Kazuyoshi Tagawa

Impulse Response Deformation Model: an Approach to Haptic Interaction with Dynamically Deformable Object

An approach to haptic interaction with dynamically deformable object is proposed. In our approach, the behavior of an object is defined by a set of temporal deformation patterns after impulse force is applied to each degree of freedom, which we call impulse response deformation model. Deformation resulting from interaction is obtained by computing convolution of the model and the history of interaction force. The time complexity of computing interaction force is independent of the complexity of the model. This feature is advantageous for time-critical applications. Also, the time complexity of computing object deformation is linearly proportional to the complexity of the model. Through implementation of a prototype environment and evaluation of its performance, feasibility of the proposed approach is demonstrated.

Online re-mesh and multi-rate deformation simulation by GPU for haptic interaction with large scale elastic objects

In this paper, we propose an approach to generate high quality force and deformation using a novel automatic space and time adaptive level of detail technique in combination with a parallel computation using a graphics processing unit (GPU). The elastic object is represented by a multi-resolution hierarchy of tetrahedral adaptive volume mesh. The tetrahedral adaptive volume mesh and the time step of the deformation simulation are locally refined by online re-mesh and multi-rate simulation to concentrate the computational load into the regions that deform the most. In order to compute the online re-mesh and multi-rate deformation simulation on a GPU efficiently, we propose a novel data structure which consists of an extended and transposed connection table, a node list and a separated mass list. This effective computation is achieved by the relocatability of the connection table and optimized memory access at the computation of both deformation and re-meshing. Through evaluation experiments, we confirm the feasibility and the effectiveness of the proposed approach.

Manipulation of Dynamically Deformable Object Using Impulse-Based Approach

Recent advancement of network and communication technologies has raised expectations for transmission of multi-sensory information and multi-modal communication. Transmission of haptic sensation has been a topic of research in tele-robotics for a long period. However, as commercial haptic device prevails, and as internet spreads world-wide, it became possible to exchange haptic information for more general communication in our daily life. Although a variety of information is transmitted through haptic sensation, the feeling of a soft object is one that is difficult to transmit through other sensations. This is because the feeling of softness is represented only by integrating both the sense of deformation by somatic sensation and intensity force by haptic sensation. Feeling of softness is apt to be considered as static information that represents static relationship between deformation and force. Our previous study on implementing a static deformation model suggested that the dynamic aspect of deformation has an important effect on the reality of interactions. A static model can not represent behavior of an object while the user is not interacting with the object. For example, it is unnatural that an object model immediately returns to its original shape just after user releases hand or finger. Also, resonant vibration of object during the interaction is often perceived through haptic sensation. These differences of dynamic model from static model are considered to become more recognizable to user as more freedom of interaction is given. In this chapter, an outline of our approach to implement a deformable model that is capable of representing dynamic response of deformation is presented. Supplemental idea that realizes non-grounded motion of the deformable model is also stated; manipulation of deformable object becomes possible by this idea. In the next section, a survey of background research is 16

A data compression method for impulse response deformation model

As an approach to real-time simulation of haptic interaction with deformable objects, we proposed a record-reproduction method called ‘impulse response deformation model’ (IRDM), in which the deformation of an object shape is computed by convolving temporal sequence of interaction force with a pre-computed response of model to impulse force. Although, IRDM has an advantage that its computation cost of interaction force is independent of model complexity, it requires a huge amount of memory to store impulse response data corresponding to the combination of all input and output degrees of freedom. This paper discusses an approach to solve this problem by compressing the impulse response data. The key idea is to substitute similar impulse response waveforms by modification of a smaller number of representative waveforms. In our prototype implementation, a correlation coefficient was used as an index of the similarity. By this proposed approach the experimental implementation performance proved that the amount of storage was reduced to 1.1% of the original data size in cases where the threshold correlation coefficient value was 0.8.

