Bioinspired passive variable recruitment of fluidic artificial muscles

2018 ◽  
Vol 29 (15) ◽  
pp. 3067-3081 ◽  
Author(s):  
Edward M Chapman ◽  
Matthew Bryant
Keyword(s):  
Control Method ◽  
Applied Pressure ◽  
Artificial Muscle ◽  
High Threshold ◽  
Artificial Muscles ◽  
Control Approach ◽  
Muscle Tissues ◽  
Wide Range ◽  
Variable Recruitment ◽  
Analogous Behavior

This article presents a novel, passive approach to creating variable actuator recruitment in bundles of fluidic artificial muscles. The passive recruitment control approach is inspired by the functionality of mammalian muscle tissues, in which a single activation signal from the nervous system sequentially triggers contraction of progressively larger actuation elements until the required force is generated. Biologically, this behavior is encoded by differences in electrical resistance properties between smaller and larger muscle-fiber groups. The approach presented here produces analogous behavior using a uniform applied pressure to all fluidic artificial muscles while creating differential pressure responses and threshold pressures among the fluidic artificial muscles via tailored bladder elasticity parameters. A model for using elastic bladder stiffness to control an artificial muscle bundle with a single valve is explored and used to compare a bundle of fluidic artificial muscles with both low and high threshold pressure units to a single fluidic artificial muscle of equivalent displacement and force capability. The results of this analysis indicate the efficacy of using this control method; it is advantageous in cases where a wide range of displacements and forces are necessary and can increase efficiency when the system primarily operates in a low-force regime but requires occasional bursts of high-force capability.

scholarly journals Variable Stiffness Structures Utilizing Pneumatic Artificial Muscles

2019 ◽  
Vol 256 ◽  
pp. 01005
Author(s):  
Feng Ning ◽  
Yingli Chang ◽  
Jingze Wang
Keyword(s):  
Artificial Muscle ◽  
Variable Stiffness ◽  
Pressure Control ◽  
Air Pressure ◽  
Homogeneous Distribution ◽  
Artificial Muscles ◽  
Wide Range ◽  
Pneumatic Artificial Muscles ◽  
Spring System

Pneumatic artificial muscles (PAMs) can offer excellent force-to-weight ratios and act as shape-changing actuator under injecting the actuation fluid into their bladders. PAMs could be easily utilized for morphing structures due to their millimeter-scale diameter. The pressurized PAM can serve not only as artificial muscle actuator which obtains contraction deformation capability but also as a spring system with variable stiffness. In this study, the stiffness behaviors of pressurized PAMs and a variable stiffness structure are investigated. By taking advantage of the designed PAMs which was conducted by the non- linear quasi-static model, significant changes in the spring stiffness can be achieved by air pressure control. A case study is presented to explore the potential behavior of a structure with circular permutation PAMs. The structure used in this case consists of sixteen PAMs with circular homogeneous distribution and a circular supporter with sixteen slide way runners. The stiffness of presented structure can vary flexibly in wide range through controlling the air pressure levels and slide deformation respectively.

On the Control of a Dielectric Elastomer Artificial Muscle With Variable Impedance

2013 ◽  
Author(s):  
Gianluca Palli ◽  
Giovanni Berselli
Keyword(s):  
Artificial Muscle ◽  
Artificial Muscles ◽  
Control Law ◽  
Model Uncertainties ◽  
Control Approach ◽  
Task Requirements ◽  
Linear Viscoelastic ◽  
Compensation Technique ◽  
Novel Strategy ◽  
Actuation Systems

Artificial Muscles based on Dielectric Elastomers (DE) can potentially enable the realization of bio-inspired actuation systems whose intrinsic compliance and damping can be varied according to the task requirements. Nonetheless, the control of DE-based Variable Impedance Actuators (VIA) is not trivial owing to the non-linear viscoelastic response which characterizes the acrylic dielectrics commonly employed in practical devices. In this context, the purpose of the present paper is to outline a novel strategy for the control of DE-based VIA. Although the proposed methodology is applicable to generic DE morphologies, the considered system is composed of a couple of conically-shaped DE films in agonistic-antagonistic configuration. Following previously published results, the system dynamic model is firstly recalled. Then, a DE viscoelasticity compensation technique is outlined together with a control law able to shape the DE actuator impedance as desired. The operative limits of the system are explicitly considered and managed in the controller by increasing the operating DE actuator stiffness if required. In addition, the problem of model uncertainties compensation is also addressed. Finally, as a preliminary step towards the realization of a practical DE-based VIA, the proposed control approach is validated by means of simulations.

scholarly journals Theoretical Hill-Type Muscle and Stability: Numerical Model and Application

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
S. Schmitt ◽  
M. Günther ◽  
T. Rupp ◽  
A. Bayer ◽  
D. Häufle
Keyword(s):  
Numerical Model ◽  
Biomechanical Model ◽  
Artificial Muscle ◽  
Biomedical Science ◽  
Artificial Muscles ◽  
Control Approach ◽  
Inverted Pendulum Model ◽  
Walking Machines ◽  
Antagonistic Muscle ◽  
Force Velocity

