**1. Introduction**

194 Haptics Rendering and Applications

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Skill has many meanings, as there are many talents: its origin comes from the late Old English scele, meaning knowledge, and from Old Norse skil (discernment, knowledge), even if a general definition of skill can be given as "the learned ability to do a process well" (McCullough, 1999) or as the acquired ability to successfully perform a specific task.

Task is the elementary unit of goal directed behaviour (Gopher, 2004) and is also a fundamental concept -strictly connected to "skill"- in the study of human behaviour, so that psychology may be defined as the science of people performing tasks. Moreover skill is not associated only to knowledge, but also to technology, since technology is -literally in the Greek- the study of skill.

Skill-based behaviour represents sensory-motor performance during activities following a statement of an intention and taking place without conscious control as smooth, automated and highly integrated patterns of behaviour. As it is shown in Figure 1, a schematic representation of the cognitive-sensory-motor integration required by a skill performance, complex skills can involve both gesture and sensory-motor abilities, but also high level cognitive functions, such as procedural (e.g. how to do something) and decision and judgement (e.g. when to do what) abilities. In most skilled sensory-motor tasks, the body acts as a multivariable continuous control system synchronizing movements with the behavioural of the environment (Annelise Mark Pejtersen, 1997). This way of acting is also named also as, action-centred, enactive, reflection-in-action or simply know-how.

Skills differ from talent since talent seems native, and concepts come from schooling, while skill is learned by doing (McCullough, 1999). It is acquired by demonstration and sharpened by practice. Skill is moreover participatory, and this basis makes it durable: any teacher knows that active participation is the way to retainable knowledge.

The knowledge achieved by an artisan throughout his/her lifelong activity of work is a good example of a skill that is difficult to transfer to another person. At present the knowledge of a specific craftsmanship is lost when the skilled worker ends his/her working

Training Motor Skills Using Haptic Interfaces 197

 Capability of sending both information and action consequences in output towards the human, through his/her afferent channel, in a way that is not disturbing the human

Fig. 1. A schematic representation of the cognitive-sensory-motor integration required by a

skill performance

next steps of the task flow or corrective actions to be implemented;

from the execution of the main task.

predicting the current human status and behaviour, formulating precise indications on

activity or when other physical impairments force him/her to give up. The above considerations are valid not only in the framework of craftsmanship but also for more general application domains, such as the industrial field, e.g. for maintenance of complex mechanical parts, surgery training and so on.

The research done stems out from the recognition that technology is a dominant ecology in our world and that nowadays a great deal of human behaviour is augmented by technology. Multimodal Human-Computer Interfaces aim at coordinating several intuitive input modalities (e.g. the user's speech and gestures) and several intuitive output modalities.

The existing level of technology in the HCI field is very high and mature, so that technological constrains can be removed from the design process to shift the focus on the real user's needs, as it is demonstrated by the fact that nowadays the user-centered design has became fundamental for devising successful everyday new products and interfaces (Norman, 1986; Norman, 1988), fitting people and that really conforming their needs.

However, until now most interaction technologies have emphasized more input channel (afferent channel in Figure 1 The role of HCI in the performance of a skill), rather than output (efferent channel); foreground tasks rather than background contexts.

Advances in HCI technology allows now to have better gestures, more sensing combinations and improve 3D frameworks, and so it is possible now to put also more emphasis on the output channel, e.g. recent developments of haptic interfaces and tactile effector technologies. This is sufficient to bring in the actual context new and better instruments and interfaces for doing better what you can do, and to teach you how to do something well: so interfaces supporting and augmenting your skills. In fact user interfaces to advanced augmenting technologies are the successors to simpler interfaces that have existed between people and their artefacts for thousands of years (M. Chignell & Takeshit, 1999).

The objective is to develop new HCI technologies and devise new usages of existing ones to support people during the execution of complex tasks, help them to do things well or better, and make them more skilful in the execution of activities, overall augmenting the capability of human action and performance.

