In this paper, two novel adaptive finite-time control schemes are proposed for position tracking of nonlinear teleoperation system, which dynamic uncertainties, actuator saturation, and time-varying communication delays are considered. First, a novel auxiliary variable is designed to provide more stable performance. The radial basis function (RBF) neural network is introduced to estimate dynamic uncertainties. Second, two adaptive finite-time control schemes are investigated. In control scheme I, the RBF neural network and the gain switching strategy are applied to compensate the actuator saturation. In control scheme II, an auxiliary compensation filter and the compensation adaptive update laws, which contain the finite-time structure, are developed for dealing with saturation. Third, the finite-time adaptive controller is designed in each of these two control schemes. Based on the multiple Lyapunov function method, the closed-loop teleoperation system with these two control methods is proved to be bounded and finite-time stability. Finally, the simulation experiments are performed and the comparisons with other control methods are shown. The effectiveness of the proposed control schemes is demonstrated.

The communication time delay and uncertain models of robotic manipulators are the major problem in the teleoperation system, which can reduce the performance and stability of the system. This article proposed a novel finite-time adaptive control scheme for position and force tracking performances of the teleoperation system. First, a combined auxiliary error system with position and force tracking errors is designed. Second, a velocity feedback filter is introduced, and a new auxiliary variable function with finite-time structure is designed for controller design. The radial basis function neural network (RBFNN) is applied to estimate the uncertain parts. Then the finite-time adaptive control scheme and adaptive laws are given. Third, based on the Lyapunov method, stability and finite-time performance are demonstrated. And finally, the simulation and experimental studies (with Phantom Ommi devices) are performed and demonstrate the effectiveness of the proposed control scheme on teleoperation position/force tracking.

This paper presents the design and development of a novel haptic sensor system. It integrates cable-driven force and ultrasonic tactile feedback, which can produce multimodal haptic stimuli. The sensing element includes a Leapmotion, an ultrasonic transducer array, tension sensors, and rotary encoders, which are used to capture hand posture, project tactile points, measure cable force and length, respectively. Firstly, a 6-DOF cable-driven force feedback apparatus based on parallel mechanism is designed and ultrasonic phased array is combined to form a multimodal haptic feedback system. Secondly, a multimodal haptic fusion method for cable-driven force and ultrasonic tactile is firstly proposed to invoke realistic compound haptic sensations. To enhance the rendering effects of each subsystem, admittance control is developed for a cable robot, and a new perceived magnitude model is established for ultrasound tactile rendering. A psychophysical experiment is conducted to study the perceived characteristics of multimodal haptic stimuli. To verify the proposed system, a series of experiments were carried out, whose results indicated that the system performs well at multi-property haptic rendering and confirm the accuracy and sensitive advantage of our system in virtual reality applications. The results of our study indicate that this device has great application potential in human-computer interaction.

In practical application, the synchronization tracking of teleoperation system requires the fast speed and strong robustness. It is the ideal control effect that the synchronization errors between master and slave robots can converge to zero in finite time. In this paper, we propose the new nonsingular terminal sliding mode and the adaptive finite-time control method for position tracking in teleoperation system. First, a novel nonsingular terminal sliding mode is designed to provide higher tracking precision and robustness. Second, the radial basis function neural networks are applied to solve dynamic uncertainties, and the adaptive laws are proposed to estimate the uncertain parameters and upper bounds of estimation. Then, the corresponding finite-time controllers of master and slave robots are designed. Third, based on the Lyapunov stability theory, synchronization performances of the closed-loop system are proved to be stable state and finite time. Finally, simulations are achieved, and some comparisons with two nonsingular terminal sliding mode control schemes and two PD methods are shown. The simulation results verify the effectiveness of the proposed control laws.

In bilateral teleoperation systems, achieving fast position synchronization while maintaining high-communication efficiency represents an essential control objective. This article proposes a simplified control scheme with a finite-time proportional damping (FTP+d) injection method and an event-driven communication mechanism to address the challenge of position synchronization in time-delayed telerobotic systems. The system takes into account the asymmetric time-varying delays and external forces. First, a novel event-triggered strategy based on noninteger power is designed. With a designed error-velocity mixed variable, a new FTP+d controller is developed by employing a continuous nonsmooth function, a damping term, an adaptive term, and noninteger power. With the Lyapunov–Krasovskii (LK) method and the finite-time stability theory, the boundedness of the telerobot’s state is established, and the finite-time synchronization performance is analytically guaranteed. Furthermore, the relationships between controller parameters, time-varying delays, and system stability are also analyzed based on linear matrix inequality (LMI). Finally, both simulation and experimental investigations are conducted to evaluate the efficacy and performance of the proposed control approach.

This paper presents a new haptics interface device based on cable-driven parallel manipulators and an ultrasonic phased array. Unlike previous studies, our method combines force and tactile feedback at the same time. It consists of two main parts: force feedback generated by cable tension and tactile feedback provided by an ultrasonic phased array. While these parts have no direct interference, combining them can offer a synergistic effect on haptic perception. Through a series of experiments, the tactile rendering algorithm for this device is established. The output pressure of ultrasonic phased array is dependent on input command value, modulation frequency, modulation waveform, and the position of the focal point in the workspace. The results of psychophysical experiments are evaluated to determine the absolute threshold of perceivable ultrasonic tactile feedback when the cable-driven force acts on fingers. Finally, we carry out a test to confirm the accuracy advantage of our system in the virtual environment. The results of our study indicate that this device has a wide range of applications in the field of aerial haptic display.