Imperial College London

DrEnricoFranco

Faculty of EngineeringDepartment of Mechanical Engineering

Research Associate
 
 
 
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708City and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

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20 results found

Franco E, Rodriguez y Baena F, Astolfi A, 2020, Robust dynamic state feedback for underactuated systems with linearly parameterized disturbances, International Journal of Robust and Nonlinear Control, Vol: 30, Pages: 4112-4128, ISSN: 1049-8923

This article investigates the control problem for underactuated port‐controlled Hamiltonian systems with multiple linearly parameterized additive disturbances including matched, unmatched, constant, and state‐dependent components. The notion of algebraic solution of the matching equations is employed to design an extension of the interconnection and damping assignment passivity‐based control methodology that does not rely on the solution of partial differential equations. The result is a dynamic state‐feedback that includes a disturbance compensation term, where the unknown parameters are estimated adaptively. A simplified implementation of the proposed approach for underactuated mechanical systems is detailed. The effectiveness of the controller is demonstrated with numerical simulations for the magnetic‐levitated‐ball system and for the ball‐on‐beam system.

Journal article

Meagher C, Franco E, Turk R, Wilson S, Steadman N, McNicholas L, Vaidyanathan R, Burridge J, Stokes Met al., 2020, New advances in mechanomyography sensor technology and signal processing: validity and intrarater reliability of recordings from muscle, Journal of Rehabilitation and Assistive Technologies Engineering, Vol: 7, ISSN: 2055-6683

IntroductionThe Mechanical Muscle Activity with Real-time Kinematics project aims to develop a device incorporating wearable sensors for arm rehabilitation following stroke. These will record kinematic activity using inertial measurement units and mechanical muscle activity. The gold standard for measuring muscle activity is electromyography; however, mechanomyography offers an appropriate alterative for our home-based rehabilitation device. We have patent filed a new laboratory-tested device that combines an inertial measurement unit with mechanomyography. We report on the validity and reliability of the mechanomyography against electromyography sensors.MethodsIn 18 healthy adults (27–82 years), mechanomyography and electromyography recordings were taken from the forearm flexor and extensor muscles during voluntary contractions. Isometric contractions were performed at different percentages of maximal force to examine the validity of mechanomyography. Root-mean-square of mechanomyography and electromyography was measured during 1 s epocs of isometric flexion and extension. Dynamic contractions were recorded during a tracking task on two days, one week apart, to examine reliability of muscle onset timing.ResultsReliability of mechanomyography onset was high (intraclass correlation coefficient = 0.78) and was comparable with electromyography (intraclass correlation coefficient = 0.79). The correlation between force and mechanomyography was high (R2 = 0.94).ConclusionThe mechanomyography device records valid and reliable signals of mechanical muscle activity on different days.

Journal article

Franco E, Garriga Casanovas A, Energy shaping control of soft continuum manipulators with in-plane disturbances, International Journal of Robotics Research, ISSN: 0278-3649

Soft continuum manipulators offer levels of compliance and inherent safety that can render thema superior alternative to conventional rigid robotsfor a variety of tasks, such as medical interventions or human-robot interaction. However, the ability of soft continuum manipulators to compensate external disturbances need to be further enhanced to meet the stringent requirements of many practical applications.In this paper, we investigate the control problem forsoft continuum manipulators that consist of one inextensible segmentof constant section, which bends under the effect of the internal pressure and is subject to unknown disturbances acting in the plane of bending. A rigid-link model of the manipulatorwith a single input pressureis employed for control purposes and an energy-shaping approach isproposedto derive thecontrol law. A method for the adaptive estimation of disturbances is detailed and a disturbance compensation strategy is proposed.Finally, the effectiveness of the controlleris demonstrated with simulations and with experiments on an inextensible soft continuum manipulator that employs pneumatic actuation.

