Wai Yu

Simultaneous remote haptic collaboration for assembling tasks

Stand-alone virtual environments (VEs) using haptic devices have proved useful for assembly/disassembly simulation of mechanical components. Nowadays, collaborative haptic virtual environments (CHVEs) are also emerging. A new peer-to-peer collaborative haptic assembly simulator (CHAS) has been developed whereby two users can simultaneously carry out assembly tasks using haptic devices. Two major challenges have been addressed: virtual scene synchronization (consistency) and the provision of a reliable and effective haptic feedback. A consistency-maintenance scheme has been designed to solve the challenge of achieving consistency. Results show that consistency is guaranteed. Furthermore, a force-smoothing algorithm has been developed which is shown to improve the quality of force feedback under adverse network conditions. A range of laboratory experiments and several real trials between Labein (Spain) and Queen’s University Belfast (Northern Ireland) have verified that CHAS can provide an adequate haptic interaction when both users perform remote assemblies (assembly of one user’s object with an object grasped by the other user). Moreover, when collisions between grasped objects occur (dependent collisions), the haptic feedback usually provides satisfactory haptic perception. Based on a qualitative study, it is shown that the haptic feedback obtained during remote assemblies with dependent collisions can continue to improve the sense of co-presence between users with regard to only visual feedback.

Haptic virtual environment performance over IP networks: a case study

This paper reports on the quality of service (QoS) requirements and the performance of virtual environment (VE) applications deployed in IP networks. We are interested specifically in systems that support communication with end-user through force feedback devices known as haptic interfaces. Little is known about networked haptic interfaces in VE. Our goal is to understand such application QoS requirements as well as the effect of other traffic when they co-exist in the same network. In this paper, we compare the peer-to-peer model with the client-server model. Our motivation is to deploy distributed haptic VE applications (DHVE) over a network connecting two departments of Queens University of Belfast. This deployment will be used for educational purposes and for implementing further research in this area, and will be evaluated by end-users; hence, the essential realization of network-based DHVE under realistic network conditions. A set of experiments was conducted to achieve this aim and their results are presented in this paper.

Characterising Distributed Haptic Virtual Environment Network Traffic Flows

The effective transmission of haptic data in Distributed Haptic Virtual Environment (DHVEs) is a new research area which presents a number of challenges to the underlying network. The transmission of reflected force in these applications has the potential to change the way humans interact with machines and communicate with each other. The future Internet will have to carry multiple DHVE type traffic and it is now established that the best effort service offered by current IP networks is insufficient to meet the needs of these type of applications, which require specific Quality of Service (QoS) from network. The aim of the work presented here is to characterise the traffic generated by multiple DHVE network connections. The approach taken is to develop a simulation model of DHVE traffic based on empirical measurements. Both synchronous and asynchronous real world DHVE traffic is analyzed, quantified and imported into a network simulation. Probability Density Function (PDF) models are subsequently derived for each type of traffic in the DHVE system. The results show the network simulation model compares favourably with the physical network, and can be used to generate a scalable haptic network model where multiple DHVE connections may be examined.

Quality of service issues for distributed virtual environments with haptic interfaces

Currently all interactions that occur between ourselves and communications networks involve only two senses (aural and visual). Moreover all these networks, including the Internet, have been designed to carry application information pertaining to these two senses (e.g. telephony, video, graphics, and text). It is clear that by introducing into networks the ability to carry information relating to other senses opens up an enormous potential for new and improved applications. However it is also clear that the network service needed to support other senses such as touch (haptics) will be significantly different from that which currently exists. The effective transmission of the sense of touch (haptics) presents a significant challenge to the current Internet architecture. Haptic information originates from a different human sense; therefore the quality of service (QoS) required to support this type of traffic is significantly different from that used to support conventional real-time traffic such as voice or video. To date there has been no specific provision of QoS parameters for haptic interaction, and each type of network impairment has different (and severe) impacts on the userpsilas haptic experience. This paper describes some of the issues and challenges that are presented whenever remote haptic interactions with virtual environments are considered, and identifies a number of techniques, in the network and in the end applications, that can be used to improve performance of such systems.

Providing QoS for distributed haptic virtual environments in IP networks

In this paper, we study the transmission of haptic traffic over a best effort IP network and a DiffServ-enabled IP network. The work involves both simulation and practical experimentation. Packet switched networks such as the Internet will shortly need to support many different types of applications which will use multi-modal data including reflected force or haptic data. Recent research has established that the Quality of Service (QoS) required to support haptic traffic is significantly different from that used to support conventional real-time traffic such as voice or video. Each type of network impairment has different (and severe) impacts on the users haptic experience. While some recent efforts have established the basic range of the network QoS parameters for haptic interaction, to date there has been no specific provision for this traffic over a QoS enabled IP network. This paper presents for the first time, an investigation into providing specific network quality for haptic traffic. The work considers two approaches: simulation and practical experimentation. Our results show the network simulation model compares favourably with the physical network, and can be used to generate a scalable haptic network model where multiple DHVE connections may be examined. Both approaches show that delay and throughput of haptic experience can be improved by using specific QoS class from DiffServ for haptic traffic.

Supporting haptic collaboration across networked peers with real time force feedback in distributed virtual environments

In this paper, we design and implement a new peer- to-peer network architecture for real time tele-haptic operation in distributed virtual environments (DVEs). We have also developed a novel force collaboration and position synchronization algorithm in order to support networked haptic interactions. In order to interact successfully in DVE with haptic devices, haptic applications require a stringent Quality of Service (QoS) service from the network. Impairments such as time delay, jitter and packet loss each have different (and severe) impacts on remote haptic collaborations. The new peer-to-peer architecture is able to support haptic interactions across time-varying networked peers. Experiments have been conducted to investigate the levels of QoS required for networked haptic collaboration. We also examine whether existing compensation algorithms can be used to enhance the performance of the system. The performance of two algorithms that compensate for delay (TiDeCtrade), and position (dead reckoning) are examined. Findings of the study, together with a set of network QoS parameter values obtained for supporting haptic collaboration over IP networks, are presented.

Haptic virtual environment performance over policy-based IP networks: a case study

This paper reports on the performance of distributed haptic virtual environment (DHVE) applications deployed over policy-based IP networks. Our previous work reported that a best effort service in IP networks is inadequate for satisfying the quality of service (QoS) requirements of such applications. The current work tries to find out whether applying differentiated services (DiffServ) satisfies DHVE QoS requirements or at least improves them. This work also determines which policies should be applied on the network. A set of experiments was conducted over a network connecting two departments of the Queens University of Belfast. The results are presented in this paper and compared with our previous work results.

Investigation of network issues for distributed haptic virtual environment applications

This paper describes the effects of network on the performance of distributed haptic virtual environments (DHVE) and an experimental platform design for this purpose. On this platform, a network infrastructure (Gigabit-Ethernet-based) is installed for developing DHVEs and conducting experiments for evaluation purposes. This is part of an on-going project, which develops technologies to support multisensory communication over IP-based networks. The results of this work will assist system developers in providing multimodal interaction in distributed virtual environments.