driver interacting with the brake pedal, the conventional haptic brake pedal feel is disturbed due to the regenerative braking. In particular, while there exists a physical coupling between the brake pedal and the conventional friction brakes, no such physical coupling exists for the regenerative braking. As a result, no reaction forces are fed back to the brake pedal, resulting in a unilateral power ow between the driver and the vehicle. Consequently, the relationship between the brake pedal force and the vehicle deceleration is strongly in uenced by the regenerative braking. This results in a unfamiliar response of the brake pedal, negatively impacting the driver's performance and posing a safety concern. The reaction forces due to regenerative braking can be fed back to the brake pedal, through actuated pedals that re-establish the bilateral power ow to recover the natural haptic pedal feel. We propose a force-feedback brake pedal with series elastic actuation to preserve the conventional brake pedal feel during regenerative braking. The novelty of the proposed design is due to the deliberate introduction of a compliant element between the actuator and the brake pedal whose de ections are measured to estimate interaction forces and to perform closed-loop force control. Thanks to its series elasticity, the force-feedback brake pedal can utilize robust controllers to achieve high delity force control, possesses favorable output impedance characteristics over the entire frequency spectrum, and can be implemented in a compact package using low-cost components. We introduce pedal feel compensation algorithms to recover the missing regenerative brake forces on the brake pedal. The proposed algorithms are implemented for both two-pedal cooperative braking and one-pedal driving conditions. For those driving conditions, the missing pedal feedback due to the regenerative brake forces are rendered through the active pedal to recover the conventional pedal force mapping. In two-pedal cooperative braking, the regenerative braking is activated by pressing the brake pedal, while in one-pedal driving the activation takes place as soon as the throttle pedal is released. The applicability and e ectiveness of the proposed series elastic brake pedal and haptic pedal feel compensation algorithms in terms of driving safety and performance have been investigated through human subject experiments. The experiments have been conducted using a haptic pedal feel platform that consists of a SEA brake pedal, a torque-controlled dynamometer, and a throttle pedal. The dynamometer renders the pedal forces due to friction braking, while the SEA brake pedal renders the missing pedal forces due to the regenerative braking. The throttle pedal is utilized for the activation of regenerative braking in one-pedal driving. The simulator implements a vehicle pursuit task similar to the CAMP protocol and provides visual feedback to the participant. The e ectiveness of the preservation of the natural brake pedal feel has been studied under two-pedal cooperative braking and one-pedal driving scenarios. The experimental results indicate that pedal feel compensation can signi cantly decrease the number of hard braking instances, improving safety for both two-pedal cooperative braking and one-pedal driving. Volunteers also strongly prefer compensation, while they equally prefer and can e ectively utilize both two-pedal and one-pedal driving conditions. The bene cial e ects of haptic pedal feel compensation on safety is evaluated to be larger for the two-pedal cooperative braking condition, as lack of compensation results in sti ening/softening pedal feel characteristics in this cas

MOTOR DEVELOPMENT OUTCOMES OF CHILDREN WHO HAVE UNDERGONE THERAPEUTIC HYPOTHERMIA: WITH PARENTS' VIEWS

Objective: Neurodevelopmental follow-up of infants with hypoxic ischemic encephalopathy (HIE) and supporting their development have great importance for the later years of their life. The aim of this study was to evaluate motor development outcomes of children with HIE who have undergone therapeutic hypothermia (TH) in Turkey with an objective assessment and the point of view of the parents, and to compare these two assessment methods

Benzotriazole Derivatives as Long Wavelength Photosensitizers for Diaryliodonium Salt Initiators

Two benzotriazole derivative dyes 4,7-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-2-dodecyl-2H-benzo[1,2,3]triazole, and 2-dodecyl-4,7-bis(4-hexylthiophen-2-yl)-2H-benzo[d][1,2,3]triazole are shown to work as efficient photosensitizers for a dipheny-liodonium salt initiator in cationic photopolymerization of epoxide and vinyl monomers. Substituted thienyl groups are attached to benzotriazole backbone to extend conjugation and enhance electron density of the molecules. Thereby, it was possible to initiate polymerizations at room temperature using long wavelength UV and visible light. The progress of photopolymerizations was monitored using optical pyrometry. The photopolymerization of an epoxide monomer using solar irradiation was also demonstrated. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 729-733, 201