Manipulation of dynamically deformable object

An approach to realize manipulation of elastic object in virtual environment is discussed. In the approach, the behavior of elastic object during interaction is separately described by two components: rigid-body motion and elastic deformation. The component of motion is simulated by solving equations of motion, while the component of deformation is reproduced from a set of deformation sequences in response to impulse force, or impulse response deformation model. A prototype algorithm and interface environment was built and experiments to evaluate the approach were carried out.

A rectangular tetrahedral adaptive mesh based corotated finite element model for interactive soft tissue simulation

In this paper, we propose a rectangular tetrahedral adaptive mesh based corotated finite element model for interactive soft tissue simulation. Our approach consists of several computation reduction techniques. They are as follows: 1) an efficient calculation approach for computing internal forces of nodes of elastic objects to take advantage of the rectangularity of the tetrahedral adaptive mesh; 2) fast shape matching approach by using a new scaling of polar decomposition; 3) an approach for the reduction of the number of times of shape matching by using the hierarchical structure. We implemented the approach into our surgery simulator and compared the accuracy of the deformation and the computation time among 1) proposed approach, 2) L-FE), and 3) NL-FEM. Finally, we show the effectiveness of our proposed approach.

Surface Contact Interaction with Dynamically Deformable Object Using Impulse-Based Approach

In our previous study, a method that allows dynamic interaction with an elastic object, which is called impulse response deformation model, has been proposed. An advantage of the method is that the order of complexity is lower than other approaches that solve equations of deformation models in real time; hence the method enables haptic interaction with more complex object. In this paper, an extension of the model that enables efficient computation of elastic deformation in interaction with surfaces, such as floor and wall, is discussed; unlike point-based interaction in our previous studies, pre-recorded response to impulse force that is applied by surface rather than point is used for the computation.

Remote Transparent Visualization of Surface-Volume Fused Data to Support Network-Based Laparoscopic Surgery Simulation

To assist a network-based laparoscopic surgery simulation, we developed a remote and fused 3D transparent visualization method. Our method enables us to create precise 3D see-through images of internal human organs at multiple distant places simultaneously. Besides, the method supports flexible fused visualization of surface data and volume data. Traditional transparent visualization methods require the time-consuming depth sort of rendering primitives. Therefore, it has been difficult to execute quick and precise fused visualization, which must treat both polygon data for surfaces and voxel data for volumes at one time. Our fused visualization is realized by applying the stochastic point based rendering that we recently proposed. We applied this rendering technique to remote fused visualization of surgery simulation, combining the technique with network-based distributed computing of visualization.

A Study on Corotated Nonlinear Deformation Model for Simulating Soft Tissue Under Large Deformation

In surgery simulators, a computationally efficient and geometrically nonlinear deformation simulation approach is required for soft tissue simulation. Especially, in the case of presenting haptic sensation to users, computational cost becomes a large problem because a higher update rate is required in stable haptic feedback. In this paper, we propose an interactive nonlinear soft tissue simulation approach using an adaptive and corotated deformation model. In the approach, computation of nonlinearity consideration and deformation simulation are performed at different suitable resolution of tetrahedral adaptive mesh. We also propose the criterion for subdivision and simplification in the adaptive and corotated deformation simulation. In evaluation experiments, we implemented the proposed approach into our surgery simulator, and we confirmed the computation time, the accuracy of deformations and the stability of reaction forces. We believe that this approach is also useful for haptic interaction with other elastic materials (e.g. jelly and rubber) under large deformation.

Object Manipulation by Hand with Force Feedback

This paper describes an implantation of object manipulation with force feedback. A force feedback device SPIDAR-U that is capable of providing independent forces to the thumb and four fingers of a hand was developed. The device was designed to reduce the influence on the magnetic field so that it can be combined with the measurement of hand motion using magnetic sensors. Also, in the simulation of interaction force between the hand model and the virtual object, nonlinearity of elasticity, or force-displacement relationship, was introduced by assuming collision between the bone and the object. A prototype system that integrate the device and the simulation was implemented, and feasibility of our approach was proved.