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ARASH:ASiST

Aras Haptics: A System for EYE Surgery Training

ARASH:ASiST II

ARASH:ASiST includes two similar devices specially designed to operate as a training system for minimally eye surgery. These similar devices operate as a dual haptic-surgery robot. In minimally invasive vitreoretinal eye surgery, unlike a general surgery, it requires 3 degrees of freedom to cover a spherical workspace. ARASH:ASiST operates as a mechanically remote center of motion (RCM) mechanism to provide the required spherical workspace for vitrectomy eye surgery and provide a safe environment for the robotic surgery process. In minimally-invasive eye surgery, the surgical instrument enters the patient’s eye through a small incision, and the surgery process takes place around this pivot point.
ARASH:ASiST takes advantage of parallelogram structure to produce a remote center of motion mechanism designed especially for minimally invasive vitreoretinal eye surgery. Designing a surgery robot requires a lot of attention to many aspects of designing procedure. Especially in vireo-retinal robotic eye surgery due to the augmented sensitivity in this vital tissue, challenges in the design procedure become manifold. ARASH:ASiST is a dual surgery-haptic device specially designed for vitrectomy eye surgery training. The integration of a surgery robot and a haptic device in one platform increase designing challenges significantly. A brief description of the parts of these challenges provided here.
For providing the force feedback that would be felt in actual operations it is desirable to carefully control the apparent inertia of the ARASH:ASiST robot. For this aim, there was a challenging design problem to reduce the moving part’s inertia as much as possible. By using light material and providing stress analysis besides organizing constant components such as force sensor and insertion actuator in an ideal configuration, the overall inertia of the robot has been reduced to the lowest amount. Inertia compensation can be used to relieve forces felt by the user during free-space motion, and it is necessary to compensate the inertia of the robot to provide an approximate real sense of traditional eye surgery which operates in a sensitive condition with forces lower than merely one newton. ARASH:ASiST benefits of concentrated mass inertia compensation method to enhance the sense of touch in a teleoperation eye surgery training procedure.

Kinematics of the ARASH:ASiST considered along with the fabrication limitations such as links intersection, troublesome inertia, and mechanical behavior of the system to cover the required workspace of the vitrectomy eye surgery. ARASH:ASiST provides over 90 degrees in both roll and pitch directions and it provides 40mm in the insertion direction. In ARASH:ASiST, smooth and accurate motions in roll and pitch directions provided using a capstan-drive back-drivable transmission mechanism which is a zero-backlash cable-driven transmission mechanism, and insertion direction actuated using a miniature cable-driven mechanism. Due to the sensitivity of the eye surgery procedure, all of the components designed carefully to provide smooth and zero-backlash movements. Along with the mechanical design of the ARASH:ASiST; robot ergonomy considered during the designing procedure to prepare a condition that feels natural and does not interfere with robot operation.

Kinematics of the ARASH:ASiST considered along with the fabrication limitations such as links intersection, troublesome inertia, and mechanical behavior of the system to cover the required workspace of the vitrectomy eye surgery. ARASH:ASiST provides over 90 degrees in both roll and pitch directions and it provides 40mm in the insertion direction. In ARASH:ASiST, smooth and accurate motions in roll and pitch directions provided using a capstan-drive back-drivable transmission mechanism which is a zero-backlash cable-driven transmission mechanism, and insertion direction actuated using a miniature cable-driven mechanism. Due to the sensitivity of the eye surgery procedure, all of the components designed carefully to provide smooth and zero-backlash movements. Along with the mechanical design of the ARASH:ASiST; robot ergonomy considered during the designing procedure to prepare a condition that feels natural and does not interfere with robot operation.

Software

  • Connection module

    Connection module has communication task with Maxon drives. With this module, we can command the position, velocity, or torque to the drives and get the motor’s current as a feedback. This module is provided in a dll file made by maxon motor company.

  • Control module

    In Control module, control and training strategy is implemented.

  • Communication module

    Communication module for connecting between two control boards is one of the most important parts of the robot’s software. Both TCP and UDP protocols are applicable but because the network is simple and short and the fact that the speed of communication is more important than the correctness of every single packet we prefer to use UDP protocol. In the UDP protocol, one of the control boards is server and the other one is client. The following figure shows the communication status.

  • Interface Module

    Interface module allows the user to adjust the working mode of the training system and observe the progress of training.

  • Data Base Module

    Data base module, we store all the information we need to analyze the status of the progress of training.

ARASH:ASiST I

The previous version of the robot provided the desired working space inside the eye, but in order to reach the parts behind the cornea, it was necessary to change the robot’s working space in such a way as to maintain the required band. This was done by adding a 40-degree angle to the base of the robot. In order to achieve this structure, a precise design was made on the installation location of the actuators. Also, structurally, in order to maintain the balance of the robot and also to optimize the occupied space around the patient’s head, major changes were made to the design of the robot base so that the forces applied by the surgeon did not disturb the robot balance. Another case was the installation location of the robot balance weights, which in the previous version was installed directly on one of the robot’s active links. To improve the security of the robot and also better access to the robot, these weights were transferred to the main cover of the robot using a cable movement transfer mechanism. In the new version of the robot, the installation mechanism of the open surgical instrument was completely redesigned so that the transfer of the surgical instrument would be at a suitable distance from the links and it would be possible for the surgeon to hold the instrument properly.

