Design, fabrication, and evaluation of a new haptic device using aparallel mechanism

This paper presents design, fabrication, and evaluation of a new 6-DOF haptic device for interfacing with virtual reality by using a parallel mechanism. The mechanism is composed of three pantograph mechanisms that are driven by ground-fixed servomotors, three spherical joints between the top of the pantograph mechanisms and the connecting bars, and three revolute joints between the connecting bars and a mobile joystick handle. Forward and inverse kinematic analyses are performed and the Jacobian matrix is derived. Performance indexes such as global payload index, global conditioning index, translation and orientation workspaces, and sensitivity are evaluated to find optimal parameters in the design stage. The proposed haptic mechanism has better load capability than those of the pre-existing haptic mechanisms due to the fact that the motors are fixed at the base. It has also a wider orientation workspace mainly due to a RRR-type spherical joint. A control method is presented with gravity compensation and force feedback by a force/torque sensor to compensate for the effects of unmodeled dynamics such as friction and inertia. Also, the dynamic performance is evaluated for force characteristics. Virtual wall simulation with the developed haptic device is demonstrated     

Structural design of a microsurgery-specific haptic device: neuroArmPLUSHD prototype

A microsurgery-specific haptic interface with articulated structure, possessing 3 active, 4 passive and 3 supplementary degrees of freedom (DOFs), was designed and developed. The system includes a 3-DOF active serial linkage design, mimicking the human upper extremity. It is combined with a microsurgery-specific end-effector, comprised of a 3-DOF passive gimbal mechanism and a 1-DOF passive exchangeable surgical toolset. The spherical gimbal workspace twinned with the larger linkage arm workspace allow accurate and delicate movements to maneuver the surgical tool in narrow corridors, corresponding to conventional surgery. The structural design of the device is based on kinematic performance measures aimed to enhance ergonomics and mitigate training limitations of novice end-users. A supplementary 3-DOF adjustable base further improved ergonomics for end-users of different sizes. Force feedback was provided to improve safety, i.e. avoidance of force errors in execution of surgical tasks. This haptic interface provides high positional and output force resolution (0.92–1.46 mm in Cartesian coordinate system and 0.2 N, respectively), wide range of allowable force (up to 15 N), high global manipulability (0.77), global isotropy (0.68) and stiffness (2.3 N/mm). The work, indeed, introduces a novel kinematic performance index, Dexterous Conditioning Index (DCI), based on the volume of dexterous workspace, correlating to ease of use and decreased singularity. Accordingly, the proposed haptic device demonstrates a high level of accuracy, haptic feedback, dexterous workspace, and performance, ideal for implementation in robot-assisted microsurgery.     

A high bandwidth interface for haptic human computer interaction

Current force feedback, haptic interface devices are generally limited to the display of low frequency, high amplitude spatial data. A typical device consists of a low impedance framework of one or more degrees-of-freedom (dof), allowing a user to explore a pre-defined workspace via an end effector such as a handle, thimble, probe or stylus. The movement of the device is then constrained using high gain positional feedback, thus reducing the apparent dof of the device and conveying the illusion of hard contact to the user. Such devices are, however, limited to a narrow bandwidth of frequencies, typically below 30 Hz, and are not well suited to the display of surface properties, such as object texture. This paper details a device to augment an existing force feedback haptic display with a vibrotactile display, thus providing a means of conveying low amplitude, high frequency spatial information of object surface properties.     

DFORCE: Delayed FOrce ReferenCE control for master–slave robotic systems

The acceptance of master–slave robotic teleoperated applications in the medical field is related not only to the accuracy and precision of the robotic systems but also to the haptic features. Indeed, the capability to render a good haptic feeling, hence the sensation to drive the real surgical tool, is necessary for reaching an effective interaction between surgeon and robotic system.In this paper an innovative controller for master–slave haptic systems for neurosurgery has been developed by getting inspiration from force reflecting controllers and non-time based control schemes. This new DFORCE (Delayed FOrce ReferenCE) controller is founded on the basic idea to control the position of the device through a system that can generate forces on the master side only when the surgeon is grasping the haptic handle. Thus, when the surgeon is not grasping the haptic handle and external forces are present, the system remains stable.The haptic sensation, the stability and the readiness of the system have been studied and a tuning procedure proposed. Moreover, simulated and experimental tests on a test-bed master system and a haptic master–slave interface for neurosurgical operations have been carried out in order to demonstrate the effectiveness of the controller.     