Journal article

Franco E, Garriga Casanovas A, Rodriguez y Baena F, Astolfi Aet al., Model based adaptive control for a soft robotic manipulator, 58th IEEE Conference on Decision and Control, Publisher: IEEE

The application of model based adaptive control to an underactuated system representative of a class of soft continuummanipulators is investigated. To this end, a rigid-linkmodel with elastic joints is employed and an energy shaping controller is designed. Additionally, model uncertainties and external disturbances, both matched and unmatched, are compensated with an adaptive algorithm. This results in a control law that only depends on the orientation and on the angular velocity of the distal link and it is therefore independent of the number of links. Finally, stability conditions are discussed and the effectiveness of the controller is verified via simulations.

Conference paper

Franco E, Brown T, Energy shaping control for robotic needle insertion, 23rd International Conference on System Theory, Control and Computing (ICSTCC), Publisher: IEEE

This work investigates the use of energy shaping control to reduce deflection in slender beams with tip load and actuation at the base. The ultimate goal of this research is a buckling avoidance strategy for robotic-assisted needle insertion. To this end, the rigid-link model of a flexible beam actuated at the base and subject to tip load is proposed, and an energy shaping approach is employed to construct a nonlinear controller that accounts for external forces. A comparative simulation study highlights the benefits of the proposed approach over a linear control baseline and a simplified nonlinear control.

Conference paper

Franco E, 2019, IDA-PBC with adaptive friction compensation for underactuated mechanical systems, International Journal of Control, ISSN: 0020-7179

In this work the control of underactuated mechanical systems with dry friction on actuated and unactuated joints is investigated. A new interconnection-and-damping-assignment passivity-based-control (IDA-PBC) design is presented, which includes the adaptive estimation of the friction forces and the introduction of a nonlinear dissipative term in the closed-loop system dynamics. As a result, the traditional IDA-PBC is complemented with an additional matching condition and the control law is augmented with a new term that accounts for the Coulomb friction forces on all joints. Two adaptive control paradigms are considered for comparison purposes and stability conditions are discussed. The control design is detailed for two demonstrative examples: the disk-on-disk system; the Acrobot system. The effectiveness of the proposed design is demonstrated with numerical simulations.

Journal article

Franco E, Energy-based design of elastic joints for inverted pendulum systems with input saturation, 27th Mediterranean Conference on Control and Automation, Publisher: IEEE

This work investigates the balancing control of underactuated inverted pendulum systems with input saturation. To this end, the design of elastic joints according to potential-energy shaping principles is combined with energy-shaping control. As a result, analytical design guidelines are synthesized and implemented fortwo classical examples: the inertia-wheel pendulum and the Acrobot system.Asimulation study demonstrates the effectiveness of the proposed approach in reducing control effort while preserving transient performance.

Conference paper

Franco E, 2019, Adaptive IDA-PBC for underactuated mechanical systems with constant disturbances, International Journal of Adaptive Control and Signal Processing, Vol: 33, Pages: 1-15, ISSN: 0890-6327

This work investigates the control of nonlinear underactuated mechanical systems with matched and unmatched constant disturbances. To this end, a new control strategy is proposed, which builds upon the interconnection‐and‐damping‐assignment passivity‐based control, augmenting it with an additional term for the purpose of disturbance compensation. In particular, the disturbances are estimated adaptively and then accounted for in the control law employing a new matching condition of algebraic nature. Stability conditions are discussed, and for comparison purposes, an alternative controller based on partial feedback linearization is presented. The effectiveness of the proposed approach is demonstrated with numerical simulations for three motivating examples: the inertia wheel pendulum, the disk‐on‐disk system, and the pendulum‐on‐cart system.

Journal article

Franco E, Rodriguez y Baena F, Astolfi A, 2018, Robust balancing control of flexible inverted-pendulum systems, Mechanism and Machine Theory, Vol: 130, Pages: 539-551, ISSN: 0094-114X

This work studies the balancing control problem for flexible inverted-pendulum systems and investigates the relationship between system parameters and robustness to disturbances. To this end, a new energy-shaping controller with adaptive disturbance-compensation for a class of underactuated mechanical systems is presented. Additionally, a method for the identification of key system parameters that affect the robustness of the closed-loop system is outlined. The proposed approach is applied to the flexible pendulum-on-cart system and a simulation study is conducted to demonstrate its effectiveness. Finally, the control problem for a classical pendulum-on-cart system with elastic joint is discussed to highlight the similarities with its flexible-link counterpart.

