The paper presents the synthesis of a nonlinear model of a wheeled vehicle suspension strut using an asymmetric (single-rod) electrohydraulic actuator. Due to differences in the active areas of the piston and the nonl...
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ISBN:
(数字)9798350350708
ISBN:
(纸本)9798350350715
The paper presents the synthesis of a nonlinear model of a wheeled vehicle suspension strut using an asymmetric (single-rod) electrohydraulic actuator. Due to differences in the active areas of the piston and the nonlinear nature of flows through the throttling orifices of the servo valve, the nonlinear model is characterised by increased complexity relative to systems using symmetric actuators (double rod). The paper covers the results of simulation studies to linearise the model and synthesise a linear quadratic controller based on the linearised model. The derived linear-quadratic controller was utilised to control a nonlinear model of the suspension strut. The control performance of the nonlinear active suspension strut model was compared with laboratory tests of the passive suspension system.
Cyber-physical systems (CPSs) enable a cross-linkage of digital and physical realms to strengthen control, monitoring, and planning capabilities. Despite these major advantages, CPSs are only marginally leveraged in h...
Cyber-physical systems (CPSs) enable a cross-linkage of digital and physical realms to strengthen control, monitoring, and planning capabilities. Despite these major advantages, CPSs are only marginally leveraged in hydraulic actuation, a widespread technology of paramount importance in many fields of industry. Thus, this paper aims to explore the prospects of closing this gap. A conceptual framework is proposed, combining human and artificial intelligence to address one or more key aspects of hydraulic systems (e.g., reliability, performance, or energy efficiency). The benefits and the technological barriers of this approach are pinpointed in preparation for the extensive use of CPSs. It is, in fact, clear that such a change of paradigm can transform hydraulics by bringing it into the 21st Century.
The industrial operation of oxy-fuel metal cutting via gas torches involves tasks such as ignition, preheating, and combustion along the target surface. Automated oxy-fuel cutting systems are exposed to risks and anom...
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Unmanned Aerial Vehicles (UAVs) are widely used in various applications, from inspection and surveillance to transportation and delivery. Navigating UAVs in complex 3D environments is a challenging task that requires ...
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In this work, we introduce a control framework that combines model-based footstep planning with Reinforcement Learning (RL), leveraging desired footstep patterns derived from the Linear Inverted Pendulum (LIP) dynamic...
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ISBN:
(数字)9798350377705
ISBN:
(纸本)9798350377712
In this work, we introduce a control framework that combines model-based footstep planning with Reinforcement Learning (RL), leveraging desired footstep patterns derived from the Linear Inverted Pendulum (LIP) dynamics. Utilizing the LIP model, our method forward predicts robot states and determines the desired foot placement given the velocity commands. We then train an RL policy to track the foot placements without following the full reference motions derived from the LIP model. This partial guidance from the physics model allows the RL policy to integrate the predictive capabilities of the physics-informed dynamics and the adaptability characteristics of the RL controller without overfitting the policy to the template model. Our approach is validated on the MIT Humanoid, demonstrating that our policy can achieve stable yet dynamic locomotion for walking and turning. We further validate the adaptability and generalizability of our policy by extending the locomotion task to unseen, uneven terrain. During the hardware deployment, we have achieved forward walking speeds of up to 1.5 m/s on a treadmill and have successfully performed dynamic locomotion maneuvers such as 90-degree and 180-degree turns.
Polymeric materials have a broad range of mechanical and physical *** have been widely used in material science,biomedical engineering,chemical engineering,and mechanical *** introduction of active elements into the s...
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Polymeric materials have a broad range of mechanical and physical *** have been widely used in material science,biomedical engineering,chemical engineering,and mechanical *** introduction of active elements into the soft matrix of polymers has enabled much more diversified functionalities of polymeric materials,such as self-healing,electroactive,magnetosensitive,pH-responsive,and many *** further enable applications of these multifunctional polymers,a mechanistic modeling method is required and of great significance,as it can provide links between materials’micro/nano-structures and their macroscopic mechanical *** this goal,molecular simulation plays an important role in understanding the deformation and evolution of polymer networks under external loads and *** molecular insights provide physical guidance in the formulation of mechanistic-based continuum models for multifunctional *** this perspective,we present a molecular simulation-guided and physics-informed modeling framework for polymeric ***,the physical theory for polymer chains and their networks is briefly *** serves as the foundation for mechanistic-models of polymers,linking their chemistry,physics,and mechanics ***,the deformation of the polymer network is used to derive the strain energy density ***,the corresponding continuum models can capture the intrinsic deformation mechanisms of polymer *** then highlight several representative examples across multiphysics coupling problems to describe in detail for this proposed *** but not least,we discuss potential challenges and opportunities in the modeling of multifunctional polymers for future research directions.
The work deals with the design, realization and functional tests of an experimental set-up equipped with a linear motor drive system. This experimental set-up is used to determine both the mechanical and electrical pr...
