scholarly journals A Review of Microrobot’s System: Towards System Integration for Autonomous Actuation In Vivo

Micromachines ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1249
Author(s):  
Zhongyi Li ◽  
Chunyang Li ◽  
Lixin Dong ◽  
Jing Zhao
Keyword(s):  
Medical Imaging ◽  
System Integration ◽  
Working Environment ◽  
Delivery Methods ◽  
Actuation System ◽  
Imaging Algorithms ◽  
Hybrid Actuation ◽  
Actuation Systems ◽  
And Control

Microrobots have received great attention due to their great potential in the biomedical field, and there has been extraordinary progress on them in many respects, making it possible to use them in vivo clinically. However, the most important question is how to get microrobots to a given position accurately. Therefore, autonomous actuation technology based on medical imaging has become the solution receiving the most attention considering its low precision and efficiency of manual control. This paper investigates key components of microrobot’s autonomous actuation systems, including actuation systems, medical imaging systems, and control systems, hoping to help realize system integration of them. The hardware integration has two situations according to sharing the transmitting equipment or not, with the consideration of interference, efficiency, microrobot’s material and structure. Furthermore, system integration of hybrid actuation and multimodal imaging can improve the navigation effect of the microrobot. The software integration needs to consider the characteristics and deficiencies of the existing actuation algorithms, imaging algorithms, and the complex 3D working environment in vivo. Additionally, considering the moving distance in the human body, the autonomous actuation system combined with rapid delivery methods can deliver microrobots to specify position rapidly and precisely.

Theoretical Modeling for Electroactive Polymer-Ceramic Hybrid Actuation Systems

Aerospace ◽  
2004 ◽  
Author(s):  
Tian-Bing Xu ◽  
Ji Su
Keyword(s):  
Performance Optimization ◽  
High Performance ◽  
Electroactive Polymer ◽  
Actuation System ◽  
Electromechanical Responses ◽  
Electromechanical Performance ◽  
New Type ◽  
Hybrid Actuation ◽  
Actuation Systems ◽  
Further Development

An electroactive polymer-ceramic hybrid actuation system (HYBAS) was recently developed. The HYBAS demonstrates significantly-enhanced electromechanical performance by utilizing advantages of cooperative contributions of the electromechanical responses of an electrostrictive copolymer and an electroactive single crystal. The hybrid actuation system provides not only a new type of device but also a concept to utilize different electroactive materials in a cooperative and efficient method for optimized electromechanical performance. In order to develop an effective procedure to optimize the performance of a hybrid actuation system (HYBAS), a theoretical model has been developed, based on the elastic and electromechanical properties of the materials utilized in the system and on the configuration of the device. The model also evaluates performance optimization as a function of geometric parameters, including the length of the HYBAS and the thickness ratios of the constituent components. The comparison between the model and the experimental results shows a good agreement and validates the model as an effective method for the further development of high performance actuating devices or systems for various applications.

A Magnetorheological Actuation System - Part II: Modeling

2007 ◽  
Author(s):  
Shaju John ◽  
Anirban Chaudhuri ◽  
Norman M. Wereley
Keyword(s):  
Active Vibration Control ◽  
Wheatstone Bridge ◽  
Bingham Plastic ◽  
Magnetic Circuits ◽  
Actuation System ◽  
System Part ◽  
Active Vibration ◽  
Hybrid Actuation ◽  
Actuation Systems ◽  
Moving Parts

There is a demand for hybrid actuation systems which combines actuation and valving systems in a compact package. Such self-contained actuation systems can be used in the field of rotorcraft as active pitch links and in the field of automotive engineering as active vibration control devices. MR fluids can be used in valves to control the motion of an output cylinder. Such a valving system will have no moving parts and thus can be used in applications where there is high centrifugal loading. In the current setup, MR valves are configured in the form of a Wheatstone bridge and bidirectional motion is produced in the output cylinder by alternate application of magnetic field in the arms of the wheatstone bridge. The actuation is performed using a compact Terfenol-D stack driven actuator. The frequency rectification of the stack motion is done using reed valves. This actuator and valve configuration form a compact hydraulic system with fluidic valves. The advantages of such systems are low parts count, absence of moving parts and the ability to control the motion of the output cylinder by controlling the fluid flow through the MR valves. By the application of different magnetic fields to the arms of the bridge (by applying different currents to the magnetic circuits), we can control the differential pressure seen by the output cylinder. This add the capability of designing controllers for the system. This work concentrates on the modeling of the entire actuation system performance. The results of the modeling effort is then compared with experimental results. The system is modeled by ordinary differential equations governing the motion of the active stack, fluid in the different sections and the output cylinder shaft. The rheological properties of the MR fluid is modeled using both Bingham plastic and bi-viscous models.