Effect of SiC and graphene nanoparticles on the mechanical properties of carbon fiber-reinforced epoxy composites

This study experimentally investigates the mechanical properties of carbon fiber reinforced epoxy composites (CFRECs) filled with Graphene (Gr) and Silicon Carbide (SiC) nanoparticles. Gr and SiC nanoparticle filled CFREC plates at 0%, 0.5%, 1%, and 2% weight ratios were fabricated using a vacuum infusion technique from unidirectional carbon fiber fabric with both 0 and 90° fiber orientation. According to ASTM standards, tensile, compression, and three point bending tests were performed to determine the effects of additive type and weight ratios. CFRECs with Gr additive exhibit improved tensile properties compared to the unfilled composites, especially at higher filler contents and at specific fiber orientations. Also, the Gr additive showed a better improvement in the tensile behavior of the CFRECs than the SiC additive. In general, it was found that the elastic modulus values of nanoparticle additive samples were higher than that of the unfilled composite material in both fiber orientations. Except for the 0.5% SiC ratio with 0° fiber orientation, the particle added nanocomposites did not exceed the value of the unfilled composite and did not make a positive effect on the compressive strength. It has been observed that Gr additives give more positive results on the bending strength of CFRECs than SiC, especially at a 2% weight ratio. Highlights: Effects of nanoparticle types on mechanical properties of CFRECs were compared. Weight ratio effects on the properties of nanoparticle-filled CFRECs were studied. The load-bearing capacity decreased as the additive ratio increased. Additives and ratios should be carefully selected for the intended applications. Overall, presence Gr resulted in enhanced properties much prominently for composites

A series elastic brake pedal to preserve conventional pedal feel under regenerative braking

We propose a force-feedback brake pedal with series elastic actuation to preserve the conventional brake pedal feel during cooperative regenerative braking. The novelty of the proposed design is due to the deliberate introduction of a compliant element between the actuator and the brake pedal whose deflections are measured to estimate interaction forces and to perform closed-loop force control. Thanks to its series elasticity, the force-feedback brake pedal can utilize robust controllers to achieve high fidelity force control, possesses favorable output impedance characteristics over the entire frequency spectrum, and can be implemented in a compact package using low-cost components. The applicability and effectiveness of the proposed series elastic brake pedal have been tested through human subject experiments that evaluate simulated cooperative regenerative braking scenarios with and without pedal feel compensation. The experimental results and responses to the accompanying questionnaire indicate that pedal feel compensation through the series elastic brake pedal can significantly decrease hard braking instances, improving safety and driver experience

Numerical Modeling of Mechanical Behavior of Functionally Graded Polylactic Acid–Acrylonitrile Benzidine Styrene Produced via Fused Deposition Modeling: Experimental Observations

Functionally graded materials (FGM) have attracted considerable attention in the field of composite materials and rekindled interest in research on composite materials due to their unique mechanical response achieved through material design and optimization. Compared to conventional composites, FGMs offer several advantages and exceptional properties, including improved deformation resistance, improved toughness, lightness properties, and excellent recoverability. This study focused on the production of functionally graded (FG) polymer materials by the additive manufacturing (AM) method. FG structures were produced by the fused deposition modeling (FDM) method using acrylonitrile benzidine styrene (ABS) and polylactic acid (PLA) materials, and tensile tests were performed according to ASTM D638. The effects of different layer thicknesses, volume ratios, and total thicknesses on mechanical behavior were investigated. The tensile standard of materials produced by additive manufacturing introduces geometric differences. Another motivation in this study is to reveal the differences between the results according to the ASTM standard. In addition, tensile tests were carried out by producing single-layer samples at certain volume ratios to create a numerical model with the finite element method to verify the experimental data. As a result of this study, it is presented that the FG structure produced with FDM improves mechanical behavior