We aimed to investigate the transfer of skills defined as the use of knowledge or skill acquired in one situation in the performance of a new, novel task, and its reproducibility by means of VEs and HCI technologies, using actual and new technology with a complete innovative approach, in order to develop and evaluating interfaces for doing better in the context of a specific task.

Figure 2 draws on the scheme of Figure 1, and shows the important role that new interfaces will play and their features. They should possess the following functionalities:


activity or when other physical impairments force him/her to give up. The above considerations are valid not only in the framework of craftsmanship but also for more general application domains, such as the industrial field, e.g. for maintenance of complex

The research done stems out from the recognition that technology is a dominant ecology in our world and that nowadays a great deal of human behaviour is augmented by technology. Multimodal Human-Computer Interfaces aim at coordinating several intuitive input modalities (e.g. the user's speech and gestures) and several intuitive output modalities.

The existing level of technology in the HCI field is very high and mature, so that technological constrains can be removed from the design process to shift the focus on the real user's needs, as it is demonstrated by the fact that nowadays the user-centered design has became fundamental for devising successful everyday new products and interfaces

However, until now most interaction technologies have emphasized more input channel (afferent channel in Figure 1 The role of HCI in the performance of a skill), rather than

Advances in HCI technology allows now to have better gestures, more sensing combinations and improve 3D frameworks, and so it is possible now to put also more emphasis on the output channel, e.g. recent developments of haptic interfaces and tactile effector technologies. This is sufficient to bring in the actual context new and better instruments and interfaces for doing better what you can do, and to teach you how to do something well: so interfaces supporting and augmenting your skills. In fact user interfaces to advanced augmenting technologies are the successors to simpler interfaces that have existed between people and

The objective is to develop new HCI technologies and devise new usages of existing ones to support people during the execution of complex tasks, help them to do things well or better, and make them more skilful in the execution of activities, overall augmenting the capability

We aimed to investigate the transfer of skills defined as the use of knowledge or skill acquired in one situation in the performance of a new, novel task, and its reproducibility by means of VEs and HCI technologies, using actual and new technology with a complete innovative approach, in order to develop and evaluating interfaces for doing better in the

Figure 2 draws on the scheme of Figure 1, and shows the important role that new interfaces

Capability of interfacing with the world, in order to get a comprehension of the status

Capability of getting input from the humans through his efferent channel, in a way not

 Local intelligence, that is the capability of having an internal and efficient representation of the task flow, correlating the task flow with the status of the environment during the human-world interaction process, understanding and

will play and their features. They should possess the following functionalities:

disturbing the human from the execution of the main task (transparency);

(Norman, 1986; Norman, 1988), fitting people and that really conforming their needs.

output (efferent channel); foreground tasks rather than background contexts.

their artefacts for thousands of years (M. Chignell & Takeshit, 1999).

of human action and performance.

context of a specific task.

of the world;

mechanical parts, surgery training and so on.

predicting the current human status and behaviour, formulating precise indications on next steps of the task flow or corrective actions to be implemented;

 Capability of sending both information and action consequences in output towards the human, through his/her afferent channel, in a way that is not disturbing the human from the execution of the main task.

Fig. 1. A schematic representation of the cognitive-sensory-motor integration required by a skill performance

Training Motor Skills Using Haptic Interfaces 199

Interfaces will be technologically invisible at their best –not to decrease the human performance-, and capable of understanding the user intentions, current behaviour and

In this chapter a proposal of one multimodal interface for the transferring of skills, it will be described. The interface is called Haptic Desktop System (HDS), it was specifically projected for the training of motor skills specifically virtual fixtures. The HDS is an integrated system that merges haptic functionalities and Video Display Terminal (VDT) systems into one. It has been designed to provide visual and haptic perceptual information in order to avoid high mental loads and enable natural interaction with the user. Two applications to assist to human users to develop their motor skills to draw simple sketches were developed. The basic idea is generate a virtual template trajectory that the user must follow assisted with the force feedback capabilities of the HDS. In the first application, the virtual templates are generated from a given image file using image processing techniques, the templates are obtained and sent to the HDS controller which in combination with a graphical user interface (GUI) permits to the user to "fill" (follow) the virtual template. In the second application the templates are generated in a more dynamic way; the basic idea is to build a sketch using a set of virtual geometrical templates (VGT). The application currently allows drawing three types of VGTs: circles, lines and arcs. The user decides when and where request the assistance of the HDS to drawn a geometric shape. Based on the results we have demonstrated that the use of haptic interfaces improves and accelerates the acquiring of

