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Yuru Zhang

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Papers by Yuru Zhang

A Hierarchical Model of Motor Skill for Haptic-assisted Virtual Reality Training

International Journal of Virtual Reality

Model of motor skill pattern is a fundamental component to support feedback mechanism in haptic-a... more Model of motor skill pattern is a fundamental component to support feedback mechanism in haptic-assisted motor skill training. Because of the diversity of manipulation tasks in real world, it is a challenge to construct a generic model for various motor skill patterns. Considering fine motor skill mediated by a rigid tool, criteria for a general model of motor skill are identified: generality, quantifiable representation and the capability to support real-time error computation. A hierarchical motor skill model is proposed in a two-level architecture: the spatial-temporal coupling mechanism in task level and the quantified representation in action level. The purpose of task level is to decompose a motor skill into basic elements that can be described with quantified representation. The purpose of the action level is to give quantified representation in each single dimension in the Cartesian Space. Based on the combinations of independent variants, mapping functions in the action lev...

Speed-accuracy tradeoff of fingertip force control with visual/audio/haptic feedback

International Journal of Human-Computer Studies

Passive Force-feedback Gloves with Joint-based Variable Impedance Using Layer Jamming

IEEE Transactions on Haptics

Six Degree-of-Freedom Haptic Simulation of a Stringed Musical Instrument for Triggering Sounds

IEEE transactions on haptics, Jan 14, 2016

Six degree-of-freedom (DoF) haptic rendering of multi-region contacts between a moving hand avata... more Six degree-of-freedom (DoF) haptic rendering of multi-region contacts between a moving hand avatar and varied-shaped components of a music instrument is fundamental to realizing interactive simulation of music playing. There are two aspects of computational challenges: first, some components have significantly small sizes in some dimensions, such as the strings on a seven-string plucked instrument (e.g. Guqin), which makes it challenging to avoid pop-through during multi-region contact scenarios. Second, deformable strings may produce high-frequency vibration, which requires simulating diversified and subtle force sensations when a hand interacts with strings in different ways. In this paper, we propose a constraint-based approach to haptic interaction and simulation between a moving hand avatar and various parts of a string instrument, using a cylinder model for the string that has a large length-radius ratio and a sphere-tree model for the other parts that have complex shapes. Col...

A novel spatial-temporal encoding strategy for presenting time on the wrist using vibrotactile cues

2016 IEEE International Conference on Mechatronics and Automation, 2016

Vision-Based Grasp Planning System for Dexterous Hands

This paper introduces a new approach of grasp planning for robotic dexterous hands. Master-slave ... more This paper introduces a new approach of grasp planning for robotic dexterous hands. Master-slave control strategy is adopted for integrating human intelligence into the planning system in which human hand directly controls the robot hand interactively. The human-machine interface is a computer vision system with two CCD cameras. The fingertips of the human hand are marked with markers of different geometry, thus can be identified by the computer vision system. When the human fingers move, the vision system firstly captures the image of the markers and performs feature-based identification. Then the images of the two cameras are matched and their image centers are used to calculate the positions of the fingertips. After this the human fingertip positions are mapped onto those of the dexterous hand in its palm frame. The human operator observes the motions of the robot fingers and decides the next step of motion. Through this procedure the human hand can guide the robot fingers to the target position of grasping and manipulation. To verify the validity of the proposed grasp planning approach, two tasks are demonstrated in a virtual environment, one is pressing a button with a single finger and the other is moving the thumb and index fingers. The tasks are simulated in real time and performed successfully.

Effect of vibrotactile cues for guiding simultaneous procedural motion of two joints on upper limbs

2015 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2015

Multi-modal Virtual Reality Dental Training System with Integrated Haptic-Visual-Audio Display

Lecture Notes in Control and Information Sciences, 2007

Multi-modal signal fusion is an important way to improve immersion and fidelity of virtual realit... more Multi-modal signal fusion is an important way to improve immersion and fidelity of virtual reality training systems. With the help of a robotic arm, haptic device, it is possible to supply haptic-visual-audio display for training dentist. Architecture is firstly proposed to integrate different signals in a training system. High efficient sound synthesis algorithm is proposed based on hybrid combination of parameter identification from recorded sound signal, then use signal synthesis method to form final sound signal. Mapping method among audio, haptic and visual signal is proposed based on parameter mapping under various interaction status. Experiment based on Phantom desktop proves the stability of the rendering algorithm and the improved fidelity after adding audio feedback to current haptic-visual dental training system.

