Wire Actuators Research Articles

Abstract 3062: Minimally Invasive Epicardial Injection Using a Miniature Crawling Robotic Device Through a Subxiphoid Approach

Itroduction: We have developed a miniature crawling robot (HeartLander) that navigates on the surface of a heart to dedicate minimally invasive intrapericardial interventions. We performed a series of epicardial injections with the HeartLander using a beating porcine heart through a closed chest subxiphoid approach. Hypothesis: The HeartLander can provide precise and safe epicardial injections under the minimally invasive approach. Methods: HeartLander consists of two articulated modules that adhere to the epicardium using suction. The modules are each 6.5 mm tall and 8 mm wide, and include two working channels for instrumentation. Vacuum pressure and wire actuation for inchworm-like locomotion are provided through the tether of the robot. The device uses 3-D magnetic tracking for navigation, and a joystick for control input. The control software also enables semi-automated navigation to a selected target location, as well as pre-planning of injection locations after the target is reached. In 8 porcine preparations, the device was inserted into the pericardial space through a subxiphoid approach. Epicardial injection on the ventricular wall was performed with a dedicated injection needle device through the working port. Results: The HeartLander could precisely be maneuvered to designated targets. Injections into left ventricles (i.e. anterior, lateral, posterior walls) were successfully accomplished in all cases. Mean depth of injection was 3.1 ± 0.34 mm. Mean path length was 48 ± 10 mm. Mean speed was 22 ± 7 mm/min. Mean suction pressure and force on wires during trials was 562 ± 26 mmHg and 4.1 ± 0.9 Newton, respectively. The magnetic tracking system provided adequate visualization. Mean deviation from the target path was 0.2 ± 1.0 mm. Target acquisition was within 2.1 ± 1.4 mm. No fatal arrhythmia and bleeding were noted during the trials. There were no injuries to the heart and surrounding structures due to the robot locomotion. A histological study verified no epicardial damage. Conclusions: The HeartLander demonstrated successful epicardial injection on a beating porcine heart through a closed chest subxiphoid approach. This approach may facilitate the cardiac cell transplantation therapy in the field of minimally invasive surgery.

Robust control of a shape memory alloy wire actuated flap

In this paper, shape memory alloy (SMA) wire actuators are used to control the flapmovement of a model airplane wing. Conventionally, the flap of an aircraft wing is drivenby electric motors or hydraulic actuators. The use of SMA actuators has the advantage ofsignificant weight reduction. Two SMA actuators are used: one to move the flap up and theother to move the flap down. A sliding mode based nonlinear robust controller isdesigned and implemented on a real-time data acquisition and control platform tocontrol the position of the flap. Feedback control experiments of both positionregulation and tracking control are conducted. To demonstrate the controller’srobustness to uncertainties and disturbances, experiments are conducted withadditional mass on the flap, changing thermodynamic conditions and time varyingaerodynamic loads. Experiments in all cases show that the actual position of theflap closely follows the desired command during experiments. In conclusion, thispaper shows the feasibility of using SMA wire actuators for aircraft flap control.

Design and control of a Nitinol wire actuated rotary servo

This paper presents the design and control of a rotary servo actuated by a shape memoryalloy (SMA) wire. A new rotary servo device using Nitinol type of SMA wire is designedand fabricated in this study. This new rotary actuator utilizes a Nitinol wire wound on athreaded non-conductive rotor. One end of the Nitinol wire is fixed to the rotor andthe other end is fixed to the supporting base plate. The rotor is connected to apre-tensioned torsional spring such that two-way rotation can be achieved. Upon heatingof the Nitinol wire using electric current, the wire contracts, causing the rotorto rotate, since the other end of the SMA wire is rigidly connected to the baseplate. This rotor design is compact and offers a space-saving solution for theuse of SMA wire actuators. To actively control the servo, a sliding-mode basedrobust control approach is used. The sliding-mode based robust control consists ofthree components: a standard proportional plus derivative (PD) control term, afeedforward term used as a bias current, and a robust term to increase systemstability and concurrently control accuracy. Experimental results confirm thefunctionality of the Nitinol wire actuated rotary servo and show this device canbe precisely controlled using the sliding-mode based robust control approach.

