scholarly journals A Hybrid Soft Actuator Inspired by Grass-Spike: Design Approach, Dynamic Model, and Applications

2020 ◽  
Vol 10 (23) ◽  
pp. 8525
Author(s):  
Dong-Woon Choi ◽  
Cho-Won Lee ◽  
Duk-Yeon Lee ◽  
Dong-Wook Lee ◽  
Han-Ul Yoon
Keyword(s):  
Dynamic Model ◽  
Design Approach ◽  
Robotic Hand ◽  
Lagrangian Mechanics ◽  
Rigid Core ◽  
Soft Actuator ◽  
Potential Applications ◽  
Propulsion Force ◽  
Fine Control ◽  
Unknown System

This paper presents the bio-mimetic design approach, the dynamic model, and potential applications for a hybrid soft actuator. The proposed hybrid soft actuator consists of two main parts: a cylinder-shaped rigid core and soft silicone spikes wrapped around the core’s surface. The key idea of the proposed design approach is to mimic the movement of a grass-spike at a functional level by converting the vibration force generated by a small electric motor with a counterweight in the rigid core into a propulsion force produced by the elastic restoration of the spikes. One advantage of this design approach is that the hybrid soft actuator does not need to be tethered by a tube line from an air compressor and is more amenable to fine control. In addition, the hybrid soft actuator can be modularized with a wire and a tubular passage, which in turn work as a linear actuator. The dynamic model of the hybrid soft actuator can be derived by applying Lagrangian mechanics, and unknown system parameters can be identified by the optimization process based on the empirical data. Two applications—an elbow manipulator and a robotic hand grasper—demonstrate the feasibility of the proposed actuator to perform a muscle-tendon action successfully.

Robotic Fish Propelled by a Servo Motor and Ionic Polymer-Metal Composite Hybrid Tail

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Zheng Chen ◽  
Piqi Hou ◽  
Zhihang Ye
Keyword(s):  
Steady State ◽  
Dynamic Model ◽  
Robotic Fish ◽  
Metal Composite ◽  
Ionic Polymer Metal Composite ◽  
Servo Motor ◽  
Ionic Polymer ◽  
Soft Actuator ◽  
Polymer Metal ◽  
Motion Dynamics

In this paper, a new robotic fish propelled by a hybrid tail, which is actuated by two active joints, is developed. The first joint is driven by a servo motor, which generates flapping motions for main propulsion. The second joint is actuated by a soft actuator, an ionic polymer-metal composite (IPMC) artificial muscle, which directs the propelled fluid for steering. A state-space dynamic model is developed to capture the two-dimensional (2D) motion dynamics of the robotic fish. The model fully captures the actuation dynamics of the IPMC soft actuator, two-link tail motion dynamics, and body motion dynamics. Experimental results have shown that the robotic fish is capable of swimming forward (up to 0.45 body length/s) and turning left and right (up to 40 deg/s) with a small turning radius (less than half a body length). Finally, the dynamic model has been validated with experimental data, in terms of steady-state forward speed and turning speed at steady-state versus flapping frequency.

Dynamical Characteristics of a Hydraulic Soft Actuator With Three Degrees of Freedom

2021 ◽  
Author(s):  
Qing Xie ◽  
Tao Wang ◽  
Shiqiang Zhu
Keyword(s):  
Dynamic Model ◽  
Degrees Of Freedom ◽  
Soft Actuator ◽  
Dynamical Characteristics ◽  
Geometrical Features ◽  
Highly Nonlinear ◽  
Series Of Experiments ◽  
Soft Actuators ◽  
Modeling Of Dynamics ◽  
Three Degrees Of Freedom

Abstract In recent years, increasing attention and expanding research have been devoted to the study and application of soft actuators. Inherent compliance equips soft actuators with such advantages as incomparable flexibility, good environmental adaptability, safe interaction with the environment, etc. However, the highly nonlinear also bring challenges to modeling of dynamics. This study aims to explore the dynamical characteristics of an underwater hydraulic soft actuator. The actuator has three fiber-reinforced elastomer chambers distributed symmetrically inside. By controlling the pressure in the chambers through a hydraulic power system, the actuator can achieve spatial motion with three degrees of freedom. To describe the relationship between the input pressure combination and the actuator movement, a dynamic model considering the nonlinearity of viscoelastic material is developed based on Lagrangian method and constant curvature hypothesis. A series of experiments are carried out, including single-chamber actuation and multi-chamber actuation. The test results verify the effectiveness and precision of the model. Finally, the effects of the geometrical features on dynamic response are investigated through model-based simulation, which can provide guidance to parameter optimization. The proposed dynamic model can also contribute to behavior analysis, performance prediction, and motion control of the hydraulic soft actuator.