Real-time solution of the forward kinematics for a parallel haptic device using a numerical approach based on neural networks

Journal of Mechanical Science and Technology, 2015

This paper proposes a neural network (NN)-based approach to solve the forward kinematics of a 3-R... more This paper proposes a neural network (NN)-based approach to solve the forward kinematics of a 3-RRR spherical parallel mechanism designed for a haptic device. The proposed algorithm aims to remarkably speed up computation to meet the requirement of highfrequency rendering for haptic display. To achieve high accuracy, the workspace of the haptic device is divided into smaller subspaces. The proposed algorithm contains NNs of two different precision levels: a rough estimation NN to identify the index of the subspace and several precise estimation networks with expected accuracy to calculate the forward kinematics. For continuous motion, the algorithm structure is further simplified to save internal memory and increase computing speed, which are critical for a haptic device control system running on an embedded platform. Compared with the mostly used Newton-Raphson method, the proposed algorithm and its simplified version greatly increase the calculation speed by about four times and 10 times, respectively, while achieving the same accuracy level. The proposed approach is of great significance for solving the forward kinematics of parallel mechanism used as haptic devices when high update frequency is needed but hardware resources are limited.

Mo deling a nd a nalysis of a force interactio n syste m

ABSTRACT

Voxel-based Modeling for Haptic-enabled Dental Drilling Simulation

：This paper establishes a uniform cube-voxel model based on linear list with deeply analyzing req... more ：This paper establishes a uniform cube-voxel model based on linear list with deeply analyzing requirements of virtual teeth drilling operation modeling. A material removal and reconstruction algorithm is designed for real-time simulation of topology update caused by drilling operation and point-based rendering is used for image processing. Experimental results show that the model decomposed by 0.1mm could well satisfy the demand of force feedback frequency in 1 KHz and model reconstruction frequency in 30Hz; at the same time, the model reconstruction algorithm can precisely simulate various drilling tools in different sizes.

Speed-accuracy tradeoff of controlling absolute magnitude of fingertip force

2015 IEEE World Haptics Conference (WHC), 2015

ABSTRACT

Dataglove Based Grasp Planning for Multi-fingered Robot Hand

Dataglove Based Grasp Planning for Multi-fingered Robot Hand

Determination of contact forces in grasping

Proceedings of IEEE/RSJ International Conference on Intelligent Robots and Systems. IROS '96, 1996

... Cheng and Orin [3,4] improved the optimization by reducing the number of constraints and vari... more

Classification of grasps by multifingered robot hands

Proceedings of IEEE/RSJ International Conference on Intelligent Robots and Systems. IROS '96, 1996

This research characterizes grasping by multifingered robot hands through an investigation of the... more This research characterizes grasping by multifingered robot hands through an investigation of the space of contact forces between fingers and the grasped object. By decomposing the space of contact forces into four subspaces, we develop a method to determine the dimensions of the subspaces with respect to the connectivity of the object. The relationship we obtain reveals the diflkrences between three qpes of grasps classified in the paper and indicates how the contact force can be decomposed corresponding to each type of grasp. Therefore, it provides a guideline for formulating the distribution of contact forces as a basis for optimization. The subspaces and the determination of their dimensions are illustrated by examples.

Evaluating the quality of grasp configurations for dextrous hands

Proceedings of International Conference on Robotics and Automation, 1997

We investigate methods for evaluating grasp configurations of multifingered mbot hands. When a gr... more We investigate methods for evaluating grasp configurations of multifingered mbot hands. When a grasped object is subjected to externally applied forces and moments, an equilibrium of the object is achieved by contact forces which are generated by the joint torques of the fingers. Assuming that the object and fingers comprise a rigid body system, we provide a general formulation relating the contact forces with the joint torques, extemal forces, and moments. We define three criteria to evaluate optimal grasp configurations. The computation of the criteria requires determining eigenvalues of a matrix. The method is applicable to all types of grasps. It is not limited by the number of contacts for each fingers, the geometry of the object, nor the contact models. In the examples, several grasp configurations are compared using these criteria.