A Study on Anthropomorphic Robot Hand Simulation Driven by SMA Wire Using Segment Control

In recent years, as the robot technology is developed, the researches on the artificial muscle actuator that enables robot to move dexterously like biological organ become active. Actuators are one of the key technologies underpinning robotics. Particularly breakthroughs of power-to-weight ratio or energy-density in actuator technology have significant impacts upon the design and the control of robotic systems. The widely used materials for artificial muscle are the shape memory alloy and electro-active polymer. These actuators have the higher energy density than the electromechanical actuators such as the electric motor. However, there are some drawbacks because these actuators have the hysteretic dynamic characteristics. In this paper, the segment control for reducing the hysteresis of SMA is proposed and the simulation of an anthropomorphic robotic hand is performed using ADAMS. A new approach to design and control of SMA actuators is presented. SMA wire is divided into many segments and their thermal states are controlled individually in a binary manner(ON/OFF). The basic experiment for evaluating the dynamic characteristics of SMA wire actuator is performed.

Design and control of a proof-of-concept variable area exhaust nozzle using shape-memoryalloy actuators

There is no reported research in the literature of using shape-memory alloy (SMA)actuators for variable area exhaust nozzles for a jet engine, to the authors’ best knowledge.SMA actuators have the advantage of a high power-to-weight ratio and can resultin dramatic weight reduction as compared to hydraulic systems. However, thedifficulty of using SMA actuators for controlling variable area exhaust nozzles liesin the fact that the temperature near the exhaust nozzle is far higher than thetransformation temperature of an SMA actuator. Due to the flexibility and smallvolume of SMA wire actuators, they can be remotely replaced in a region where thetemperature is lower than that of its transformation temperature. By exploitingthis fact, this paper presents a novel design of a proof-of-concept variable areaexhaust nozzle using shape-memory alloy wire actuators. The SMA actuators areremotely placed away from the exhaust nozzle area so that the environmentaltemperature is below their transformation temperature. By electrically heating theSMA actuators, the exhaust nozzle will experience an area reduction of up to40%. Bias springs will apply forces to return the exhaust nozzle to the open-upconfiguration. A feedback controller based sliding-mode method is used to regulate theSMA actuator position. Experimental results demonstrate that the proposeddesign meets the desired area variation specifications and shows the promise of alightweight and simple exhaust nozzle design by using shape-memory alloy actuators.

Cooling and Heating Characteristics of Ti-Ni Based Shape Memory Alloy Wire Actuators

Ti-51Ni(at%) and Ti-40Ni-10Cu(at%) alloy wires with diameters of 0.3mm, 0.5mm and 0.7mm were prepared by drawing the alloy ingots fabricated by vacuum induction melting. Heating rates of the wires were investigated by measuring changes in temperatures of them while applying currents in the range of 1 A and 6 A to them and cooling rates were investigated by measuring changes in temperatures of them after cutting currents. Heating rate increased with increasing the amount of current, while cooling rate was kept constant. Both heating rate and cooling rate increased with decreasing diameter of wire. This suggested that high amount of current and small wire diameter were required for high heating and cooling rate. Comparing Ti-50Ni alloy wires with Ti-40Ni-10Cu alloy wires, heating rates of the latter was faster than that of the former, although cooling rates were almost same. This suggested that Ti-40Ni-10Cu alloy wires is better than Ti-50Ni alloy wires for the applications requiring high actuating rates.

A force‐feedback six‐degrees‐of‐freedom wire‐actuated master for teleoperation: the WiRo‐6.3

PurposeThis paper aims to present an innovative example of a master for teleoperation capable of moving in six degrees of freedom and of providing a force and torque feedback on the operator's hand.Design/methodology/approachAfter a brief overview of what the state of the art in teleoperation has to offer, the paper outlines the choice of an innovative structure in terms of both geometry and components, pointing out its main characteristics compared with traditional interfaces.FindingsThe master for teleoperation WiRo‐6.3 has been designed and constructed and is fully operative, thanks to the following theoretical analyses: positional and orientation workspace(s), forward and inverse kinematics, statics, overall control strategies. The mechanical details are also presented.Research limitations/implicationsThe WiRo‐6.3 is suitable to those applications in which human command is necessary but potentially harmful, and where a force‐feedback interface is preferred to obtain better control over the task to be accomplished. A possible field of interest could be the control of robot arms in dangerous environments, nuclear applications, uncomfortable climates, remote operations.Originality/valueThe master WiRo‐6.3 is a novel device both for its geometric structure and for the wire actuation choice; those characteristics provide very interesting results in terms of dexterity, force feedback performance and overall user‐friendliness.