Constrained haptic-guided shared control for collaborative human–robot percutaneous nephrolithotomy training

Percutaneous nephrolithotomy is a procedure used to treat patients with large or irregularly shaped kidney stones. Surgical instruments are inserted through a small incision to access the kidney and remove the calculi. Surgeons who have less experience with the procedure manifest significantly higher rates of complications due to the procedure’s steep learning curve. This issue is further exacerbated by a lack of training opportunities in clinical settings. This paper introduces a teleoperative framework that can provide training to surgeons as well as assistance during procedures, based on two main components. Firstly, a type of constrained inverse kinematics that decouples the tooltip position from its orientation using a remote centre of motion, and incorporates the joint limits analytically. This reduces the workload of the procedure by having the surgeon control only the tooltip position rather than the position and the orientation while preventing the inverse kinematics from returning joint angles outside of the robot’s abilities. This kinematic framework also allows a three-degrees-of-freedom haptic device to control a six-degrees-of-freedom manipulator. Secondly, haptic feedback is provided to help guide and teach the surgeon during the procedure. Haptic feedback allows the surgeon to remain in full control during the procedure while still receiving haptic cues and assistance.Experimental results indicate that the haptic cues improved user’s accuracy, and they had shorter and smoother paths. This leads to a shorter procedure time overall. The results also indicate that the haptic assistance helped teach users the ideal trajectory of the procedure and that users who were taught with haptic feedback performed better than those who never experienced any haptic feedback.     

Development of micromanipulator and haptic interface for networkedmicromanipulation

Telemicromanipulation systems with haptic feedback, which are connected through a network, are proposed. It is based on scaled bilateral teleoperation systems between different structures. These systems are composed of an original 6 degree of freedom (DOF) parallel link manipulator to carry out micromanipulation and a 6-DOF haptic interface with force feedback. A parallel mechanism is adopted as a slave micromanipulator because of its good features of accuracy and stiffness. The system modeling and control of the parallel manipulator system are conducted. Parallel manipulator feasibility as a micromanipulator, positioning accuracy and device control characteristics are investigated. A haptic master interface is developed for micromanipulation systems. System modeling and a model reference adaptive controller are applied to compensate friction force, which spoils free motion performance and force response isotropy of the haptic interface. These systems aim to make the micromanipulation more productive constructing a better human interface through the microenvironment force and scale expansion     

Performance evaluation of a tactile and kinesthetic finger feedback system for teleoperation

Teleoperation during a catastrophic event requires an interface that can perform under frequently changing circumstances caused by unpredictable and dangerous conditions. Thus, teleoperation interfaces are under active development to provide both visual and haptic feedback to the fingers. However, studies of teleoperation systems with finger haptic feedback based on force profiles are difficult to conduct because of interface limitations. Therefore, in this paper, we introduce an intuitive teleoperation interface, an anthropomorphic teleoperated robot, and a hand-wearable force-feedback system that provides various feedbacks to the fingers. We combined these systems to compare and evaluated the performance of tactile and kinesthetic finger feedback using two experiments: maintaining appropriate grip force for variably fragile objects and following a force trajectory that changed in real time. Ten subjects participated in the experiments. The results were analyzed using repeated measures analysis of variance. Feedback factors differed significantly. Provision of force feedback to the user’s finger was most effective in both teleoperation experiments.     