Definition and force distribution of power grasps

Proceedings of 1995 IEEE International Conference on Robotics and Automation, 1995

... apower grasp was empirically viewed as that having large areas of contact between the grasped... more

Design and control of the BUAA four-fingered hand

Proceedings 2001 ICRA. IEEE International Conference on Robotics and Automation (Cat. No.01CH37164), 2001

... May 21-26, 2001 Design and Control of the BUAA Four-Fingered Hand Y. Zhang, Z. Han, H. Zhang,... more

Modeling of Intelligent Behaviour in Haptic Enabled Tug-of-War Simulation

The Proceedings of the Multiconference on "Computational Engineering in Systems Applications", 2006

Virtual environment (VE) is a prime component in haptic interaction system. Traditional passive V... more Virtual environment (VE) is a prime component in haptic interaction system. Traditional passive VE is not suitable to model human-machine interaction intelligence in haptic system such as a virtual tug-of-war system. Novel taxonomy of virtual environment is proposed according to different interaction tasks in physical world. Based on the difference between passive and active VE, intelligent VE is defined as a special type of nonlinear and active VE. The components of intelligent VE are identified and challenges within modeling and rendering method are discussed. Based on a one-dimensional haptic device, a virtual tug-of-war prototype is developed and different rendering algorithms are compared. Experiment results illustrate that the intelligent VE enhance the fidelity of the tug-of-war process and the rendering algorithm could ensure stability of the haptic system. The developed prototype can be utilized in entertainment areas.

Analysis of contact localization of dexterous robot hand using force/torque measurement

ICARCV 2004 8th Control, Automation, Robotics and Vision Conference, 2004., 2004

It is important to detect the position of contact points between the grasped object and the finge... more It is important to detect the position of contact points between the grasped object and the fingertips of dexterous hand. The method using force/torque sensor mounted at fingertip is simpler and easier than the tactile sensor to get the contact position. However, there are two problems held back the application of the former when the sensing data is contaminated with disturbance. First, when the hard finger contact model is used to calculate the points, the solution may not exist. This paper investigates the problem under the contact models of hard finger and soft finger respectively. Mathematical verification is developed to find the existence condition of solutions. A simple criterion is provided to determine which contact model must be selected for calculating contact points. The next problem is accuracy. The error of soft finger contact model is analyzed. Some strategies are given to improve the accuracy of the contact localization. Simulations and experiments show that the reliable and precise measurement of contact points can be achieved by the proposed approaches.

A Hierarchical Model of Motor Skill for Haptic-assisted Virtual Reality Training

International Journal of Virtual Reality

Model of motor skill pattern is a fundamental component to support feedback mechanism in haptic-a... more Model of motor skill pattern is a fundamental component to support feedback mechanism in haptic-assisted motor skill training. Because of the diversity of manipulation tasks in real world, it is a challenge to construct a generic model for various motor skill patterns. Considering fine motor skill mediated by a rigid tool, criteria for a general model of motor skill are identified: generality, quantifiable representation and the capability to support real-time error computation. A hierarchical motor skill model is proposed in a two-level architecture: the spatial-temporal coupling mechanism in task level and the quantified representation in action level. The purpose of task level is to decompose a motor skill into basic elements that can be described with quantified representation. The purpose of the action level is to give quantified representation in each single dimension in the Cartesian Space. Based on the combinations of independent variants, mapping functions in the action lev...

Speed-accuracy tradeoff of fingertip force control with visual/audio/haptic feedback

International Journal of Human-Computer Studies

Passive Force-feedback Gloves with Joint-based Variable Impedance Using Layer Jamming

IEEE Transactions on Haptics

Six Degree-of-Freedom Haptic Simulation of a Stringed Musical Instrument for Triggering Sounds

IEEE transactions on haptics, Jan 14, 2016

Six degree-of-freedom (DoF) haptic rendering of multi-region contacts between a moving hand avata... more Six degree-of-freedom (DoF) haptic rendering of multi-region contacts between a moving hand avatar and varied-shaped components of a music instrument is fundamental to realizing interactive simulation of music playing. There are two aspects of computational challenges: first, some components have significantly small sizes in some dimensions, such as the strings on a seven-string plucked instrument (e.g. Guqin), which makes it challenging to avoid pop-through during multi-region contact scenarios. Second, deformable strings may produce high-frequency vibration, which requires simulating diversified and subtle force sensations when a hand interacts with strings in different ways. In this paper, we propose a constraint-based approach to haptic interaction and simulation between a moving hand avatar and various parts of a string instrument, using a cylinder model for the string that has a large length-radius ratio and a sphere-tree model for the other parts that have complex shapes. Col...