Position estimation and control of SMA actuators based on electrical resistance measurement

As a functional material, shape memory alloy (SMA) has attracted much attention and research effort to explore its unique properties and its applications in the past few decades. Some of its properties, in particular the electrical resistance (ER) based self-sensing property of SMA, have not been fully studied. Electrical resistance of an SMA wire varies during its phase transformation. This variation is an inherent property of the SMA wire, although it is highly nonlinear with hysteresis. The relationship between the displacement and the electrical resistance of an SMA wire is deterministic and repeatable to some degree, therefore enabling the self-sensing ability of the SMA. The potential of this self-sensing ability has not received sufficient exploration so far, and even the previous studies in literature lack generality. This paper concerns the utilization of the self-sensing property of a spring-biased Nickel-Titanium (Nitinol) SMA actuator for two applications: ER feedback position control of an SMA actuator without a position sensor, and estimation of the opening of a SMA actuated valve. The use of the self-sensing property eliminates the need for a position sensor, therefore reducing the cost and size of an SMA actuator assembly. Two experimental apparatuses are fabricated to facilitate the two proposed applications, respectively. Based on open-loop testing results, the curve fitting technique is used to represent the nonlinear relationships between the displacement and the electrical resistance of the two SMA wire actuators. Using the mathematical models of the two SMA actuators, respectively, a proportional plus derivative controller is designed for control of the SMA wire actuator using only electrical resistance feedback. Consequently, the opening of the SMA actuated valve can be estimated without using an extra sensor.

Numerical simulation of a double SMA wire actuator using the two-way shape memoryeffect of SMA

A structure using the two-way shape memory effect (TWSME) returns to its initialshape by increasing or decreasing the temperature under initial residual stress.Through the thermo-mechanical constitutive equation of the shape memory alloy(SMA) proposed by Lagoudas et al (1996 Mech. Compos. Mater. Struct. 3 153–79), wesimulate the behavior of a double SMA wire actuator in which two SMA wires areattached to the tip of a bar under the initially given residual stress. Through thenumerical results conducted in the present study, the behavior and characteristicsof an SMA actuator with two SMA wires are shown to be quite different fromthose of a single wire actuator, and the proposed actuator device is suitable forrepeated actuation. A thermal cycle needs to be applied to the double SMA wireactuator for it to return to the original position. The proper thermal cycle forrepeated actuation is proposed in the present study. The simulation algorithmproposed in the present study can be applied extensively to the analysis of theassembled system of SMA actuator and host structure in practical applications.

Wrinkling control of inflatable booms using shape memory alloy wires

An inflatable boom is a fundamental structural part of inflatable space structuresmaintaining the expected configuration of the whole system, supporting external loads andguaranteeing the efficiency of the membrane surface. The inflatable structure is a thin filmstructure compactly packaged and expanded to the desired configuration by the internalgas pressure. But the structures can be easily distorted and even collapsed by wrinkling. Inthis study, the behavior of an inflatable boom structure is investigated numerically andexperimentally. To achieve a better bending strength, the methodology to control thewrinkling growth and the deformed configuration of the inflatable boom structure with ashape memory alloy (SMA) wire actuator is developed. To understand the nonlinearbehavior of an inflatable boom due to wrinkling, the structure is numerically modeledusing the ABAQUS finite element program with a wrinkling algorithm developedbased on the Miller–Hedgepeth membrane theory. To verify the present analysismethod, the inflatable boom made of Kapton film is examined by the bending testswith various internal pressures. To delay the growth of wrinkling that rapidlydeteriorates the bending strength of the inflatable boom, a SMA wire actuator isapplied. SMA wires are attached on the edge of the inflatable boom and generate arecovery force to remove wrinkling and restore the deformation of the boom.

Kinematic calibration of a wire-actuated parallel robot

In this article kinematic calibration of a wire-actuated parallel robot is discussed. Available redundant sensing of joint displacements makes it feasible to consider central linkage and wire actuators of the robot one at a time for calibration purposes. Identifiability issues due to the existence of a parallelogram in the central linkage are discussed. Kinematic modelling and parameter estimation of the wire actuators are also carried out. The results are validated through simulations.

