Sebastian Kassner

Setting the standards for haptic and tactile interactions: ISO's work

Tactile and haptic interaction is becoming increasingly important and ergonomic standards can ensure that systems are designed with sufficient concerns for ergonomics and interoperability. ISO (through working group TC159/SC4/WG9) is working toward international standards, which are being dual-tracked as both ISO and CEN standards. This paper gives an update on the status of the work in progress and the recently published International Standard on tactile/haptic interactions. Active involvement of experts is sought for work on terms and definitions and measures to characterize devices and operator capabilities.

A novel piezoelectric driven laparoscopic instrument with multiple degree of freedom parallel kinematic structure

The development of a novel actuator driven laparoscopic instrument with parallel kinematic instrument tip serves to overcome the workspace restrictions of classic laparoscopic instruments and provides the surgeon multiple degrees of freedom (DOF) inside the patients body.

A Novel Laparoscopic Instrument with Multiple Degrees of Freedom and Intuitive Control

The development of a novel laparoscopic instrument INKOMAN (intracorporeal manipulator) serves to overcome the workspace restrictions of classic laparoscopic instruments and provide the surgeon multiple degrees of freedom (DOF) inside the body.

Analysis of mechanical properties of liver tissue as a design criterion for the development of a haptic laparoscopic tool

In this paper we present a mechanical soft tissue model serving as a design criterion for a novel haptic telemanipulation system for laparoscopic liver surgery. Haptic properties of this tool can be characterized by transparency T. T is defined as the ration of the mechanical impedance of the manipulated tissue Z Tissue detected by an intracorporal force sensor to the mechanical impedance generated by the haptic human-machine interface Z feedback. In order to use T as a design criterion a mechanically interpretable closed form description of the mechanical impedance is desired. Assuming visco-elastic behaviour we adopt a mechanical network with lumped elements, based on an extended Kelvin model. Since human fingers need to sense vibrations during skilful manipulative tasks up to several kilohertz we present a new experimental setup which enables us to determine lumped network parameters in a broad bandwidth: A sinusoidal force sweep from 10 Hz to 10 kHz is generated by an electrodynamic shaker. The speed and force response of the liver tissue is detected by an impedance head and parameters of the lumped network are determined by a fit, using a trust-region algorithm (RSME ≦ 0.7). Comparison measurements were taken on ex vivo porcine liver and a haptic rubber phantom.

Towards a standard on evaluation of tactile/haptic interactions

Tactile and haptic interaction is becoming increasingly important; ergonomic standards can ensure that systems are designed with sufficient concern for ergonomics and interoperability. ISO (through working group TC159/SC4/WG9) is developing international standards in this subject area, dual-tracked as both ISO and CEN standards. A framework and guidelines for tactile/haptic interactions have recently been published as ISO 9241-910 and ISO 9241-920 respectively. We describe the main concepts and definitions in support of a new standard that describes how to evaluate tactile/haptic interactions and how to link this evaluation to previous standards. The new standard addresses three major aspects of the evaluation of a tactile/haptic system the validation of system requirements, the verification that the system meets the requirements, and the overall usability of the system. Several measurement and analysis techniques are discussed, such as the calculation of scores for the determination of effectiveness. Tactile/haptic measurements have to be repeatable, and as an example we discuss how an appropriate model of the interaction with a virtual wall can be formed and used in evaluating a device.

Operational Concept for a Handheld Laparoscopic Telemanipulation System: Design and Animal Experiment

In this paper the design of a control element for a novel telemanipulation system for laparoscopic surgery is presented. This control element is used to operate a manipulator with a four-degree-of-freedom intracorporeal kinematic structure. In order to be applicable in medical interventions it has to be designed in a way that it can be easily captured and released by the surgeon. Therefore various grips are discussed and a clasp grip using little, ring and middle finger is chosen. The handle is designed with respect to ergonomic measures. In a first concept the manipulator is operated by a 3-DOF joystick implementing a direct input of position commands. Due to surgeons’ feedback a second prototype is built based on the control the of the manipulator’s speed by a 2-DOF joystick. The latter has sucessfully been tested in an animal experiment. In the future the control element will be equipped with active haptic feedback.

Parallel kinematics for haptic feedback in three degrees of freedom: application in a handheld laparoscopic telemanipulation system

In this paper parallel kinematic structures are analyzed to realize a haptic joystick with three translational degrees of freedom. The Chebychev-Grubler-Kutzbach criterion is applied to determine kinematic topologies. Resulting topologies are listed comprising prismatic, rotational, universal and cylindrical joints. Furthermore restrictions are compiled to enforce pure translational behaviour. An RUU mechanism is chosen as an applicable structure and adapted to be applied in a handheld control interface for a laparoscopic telesurgical system. An algorithm has been implemented to determine workspace size and shape. Three exemplary workspace shapes are shown and the occurring actor torques are calculated using the Jacobian matrix.