Author name cluster

Dangxiao Wang

Possible papers associated with this exact author name in Arrow. This page groups case-insensitive exact name matches and is not a full identity disambiguation profile.

14 papers

1 author row

IROS Conference 2016 Conference Paper

WALS-robot: A compact and transformable Wheel-Arm-Leg-Sucker hybrid robot

Dandan Zhang
Dangxiao Wang

Based on the integrated design concept of using the robot's mechanical arm for both locomotion and manipulation, we proposed a compact and transformable robot, i. e. the WALS-Robot, which utilizes combination and switch among four components: wheels, arms, legs and suckers. The WALS-Robot could transform among five locomotion modes to fulfill locomotion requirements in indoor unstructured environments, and have dexterous manipulation, and low power consumption. To reduce the redundancy of mechanical structure and the moving payload for the robot, the mobile platform and the mechanical arm could work as a unity, i. e. the mechanical arm can switch into a leg of the robot to reduce payload during moving modes. Experimental results validated key performance of the robot, including locomotion accuracy and efficiency, compact volume and low power consumption. The integrated design concept illustrated the adaptability in diverse unstructured indoor environments, enlarging the manipulation workspace, and enhancing the energy efficiency.

Details

IROS Conference 2015 Conference Paper

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

Mu Xu
Dangxiao Wang
Yuru Zhang
Dong Wu

Simultaneous motion control of multiple joints has many potential applications such as Tai Chi, Yoga etc. The capability of vibrotactile cues to assist this kind of motor task has not been well explored. In this paper, we studied the effect of vibrotactile cues for guiding procedural motion of two joints on human's upper limbs. By mounting eight vibrotactile motors on two arms, we performed two experiments to measure human's perception and motor performance in response to the vibrotactile commands. In the first experiment, we measured perceptual performance of correctly identifying the location of two active vibrotactile cues. The difference between sustained, pulsed and hybrid vibration conditions was compared. To explore the possible reasons leading to the wrong perception results, the correct rate was ranked among different combinations of cues. In the second experiment, the correct rate of procedural motion control of two joints was measured, while vibrotactile cues were used as guidance signals to produce the motion command. The results showed that average correct rate of two cues localization on upper limbs was as high as 98%, while the average correct rate of procedural motion control of two joints was only 86%. Further analysis revealed that low correct rate of procedural motion control was caused by the unnatural motion pattern, i. e. two joints on a same arm and rotate in opposite directions.

Details

ICRA Conference 2015 Conference Paper

Interactive haptic simulation of tooth extraction by a constraint-based haptic rendering approach

Dangxiao Wang
Hao Tong
Youjiao Shi
Yuru Zhang

Tooth extraction is a typical process in clinical dental operations. Interactive haptic simulation of tooth extraction may provide a useful tool for dental students to learn the correct force pattern and tool posture to accomplish a safe tooth extraction. In this paper, we extended our previous configuration-based optimization approach to simulate the six Degree-of-Freedom (DoF) haptic interaction process of tooth extraction. A multi-phase model was proposed to simulate progressive changes of the connection strength between the target tooth and its surrounding gingiva. An energy accumulation model was proposed to compute the small-scale rotation and translation of the target tooth under active forces from a dental forceps. The proposed approach could support training of coordinated force and motion control skill required for tooth extraction. Experimental results validated the stability and efficiency of the proposed approach to simulate various force-displacement profiles for extracting diversified target teeth.

Details

ICRA Conference 2014 Conference Paper

3D path planning of a laser manipulation robotic system for tooth preparing

Lei Ma
Dangxiao Wang
Yuru Zhang
Lei Wang
Pei-jun Lv
Yuchun Sun

In this paper, we proposed a 3D path planning method for a miniature robotic system, which can manipulate a beam of ultra-short pulse laser to cut a decayed tooth to formulate an expected 3D shape. Using high resolution STereo Lithography (STL) models of the original decayed tooth and the target preparing shape as the input, our method consists of a fast slicing algorithm and an optimized path generating algorithm, which realized a high efficient layer-by-layer cutting for laser ablation. Theoretical analysis on the geometric distortion and surface roughness was carried out to model the influence of the path planning algorithms on the accuracy of the prepared tooth. Experimental results on a real tooth indicate that the path planning method can maintain the accuracy for the laser ablation process.