Journal article

Franco E, 2018, Discrete-time IDA-PBC for underactuated mechanical systems with input-delay and matched disturbances, 2018 26th Mediterranean Conference on Control and Automation (MED), Publisher: IEEE, ISSN: 2473-3504

This work investigates the control problem of discrete-time underactuated mechanical systems with fixed input-delay and matched disturbances. A new control strategy is proposed, which builds upon a discrete-time implementation of the interconnection-and-damping-assignment passivity-based control (IDA-PBC) and extends it in two ways: the disturbances are estimated adaptively; the input-delay is compensated with a recursive algorithm. The resulting control law is constructed from IDA-PBC without solving any additional partial-differential-equation (PDE). Stability conditions are discussed and compared to alternative designs. Numerical simulations for the ball-on-beam system and for the Acrobot system demonstrate the effectiveness of the proposed approach.

Conference paper

Franco E, 2017, Immersion and invariance adaptive control for discrete-time systems in strict feedback form with input delay and disturbances, International Journal of Adaptive Control and Signal Processing, Vol: 32, Pages: 69-82, ISSN: 0890-6327

This work presents a new adaptive control algorithm for a class of discrete-time systems in strict-feedback form with input delay and disturbances. The immersion and invariance formulation is used to estimate the disturbances and to compensate the effect of the input delay, resulting in a recursive control law. The stability of the closed-loop system is studied using Lyapunov functions, and guidelines for tuning the controller parameters are presented. An explicit expression of the control law in the case of multiple simultaneous disturbances is provided for the tracking problem of a pneumatic drive. The effectiveness of the control algorithm is demonstrated with numerical simulations considering disturbances and input-delay representative of the application.

Journal article

Burridge JH, Lee ACW, Turk R, Stokes M, Whitall J, Vaidyanathan R, Clatworthy P, Hughes A-M, Meagher C, Franco E, Yardley Let al., 2017, Telehealth, Wearable Sensors, and the Internet: Will They Improve Stroke Outcomes Through Increased Intensity of Therapy, Motivation, and Adherence to Rehabilitation Programs?, JOURNAL OF NEUROLOGIC PHYSICAL THERAPY, Vol: 41, Pages: S32-S38, ISSN: 1557-0576

Journal article

Franco E, Rea M, Gedroyc W, Ristic Met al., 2016, Robot-Assistant for MRI-Guided Liver Ablation: a pilot study, Medical Physics, Vol: 43, ISSN: 0094-2405

Purpose:Percutaneous ablation under MRI-guidance allows treating otherwise inoperable liver tumors locally using a catheter probe. However, manually placing the probe is an error-prone and time consuming task that requires a considerable amount of training. The aim of this paper was to present a pneumatically actuated robotic instrument that can assist clinicians in MRI-guided percutaneous intervention of the liver and to assess its functionality in a clinical setting. The robot positions a needle-guide inside the MRI scanner bore and assists manual needle insertions outside the bore.Methods:The robot supports double oblique insertions that are particularly challenging for less experienced clinicians. Additionally, the system employs only standard imaging sequences and can therefore be used on different MRI scanners without requiring prior integration. The repeatability and the accuracy of the robot were evaluated with an optical tracking system. The functionality of the robot was assessed in an initial pilot study on two patients that underwent MRI-guided laser ablation of the liver.Results:The robot positioned the needle-guide in a repeatable manner with a mean error of 0.35 mm and a standard deviation of 0.32 mm. The mean position error corresponding to the needle tip, measured for an equivalent needle length of 195 mm over 25 fixed points, was 2.5 mm with a standard deviation of 1.2 mm. The pilot study confirmed that the robot does not interfere with the equipment used for MRI-guided laser ablation and does not visibly affect the MR images. The robot setup integrated seamlessly within the established clinical workflow. The robot-assisted procedure was successfully completed on two patients, one of which required a complex double oblique insertion. For both patients, the insertion depth and the tumor size were within the range reported for previous MRI-guided percutaneous interventions. A third patient initially enrolled in the pilot study and was considerably he