Upper limb motion analysis using haptic interface

An objective test for evaluating the functional studies of the upper limbs (UL) in patients with neurological diseases (ND) is presented. The method allows assessment of kinematic and dynamic motor abilities of UL. Our methodology is based on creating a virtual environment, using a computer display for visual information and a PHANTOM haptic interface. The haptic interface is used as a kinematic measuring device and for providing tactile feedback to the patient. In virtual environment, a labyrinth in patient's frontal plane was created at the start of each test. By moving the haptic interface control stick the patient was able to move the pointer (a ball) through the labyrinth in three dimensions and to feel the reactive forces of the wall. The new test offers a wide range of numerical and graphic results. It has so far been applied to 13 subjects with various forms of ND (e.g., Friedreich Ataxia, Parkinson's disease, Multiple Sclerosis) as well as to healthy subjects. The comparison in performance between right and left UL has been carried out in healthy subjects     

Design of a haptic arm exoskeleton for training and rehabilitation

A high-quality haptic interface is typically characterized by low apparent inertia and damping, high structural stiffness, minimal backlash, and absence of mechanical singularities in the workspace. In addition to these specifications, exoskeleton haptic interface design involves consideration of space and weight limitations, workspace requirements, and the kinematic constraints placed on the device by the human arm. These constraints impose conflicting design requirements on the engineer attempting to design an arm exoskeleton. In this paper, the authors present a detailed review of the requirements and constraints that are involved in the design of a high-quality haptic arm exoskeleton. In this context, the design of a five-degree-of-freedom haptic arm exoskeleton for training and rehabilitation in virtual environments is presented. The device is capable of providing kinesthetic feedback to the joints of the lower arm and wrist of the operator, and will be used in future work for robot-assisted rehabilitation and training. Motivation for such applications is based on findings that show robot-assisted physical therapy aids in the rehabilitation process following neurological injuries. As a training tool, the device provides a means to implement flexible, repeatable, and safe training methodologies.     

Force controlled and teleoperated endoscopic grasper for minimallyinvasive surgery-experimental performance evaluation

Minimally invasive surgery generates new user interfaces which create visual and haptic distortion when compared to traditional surgery. In order to regain the tactile and kinesthetic information that is lost, a computerized force feedback endoscopic surgical grasper (FREG) was developed with computer control and a haptic user interface. The system uses standard unmodified grasper shafts and tips. The FREG can control grasping forces either by surgeon teleoperation control, or under software control. The FREG performance was evaluated using an automated palpation function (programmed series of compressions) in which the grasper measures mechanical properties of the grasped materials. The material parameters obtained from measurements showed the ability of the FREG to discriminate between different types of normal soft tissues (small bowel, lung, spleen, liver, colon, and stomach) and different kinds of artificial soft tissue replication materials (latex/silicone) for simulation purposes. In addition, subjective tests of ranking stiffness of silicone materials using the FREG teleoperation mode showed significant improvement in the performance compared to the standard endoscopic grasper. Moreover, the FREG performance was closer to the performance of the human hand than the standard endoscopic grasper. The FREG as a tool incorporating the force feedback teleoperation technology may provide the basis for application in telesurgery, clinical endoscopic surgery, surgical training, and research.     

Design of a force control grasper through stiffness modulation for endosurgery: theory and experiments

In endosurgery, tissue manipulation is performed by long graspers which have a poor force-reflection property, i.e. they do not reflect the grasping force to the hand of the surgeon. In this paper, a novel design of an electro-mechanical system is considered which can enhance the force–reflecting capability of endosurgical graspers. The type of synthesis of such a haptic interface leads to the application of a tunable spring. The design of a tunable spring is optimized based on the haptic and surgical requirements. Moreover, by using suitable control laws, it is shown that the primary requirements of the design application can be met. Simulation and experimental results are presented using a prototype model of such a haptic interface to demonstrate the practicality of such a design concept.     

The effect of force saturation on the haptic perception of detail

This paper presents a quantitative study of the effects of maximum capable force magnitude of a haptic interface on the haptic perception of detail. Specifically, the haptic perception of detail is characterized by identification, detection, and discrimination of round and square cross-section ridges, in addition to corner detection tests. Test results indicate that performance, measured as a percent correct score in the perception experiments, improves in a nonlinear fashion as the maximum allowable level of force in the simulation increases. Further, all test subjects appeared to reach a limit in their perception capabilities at maximum-force output levels of 3-4 N, while the hardware was capable of 10 N of maximum continuous force output. These results indicate that haptic interface hardware may be able to convey sufficient perceptual information to the user with relatively low levels of force feedback. The data is compiled to aid those who wish to design a stylus-type haptic interface to meet certain requirements for the display of physical detail within a haptic simulation.     