The construction of artificial muscles is one of the most challenging developments in today’s biomedical science. The application of artificial muscles is focused both on the construction of orthotics and prosthetics for rehabilitation and prevention purposes and on building humanoid walking machines for robotics research. Research in biomechanics tries to explain the functioning and design of real biological muscles and therefore lays the fundament for the development of functional artificial muscles. Recently, the hyperbolic Hill-type force-velocity relation was derived from simple mechanical components. In this contribution, this theoretical yet biomechanical model is transferred to a numerical model and applied for presenting a proof-of-concept of a functional artificial muscle. Additionally, this validated theoretical model is used to determine force-velocity relations of different animal species that are based on the literature data from biological experiments. Moreover, it is shown that an antagonistic muscle actuator can help in stabilising a single inverted pendulum model in favour of a control approach using a linear torque generator.

Toward Variable Recruitment Fluidic Artificial Muscles

2013 ◽  
Author(s):  
Matthew Bryant ◽  
Michael A. Meller ◽  
Ephrahim Garcia
Keyword(s):  
Traditional Method ◽  
Artificial Muscle ◽  
Artificial Muscles ◽  
Experimental Characterization ◽  
Force Output ◽  
Preliminary Results ◽  
Fluidic Control ◽  
Variable Recruitment ◽  
Save Energy

We investigate taking advantage of the lightweight, compliant nature of fluidic artificial muscles to create variable recruitment actuators in the form of artificial muscle bundles. Several actuator elements at different diameter scales are packaged to act as a single actuator device. The actuator elements of the bundle can be connected to the fluidic control circuit so that different groups of actuator elements, much like individual muscle fibers, can be activated independently depending on the required force output and motion. This novel actuation concept allows us to save energy by effectively selecting the size of the actuators on the fly based on the instantaneous required load, versus the traditional method wherein actuators are sized for the maximum required load, and energy is wasted by oversized actuators most of the time. This design also allows a single bundled actuator to operate in substantially different force regimes, which could be valuable for robots that need to perform a wide variety of tasks and interact safely with humans. This paper will propose this actuator concept and show preliminary results of the design, fabrication, and experimental characterization of three such bioinspired variable recruitment actuator prototypes.

Development and Demonstration of an Orderly Recruitment Valve for Fluidic Artificial Muscles

2020 ◽  
Author(s):  
Jeong Yong Kim ◽  
Nicholas Mazzoleni ◽  
Dheeraj Vemula ◽  
Matthew Bryant
Keyword(s):  
Motor Unit ◽  
Artificial Muscle ◽  
Motor Units ◽  
Artificial Muscles ◽  
Proof Of Concept ◽  
Experimental Proof ◽  
Load Demand ◽  
Variable Recruitment ◽  
And Performance ◽  
Spool Valve

Abstract Variable recruitment fluidic artificial muscle (FAM) bundles consist of multiple FAMs arranged in motor units that are sequentially activated as load demand increases. The conventional configuration of a variable recruitment FAM bundle requires a valve for each motor unit, which is referred to as a multi-valve system (MVS). As each motor unit within the bundle is selectively recruited, this configuration is highly adaptable and flexible in performance. However, as the number of motor units increases, the valve network can become complex and heavy in its design. To decrease complexity and weight, the concept of an orderly recruitment valve (ORV) has been proposed and analyzed. The ORV allows multiple motor units to be controlled using a single valve that recruits and pressurizes all motor units. The ORV concept consists of a spool valve with multiple outlet ports and a motor unit connected to each port. A linear actuator controls the position of the spool, allowing fluid flow into each port in succession. Naturally, de-recruitment happens in reverse order. The objective of the ORV is to strike a balance between performance and compactness of design. The purpose of this paper is to present analytical modeling that can be used to understand the behavior and performance of an ORV system and develop an experimental proof-of-concept that illustrates the ORV operation in hardware. A pneumatic ORV prototype was constructed and used to actuate two FAMs sequentially, each representing a motor unit. The results demonstrate the ORV as a compact system with which a variable recruitment bundle with multiple recruitment states can be controlled.

Sliding Mode Impedance Control of a Hydraulic Artificial Muscle

2018 ◽  
Author(s):  
Jonathon E. Slightam ◽  
Mark L. Nagurka ◽  
Eric J. Barth
Keyword(s):  
Sliding Mode ◽  
Impedance Control ◽  
Artificial Muscle ◽  
Lumped Parameter Model ◽  
Superior Performance ◽  
Specific Power ◽  
Artificial Muscles ◽  
Control Approach ◽  
Model Based ◽  
Improved Performance

Hydraulic artificial muscles offer unrivaled specific power and power density and are instrumental to the improved performance and success of soft robotics and lightweight mobile applications. This paper addresses the lack of model-based impedance control approaches for soft actuators such as hydraulic artificial muscles. Impedance control of actuators and robotic systems has been proven to be an effective approach for interacting with physical objects in the presence of uncertainty. A sliding mode impedance control approach based on Filippov’s principle of equivalent dynamics is introduced and applied to a hydraulic artificial muscle. A nonlinear lumped parameter model of the system is presented and a sliding mode impedance controller is derived. Experimental results show superior performance using model-based sliding mode impedance control versus a linear impedance control law in both tracking of position and stiffness when disturbances are introduced.