Details

ICRA Conference 2013 Conference Paper

A novel design of a wearable device for measuring force and torque in vascular surgery

Dangxiao Wang
Cailing Yang
Yuru Zhang
Jing Xiao 0001
Yongpan Dong
Tiange Wang

In-vivo measurement of force/torque signals between a surgical tool and human vessels during vascular surgery operations could provide a ground-truth data-set for constructing and evaluating haptics-enabled surgical simulation systems. In this paper, we introduce a novel wearable device for measuring such signals. This new design provides much higher measurement accuracy than a previous prototype. Experimental results by using standard weights provide that the relative force and torque error is about 5%. With time-varying load, the new device is compared with an ATI Nano17 force/torque sensor; average relative errors between the force signals is about 16. 85%, and average relative errors between the torque signals is about 28. 74%. Preliminary manipulation experiments of inserting a catheter into a vascular phantom model illustrated that the device can detect the collision between the catheter and the vascular walls. Subtle force/torque changes caused by changes of movement direction can be detected. Force/torque changes at some critical point (such as the interaction point of vessels) can also be detected.

Details

IROS Conference 2013 Conference Paper

Accelerating optimization-based haptic rendering by parallel quadratic programming method

Ge Yu
Dangxiao Wang
Yuru Zhang

It is a challenging problem to achieve fast and realistic six degree-of-freedom (DOF) haptic simulation of scenarios involving large number of multi-region contacts. In this paper, we propose an optimization-based constrained method enhanced by parallel quadratic programming to solve the rendering problem. Hierarchical sphere-tree models are used to represent the moving haptic tool and its surrounding static objects. Given a moving graphic tool as the avatar of the haptic tool in the virtual environment, we compute its quasi-static motion by solving a configuration-based optimization. Instead of using traditional active-set method, we transform the original optimization problem into its dual problem and solve the optimum about the graphic tool using a parallel quadratic programming method. Our algorithm has been implemented with a 6-DoF Phantom Premium 3. 0. We validate the proposed algorithm in several benchmarks involving complex, large-region contacts. The results demonstrate that the proposed method can achieve a two to three times speed improvement than the active-set method. A further speed-up for haptic rendering may be achieved by the parallel implementation on parallel processor such as graphic processing units.

Details

IROS Conference 2013 Conference Paper

Preliminary experiments of a miniature robotic system for tooth ablation using ultra-short pulsed lasers

Lei Wang
Dangxiao Wang
Lei Ma
Yuru Zhang
Fusong Yuan
Yuchun Sun
Pei-jun Lv

As a preliminary step to achieve a long-term goal of developing an automatic dental preparation system for clinical operations, we design and build a miniature robotic system which can manipulate a laser beam to move in three dimensional spaces to remove hard tissue from a target tooth. The dental preparation requires the robotic system to own high accuracy, high ablation speed and small size. A 2D galvanometer scanners module is integrated to meet the requirement of a high moving speed of the laser focus. A closed-loop system based on a miniature-sized voice-coil motor and a grating ruler are developed to realize the accurate control of the focus. The overall size of the developed prototype is 108mm×56mm×43mm, which is small enough to be used in close proximity to a patient's mouth. The prototype has been tested by using two different kinds of laser generators, i. e. , a nanosecond laser and a picosecond laser. The experiment results show that the robotic system can provide high moving speed of 1000mm/s with good shape accuracy. From the results, we found that nanosecond laser beam can be controlled to ablate zirconia and aluminum, but not suitable to ablate tooth because of tissue carbonization. By selecting suitable parameters of the picosecond laser generator, a target tooth could be ablated to produce a cylinder shape without carbonization. Limitations of the prototype are identified according to the experiment results.