Effects of thermo-mechanical cycling on the strain response of Ni–Ti–Cu shape memory alloy wire actuator

The present paper deals with the strain response of Ni–Ti–Cu shape memory alloy (SMA) wire actuators on thermo-mechanical cycling (TMC). The characteristics of the actuators such as austenite (hot shape) remnant deformation and recovery strain undergo changes upon TMC. These changes are significant in the initial few cycles and the properties of SMA tend to reach a steady state on further cycling. It is believed that TMC induces defects in the microstructure and stabilizes the martensite/austenite phase. These in turn result in continuous change in strain response with the progress of TMC. It has been shown that for a stable strain response, the wire actuators need to be subjected to TMC at a higher stress than the working stress prior to application. Experiments were also conducted in order to minimize the number of TMC required for achieving stable strain response.

1P1-B05 ワイヤ懸垂系によるリンク機構の操り

The manipulation of wire driven multiple link mechanisms by wire actuation is discussed. The relationship between the wire tensions and generated forces and torques on each link and joint is obtained. Then, the necessary number of wires and geometrical conditions of achieving arbitrary postures of link mechanisms are derived. Then, the number and conditions under gravity are also discussed. Using the obtained equations, how to install the wires into a two link mechanism is shown.

Preliminary evaluation of a mobile robotic device for navigation and intervention on the beating heart

This article describes the development and preliminary testing of a mobile robotic device to facilitate minimally invasive beating-heart intrapericardial intervention. The HeartLander robot will be introduced beneath the pericardium via subxiphoid incision, adhere to the epicardium, navigate to any location, and administer therapy under the control of the physician. As compared to current robotic cardiac surgical techniques, this novel paradigm obviates immobilization of the heart and eliminates access limitations. Furthermore, it does not require lung deflation and differential ventilation and thus could enable outpatient cardiac surgery. The current HeartLander prototypes use suction to maintain prehension of the epicardium and wire actuation to perform locomotion. A fiber optic videoscope displays visual feedback to the physician, who controls the device through a joystick interface. The initial prototype demonstrated successful prehension, turning, and locomotion on open-chest, beating-heart porcine models where the pericardium was removed (N = 3). A smaller second-generation prototype with an injection system demonstrated locomotion and myocardial injection of dye, both performed with the pericardium intact (N = 3). These trials illustrate the feasibility of using a miniature mobile robot to navigate upon the beating heart and perform intrapericardial therapy.

1A1-N-073 非線形バネSATの耐久性評価試験(ワイヤ駆動系の機構と制御,生活を支援するロボメカ技術のメガインテグレーション)

1A1-N-073 非線形バネSATの耐久性評価試験(ワイヤ駆動系の機構と制御,生活を支援するロボメカ技術のメガインテグレーション)

1A1-N-074 非線形バネSATを用いた関節剛性,トルクおよび位置制御(ワイヤ駆動系の機構と制御,生活を支援するロボメカ技術のメガインテグレーション)

1A1-N-074 非線形バネSATを用いた関節剛性,トルクおよび位置制御(ワイヤ駆動系の機構と制御,生活を支援するロボメカ技術のメガインテグレーション)

1A1-N-076 CCDカメラによるワイヤ振れ角計測と懸垂物の振れ止め制御(ワイヤ駆動系の機構と制御,生活を支援するロボメカ技術のメガインテグレーション)

1A1-N-076 CCDカメラによるワイヤ振れ角計測と懸垂物の振れ止め制御(ワイヤ駆動系の機構と制御,生活を支援するロボメカ技術のメガインテグレーション)

1A1-N-078 ワイヤ拘束による柔軟物の形状制御(ワイヤ駆動系の機構と制御,生活を支援するロボメカ技術のメガインテグレーション)

1A1-N-078 ワイヤ拘束による柔軟物の形状制御(ワイヤ駆動系の機構と制御,生活を支援するロボメカ技術のメガインテグレーション)

1A1-N-077 ワイヤ懸垂型室内移動マニピュレータの開発(ワイヤ駆動系の機構と制御,生活を支援するロボメカ技術のメガインテグレーション)

1A1-N-077 ワイヤ懸垂型室内移動マニピュレータの開発(ワイヤ駆動系の機構と制御,生活を支援するロボメカ技術のメガインテグレーション)

1A1-N-075 パラレルワイヤ機構を用いたパワーアシスト搬送装置の目標移動軌跡追従性能向上に関する研究(ワイヤ駆動系の機構と制御,生活を支援するロボメカ技術のメガインテグレーション)

1A1-N-075 パラレルワイヤ機構を用いたパワーアシスト搬送装置の目標移動軌跡追従性能向上に関する研究(ワイヤ駆動系の機構と制御,生活を支援するロボメカ技術のメガインテグレーション)