Parametric Study of a Fluidic Artificial Muscle Actuated Electrohydraulic System

2016 ◽  
Author(s):  
Edward Chapman ◽  
Tyler Jenkins ◽  
Matthew Bryant
Keyword(s):  
Hydraulic System ◽  
Artificial Muscle ◽  
Small Scale ◽  
Artificial Muscles ◽  
Operating Pressure ◽  
Control Force ◽  
Hydraulic Systems ◽  
Force Output ◽  
Injury Rehabilitation ◽  
Wide Range

Fluidic artificial muscles have the potential for a wide range of uses; from injury rehabilitation to high-powered hydraulic systems. Their modeling to date has largely been quasi-static and relied on the operator to adjust pressure so as to control force output and utilization while little work has been done to analyze the kinematics of the driving-systems involved in their operation. This paper utilizes an established electro-hydraulic model to perform a study of the components of a fluidic artificial muscle actuated climbing robot. Its purpose is to determine the effect of the robotic subsystems on function and efficiency for a small-scale system in order to extrapolate more general design and analysis schemes for future use. Its results indicate that important aspects to consider in design of the hydraulic system are system payload, operating pressure, pump selection, and FAM construction.

ICMA: AN EFFICIENT INTEGRATED CONGESTION CONTROL APPROACH

2019 ◽  
Vol 14 ◽  
Author(s):  
Tayyab Khan ◽  
Karan Singh ◽  
Kamlesh C. Purohit
Keyword(s):  
Congestion Control ◽  
Packet Loss ◽  
Control Method ◽  
Multicast Communication ◽  
Bandwidth Utilization ◽  
File Transfer ◽  
Control Approach ◽  
Communication Technique ◽  
Control Scheme ◽  
Multiparty Video Conferencing

Background: With the growing popularity of various group communication applications such as file transfer, multimedia events, distance learning, email distribution, multiparty video conferencing and teleconferencing, multicasting seems to be a useful tool for efficient multipoint data distribution. An efficient communication technique depends on the various parameters like processing speed, buffer storage, and amount of data flow between the nodes. If data exceeds beyond the capacity of a link or node, then it introduces congestion in the network. A series of multicast congestion control algorithms have been developed, but due to the heterogeneous network environment, these approaches do not respond nor reduce congestion quickly whenever network behavior changes. Objective: Multicasting is a robust and efficient one-to-many (1: M) group transmission (communication) technique to reduced communication cost, bandwidth consumption, processing time and delays with similar reliability (dependability) as of regular unicast. This patent presents a novel and comprehensive congestion control method known as integrated multicast congestion control approach (ICMA) to reduce packet loss. Methods: The proposed mechanism is based on leave-join and flow control mechanism along with proportional integrated and derivate (PID) controller to reduce packet loss, depending on the congestion status. In the proposed approach, Proportional integrated and derivate controller computes expected incoming rate at each router and feedback this rate to upstream routers of the multicast network to stabilize their local buffer occupancy. Results: Simulation results on NS-2 exhibit the immense performance of the proposed approach in terms of delay, throughput, bandwidth utilization, and packet loss than other existing methods. Conclusion: The proposed congestion control scheme provides better bandwidth utilization and throughput than other existing approaches. Moreover, we have discussed existing congestion control schemes with their research gaps. In the future, we are planning to explore the fairness and quality of service issue in multicast communication.

scholarly journals A Critical Review of Supersonic Flow Control for High-Speed Applications

2021 ◽  
Vol 11 (15) ◽  
pp. 6899
Author(s):  
Abdul Aabid ◽  
Sher Afghan Khan ◽  
Muneer Baig
Keyword(s):  
Supersonic Flow ◽  
Flow Control ◽  
Active Control ◽  
Critical Review ◽  
High Speed ◽  
Passive Control ◽  
Control Method ◽  
Sudden Expansion ◽  
Control Approach ◽  
Cost Efficient

In high-speed fluid dynamics, base pressure controls find many engineering applications, such as in the automobile and defense industries. Several studies have been reported on flow control with sudden expansion duct. Passive control was found to be more beneficial in the last four decades and is used in devices such as cavities, ribs, aerospikes, etc., but these need additional control mechanics and objects to control the flow. Therefore, in the last two decades, the active control method has been used via a microjet controller at the base region of the suddenly expanded duct of the convergent–divergent (CD) nozzle to control the flow, which was found to be a cost-efficient and energy-saving method. Hence, in this paper, a systemic literature review is conducted to investigate the research gap by reviewing the exhaustive work on the active control of high-speed aerodynamic flows from the nozzle as the major focus. Additionally, a basic idea about the nozzle and its configuration is discussed, and the passive control method for the control of flow, jet and noise are represented in order to investigate the existing contributions in supersonic speed applications. A critical review of the last two decades considering the challenges and limitations in this field is expressed. As a contribution, some major and minor gaps are introduced, and we plot the research trends in this field. As a result, this review can serve as guidance and an opportunity for scholars who want to use an active control approach via microjets for supersonic flow problems.

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