Journal article

Franco E, 2016, Combined Adaptive and Predictive Control for a Teleoperation System with Force Disturbance and Input Delay, Frontiers in Robotics and AI, Vol: 3, ISSN: 2296-9144

This work presents a new discrete-time adaptive-predictive control algorithm for a system with force disturbance and input delay. This scenario is representative of a mechatronic device for percutaneous intervention with pneumatic actuation and long supply lines which is controlled remotely in the presence of an unknown external force resulting from needle-tissue interaction or gravity. The ultimate goal of this research is the robotic-assisted percutaneous intervention of the liver under Magnetic Resonance Imaging (MRI) guidance. Since the control algorithm is intended for a digital microcontroller, it is presented in the discrete-time form. The controller design is illustrated for a 1 degree-of-freedom system and is conducted with a modular approach combining position control, adaptive disturbance compensation, and predictive control. The controller stability is analyzed and the effect of the input delay and of the tuning parameters is discussed. The controller performance is assessed with simulations considering a disturbance representative of needle insertion forces. The results indicate that the adaptive-predictive controller is effective in the presence of a variable disturbance and of a known or variable input delay.

Journal article

Franco E, Rea M, Gedroyc W, Ristic Met al., 2016, Control of a master-slave pneumatic system for teleoperated needle insertion in MRI, IEEE-ASME Transactions on Mechatronics, Vol: 21, ISSN: 1941-014X

This paper presents the control of a pneumatically actuated master-slave system intended for teleoperated needle insertion in the liver under MRI-guidance. It addresses the challenge of achieving accurate needle positioning and force feedback to the operator in the case of pneumatic actuation with significant friction.Using time delay position control as the basis, we investigate force feedback via impedance control and admittance control. For impedance control, we propose a new adaptive friction compensation algorithm that only requires a single tuning parameter. Experiments on a 1 DOF prototype system using silicone rubber phantoms with distinct densities highlight the differences between impedance control and admittance control, and demonstrate superiorperformance compared to a traditional impedance control scheme.

Journal article

Franco E, Ristic M, 2016, Needle-guiding Robot for Laser Ablation of Liver Tumors under MRI Guidance, IEEE/ASME Transactions on Mechatronics, Vol: 21, Pages: 931-944, ISSN: 1083-4435

This paper presents the design, control and experimental evaluation of a needle-guiding robot intended for use in laser ablation (LA) of liver tumors under guidance by Magnetic Resonance Imaging (MRI). The robot provides alignment of a needle guide inside the MRI scanner bore and employs manual needle insertion. In order to minimize MR-image deterioration, the robot is actuated using plastic pneumatic cylinders and long pipes connecting to control valves located outside the MRI scanner room. A new Time Delay Control scheme (TDC) was employed to achieve high position accuracy without requiring pressure or force measurements in the MRI scanner. The control scheme was compared with experiments to a previously developed Sliding Mode Controller (SMC). A marker localization method based on the convolution theorem of Fourier transform was employed to register the robot in the MRI scanner coordinate system and to verify the position of the needle guide before the manual needle insertion. Experiments in a closed-bore MRI scanner showed a variation in SNR below 5%. A phantom study indicates that the targeting error in robot-assisted needle insertions is below 5 mm and suggest a potential time saving of 30 minutes compared to the manual MRI-guided LA procedure.