Dynamic Modeling and Control of an Electromechanical Control Actuation System

2017 ◽  
Author(s):  
Ümit Yerlikaya ◽  
R. Tuna Balkan
Keyword(s):  
Nonlinear Model ◽  
Equations Of Motion ◽  
Ball Screw ◽  
Loop Control ◽  
Modeling And Control ◽  
Performance Requirements ◽  
Actuation System ◽  
Lever Mechanism ◽  
Actuation Systems ◽  
And Control

Electromechanical actuators are widely used in miscellaneous applications in engineering such as aircrafts, missiles, etc. due to their momentary overdrive capability, long-term storability, and low quiescent power/low maintenance characteristics. This work focuses on electromechanical control actuation systems (CAS) that are composed of a brushless direct current motor, ball screw, and lever mechanism. In this type of CAS, nonlinearity and asymmetry occur due to the lever mechanism itself, saturation limits, Coulomb friction, backlash, and initial mounting position of lever mechanism. In this study, both nonlinear and linear mathematical models are obtained using governing equations of motion. By using the linear model, it is shown that employing a PI-controller for position and a P-controller for velocity will be sufficient to satisfy performance requirements in the inner-loop control of an electromechanical CAS. The unknown controller parameters and anti-windup coefficient are obtained by the Optimization Tools of MATLAB using nonlinear model. Results obtained from the nonlinear model and real-time unloaded and loaded tests on a prototype developed are compared to verify the nonlinear model.

Research on Performances of Hybrid Actuation System with Dissimilar Redundancies

2012 ◽  
Vol 430-432 ◽  
pp. 1559-1563 ◽  
Author(s):  
Li Ming Yu ◽  
Zi Qing Ye
Keyword(s):  
Operating Mode ◽  
Development Trend ◽  
Hydraulic Actuator ◽  
Actuation System ◽  
Electric Aircraft ◽  
Hybrid Actuation ◽  
Actuation Systems ◽  
The Development Trend ◽  
More Electric Aircraft ◽  
Mode A

Hybrid actuation system (HAS) with dissimilar redundancies conforms to the development trend of future actuation systems in more electric aircraft (MEA). Hybrid Actuation system is composed of a traditional servo valve controlled hydraulic actuator (SHA) and an electro-hydraulic actuator (EHA). It has two operating models, active/passive mode (A/P) and active/active mode (A/A). In A/A model both actuators are actively controlled. Corresponding to A/A model, SHA is actively controlled and EHA is passively controlled in A/P model. The hybrid actuation system is built in the AMESim simulation environment, comparative analysis is performed when system operates in these two modes, such as signal response and force fighting. The simulation results provide a guideline to determine the specific operating mode of the system in different circumstances.

Design, development, and testing of a lightweight hybrid robotic knee prosthesis

2018 ◽  
Vol 37 (8) ◽  
pp. 953-976 ◽  
Author(s):  
Tommaso Lenzi ◽  
Marco Cempini ◽  
Levi Hargrove ◽  
Todd Kuiken
Keyword(s):  
Electric Motor ◽  
Knee Prosthesis ◽  
Gait Pattern ◽  
Design Development ◽  
Passive Mode ◽  
Active Mode ◽  
Actuation System ◽  
Hybrid Actuation ◽  
And Control ◽  
Stair Ambulation

We present a lightweight robotic knee prosthesis with a novel hybrid actuation system that enables passive and active operation modes. The proposed hybrid knee uses a spring-damper system in combination with an electric motor and transmission system, which can be engaged to provide a stair ambulation capability. In comparison to fully powered prostheses that power all ambulation activities, a hybrid knee prosthesis can achieve significant weight reduction by focusing the design of the actuator on a subset of activities without losing the ability to produce equivalent torque and mechanical power in the active mode. The hybrid knee prototype weighs 1.7 kg, including battery and control, and can provide up to 125 Nm of repetitive torque. Experiments with two transfemoral amputee subjects show that the proposed hybrid knee prosthesis can support walking on level ground in the passive mode, as well as stair ambulation with a reciprocal gait pattern in the active mode.

