This paper presents a new model which computes the deformation and the feedback force of high-resolution biomedical volumetric objects consisting of hundreds of thousands of volume elements. The main difficulty in the simulation of these high-resolution volumetric objects is to compute and generate stable feedback force from the objects within a haptic update time (1 msec). In our model, springs are used in order to represent material properties of volume elements and cylinders are used to activate corresponding springs according to the amount of deformation. Unlike in a mass-spring model, springs in our model have constraint conditions. In our model, the deformation is calculated locally and then is propagated outward through object's volume as if a chain is pulled or pushed. The deformed configuration is then used to compute the object's internal potential energy that is reflected to the user. The simple nature of our model allows the much faster calculation of the deformation and the feedback force from the volumetric deformable object than the conventional model (an FEM or a mass-spring model). Experiments are conducted with homogenous and non-homogenous volumetric cubic objects and a volumetric human liver model obtained from CT data at a haptic update rate of 1000 Hz and a graphic update rate of 100 Hz to show that our model can be utilized in the real-time volume haptic rendering. We verify that our model provides a realistic haptic feeling for the user in real time through comparative study.

For tactile feedback in mobile devices, the size and the power consumption of tactile modules are the dominant factors. Thus, vibration motors have been widely used in mobile devices to provide tactile sensation. However, the vibration motor cannot sufficiently generate a great amount of tactile sensation because the magnitude and the frequency of the vibration motor are coupled. For the generation of a wide variety of tactile sensations, this paper presents a new tactile actuator that incorporates a solenoid, a permanent magnet and an elastic spring. The feedback force in this actuator is generated by elastic and electromagnetic force. This paper also proposes a tiny tactile module with the proposed actuators. To construct a tiny tactile module, the contactor gap of the module is minimized without decreasing the contactor stroke, the output force, and the working frequency. The elastic springs of the actuators are separated into several layers to minimize the contactor gap without decreasing the performance of the tactile module. Experiments were conducted to investigate each contactor output force as well as the frequency response of the proposed tactile module. Each contactor of the tactile module can generate enough output force to stimulate human mechanoreceptors. As the contactors are actuated in a wide range of frequency, the proposed tactile module can generate various tactile sensations. Moreover, the size of the proposed tactile module is small enough to be embedded it into a mobile device, and its power consumption is low. Therefore, the proposed tactile actuator and module have good potential in many interactive mobile devices.