A novel spatial-temporal encoding strategy for presenting time on the wrist using vibrotactile cues

2016 IEEE International Conference on Mechatronics and Automation, 2016

Vision-Based Grasp Planning System for Dexterous Hands

This paper introduces a new approach of grasp planning for robotic dexterous hands. Master-slave ... more This paper introduces a new approach of grasp planning for robotic dexterous hands. Master-slave control strategy is adopted for integrating human intelligence into the planning system in which human hand directly controls the robot hand interactively. The human-machine interface is a computer vision system with two CCD cameras. The fingertips of the human hand are marked with markers of different geometry, thus can be identified by the computer vision system. When the human fingers move, the vision system firstly captures the image of the markers and performs feature-based identification. Then the images of the two cameras are matched and their image centers are used to calculate the positions of the fingertips. After this the human fingertip positions are mapped onto those of the dexterous hand in its palm frame. The human operator observes the motions of the robot fingers and decides the next step of motion. Through this procedure the human hand can guide the robot fingers to the target position of grasping and manipulation. To verify the validity of the proposed grasp planning approach, two tasks are demonstrated in a virtual environment, one is pressing a button with a single finger and the other is moving the thumb and index fingers. The tasks are simulated in real time and performed successfully.

Effect of vibrotactile cues for guiding simultaneous procedural motion of two joints on upper limbs

2015 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2015

Multi-modal Virtual Reality Dental Training System with Integrated Haptic-Visual-Audio Display

Lecture Notes in Control and Information Sciences, 2007

Multi-modal signal fusion is an important way to improve immersion and fidelity of virtual realit... more Multi-modal signal fusion is an important way to improve immersion and fidelity of virtual reality training systems. With the help of a robotic arm, haptic device, it is possible to supply haptic-visual-audio display for training dentist. Architecture is firstly proposed to integrate different signals in a training system. High efficient sound synthesis algorithm is proposed based on hybrid combination of parameter identification from recorded sound signal, then use signal synthesis method to form final sound signal. Mapping method among audio, haptic and visual signal is proposed based on parameter mapping under various interaction status. Experiment based on Phantom desktop proves the stability of the rendering algorithm and the improved fidelity after adding audio feedback to current haptic-visual dental training system.

Real-time solution of the forward kinematics for a parallel haptic device using a numerical approach based on neural networks

Journal of Mechanical Science and Technology, 2015

This paper proposes a neural network (NN)-based approach to solve the forward kinematics of a 3-R... more This paper proposes a neural network (NN)-based approach to solve the forward kinematics of a 3-RRR spherical parallel mechanism designed for a haptic device. The proposed algorithm aims to remarkably speed up computation to meet the requirement of highfrequency rendering for haptic display. To achieve high accuracy, the workspace of the haptic device is divided into smaller subspaces. The proposed algorithm contains NNs of two different precision levels: a rough estimation NN to identify the index of the subspace and several precise estimation networks with expected accuracy to calculate the forward kinematics. For continuous motion, the algorithm structure is further simplified to save internal memory and increase computing speed, which are critical for a haptic device control system running on an embedded platform. Compared with the mostly used Newton-Raphson method, the proposed algorithm and its simplified version greatly increase the calculation speed by about four times and 10 times, respectively, while achieving the same accuracy level. The proposed approach is of great significance for solving the forward kinematics of parallel mechanism used as haptic devices when high update frequency is needed but hardware resources are limited.

Mo deling a nd a nalysis of a force interactio n syste m

ABSTRACT

Voxel-based Modeling for Haptic-enabled Dental Drilling Simulation

：This paper establishes a uniform cube-voxel model based on linear list with deeply analyzing req... more ：This paper establishes a uniform cube-voxel model based on linear list with deeply analyzing requirements of virtual teeth drilling operation modeling. A material removal and reconstruction algorithm is designed for real-time simulation of topology update caused by drilling operation and point-based rendering is used for image processing. Experimental results show that the model decomposed by 0.1mm could well satisfy the demand of force feedback frequency in 1 KHz and model reconstruction frequency in 30Hz; at the same time, the model reconstruction algorithm can precisely simulate various drilling tools in different sizes.