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ISBN:
(数字)9798350350708
ISBN:
(纸本)9798350350715
The work deals with the design, realization and functional tests of an experimental set-up equipped with a linear motor drive system. This experimental set-up is used to determine both the mechanical and electrical properties of linear magnetorheological (MR) dampers. The main elements of the experimental set-up are: a Linmot P10-70 linear motor operating with a Servo Drive E1400 controller, a Sensopart RLA50-220 laser triangulation displacement sensor, a ZEPWN CL-14 strain gauge force sensor operating with a CL 100P amplifier, and a power amplifier based on an OPA549 silicon chip. The linear motor allows the damper piston rod to be moved by a maximum of 150 mm. The power amplifier can operate as a controllable current or voltage source, supplying the damper coil. Its maximum output current is 5 A. The power amplifier internal circuits enable simultaneous measurement of both voltage and current. The physical quantities measured at the experimental set-up, i.e., displacement (0 - 220 mm), force (± 5 kN), coil voltage (± 10 V) and current (± 5 A), are converted into voltage signals in the range ± 10 V and fed to an Inteco RT-DAC 4 PCI measurement-control card supported by the MATLAB/Simulink environment. This card simultaneously generates analogue signals representing the set value of the linear drive slider displacement. A commercial MR damper applied in Audi TT passenger cars was used for functional tests carried out on the designed and constructed experimental set-up. The force-displacement and force-velocity characteristics were experimentally determined at constant coil currents. The temperature of both the stand elements and tested damper was also determined using a FLIR E50 thermal imaging camera.
In this paper, we present an approach for fleet sizing in the context of flash delivery, a time-sensitive delivery service that requires the fulfilment of customer requests in minutes. Our approach effectively combine...
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ISBN:
(数字)9798331505929
ISBN:
(纸本)9798331505936
In this paper, we present an approach for fleet sizing in the context of flash delivery, a time-sensitive delivery service that requires the fulfilment of customer requests in minutes. Our approach effectively combines individual delivery requests into groups and generates optimized operational plans that can be executed by a single vehicle or autonomous robot. The groups are formed using a modified routing approach for the flash delivery problem. Combining the groups into operational plans is done by solving an integer linear problem. To evaluate the effectiveness of our approach, we compare it against three alternative methods: fixed vehicle routing, non-pooled deliveries and a strategy encouraging the pooling of requests. The results demonstrate the value of our proposed approach, showcasing its ability to optimize the fleet size and improve operational efficiency. Our experimental analysis is based on a real-world dataset provided by a Dutch retailer, allowing us to gain valuable insights into the design of flash delivery operations and to analyze the effect of the maximum allowed delay, the number of stores to pick up goods from and the employed cost functions.
Accurate control of surgical robotics under uncertainty is crucial for achieving surgical autonomy. This uncertainty arises from sensor or model inaccuracies in surgical platforms, e.g., dVRK system, where joint bias ...
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ISBN:
(数字)9798331509644
ISBN:
(纸本)9798331509651
Accurate control of surgical robotics under uncertainty is crucial for achieving surgical autonomy. This uncertainty arises from sensor or model inaccuracies in surgical platforms, e.g., dVRK system, where joint bias in positioning and complex transmission effects caused by backlash and cable stretch. Previous approaches usually rely on depth sensors or additional offline calibration steps, making them difficult to deploy in real-world laparoscopy surgeries. In this paper, we propose a real-time geometric approach for calibrating joint errors on-the-fly combined with geometric features. An efficient visual detector is employed to identify the shaft mask and wrist keypoints. Based on the extracted features, we introduce a geometric model to recover the shaft axis pose and determine the first two joints uncertainty. Additionally, we develop a geometric model for wrist joints in projection space, calibrating remaining joint uncertainty through spatial geometry and the analytical structure of dVRK platform. Experimental results in simulation show that our approach significantly reduces joint error from 15° to 0.02°, with end-effector pose accuracy improving from centimeter to sub-millimeter level. This greatly enhances the accuracy and success rate of surgical automation. We also demonstrate robust control performance in diverse surgical tasks, highlighting the effectiveness of our geometric model in achieving accurate control despite joint offsets.
This study focus on passive and active learning within the context of robotics education on public high schools. By synthesizing research findings and practical insights, this paper offers valuable recommendations for...
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ISBN:
(数字)9798350391084
ISBN:
(纸本)9798350391091
This study focus on passive and active learning within the context of robotics education on public high schools. By synthesizing research findings and practical insights, this paper offers valuable recommendations for educators aiming to optimize the delivery of robotics education in public high schools, addressing the significance of the utilization of appropriate resources and technologies to support effective instruction. We implemented two distinct teaching methodologies to compare and study students' reactions and learning outcomes: Group A experienced a passive methodology, while Group B engaged with an active methodology. We conducted a survey and the results show that the majority of the students prefer the active approach used in classes.
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