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.
Touch screen technology supplies a new approach to interact with virtual environments. For haptic interaction on a touch screen, haptic devices that are capable of simultaneously conveying tactile and force information to users are highly desired for enhancing the sense of reality and immersion. To this end, a prototype haptic interface, called MH-Pen, was developed and fabricated to display the virtual interactive information through multi-mode haptic feedback. The MH-Pen is a self-contained system that provides vibrotactile feedback and precise force feedback by integrating three types of actuators. In this paper, MH-Pen's design, specifications, and working principle are described. Subsequently, to accurately display the interaction force, a hybrid actuator was designed by combining a piston-type magnetorheological (MR) actuator and a voice coil motor (VCM), and a closed-loop control scheme was built to manage the hybrid actuator. Finally, we objectively and subjectively evaluated the force feedback performance and the effect of multi-mode haptic display of the MH-Pen through physical measurements and psychophysical experiments of virtual surface stiffness display. The results show that improving the precision of force feedback and using multi-mode haptic display are both useful and necessary to enhance the sense of human-computer interaction realism.
This paper introduces a haptic interface based on cable robot and ultrasonic transducers array. This novel haptic interface device is capable of invoking compound haptic sensations and displaying multiple properties of virtual objects, including texture, three-dimensional shape, and weight etc. With a network of cables kept in tension, users are able to perceive force feedback in virtual reality applications. 1-DOF grasping and 6-DOF manipulation are provided by the cable-driven parallel mechanism. The kinematic models and static analysis are presented. The tactile feedback is provided by an ultrasonic transducers array. Cable-driven force and ultrasonic tactile feedback are applied to the hand simultaneously. An implementation of the theory and system design is proposed in this paper. Experiments are conducted to confirm the accuracy advantage of our system in the virtual environment. The results of our study indicate that this device has great application potential in human-robot interaction.
Digital image is always polluted by noise and made data postprocessing difficult. To remove noise and preserve detail of image as much as possible, this paper proposed image filter algorithm which combined the merits of Shearlet transformation and particle swarm optimization (PSO) algorithm. Firstly, we use classical Shearlet transform to decompose noised image into many subwavelets under multiscale and multiorientation. Secondly, we gave weighted factor to those subwavelets obtained. Then, using classical Shearlet inverse transform, we obtained a composite image which is composed of those weighted subwavelets. After that, we designed fast and rough evaluation method to evaluate noise level of the new image; by using this method as fitness, we adopted PSO to find the optimal weighted factor we added; after lots of iterations, by the optimal factors and Shearlet inverse transform, we got the best denoised image. Experimental results have shown that proposed algorithm eliminates noise effectively and yields good peak signal noise ratio (PSNR).
Takeoff is the start of flying. Self-takeoff of flapping-wing robots can improve their practical values in large area surveillance, search and rescue, etc. However, self-takeoff for this kind of robots is still a challenging problem. Inspired by the takeoff of birds and insects assisted by their legs and feet pushing the ground during taking off, this work presents the conceptual design of a jumping-flapping multi-modal locomotion robot to study the feasibility of jumping aided takeoff. A multi-modal robots design method is proposed which makes the robots as light as possible. The jumping, flapping, tail, and driving mechanisms are designed respectively. The sensing and control systems are introduced. The self-takeoff motion planning and aerial maneuvers are studied. The simplified jumping model and the simulation results are also presented. The results of this paper could give guidelines for this kind of robots design.
Random time delay may cause instability in the internet based teleoperation system. Transparency and intuitiveness are also very important for operator to control the system to accurately perform the desired action, especially for the gripper teleoperation system. This paper presents a new grip force control method of gripper teleoperation system with haptic feedback. The system employs the SEMG signal as the control parameter in order to enhance the intuitive control experience for operator. In order to eliminate the impacts on the system stability caused by random time delay, a non-time based teleoperation method is applied to the control process. Besides, neural network and designed fuzzy logic controller is also utilized to improve this control method. The effectiveness of the proposed method is demonstrated by experiment results.
Sampled-data system nature is the main factor for a haptic system to exhibit non-passive behaviors or instabilities through "energy leaks", particularly for stiff objects rendering. An energy-compensating method is presented aiming to improve the haptic system's performance based on the concept of doing work. Using ideal continuous-time haptic system as a reference, we define an energy-compensating controller (ECC controller) which compensates the energy leaks caused by zero-order-hold and asynchronous switching during entering and leaving contacts. The ECC controller not only removes the unwanted over-work from the virtual environment during leaving contacts to eliminate the system's potential non-passive behaviors, but also enlarges the work that should be done by the operator according to the reference system's value when new contacts arise. The proposed method was tested and verified with the implementation of a "virtual stiff-wall" via Delta 6-DOF haptic device.
Comparing to the big volume, large weight and high power consumption of the conventional samplers which are fixed on the lunar rover, the paper firstly described a novel flexible mini lunar sampling robot.Then the nonlinear dynamics resonance broken system is built to model the contact between the sampling robot and the lunar regolith.It is found to be suitable for drilling when the sampling robot is in the resonance condition.For the nonlinear time-varying system of the dynamic modeling of the sampler in drilling, we presented the method of the frequency neural-fuzzy adaptive control based on the dynamic resonant frequency prediction of the flexible sampling robot using neural networks.Firstly the algorithm predicts the dynamic resonant frequency of the sampling robot by GRNN.Then a neural-fuzzy adaptive control system is established, in which the frequency prediction error, the amplitude and its variable are adopted as the input and the sweep frequency bandwidth as the output, to adjust the frequency bandwidth dynamically.What's more, the simulation results verify the effectiveness of the control strategy.Finally, the experimental results show that the control algorithm can improve the drilling depth, drilling efficiency and the discarding efficiency by 66. 7%, 65.2% and 67.4%, respectively, in stimulant lunar regolith.
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.