Experimental Study of the Impact of Alisma plantago-aquatica Secretions on Pathogenic Bacteria

2014 ◽  
Vol 1 (3) ◽  
pp. 3-7
Author(s):  
O. Zhukorskyy ◽  
O. Hulay
Keyword(s):  
Pathogenic Bacteria ◽  
Initial Density ◽  
Biologically Active ◽  
Erysipelothrix Rhusiopathiae ◽  
Natural Focus ◽  
Test Species ◽  
Popula Tions ◽  
And Control ◽  
The Impact

Aim. To estimate the impact of in vivo secretions of water plantain (Alisma plantago-aquatica) on the popula- tions of pathogenic bacteria Erysipelothrix rhusiopathiae. Methods. The plants were isolated from their natural conditions, the roots were washed from the substrate residues and cultivated in laboratory conditions for 10 days to heal the damage. Then the water was changed; seven days later the selected samples were sterilized using fi lters with 0.2 μm pore diameter. The dilution of water plantain root diffusates in the experimental samples was 1:10–1:10,000. The initial density of E. rhusiopathiae bacteria populations was the same for both experimental and control samples. The estimation of the results was conducted 48 hours later. Results. When the dilution of root diffusates was 1:10, the density of erysipelothrixes in the experimental samples was 11.26 times higher than that of the control, on average, the dilution of 1:100 − 6.16 times higher, 1:1000 – 3.22 times higher, 1:10,000 – 1.81 times higher, respectively. Conclusions. The plants of A. plantago-aquatica species are capable of affecting the populations of E. rhusiopathiae pathogenic bacteria via the secretion of biologically active substances into the environment. The consequences of this interaction are positive for the abovementioned bacteria, which is demon- strated by the increase in the density of their populations in the experiment compared to the control. The intensity of the stimulating effect on the populations of E. rhusiopathiae in the root diffusates of A. plantago-aquatica is re- ciprocally dependent on the degree of their dilution. The investigated impact of water plantain on erysipelothrixes should be related to the topical type of biocenotic connections, the formation of which between the test species in the ecosystems might promote maintaining the potential of natural focus of rabies. Keywords: Alisma plantago-aquatica, in vivo secretions, Erysipelothrix rhusiopathiae, population density, topical type of connections.

In-vivo evaluation of lipid lowering ability of Chloris paraguaiensis extracts

2020 ◽  
Vol 7 (2) ◽  
pp. 21-24
Author(s):  
Pavani C H
Keyword(s):  
Medicinal Plants ◽  
Chemical Constituents ◽  
The Body ◽  
Lipid Lowering ◽  
Medical Systems ◽  
In Vivo Evaluation ◽  
Standard Drug ◽  
Anti Oxidant ◽  
And Control

Hyperlipidemia is the immediate results of the excessive fat intake in food. This results in the elevated levels of cholesterol and triglycerides in the blood. This leads to heart conditions like CAD, hypertension, congestive heart failure as risk factors which can be lethal. There are many drugs to treat and control the lipids levels in the body. These drugs are either designed to prevent LDL accumulation and VLDL synthesis. Some drugs also lower the elevated levels of saturated lipids in the body. But many drugs are known to cause side effects and adverse effects; therefore, alternatives to the drugs are the subjects for current investigations. Herbs and medicinal plants are used as treatment sources for many years. They have been used in the Indian medical systems like Ayurveda, Siddha etc. As the application of herbs in the treatment is growing, there is an urgent need for the establishment of Pharmacological reasoning and standardization of the activity of the medicinal plants. Chloris paraguaiensis Steud. is Poyaceae member that is called locally as Uppugaddi. Traditionally it is used to treat Rheumatism, Diabetes, fever and diarrhoea. The chemical constituents are known to have anti-oxidant properties and most of the anti-oxidants have anti-hyperlipidemic activity too. Since the plant has abundant flavonoid and phenol content, the current research focusses on the investigation of the anti-hyperlipidemic activity of the plant Chloris extracts. Extracts of Chloris at 200mg/kg showed a comparably similar anti hyperlipidemia activity to that of the standard drug. The extracts showed a dose based increase in the activity at 100 and 200mg/kg body weight.