The Haptic Desktop System (HDS) developed at PERCRO is our multimodal interface solution for design simple sketches. In Figure 3 a conceptual representation of this interface is shown, the user can freely design sketches inside the workspace of the interface which correspond with the superficies of a screen, enabling to the interface render the haptic and

Two types of design guidelines have been employed during the preliminary definition of the system: qualitative and performance guidelines. According to qualitative guidelines the device had to show ergonomic features, which make the use of the system very comfortable. These guidelines have regarded: the workplace, the quality of the visual feedback, the aesthetics of the system, and the modality of interaction. Another very important guideline

The system design and control should allow the user to feel and control haptic interaction just below his fingertips, while directly viewing the effects of his actions on the computer screen (co-location). Specific state of the art analyses [Jansson & Öström, 2004] have verified that co-location greatly enhances the user performances in HCI while reducing the mental load of the interaction. The haptic device has therefore to be calibrated in order to collimate the position of the usage tool (end-effector), with the pointer within the computer screen. The accuracy provided in design, should ensure that the sensitivity of the system is far

purpose, contextualized in the task.

sketching skills.

**2. Haptic desktop**

**2.1 Design guidelines** 

visual feedback in the same point in the 2D space.

is the reduction of mental load during the use of the device.

beyond the pixel resolution of the screen.

We desire improving both input and output modalities of interfaces, and on the interplay between the two, with interfaces in the loop of decision and action (Flach, 1994) in strictly connection with human, as it is shown clearly in Figure 2. The interfaces will boost the capabilities of the afferent-efferent channel of humans, the exchange of information with the world, and the performance of undertaken actions, acting in synergy with the sensorymotor loop.

Fig. 2. The role of HCI in the performance of a skill

We desire improving both input and output modalities of interfaces, and on the interplay between the two, with interfaces in the loop of decision and action (Flach, 1994) in strictly connection with human, as it is shown clearly in Figure 2. The interfaces will boost the capabilities of the afferent-efferent channel of humans, the exchange of information with the world, and the performance of undertaken actions, acting in synergy with the sensory-

motor loop.

Fig. 2. The role of HCI in the performance of a skill

Interfaces will be technologically invisible at their best –not to decrease the human performance-, and capable of understanding the user intentions, current behaviour and purpose, contextualized in the task.

In this chapter a proposal of one multimodal interface for the transferring of skills, it will be described. The interface is called Haptic Desktop System (HDS), it was specifically projected for the training of motor skills specifically virtual fixtures. The HDS is an integrated system that merges haptic functionalities and Video Display Terminal (VDT) systems into one. It has been designed to provide visual and haptic perceptual information in order to avoid high mental loads and enable natural interaction with the user. Two applications to assist to human users to develop their motor skills to draw simple sketches were developed. The basic idea is generate a virtual template trajectory that the user must follow assisted with the force feedback capabilities of the HDS. In the first application, the virtual templates are generated from a given image file using image processing techniques, the templates are obtained and sent to the HDS controller which in combination with a graphical user interface (GUI) permits to the user to "fill" (follow) the virtual template. In the second application the templates are generated in a more dynamic way; the basic idea is to build a sketch using a set of virtual geometrical templates (VGT). The application currently allows drawing three types of VGTs: circles, lines and arcs. The user decides when and where request the assistance of the HDS to drawn a geometric shape. Based on the results we have demonstrated that the use of haptic interfaces improves and accelerates the acquiring of sketching skills.