Analysis of propulsion performance of wave-propelled mechanism based on fluid-rigid body coupled model

2021 ◽  
pp. 147509022110620
Author(s):  
Zongyu Chang ◽  
Zhanxia Feng ◽  
Chao Deng ◽  
Lin Zhao ◽  
Jiakun Zhang ◽  
...  
Keyword(s):  
Rigid Body ◽  
Dynamic Model ◽  
Coupled Model ◽  
Rigid Body Dynamics ◽  
Design And Optimization ◽  
Marine Vehicles ◽  
Propulsion Performance ◽  
Operation Conditions ◽  
Propulsion Force ◽  
Cfd Method

Wave-propelled mechanisms are applied to propel unmanned marine vehicles such as Wave Glider and wave-powered boats, which can convert wave energy directly into propulsion. In this paper, a fluid-rigid body coupled dynamic model is utilized to investigate the propulsion performance of the wave-propelled mechanism. Firstly, the coupled dynamic model of the wave-propelled mechanism is developed based on relative motion principle by combining rigid body dynamics model and CFD method. Then, the motion responses of wave-propelled mechanism are calculated. The relationship between the propulsion force, heave and pitch motion of hydrofoil are analyzed by using phase diagrams and the actual operation conditions of propulsion mechanism are obtained. Besides, the effects of restoring spring stiffness and wave heights on the propulsion performance are also investigated, and the vortex evolution is illustrated at different moments of movement and different restoring stiffness. These works can be helpful for the design and optimization of different kinds of wave-propelled vehicles.

LQR Feedback Control Development for Wind Turbines Featuring a Digital Fluid Power Transmission System

2016 ◽  
Author(s):  
Niels H. Pedersen ◽  
Per Johansen ◽  
Torben O. Andersen
Keyword(s):  
Wind Turbine ◽  
Dynamic Model ◽  
Control Strategy ◽  
Linear Time ◽  
Control Design ◽  
Design Approach ◽  
Fluid Power ◽  
Full Field ◽  
Delta Sigma ◽  
Pulse Density

Research within digital fluid power (DFP) transmissions is receiving an increased attention as an alternative to conventional transmission technologies. The use of DFP displacement machines entails a need for applicable control algorithms. However, the design and analysis of controllers for such digital systems are complicated by its non-smooth behavior. In this paper a control design approach for a digital displacement machine® is proposed and a performance analysis of a wind turbine using a DFP transmission is presented. The performance evaluation is based on a dynamic model of the transmission with a DFP motor, which has been combined with the NREL 5-MW reference wind turbine model. A classical variable speed control strategy for wind speeds below rated is proposed for the turbine, where the pump displacement is fixed and the digital motor displacement is varied for pressure control. The digital motor control strategy consists of a full stroke operation strategy, where a Delta-Sigma pulse density modulator is used to determine the chamber activation sequence. In the LQR-control design approach, the discrete behavior of the motor and Delta-Sigma modulator is described by a discrete linear time invariant model. Using full-field flow wind profiles as input, the design approach and control performance is verified by simulation in the dynamic model of the wind turbine featuring the DFP transmission. Additionally, the performance is compared to that of the conventional NREL reference turbine, transmission and controller.

scholarly journals Smart Devices Based on the Soft Actuator with Nafion-Polypropylene-PDMS/Graphite Multilayer Structure

2020 ◽  
Vol 10 (5) ◽  
pp. 1829
Author(s):  
Yao Wei ◽  
Shihao Li ◽  
Xiaofan Zhang ◽  
Yanjun Fu ◽  
Kejian Chen
Keyword(s):  
Fast Response ◽  
Smart Devices ◽  
Asymmetric Structure ◽  
Soft Sensors ◽  
Bending Angle ◽  
Soft Actuator ◽  
Stimulus Responsive ◽  
Potential Applications ◽  
Control Circuits ◽  
Soft Actuators

The demand for multi-functional soft actuators with simple fabrication and fast response to multiple stimuli is increasing in the field of smart devices. However, for existing actuators that respond to a single stimulus, it is difficult to meet the requirements of application diversity. Herein, a type of multi-stimulus responsive soft actuator based on the Nafion-Polypropylene-polydimethylsiloxane (PDMS)/Graphite multilayer membranes is proposed. Such actuators have an excellent reversible response to optical/thermal and humidity stimulation, which can reach a 224.56° bending angle in a relative humidity of 95% within 5 s and a maximum bending angle of 324.65° in 31 s when the platform temperature is 80 °C, and has a faster response (<0.5 s) to optical stimuli, as an asymmetric structure allows it to bend in both directions. Based on such an actuator, some applications like flexible grippers and switches to carry items or control circuits, bionic flytraps to capture and release “prey”, have also been developed and studied. These provide potential applications in the fields of soft sensors, artificial skin and flexible robots.