Selected Related Publications

TitleAbstractYearTypePDFResearch Group
A force reflection robust control scheme with online authority
adjustment for dual user haptic system
Mohammad Motaharifar, Hamid D. Taghirad
Mechanical Systems and Signal Processing		Abstract:

This article aims at developing a control structure with online authority adjustment for a
dual-user haptic training system. In the considered system, the trainer and the trainee
are given the facility to cooperatively conduct the surgical operation. The task dominance
is automatically adjusted based on the task performance of the trainee with respect to the trainer. To that effect, the average norm of position error between the trainer and the trainee is calculated in a sliding window and the relative task dominance is assigned to the operators accordingly. Moreover, a robust controller is developed to satisfy the require-
ment of position tracking. The stability analysis based on the input-to-state stability (ISS) methodology is reported. Experimental results demonstrate the effectiveness of the
proposed control approach.

2020JournalPDFSurgical Robotics
Control Synthesis and ISS Stability Analysis of Dual-User Haptic Training System Based on S-Shaped Function
Mohammad Motaharifar, Hamid D. Taghirad, Keyvan Hashtrudi-Zaad, Seyed Farzad Mohammadi
IEEE/ASME Transactions on Mechatronics 		Abstract:

The controller design and stability analysis of dual user training haptic system is studied. Most of the previously proposed control methodologies for this system have not simultaneously considered special requirements of surgery training and stability analysis of the nonlinear closed loop system which is the objective of this paper. In the proposed training approach, the trainee is allowed to freely experience the task and be corrected as needed, while the trainer maintains the task dominance. A special S-shaped function is suggested to generate the corrective force according to the magnitude of motion error between the trainer and the trainee. The closed loop stability of the system is analyzed considering the nonlinearity of the system components using the Input-to-State Stability (ISS) approach. Simulation and experimental results show the effectiveness of the proposed approach.

2019ConferencePDFSurgical Robotics
Control Synthesis and ISS Stability A5Analysis of Dual-User Haptic Training System Based on S-Shaped Function
Mohammad Motaharifar, Hamid D. Taghirad, Keyvan Hashtrudi-Zaad and Seyed Farzad Mohammadi
IEEE/ASME Transactions on Mechatronics		Abstract:

The controller design and stability analysis of dual user training haptic system is studied. Most of the previously proposed control methodologies for this system have not simultaneously considered special requirements of surgery training and stability analysis of the nonlinear closed loop system which is the objective of this paper. In the proposed training approach, the trainee is allowed to freely experience the task and be corrected as needed, while the trainer maintains the task dominance. A special S-shaped function is suggested to generate the corrective force according to the magnitude of motion error between the trainer and the trainee. The closed loop stability of the system is analyzed considering the nonlinearity of the system components using the Input-to-State Stability (ISS) approach. Simulation and experimental results show the effectiveness of the proposed approach.

2019JournalPDFSurgical Robotics
Control Synthesis and ISS Stability Analysis of a Dual-User Haptic Training System Based on S-Shaped Function
Mohammad Motaharifar, Hamid D. Taghirad, Keyvan Hashtrudi-Zaad, and Seyed Farzad Mohammadi
IEEE/ASME Transactions on Mechatronics		Abstract:

The controller design and stability analysis of
a dual user training haptic system is studied. Most of the previously proposed control methodologies for this system
have not simultaneously considered special requirements
of surgery training and stability analysis of the nonlinear
closed-loop system which is the objective of this paper. In the proposed training approach, the trainee is allowed
to freely experience the task and be corrected as needed,
while the trainer maintains the task dominance. A special S-shaped function is suggested to generate the corrective force according to the magnitude of motion error between the trainer and the trainee. The closed-loop stability of the system is analyzed considering the nonlinearity of
the system components using the Input-to-State Stability approach. Simulation and experimental results show the effectiveness of the proposed approach.

2019JournalPDFSurgical Robotics
Control of Dual-User Haptic Training System With Online Authority Adjustment: An Observer-Based Adaptive Robust Scheme
Mohammad Motaharifar, Hamid D. Taghirad, Keyvan Hashtrudi-Zaad and Seyed Farzad Mohammadi
IEEE Transactions on Control Systems Technology 		Abstract:

The design problem for the control a dual-user
haptic surgical training system is studied in this article. The
system allows the trainee to perform the task on a virtual environment, while the trainer is able to interfere in the operation and correct probable mistakes made by the trainee. The proposed
methodology allows the trainer to transfer the task authority to or from the trainee in real time. The robust adaptive nature
of the controller ensures position tracking. The stability of the closed-loop system is analyzed using the input-to-output stability approach and the small-gain theorem. Simulation and
experimental results are presented to validate the effectiveness
of the proposed control scheme.

