**2.3 General issues related with integration**

Integration of haptic devices can generally raise several problems especially when both the tactile components and kinesthetic device are not conceived for the integration. Problems that may occur can be related to mechanics and electronics integration.

Mechanics:


The tactile device must be lightweight as thin as possible and at the same time it has to be strong and must guarantee a sufficient array spatial density


The force that is exerted by the force feedback device to the user fingers have to be transmitted through a contact surface. In particular the way to transmit force has to take into account that the palmar side of the user finger surface is taken up by the tactile device. Such surface is than involved in the transmission of contact forces and the tactile array has to be capable of sustaining such efforts without compromising its functionalities.


52 Haptics Rendering and Applications

A possible idea for implementing a more general and flexible interface consists in designing

The mechanical architecture of this kind of integrated device can be visualized as in Fig. 1.



This type of architecture can be found in many of the integrated haptic system that have been developed in (Frisoli et al., 2008), (Fontana et al., 2007),(Wagner et al., 2005) (Scilingo et

Integration of haptic devices can generally raise several problems especially when both the tactile components and kinesthetic device are not conceived for the integration. Problems

The tactile device must be lightweight as thin as possible and at the same time it has to be

When interaction requires more than one finger the encumbrance under the fingertip must be reduced in order to allow the fingers to get close together for grasping and

that may occur can be related to mechanics and electronics integration.

strong and must guarantee a sufficient array spatial density

a device that integrates together devices conceived for different scales.


The system is composed by different layers:

distribution on the fingertip.

surface of the virtual object.

Fig. 1. Mechanical architecture of integrated haptic

**2.3 General issues related with integration** 


manipulating virtual objects.


al. 2010), (Sato et al.,2007).

Mechanics:

Several kinesthetic devices are equipped with force sensors that measure the interaction force at the level of the fingers of the user. The force signal is generally employed to compensate friction and inertia effects. The integration of a tactile feedback with the force sensor is a trivial problem since the vibration generated by the tactile transducer may introduce a force noise reading (Fontana et al., 2007).

Electronics and wiring


Arrays with high density are desirable but as the number of transducers to be driven raises, the electrical cabling and the electronics get more and more complicated.


Processing electronics for controlling independently each actuator of a tactile array can be complex. For example a 5x5 array requires to independently control 25 current or voltage signals (depending from the actuation technology) over a bandwidth of 1-2 kHz. Moreover if we want to simplify the cabling this control electronics must should be placed as close as possible to the tactile display thus its dimension and weight must be reduced in order to minimize additional weight and inertia compensation forces for the kinesthetic stage.