Dynamic Modelling of a Cubic Flying Robot

2010 ◽  
Author(s):  
David St-Onge ◽  
Cle´ment Gosselin ◽  
Nicolas Reeves
Keyword(s):  
Experimental Data ◽  
Dynamic Model ◽  
Dynamic Modelling ◽  
Inertial Effects ◽  
Proper Selection ◽  
Art Galleries ◽  
Proposed Model ◽  
Potential Applications ◽  
Flying Robot ◽  
Flying Robots

This paper presents preliminary results on the dynamic modelling of a cubic flying robot referred to as the Tryphon. Several Tryphons and other similar cubic flying robots have been built in the course of this project. They are used for artistic performances in museums, art galleries or theatres. Although the Tryphons are functional, they are difficult to control because of limited knowledge of their behaviour. Hence, the development of a dynamic model has the potential to significantly improve the control performances. Based on models found in the literature, the aerostatics, aerodynamics, gravity, buoyancy and inertial effects of the Tryphon are combined into a dynamic model in this paper. The parameters of the proposed model are adjusted based on experimental data obtained with the Tryphons. It is shown that a proper selection and optimization of the parameters can accurately predict the dynamics of the robot. Further extensions of the model are discussed and potential applications are proposed.

scholarly journals An Overview of High-Entropy Alloys as Biomaterials

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 648
Author(s):  
Diogo Castro ◽  
Pedro Jaeger ◽  
Ana Catarina Baptista ◽  
João Pedro Oliveira
Keyword(s):  
Literature Review ◽  
Biomedical Applications ◽  
Design Approach ◽  
Special Focus ◽  
High Entropy Alloys ◽  
Biomedical Materials ◽  
High Entropy ◽  
Short Overview ◽  
Theoretical Design ◽  
Potential Applications

High-entropy alloys (HEAs) have been around since 2004. The breakthroughs in this field led to several potential applications of these alloys as refractory, structural, functional, and biomedical materials. In this work, a short overview on the concept of high-entropy alloys is provided, as well as the theoretical design approach. The special focus of this review concerns one novel class of these alloys: biomedical high-entropy alloys. Here, a literature review on the potential high-entropy alloys for biomedical applications is presented. The characteristics that are required for these alloys to be used in biomedical-oriented applications, namely their mechanical and biocompatibility properties, are discussed and compared to commercially available Ti6Al4V. Different processing routes are also discussed.

scholarly journals Design and synthesis of an antigenic mimic of the Ebola glycoprotein

2008 ◽  
Vol 23 (12) ◽  
pp. 3161-3168 ◽  
Author(s):  
Ryan D. Rutledge ◽  
Brian J. Huffman ◽  
David E. Cliffel ◽  
David W. Wright
Keyword(s):  
Rational Design ◽  
Epitope Mapping ◽  
Vaccine Development ◽  
Suitable Method ◽  
Design Approach ◽  
Sensor Technology ◽  
Native Protein ◽  
Design And Synthesis ◽  
Potential Applications ◽  
Further Development

An antigenic mimic of the Ebola glycoprotein was synthesized and tested for its ability to be recognized by an anti-Ebola glycoprotein antibody. Epitope-mapping procedures yielded a suitable epitope that, when presented on the surface of a nanoparticle, forms a structure that is recognized by an antibody specific for the native protein. This mimic-antibody interaction has been quantitated through ELISA and QCM-based methods and yielded an affinity (Kd = 12 × 10−6 M) within two orders of magnitude of the reported affinity of the native Ebola glycoprotein for the same antibody. These results suggest that the rational design approach described herein is a suitable method for the further development of protein-based antigenic mimics with potential applications in vaccine development and sensor technology.

Dynamic Modeling for a Cylindrical Mobile Robot on Rough-Terrain

2004 ◽  
Author(s):  
Giulio Reina ◽  
Mario Foglia ◽  
Annalisa Milella ◽  
Angelo Gentile
Keyword(s):  
Mobile Robot ◽  
Dynamic Model ◽  
Autonomous Vehicles ◽  
Mobile Robotics ◽  
Tactile Sensor ◽  
Physical Models ◽  
Rough Terrain ◽  
Potential Applications ◽  
Planning Methods ◽  
Vehicle Dynamic Model

Ground autonomous mini-mobile robots have important potential applications, such as reconnaissance, patrol, planetary exploration and military applications. To accomplish tasks on rough-terrain, control and planning methods must consider the physical characteristics of the vehicle and of its environment. Failure to understand these characteristics could lead to vehicle endangerment and mission failure. This paper describes recent and current work at Mobile Robotics Laboratory of the Politecnico of Bari in the area of rough terrain mobility and traversability of autonomous vehicles. A cylindrical shaped mobile robot is presented and its rolling motion on rough terrain is studied from both theoretical and experimental prospect. A comprehensive vehicle dynamic model is proposed based on well-established physical models of mobile robot-terrain interaction. The model is experimentally validated and it allows employing the vehicle as a tactile sensor for terrain characterization and identification. Innovative vision-based-methods are also introduced for estimating relevant kinematic parameters of the vehicle motion. It is shown that the dynamic model can describe efficiently the vehicle behavior and could enhance its mobility on rough-terrain through integration with control and planning algorithms.

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