Haptic Control System Research Articles

Active constraint control for the surgical robotic platform with concentric connector joints

Robotic minimally invasive surgery (MIS) has changed numerous surgical techniques in the past few years and enhanced their results. Haptic feedback is integrated into robotic surgical systems to restore the surgeon's perception of forces in response to interaction with objects in the surgical environment. The ideal exact emulation of the robot's interaction with its physical environment in free space is a very challenging problem to solve completely. Previously, we introduced the surgical robotic platform (SRP) with a novel concentric connector joint (CCJ). This study aims to develop a haptic control system that integrates an active constraint controller into a surgical robot platform. We have successfully established haptic feedback control for the surgical robot using constraint control and inverse kinematic relationships integrated into the overall positioning structure. A preliminary feasibility study, modelling, and simulation were presented.

Problems of using haptic feedback to control manipulator tools

The paper reviews the machine operators support technologies used in carrying out work tasks. The limitations of the current design solutions have been identified. The construction of control systems using haptic feedback was discussed and the research carried out on this technology was reviewed. The concept of hydraulic manipulator tool and its haptic feedback control system for monitoring loads during working movements is presented. The concept of the test stand for testing haptic feedback control systems and the preliminary experiment plan are presented.

Robust Controller Analysis and Design of Medical Haptic Control System

Robust Controller Analysis and Design of Medical Haptic Control System

Effect of Scaling on the Performance and Stability of Teleoperation Systems Interacting with Soft Environments

There is generally a tradeoff between stability and performance in haptic control systems. Teleoperation systems with haptic feedback are no exception. Scaling in these systems used in applications such as telemicrosurgical systems has further effects on the stability and performance. This paper focuses on those applications interacting with soft tissues and analyzes the effects of the scaling in an effort to increase the performance of these systems while maintaining the stability. Position tracking and kinesthetic perception are especially important in the tele-surgical systems and, hence, are used as the performance criteria. Quantitatively defined stability robustness, which is based on Llewellyn's absolute stability criterion, is used as a metric for stability analysis. Various choices of scaling factors, and human and environment impedances are then investigated. The proposed kinesthetic perception concept is validated using psychophysical experiments. Widely used bilateral control architectures such as the two-channel position–position, two-channel force–position and four-channel controls are specifically analyzed and evaluated using simulations and experiments with phantom soft tissues. Results also show that the force–position control architecture shows the best position tracking performance irrespective of the scaling factors while the four-channel controller shows the best kinesthetic perception capability.

A Comparison of Haptic Transmission Methods and Influences of Network Latency in a Remote Haptic Control System

A Comparison of Haptic Transmission Methods and Influences of Network Latency in a Remote Haptic Control System

Dynamic Switching Control of Haptic Transmission Direction and Automatic Selection of Switching Time in Remote Haptic Control System

Dynamic Switching Control of Haptic Transmission Direction and Automatic Selection of Switching Time in Remote Haptic Control System

An Analog Input Shaper for Stability Enhancement of Haptic Interfaces and Its Application to Energy-Bounding Algorithm

An analog input shaper is proposed for a haptic control system to improve stability when interacting with virtual environments. High frequency inputs to a haptic device, which usually occur in collision with virtual objects with high stiffness, can induce limit cycle oscillations and instabilities. In order to reduce these high frequency inputs to haptic devices, an analog input shaper is added to the control system. In order to minimize the delay, which is also one of major causes of instabilities, the analog input shaper is implemented with a high-pass filter instead of a low-pass filter. Since the input shaper has its own dynamics, when a haptic pointer leaves a virtual wall, a user may feel slow decrease of impedance. Moreover there may be negative impedance as if the wall is pulling. In order to solve these problems, we add linear half-wave rectifiers which allow fast decrease of impedance and no negative input to a haptic device. The rectifiers can also eliminate the undesirable energy. The input shaper reduces the total energy supplied to a haptic device by preventing high frequency inputs from flowing into a haptic device and by using rectifiers, therefore, it can be regarded as an artificial damping element. Energy-bounding algorithm, which is an energy-based method, can guarantee stable haptic interaction by limiting the input energy. So, it inevitably sacrifices transparency in haptic interaction. The analog input shaper is incorporated into energy-bounding algorithm to increase the impedance range that the algorithm can stably display. A digital filtering scheme, which uses the same structure as in an analog input shaper, is also tested. Through experiments, we show that the analog input shaper can enhance the stability and thus increase the impedance range which can be stably displayed by a haptic device.

Friction Modeling and Compensation for Haptic Display Based on Support Vector Machine

As the presence of friction in a haptic display device seriously affects its performance, proper compensation of the frictional effects in such a device is of practical importance for advanced virtual reality applications where haptic display plays a critical role. This paper addresses the issue of friction modeling and compensation for haptic control system designs. A new method based on the Support Vector Machine (SVM) is developed in a controller design based on a two-port network to achieve accurate haptic display. The approximation model of friction is established offline through SVM learning and is used for online feed forward friction compensation. The advantages of this novel method are demonstrated through the experiments performed.