Details

IROS Conference 2012 Conference Paper

Six degree-of-freedom haptic simulation of periodontal pathological changes

Dangxiao Wang
Shuai Liu
Xin Zhang
Jing Xiao 0001
Jianxia Hou
Yuru Zhang

Geometric modeling and haptic simulation of pathological changes is an important topic for high-fidelity surgical simulators. In this paper, we introduce a constraint-based six degree-of-freedom (DOF) haptic simulation method incorporating multi-contact friction. We use this method to simulate periodontal operations on typical pathological tissues, including periodontal pocket and two kinds of calculi. A continuous collision detection method based on sphere-trees is proposed to avoid the pop-through phenomenon during tool manipulation against thin objects (such as small sized calculus adhered to the surface of the target tooth). For particle shaped calculus, a friction model is adapted to simulate decreasing frictions during the removal of the calculus. Experiments using a Phantom Premium 3. 0 6DOF were carried out to validate the performance of our method. Stable haptic rendering and about 1 kHz update rate was maintained for all the operations, including depth measurement of the periodontal pocket and removal of the invisible block-shaped and particle-shaped calculi.

Details

IROS Conference 2012 Conference Paper

Six degree-of-freedom haptic simulation of sharp geometric features using a hybrid sphere-tree model

Ge Yu
Dangxiao Wang
Yuru Zhang
Xin Zhang

Subtle force feelings caused by contacts at sharp geometric features are necessary to achieve high-fidelity haptic rendering. It is a challenging problem to achieve six degree-of-freedom (6-DOF) haptic simulation with sharp features for multi-region contacts scenario. We propose a configuration-based optimization method using a hybrid sphere-tree model to compute constraint-based collision response. Based on the variance of dihedral angle between adjacent triangles, an original triangle mesh of the simulated object is segmented into a hybrid sphere-tree model, i. e. a hierarchical sphere-tree for global shape and several linear-lists of spheres for local areas with sharp features. In each local area with sharp features, we first identify those spheres which radius is larger than a pre-defined perceptual threshold. Then these spheres are divided into a linear list of smaller spheres by a splitting method. The experiment results on a sphere-cube interaction and a spline-shaped peg-hole interaction validate that the proposed method can simulate a subtle force direction change when sliding contact occurs across the sharp edges. Non-penetration between the two objects can be maintained for multi-region contacts scenario. The haptic rendering rate is over 1kHz and the interaction is stable.

Details

ICRA Conference 2012 Conference Paper

Six-degree-of-freedom haptic simulation of organ deformation in dental operations

Dangxiao Wang
Shuai Liu
Xin Zhang
Yuru Zhang
Jing Xiao 0001

Six-degree-of-freedom (6-DOF) haptic rendering is challenging when multi-region contacts occur between the graphic avatar of a haptic tool operated by a human user, which we call the graphic tool, and deformable objects. In this paper, we introduce a novel approach for deformation modeling based on a spring-sphere tree representation of deformable objects and a configuration-based constrained optimization method for determining the 6-dimensional configuration of the graphic tool and the contact force/torque response to the tool. This method conducts collision detection, deformation computation, and tool configuration optimization very efficiently based on the spring-sphere tree model, avoids inter-penetration, and maintains stability of haptic display without using virtual coupling. Experiments on typical dental operations are carried out to validate the efficiency and stability of the proposed method. The update rate of the haptic simulation loop is maintained at ∼1kHz.