The Rutgers Master II-new design force-feedback glove

The Rutgers Master II-ND glove is a haptic interface designed for dextrous interactions with virtual environments. The glove provides force feedback up to 16 N each to the thumb, index, middle, and ring fingertips. It uses custom pneumatic actuators arranged in a direct-drive configuration in the palm. Unlike commercial haptic gloves, the direct-drive actuators make unnecessary cables and pulleys, resulting in a more compact and lighter structure. The force-feedback structure also serves as position measuring exoskeleton, by integrating noncontact Hall-effect and infrared sensors. The glove is connected to a haptic-control interface that reads its sensors and servos its actuators. The interface has pneumatic servovalves, signal conditioning electronics, A/D/A boards, power supply and an imbedded Pentium PC. This distributed computing assures much faster control bandwidth than would otherwise be possible. Communication with the host PC is done over an RS232 line. Comparative data with the CyberGrasp commercial haptic glove is presented     

Interactive Dynamic Simulation Schemes for Articulated Bodies through Haptic Interface

This paper describes interactive dynamic simulation schemes for articulated bodies in virtual environments, where user interaction is allowed through a haptic interface. We incorporated these schemes into our dynamic simulator I‐GMS, which was developed in an object‐oriented framework for simulating motions of free bodies and complex linkages, such as those needed for robotic systems or human body simulation. User interaction is achieved by performing push and pull operations with the PHANToM haptic device, which runs as an integrated part of I‐GMS. We use both forward and inverse dynamics of articulated bodies for the haptic interaction by the push and pull operations, respectively. We demonstrate the userinteraction capability of I‐GMS through on‐line editing of trajectories for 6‐dof (degrees of freedom) articulated bodies.     

Transparency maximization methodology for haptic devices

In this paper, a design methodology is presented aimed at maximizing haptic device transparency, as seen from the user side. The methodology developed focuses on endpoint side fidelity, and optimizes not only mechanism dimensions, but also all relevant design parameters including relative position of endpoint desired path to device location, motor transmission ratios, and rotor inertias or motor sizes. The methodology is applied to a 5-degree-of-freedom (5-DOF) haptic device, part of a training medical urological simulator, and is applicable to any haptic mechanism. The transparency maximization is achieved using a multivariable optimization approach and an objective function including mechanism-induced parasitic torques/forces and motor and transmission parameters, as seen from the user side, under several constraints. The objective function and the kinematical and operational constraints are described and discussed. A new 5-DOF haptic mechanism is constructed according to the developed procedure, resulting in a substantially improved device with respect to an existing one, developed with a standard optimization method.     

Kinematic and workspace-based dimensional optimization of a 2-DOF mechanism for a novel multipoint device

This paper presents the development of a novel haptic device that allows a user to interact with a computer using force feedback. The mechanism used in this work is expected to interact with a finger without the use of a fixture attached to the body, and by further including multiple identical mechanisms for each finger of the hand; it is possible to interact with virtual objects with gestures such as grabbing or pinching. This work investigates the theoretical workspace of a human index finger and compares it with an experimental workspace, which is obtained using a computer vision system, resulting in a modified theoretical model. Furthermore, the paper uses a two degree-of-freedom 7-bar linkage mechanism, whose dimensions are optimized according to the finger workspace. The paper obtains the mobility of the mechanism by using screw theory and analyzing the constraint screw system of the end-effector. Furthermore, the paper determines the closed-form solutions to the forward and inverse position, velocity and acceleration problems that are of interest in haptic simulations. In addition to this, the singular configurations are obtained by analyzing the Jacobian matrix and screw theory is further used to gain insight into the constraints applied to the end effector in these configurations. Theoretical workspaces are compared with experimental results, where a new finger workspace is proposed in order to account the difference between literature models and experiments. A prototype is built and tested as a proof of concept of the novel device, where the apparatus is comprised by a set of five 2-DOF mechanism; each mechanism sustains the proposed workspace but the dimensions of their components vary in order to fit all the end effectors within the fingers reach. The workspace of the constructed mechanism is compared with their theoretical models for assessing their effectiveness, and the feasibility of the use of accelerometers as position sensing instruments. The paper determines a closed-form solution to the applied force and performs an experiment to determine the force feedback that is experienced by the user. The torque produced by the motors of each mechanism is measured and the results extrapolated to cover the maximum current that can be applied to the motors.     

