**2. Hardware design of integrated devices**

This section deals with the aspects that are related with the Machine Haptics issues of integrated tactile and kinesthetic devices. The scope is to provide a clear view of the problems that arise when these two type of feedback are closely integrated. In the first part of this section we briefly analyze the physics of contact with bare fingers. In the second part we give an overview of the general architecture of integrated kinesthetic and tactile systems and analyze typical issues related with mechanical design.

However, as many researches have demonstrated, those abilities are not only based on the high elaborated structural properties of our hands but the haptic sensory input is highly

Basically, there are two types of interaction mode with objects: Active Haptic Sensing and Grasping/Manipulation (Jones & Lederman, 2006). In both of them the multimodal sensing given by the simultaneous tactile and kinesthetic sensory input strongly come into play. It has been largely demonstrated that in Active Haptic Sensing the information gathered by tactile and kinesthetic channels are somehow integrated while performing explorations and recognition tasks. Lederman and Klatzky for example (Lederman & Klatzky, 1999) demonstrated that in absence of distributed tactile information the perceptual capabilities of our fingers are strongly impaired. In addition our ability in grasping/manipulation of objects strongly relies on both the sensory inputs. Several research works have demonstrated how the absence of tactile or kinesthetic sensory input makes our ability worse. Johansson and Flanagan for example in (Johansson & Flanagan, 2007) show how the distributed tactile information are deeply involved even in very simple manual tasks like

These considerations lead to conclude that a system that is asked to replicate with high level of realism the direct interaction of virtual objects with the human hands should include both

Unluckily, most of present day haptic feedback systems are able to stimulate only kinesthetic or tactile interactions separately. Traditional force feedback devices like Phantom® (Salisbury & Srinivasan, 1997) are typically only able to provide sensory input correlated with kinaesthetic information. Such device are usually employed for realistic rendering of "mediated contacts", however they can be connected to the user body through mechanical components like a thimble that guarantees a constant contact surface for the simulation of interaction with bare fingers. From the functional point of view these class of devices are able to provide as output a controlled force and/or torques and get as input the position and/or orientation of the interaction surface. The system is unable to transmit distributed and programmable sensory input on the skin surface and the exchanged information only relates

The technical challenge of integrating tactile feedback on kinesthetic has been faced only in few research works. In this chapter we are going to summarize the issues that concern the Direct Contact simulation with the integration of tactile and kinesthetic feedback. The topic is treated on both the hardware and software perspective illustrating the basic problems found in mechanical and control electronics integration and in haptic rendering for efficient

This section deals with the aspects that are related with the Machine Haptics issues of integrated tactile and kinesthetic devices. The scope is to provide a clear view of the problems that arise when these two type of feedback are closely integrated. In the first part of this section we briefly analyze the physics of contact with bare fingers. In the second part we give an overview of the general architecture of integrated kinesthetic and tactile systems

with global force and/or torque and global position and/or orientation of a body.

involved in such tasks and it plays a fundamental role.

grasping and lifting an object.

computation.

tactile and kinaesthetic sensory inputs.

**2. Hardware design of integrated devices** 

and analyze typical issues related with mechanical design.

We decided not to include the topic of thermal display and feedback since it would require a special treatise.