Journal article

Franco E, Aurisicchio M, Ristic M, Design and control of 3-DOF needle positioner for MRI-guided laser ablation of liver tumours, International Journal of Biomechatronics and Biomedical Robotics, Vol: 3, ISSN: 1757-6792

This article presents the design and control of a pneumatic needle positioner for laser ablation of liver tumours under guidance by magnetic resonance imaging (MRI). The prototype was developed to provide accurate point-to-point remote positioning of a needle guide inside an MR scanner with the aim of evaluating the potential advantages over the manual procedure. In order to minimise alterations to the MR environment, the system employs plastic pneumatic actuators and 9 m long supply lines connecting with the control hardware located outside the magnet room. An improved sliding mode control (SMC) scheme was designed for the position control of the device. Wireless micro-coil fiducials are used for automatic registration in the reference frame of the MR scanner. The MRI-compatibility and the accuracy of the prototype are demonstrated with experiments in the MR scanner.

Journal article

Franco E, Ristic M, 2015, Adaptive control of a master-slave system for teleoperated needle insertion under MRI-guidance, 23rd Mediterranean Conference on Control and Automation (MED), Publisher: IEEE, Pages: 61-67, ISSN: 2325-369X

This paper presents the control of a master-slave system for teleoperated needle insertion under guidance by Magnetic Resonance Imaging (MRI). The primary aim of our research is the robot-assisted laser ablation of liver tumors. The master-slave system consists of a master unit that sits next to the operator, outside the scanner room, and of a slave unit located inside the cylindrical MRI scanner. The needle insertion force is measured with a specially designed fiber optic force sensor mounted on the slave unit. Pneumatic actuation is employed in both master and slave in order to minimize the interference with the MRI environment. Accurate position control of the slave unit is achieved with a Time Delay Control scheme (TDC). Differently from previous designs, the force feedback on the master unit is provided by an adaptive controller that compensates the friction of the pneumatic actuator. The advantages over a baseline force controller are demonstrated with experiments on silicone rubber phantoms.

Conference paper

Franco E, Ristic M, 2014, Design and control of needle positioner for MRI-guided laser ablation of the liver, IEEE/ASME 10th International Conference on Mechatronic and Embedded Systems and Applications (MESA), Publisher: IEEE

This paper presents the design and control of a pneumatic needle positioner for laser ablation of liver tumors under guidance by Magnetic Resonance Imaging (MRI). The prototype was developed to provide accurate point-to-point remote positioning of a needle guide inside an MR scanner with the aim of evaluating the potential advantages over the manual procedure. In order to minimize alterations to the MR environment the system employs plastic pneumatic actuators and 9 m long supply lines connecting with the control hardware located outside the magnet room. An optimized Sliding Mode Control (SMC) scheme was designed for the position control of the device. Wireless micro-coil fiducials are used for automatic registration in the reference frame of the MR scanner. The MRI-compatibility and the accuracy of the prototype are demonstrated with experiments in the MR scanner.

Conference paper

Franco E, Ristic M, 2014, Time delay controller for the position control of a MRI-compatible pneumatic actuation with long supply lines, IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM), Publisher: IEEE, Pages: 683-689, ISSN: 2159-6255

Pneumatic actuation with long supply lines is widely employed in robotic devices operating in the Magnetic Resonance Imaging (MRI) environment because it produces minimum alteration to the magnetic field. However the high friction of the cylinders and the delay introduced by the pipes make accurate position control challenging. This work presents design and control of an MRI-compatible pneumatic actuation that employs a commercially available, plastic cylinder and long supply lines connecting with the control hardware located outside the magnet room. The system has been designed to actuate a MRI-compatible needle-guiding robot intended for MRI-guided intervention of liver tumors. Accurate position control is achieved with a new Time Delay Control (TDC) scheme that includes a saturation function. The controller requires limited knowledge of the system's parameters and does not rely on pressure or force measurements. Simulation results and experiments demonstrate the advantages of the proposed controller over existing TDC schemes. The MRI-compatibility of the pneumatic actuation is verified in a 3T MRI scanner.

Conference paper

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