Speed-accuracy tradeoff of controlling absolute magnitude of fingertip force

2015 IEEE World Haptics Conference (WHC), 2015

ABSTRACT

Dataglove Based Grasp Planning for Multi-fingered Robot Hand

Dataglove Based Grasp Planning for Multi-fingered Robot Hand

Determination of contact forces in grasping

Proceedings of IEEE/RSJ International Conference on Intelligent Robots and Systems. IROS '96, 1996

... Cheng and Orin [3,4] improved the optimization by reducing the number of constraints and vari... more

Classification of grasps by multifingered robot hands

Proceedings of IEEE/RSJ International Conference on Intelligent Robots and Systems. IROS '96, 1996

This research characterizes grasping by multifingered robot hands through an investigation of the... more This research characterizes grasping by multifingered robot hands through an investigation of the space of contact forces between fingers and the grasped object. By decomposing the space of contact forces into four subspaces, we develop a method to determine the dimensions of the subspaces with respect to the connectivity of the object. The relationship we obtain reveals the diflkrences between three qpes of grasps classified in the paper and indicates how the contact force can be decomposed corresponding to each type of grasp. Therefore, it provides a guideline for formulating the distribution of contact forces as a basis for optimization. The subspaces and the determination of their dimensions are illustrated by examples.

Evaluating the quality of grasp configurations for dextrous hands

Proceedings of International Conference on Robotics and Automation, 1997

We investigate methods for evaluating grasp configurations of multifingered mbot hands. When a gr... more We investigate methods for evaluating grasp configurations of multifingered mbot hands. When a grasped object is subjected to externally applied forces and moments, an equilibrium of the object is achieved by contact forces which are generated by the joint torques of the fingers. Assuming that the object and fingers comprise a rigid body system, we provide a general formulation relating the contact forces with the joint torques, extemal forces, and moments. We define three criteria to evaluate optimal grasp configurations. The computation of the criteria requires determining eigenvalues of a matrix. The method is applicable to all types of grasps. It is not limited by the number of contacts for each fingers, the geometry of the object, nor the contact models. In the examples, several grasp configurations are compared using these criteria.

Definition and force distribution of power grasps

Proceedings of 1995 IEEE International Conference on Robotics and Automation, 1995

... apower grasp was empirically viewed as that having large areas of contact between the grasped... more

Design and control of the BUAA four-fingered hand

Proceedings 2001 ICRA. IEEE International Conference on Robotics and Automation (Cat. No.01CH37164), 2001

... May 21-26, 2001 Design and Control of the BUAA Four-Fingered Hand Y. Zhang, Z. Han, H. Zhang,... more

Modeling of Intelligent Behaviour in Haptic Enabled Tug-of-War Simulation

The Proceedings of the Multiconference on "Computational Engineering in Systems Applications", 2006

Virtual environment (VE) is a prime component in haptic interaction system. Traditional passive V... more Virtual environment (VE) is a prime component in haptic interaction system. Traditional passive VE is not suitable to model human-machine interaction intelligence in haptic system such as a virtual tug-of-war system. Novel taxonomy of virtual environment is proposed according to different interaction tasks in physical world. Based on the difference between passive and active VE, intelligent VE is defined as a special type of nonlinear and active VE. The components of intelligent VE are identified and challenges within modeling and rendering method are discussed. Based on a one-dimensional haptic device, a virtual tug-of-war prototype is developed and different rendering algorithms are compared. Experiment results illustrate that the intelligent VE enhance the fidelity of the tug-of-war process and the rendering algorithm could ensure stability of the haptic system. The developed prototype can be utilized in entertainment areas.

Analysis of contact localization of dexterous robot hand using force/torque measurement

ICARCV 2004 8th Control, Automation, Robotics and Vision Conference, 2004., 2004

It is important to detect the position of contact points between the grasped object and the finge... more It is important to detect the position of contact points between the grasped object and the fingertips of dexterous hand. The method using force/torque sensor mounted at fingertip is simpler and easier than the tactile sensor to get the contact position. However, there are two problems held back the application of the former when the sensing data is contaminated with disturbance. First, when the hard finger contact model is used to calculate the points, the solution may not exist. This paper investigates the problem under the contact models of hard finger and soft finger respectively. Mathematical verification is developed to find the existence condition of solutions. A simple criterion is provided to determine which contact model must be selected for calculating contact points. The next problem is accuracy. The error of soft finger contact model is analyzed. Some strategies are given to improve the accuracy of the contact localization. Simulations and experiments show that the reliable and precise measurement of contact points can be achieved by the proposed approaches.