Details

ICRA Conference 2011 Conference Paper

Configuration-based optimization for six degree-of-freedom haptic rendering for fine manipulation

Dangxiao Wang
Xin Zhang
Yuru Zhang
Jing Xiao 0001

Six-degree-of-freedom (6-DOF) haptic rendering for fine manipulation in narrow space is a challenging topic because of frequent constraint changes caused by small tool movement and the requirement to preserve the feel of fine-features of objects. In this paper, we introduce a configuration-based constrained optimization method for solving this rendering problem. The six-dimensional configuration (position and orientation) of the graphic tool is defined as the solution variable of the optimization problem. Contact constraints are obtained based on identifying principal contacts between the graphic avatar of the haptic tool, called the graphic tool, and the virtual task environment. In order to maintain stability during contact switch, a hybrid method combining collision detection, local search and parallel optimization is introduced. Based on parallel optimization and selection of local solution, we can maintain the local solution of the optimization model. Our method has been validated in experiments of moving a convex tool to probe a narrow cavity with or without bulges. Force rendering is stable even when the free space is very small and involves fine features of objects. Non-penetration between the tool and the object forming the cavity are maintained under frequent contact switches. Update rate of the simulation loop including the optimization and constraint identification is maintained at about 1kHz.

Details

IROS Conference 2011 Conference Paper

Configuration-based optimization for six degree-of-freedom haptic rendering using sphere-trees

Xin Zhang
Dangxiao Wang
Yuru Zhang
Jing Xiao 0001

This paper presents a novel constraint-based six degree-of-freedom (6-DoF) haptic rendering algorithm for simulating both contact forces and torques between interacting rigid bodies. We represent an object using a hierarchy of spheres, i. e. , a sphere-tree. Such a representation allows fast detection of multiple contacts/collisions among objects and facilitates contact constraint formulation. Given a moving graphic tool as the avatar of the haptic tool in the virtual environment, we constrain its position and orientation, i. e. , its six dimensional configuration, by solving a constrained optimization problem. The constraints in the 6-D configuration space (C-space) of the graphic tool is obtained and updated through on-line mapping of the non-penetration constraint between the spheres of the graphic tool and those of the other objects in the three dimensional physical space, based on the result of collision detection. The problem is further modeled as a quadratic programming problem and solved by classic active-set methods. Our algorithm has been implemented and interfaced with a 6-DoF Phantom Premium 3. 0. We demonstrate its performance in dental surgery simulations involving complex, multi-contact virtual environments. Our method enables stable operations and realistic feel of haptic sensation.

Details

IROS Conference 2006 Conference Paper

Machine-mediated Motor Skill Training Method in Haptic-enabled Chinese Handwriting Simulation System

Dangxiao Wang
Yuru Zhang
Chong Yao

Training of motor skill through machine-mediated method is a promising way to improve complex dexterous manipulation skill. New method of fusion between human motor skill and machine capability is studied to transfer skill from expert to novice. Haptic-enabled Chinese handwriting training system is established as a benchmark platform for studying learning and transfer of motor skill. Perceptible element of haptic skill is proposed to model human motor skill. Four rules of machine-mediated training system are identified according to human's skill learning characteristics. Architecture of a hierarchical hybrid control training system is proposed based on the learning rules. Phantom desktop is used as the haptic interface and haptic-visual feedback is developed for three training modes, which includes facsimile mode, transcribe mode and reciting mode. Human subject experiments validate the proposed training rules. Fusion of human skill and machine capability by haptic-enable multiple signal feedback system is proved effective to train novice to get familiar with Chinese character handwriting skill

Details

IROS Conference 2005 Conference Paper

Cutting force model of dental training system

Guanyang Liu
Yuru Zhang
Dangxiao Wang
J. Hao
P. Lu
Y. Wang

This paper presents a cutting force model for dental training system with haptic display capability. The force model is proposed by theoretic analysis of the cutting force between dental tools and tooth. A damping matrix is developed for obtaining a unified formulation for all components of cutting forces. All factors that affect the cutting force are considered in the model by including a number of parameters. These parameters are identified by tooth-cut experiments, which measure the cutting force with a six-dimensional force sensor. A prototype system of haptic simulation is developed to test the model. Dentists performing virtual operation on the system have confirmed the realistic sense of cutting force.

Details