2019JournalPDFSurgical Robotics
A Force Reflection Impedance Control Scheme for Dual User Haptic Training System
M. Motaharifar, A. Iranfar, and H. D. Taghirad
2019 27th Iranian Conference on Electrical Engineering (ICEE)		Abstract:

In this paper, an impedance control based training scheme for a dual user haptic surgery training system is introduced. The training scheme allows the novice surgeon (trainee) to perform a surgery operation while an expert surgeon (trainer)
supervises the procedure. Through the proposed impedance control structure, the trainer receives trainee’s position to detect
his (her) wrong movements. Besides, a novel force reflection term is proposed in order to efficiently utilize trainer’s skill in the training loop. Indeed, the trainer can interfere into the procedure
whenever needed either to guide the trainee or suppress his (her)
authority due to his (her) supposedly lack of skill to continue
the operation. Each haptic device is stabilized and the closed
loop stability of the nonlinear system is investigated. Simulation
results show the appropriate performance of the proposed control
scheme.

2019ConferencePDFSurgical Robotics
Robust Impedance Control for Dual User Haptic Training System
R. Heidari, M. Motaharifar and H. D. Taghirad
International Conference on Robotics and Mechatronics		In this paper, an impedance controller with switching parameters for a dual-user haptic training system is introduced. The trainer and the trainee are connected through their
haptic consoles, and the trainee performs the surgical procedure
on the environment. The trainer can intervene in the procedure
by pressing a mechanical pedal; thus, the control parameters are
switched to transfer the authority over the task from the trainee
to the trainer. The stability of each subsystem and the closed-loop
stability of the overall system are investigated. The simulation
results verify the performance of the proposed controller.		2019ConferencePDFSurgical Robotics
Skill Assessment Using Kinematic Signatures: Geomagic Touch Haptic Device
N. S. Hojati, M. Motaharifar, H. D. Taghirad, A. Malekzadeh
International Conference on Robotics and Mechatronics		he aim of t his paper is to develop a practical
skill assessment for some designed experimental tasks, retrieved
from Minimally Invasive Surgery. The skill evaluation is very
important in surgery training, especially in MIS. Most of the
previous studies for skill assessment methods are limited in the
Hidden Markov Model and some frequency transforms, such as
Discret e Fourier transform, Discrete Cosine Transform and etc.
In this paper , some features have been ext racted from timefrequency analysis with t he Discret e Wavelet Transform and
t emporal signa l ana lysis of some kinematic metrics whi ch were
compute d from Geom agic Touch kinematic data. In addition,
the k-n earest neighbors classifier are employed to detect skill
level based on ext racted features. Through cross-validation
results, it is demonstrated that t he proposed methodology has
appropriate accuracy in skill level det ection		2019ConferencePDFSurgical Robotics
An Observer-Based Force Reflection Robust Control for Dual User Haptic Surgical Training System
M. Motaharifar and H. D. Taghirad
2017 5th RSI International Conference on Robotics and Mechatronics (ICRoM)		Abstract:

This paper investigates the controller design problem for the dual user haptic surgical training system. In this system, the trainer and the trainee are interfaced together through their haptic devices and the surgical operations on the virtual environment is performed by the trainee. The trainer is able to interfere into the procedure in the case that any mistakes is made by the trainee. In the proposed structure, the force of the trainer's hands is reflected to the hands of the trainee to give necessary guidance to the trainee. The force signal is obtained from an unknown input high gain observer. The position of the trainee and the contact force with the environment are sent to the trainer to give him necessary information regarding the status of surgical operations. Stabilizing control laws are also designed for each haptic device and the stability of the closed loop nonlinear system is proven. Simulation results are presented to show the effectiveness of the proposed controller synthesis.

2017ConferencePDFSurgical Robotics
Type Synthesis of 2R-T Parallel Mechanisms Based on the Screw Theory for Haptic Applicationsa
Nahid Khajeh Ahmadi, Fateme Zarei and Hamid D.Taghirad
2016 4th International Conference on Robotics and Mechatronics (ICROM)		Abstract:

Recently haptic devices are increasingly used in industry and research. As their applications become widespread, their design is needed to be more efficient. At design stage, determinant features of haptic devices such as rigidity, force bandwidth, accuracy etc. must be considered and improved. Structurally, parallel mechanisms (PMs) are appropriate candidates for haptic devices. Due to multi legged structure of PMs and their grounded motors, inertia and stiffness feautures of them are desirable and it also made them popular for applications that require high mechanical transparency. Spherical kinematics (two rotational and one translational motion, 2R-T) is a very common type of motion in haptic devices that is also capable of general rendering. In this paper, several 3-DOF 2R-T PMs are synthesized for haptic applications by means of the screw theory. All of these mechanisms have center of motion (CM) which is a key property in variety of applications such as surgery. These mechanisms are compared qualitatively and their applications as haptic devices are discussed.

2016ConferencePDFParallel and Cable Robotics
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