scholarly journals Stage-dependent effect of deferoxamine on growth of Plasmodium falciparum in vitro

Blood ◽  
1990 ◽  
Vol 76 (6) ◽  
pp. 1250-1255 ◽  
Author(s):  
S Whitehead ◽  
TE Peto
Keyword(s):  
Plasmodium Falciparum ◽  
Growth Inhibition ◽  
Antimalarial Activity ◽  
Clinical Malaria ◽  
Inhibitory Effect ◽  
Parasite Development ◽  
And Control ◽  
Speed Of Onset

Abstract Deferoxamine (DF) has antimalarial activity that can be demonstrated in vitro and in vivo. This study is designed to examine the speed of onset and stage dependency of growth inhibition by DF and to determine whether its antimalarial activity is cytostatic or cytocidal. Growth inhibition was assessed by suppression of hypoxanthine incorporation and differences in morphologic appearance between treated and control parasites. Using synchronized in vitro cultures of Plasmodium falciparum, growth inhibition by DF was detected within a single parasite cycle. Ring and nonpigmented trophozoite stages were sensitive to the inhibitory effect of DF but cytostatic antimalarial activity was suggested by evidence of parasite recovery in later cycles. However, profound growth inhibition, with no evidence of subsequent recovery, occurred when pigmented trophozoites and early schizonts were exposed to DF. At this stage in parasite development, the activity of DF was cytocidal and furthermore, the critical period of exposure may be as short as 6 hours. These observations suggest that iron chelators may have a role in the treatment of clinical malaria.

Porphyrin-lipid nanovesicles (Porphysomes) are effective photosensitizers for photodynamic therapy

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Keegan Guidolin ◽  
Lili Ding ◽  
Juan Chen ◽  
Brian C. Wilson ◽  
Gang Zheng
Keyword(s):  
Photodynamic Therapy ◽  
Tumor Growth ◽  
Intrinsic Structure ◽  
Therapeutic Applications ◽  
Positron Emission ◽  
Theranostic Agents ◽  
Negative Controls ◽  
And Control ◽  
Complete Tumor

Abstract Porphysomes (PS) are liposome-like nanoparticles comprising pyropheophorbide-conjugated phospholipids that have demonstrated potential as multimodal theranostic agents for applications that include phototherapies, targeted drug delivery and in vivo fluorescence, photoacoustic, magnetic resonance or positron emission imaging. Previous therapeutic applications focused primarily on photothermal therapy (PTT) and suggested that PSs require target-triggered activation for use as photodynamic therapy (PDT) sensitizers. Here, athymic nude mice bearing subcutaneous A549 human lung tumors were randomized into treatment and control groups: PS-PDT at various doses, PS-only and no treatment negative controls, as well as positive controls using the clinical photosensitizer Photofrin. Animals were followed for 30 days post-treatment. PS-PDT at all doses demonstrated a significant tumor ablative effect, with the greatest effect seen with 10 mg/kg PS at a drug-light interval of 24 h. By comparison, negative controls (PS-only, Photofrin-only, and no treatment) showed uncontrolled tumor growth. PDT with Photofrin at 5 mg/kg and PS at 10 mg/kg demonstrated similar tumor growth suppression and complete tumor response rates (15 vs. 25%, p = 0.52). Hence, porphysome nanoparticles are an effective PDT agent and have the additional advantages of multimodal diagnostic and therapeutic applications arising from their intrinsic structure. Porphysomes may also be the first single all-organic agent capable of concurrent PDT and PTT.

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