• Journal of Institute of Control, Robotics and Systems
• /
• v.13 no.12
• /
• pp.1207-1212
• /
• 2007

We propose a haptic interface algorithm for joystick operators working in remote control systems of unmanned vehicles. The haptic interface algorithm is implemented using a force-feedback joystick, which is equipped with low price DC motors without encoders. Generating specific amounts of forces on the joystick pole according to the distance between a remote controlled vehicle and obstacles, the haptic interface enables the operator to perceive the distance information by the sense of touch. For the case of no joystick operation or no obstacles in the working area, we propose an origin control algorithm, which positions the joystick pole at the origin. The origin control algorithm prevents the false movement of the remote vehicles and provides the operator with a realistic force resisting the joystick pole's movement. The experiment results obtained under various scenarios exemplify the validity of the proposed haptic interface algorithm and the origin control algorithm.

• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.1673-1678
• /
• 2005

This paper addresses both theoretical and experimental studies of the stability of haptic interfaces during the simulation of virtual Coulomb friction. The first objective of this paper is to present an analysis of how friction affects stability in terms of the describing function method and the absolute stability theory. Two different feedback methods are introduced and are used to evaluate the analysis: an active force feedback, using a motor, and a passive force feedback, using controllable brake. The second objective of this paper is to present a comparison of the theoretical and experimental results. The results indicate that the sustained oscillations due to the limit cycle occur when simulating friction with an active force feedback. In contrast, a passive force feedback can simulate virtual friction without the occurrence of instability. In conclusion, a hybrid active/passive force feedback is proposed to simulate a highly realistic friction display.

• Journal of the Korea Convergence Society
• /
• v.8 no.12
• /
• pp.291-298
• /
• 2017

In recent years, the increase of secondary controls within vehicles requires a mechanism to integrate various controls into a single device. This paper presents control performance of an integrated magnetorheological (MR) haptic device which can adjust various in-vehicle comfort instruments. As a first step, the MR fluid-based haptic device capable of both rotary and push motions within a single device is devised as an integrated multi-functional instrument control device. Under consideration of the torque and force model of the proposed device, a magnetic circuit is designed. The proposed MR haptic device is then manufactured and its field-dependent torque and force are experimentally evaluated. Furthermore, an inverse model compensator is synthesized under basis of the Bingham model of the MR fluid and torque/force model of the device. Subsequently, haptic force-feedback maps considering in-vehicle comfort functions are constructed and interacts with the compensator to achieve a desired force-feedback. Control performances such as reflection force are experimentally evaluated for two specific comfort functions.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.11a
• /
• pp.422-427
• /
• 2006

This paper presents force-feedback control performance of a haptic device in virtual environment of minimally invasive surgery(MIS). As a first step, based on an electrorheological(ER) fluid and spherical geometry, a new type of master device is developed and integrated with a virtual environment of MIS such as a surgical tool and human organ. The virtual object is then mathematically formulated by adopting the shape retaining chain linked(S-Chain) model. After evaluating reflection force, computational time, and compatibility with real time control, the virtual environment of MIS is formulated by interactivity with the ER haptic device in real space. Tracking control performances for virtual force trajectory are presented in time domain, and theirtrackingerrorsareevaluated.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.16 no.12 s.117
• /
• pp.1286-1293
• /
• 2006

This paper presents force-feedback control performance of a haptic device in virtual environment of minimally invasive surgery(MIS). As a first step, based on an electrorheological (ER) fluid and spherical geometry, a new type of master device is developed and integrated with a virtual environment of MIS such as a surgical tool and human organ. The virtual object is then mathematically formulated by adopting the shape retaining chain linked(S-chain) model. After evaluating reflection force, computational time, and compatibility with real time control, the virtual environment of MIS is formulated by interactivity with the ER haptic device in real space. Tracking control performances for virtual force trajectory are presented in time domain.

• Journal of Institute of Control, Robotics and Systems
• /
• v.20 no.8
• /
• pp.801-806
• /
• 2014

LAS (Laparoscopy Assisted Surgery) has been substituted alternatively for traditional open surgery. However, when using a commercialized robot assisted laparoscopic such as Da Vinci, surgeons have encountered some problems due to having to depend only on information by visual feedback. To solve this problem, a haptic function is required. In order to realize the haptic teleoperation system, a force feedback and bilateral control system are needed. Previous research showed that the perturbation value estimated by a SPO (Sliding Perturbation Observer) followed a reaction force that loaded on the surgical robot instrument. Thus, in this paper, the force feedback problem of surgical robots is solved through the reaction force estimation method. This paper then introduces the possibility of the haptic function realization of a laparoscopic surgery robot using a bilateral control system. For bilateral control, the master uses an impedance control and the slave uses a SMC (Sliding Mode Control). The experiment results show that a torque and force sensorless teleoperation system can be implemented using a bilateral control structure.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.51 no.10
• /
• pp.439-445
• /
• 2002

In this paper force feedback control system is investigated for improving the quality of the haptic feedback in virtual reality applications. We suggested the method of controlling the haptic device and modelling the virtual environment. Haptic device is composed of five bar link structure, voice coil motor, control board, and virtual environment modeling program. We applied voice coil motor in the actuating system for simple structure and easy control. Virtual environment modelling is constructed in PC, and the control signals of the actuators and the encoder data are transferred to the control system through USB. Experiment is performed to evaluate the characteristics of the haptic device.

• Journal of Institute of Control, Robotics and Systems
• /
• v.20 no.8
• /
• pp.815-821
• /
• 2014

In this paper, we propose a novel CALL (Computer-Assisted Language Learning) system, which is called POMY (POSTECH Immersive English Study). In our system, students can study English while talking to characters in a computer-generated virtual environment. POMY also supports haptic feedback, so students can study English in a more interesting manner. Haptic feedback is provided by two platforms, a haptic chair and a force-feedback device. The haptic chair, which is equipped with an array of vibrotactile actuators, delivers directional information to the student. The force-feedback device enables the student to feel the physical properties of an object. These haptic systems help the student better understand English conversations and focus on studying. We conducted a user experiment and its results showed that our haptic-enabled English study contributes to better learning of English.

• 제어로봇시스템학회:학술대회논문집
• /
• 2004.08a
• /
• pp.1131-1135
• /
• 2004

In the virtual environment, force feedback to the human operator makes virtual experiences more realistic. However, the force feedback using active actuators such as motors can make the system active and sometimes unstable. To ensure the safe operation and enhance the haptic feeling, stability should be guaranteed. Both motors and brakes are commonly used for haptic device. A brake can generate a torque only against its rotation, but it is intrinsically stable. Consequently, motors and brakes are complementing each other. In this research, a two degree-of-freedom (DOF) haptic device equipped with both motors and brakes has been developed to provide better haptic effects. Each DOF is actuated by a pair of motor and brake. Modeling of the environment and the control method are needed to utilize both actuators. For various haptic effects, contact with the virtual wall and representation of friction effect are extensively investigated in this paper. It is shown that the hybrid haptic system is more suited to some applications than the motor-based active haptic system.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.3 no.2
• /
• pp.161-165
• /
• 2003

In this paper, we investigate the issues on the design and implementation of tele-operation system based on the haptic interface. Here, the 3-DOF haptic device and the X-Y-Z stage are employed as master controller and slave system respectively. For this master-slave system, the force feedback algorithm, the modeling of virtual environments and the control method of X-Y-Z stage are presented. In this paper, internet network is used for data communication between master and slave. We construct virtual environment of the real convex surface from the force-feedback in controlling the X-Y-Z stage and measuring the force applied by the 3-DOF haptic device.