Dynamic force simulator for multifinger force display

In this paper, the authors present a dynamic force simulator (DFS) for force feedback in human-machine systems. They propose a virtual world model with two force flows: one is the force flow from human to an object, the other is the force flow from an object to human. To use this model, the DFS simulates object dynamics, contact models, and friction characteristics of the human hand interacting with the object in virtual reality. After the derivation of kinematic and force relations between hand and object space, they balance the two forces: one from the human and the other from the object in the contact force space in virtual world and then realize the adequate feedback forces to human operator. Interaction with the DFS allows calculation and feedback of appropriate forces to the force controlled actuators of the sensor glove they have developed. In this paper grasping of a cylinder in the virtual world is presented. During object grasping, they measure joint angles and torques using the sensor glove system. In the future, they will use this system to analyze human dextrous manipulations called human skill     

Adaptive impedance control of a haptic interface

Teleoperation enables an operator to manipulate remote objects. One of the main goals in teleoperation research is to provide the operator with the feeling of the telepresent object and of being present at the remote site. In order for this to happen, a master robot must be designed as a bilateral control system that can transmit position commands to a slave robot and reflect the interaction force. A newly proposed adaptive impedance algorithm is applied to the force control of a haptic interface that has been developed as a master robot. With the movement of the haptic interface for position command generation, the impedance between an operator and the haptic interface varies dynamically. When the impedance parameters and the dynamics of the haptic interface are known precisely, many model based control theories and methods can be used to control the interface accurately. However, due to the parameters’ variations and the uncertainty in the dynamic model, it is difficult to control the interface precisely. Therefore, this paper proposes a new adaptive impedance control algorithm and experimentally verifies the effectiveness of the algorithm for control of the haptic interface.     

On the Design of Miniature Haptic Devices for Upper Extremity Prosthetics

We have developed three different versions of a multifunction haptic device that can display touch, pressure, vibration, shear force, and temperature to the skin of an upper extremity amputee, especially the one who has undergone targeted nerve reinnervation (TR) surgery. In TR patients, sensation from the reinnervated skin is projected to the missing hand. This paper addresses the design of the mechanical display, the portion responsible for contact, pressure, vibration, and shear force. A variety of different overall design approaches satisfying the design specifications and the performance requirements are considered. The designs of the fully prototyped haptic devices are compared through open-loop frequency response, closed-loop force response, and tapping response in constrained motion. We emphasize the tradeoffs between key design factors, including force capability, workspace, size, bandwidth, weight, and mechanism complexity.      

Networked telemicromanipulation systems "Haptic Loupe"

In this paper, "Haptic Loupe" telemicromanipulation systems are proposed. We have developed telemicromanipulation systems that enable human operators to perform micro tasks, such as assembly or manufacturing without stress . These systems are based on a scaled bilateral teleoperation system between different structures. The systems are composed of an original six-degrees-of-freedom (6-DOF) parallel link manipulator to carry out micromanipulation and a 6-DOF haptic interface with force feedback. A parallel mechanism is adopted as a slave micromanipulator because of its good features of accuracy and stiffness. The haptic master interface is developed for micromanipulation systems. Haptic device system modeling and a model reference adaptive controller are implemented to compensate for friction forces, which spoil the free motion performance and force response isotropy of the system. Total system performance as a telemicromanipulator system is evaluated by performing some primitive manipulation tasks in a teleoperation experiment. Experimental results are presented and discussed.