Haptic

"Haptic Simulation of Manipulator Collisions Using Dynamic Proxies"
Probal Mitra, Günter Niemeyer
Presence: Teleoperators & Virtual Environments, August 2007, Vol. 16, No. 4, Pages 367-384.

Haptic simulations aim to create an immersive, interactive computer generated environment, using haptic devices to render forces to the user based on interactions in the virtual world. In many applications, these simulations must be capable of handling interactions between multiple users, multiple hands, and complex virtual tools. In particular, consider the example of simulating two-handed robotic surgery, where each hand independently directs its own surgical robot to manipulate a tool.

Traditionally only quasi-static, point-like proxies are used to represent the human in virtual environments. In previous works, we proposed dynamic proxies to improve upon this notion. Giving the proxy first order, velocity based dynamics makes it massless but capable of producing crisp dynamic interaction forces. With this paper, we generalize the proxy concept to the case of independent, multiple degree-of-freedom virtual manipulators, by giving the proxy not only first-order dynamics, but its own kinematic properties as well. Like real robots, the virtual manipulators' tips track the user and master motion while generating force feedback. Interactions between the virtual arms and with other objects are implemented as geometric constraints on the tip velocities, and solved in a linearly constrained least-squares minimization. A stability proof is given in terms of passivity. The approach is demonstrated on an actual two-handed haptic console, running a real-time simulation of a pair of six degree-of-freedom virtual manipulators with cylindrical links.

This gizmag article reports Haptic Telexistence will be demonstrating its latest sophisticated haptic interface at SIGGRAPH 07. From the article: "Man-machine interfaces have predominantly targeted the aural and visual senses but improving technology has opened up the potential for new levels of interaction based on touch. At SIGGRAPH (Special Interest Group for Computer Graphics) this year, Haptic Telexistence will be demonstrating its latest sophisticated touch interface and providing a glimpse of the huge potential for haptic interfaces.

Take a look at the Haptic Cow project: a virtual reality simulator developed to train veterinary students to palpate the bovine reproductive tract, to perform fertility examinations and to diagnose pregnancy. From the project website: "The simulator uses haptic (touch feedback) technology, which allows a user to interact with a 3D virtual environment through the sense of touch. When being trained with the Haptic Cow, the student palpates computer generated virtual objects resembling parts of the bovine reproductive tract. The teacher provides instruction and feedback while following the student's actions inside the cow on the computer monitor.

"Perceived Instability of Virtual Haptic Texture: III. Effect of Update Rate"
Seungmoon Choi, Hong Z. Tan
Presence: Teleoperators & Virtual Environments, June 2007, Vol. 16, No. 3, Pages 263-278.

This study investigates the effect of update rate on the quality of haptic virtual textures, with the goal to develop a guideline for choosing an optimal update rate for haptic texture rendering. Two metrics, control stability and perceived quality of the virtual haptic texture, were used. For control stability, we examined the effect of update rate on the “buzzing” of virtual haptic textures. For perceived quality, we measured the discriminability of virtual haptic textures rendered at different update rates. Our study indicates that update rates much higher than the conventional 1 kHz are needed in order to achieve a stable rendering of “clean and hard” textured surfaces. We also found that our ability to distinguish textures rendered with different update rates depends on whether the virtual textures contain perceived instability. Based on these results, we provide a general guideline for selecting an optimal update rate for rendering virtual textured surfaces.

This Pinktentacle article reports Japanese company NTT is developing a tangible-3D virtual reality system where users can physically feel three-dimensional video thanks to an actuator glove. From the article: "Researchers at NTT Comware have just made virtual reality a little more real. On June 20, the company unveiled a 3D display system that reproduces the physical feel of three-dimensional video by means of an actuator glove worn on the hand, allowing viewers to literally reach out and touch the person or object on the screen.

This Science Daily article take a look at haptic devices for industrial applications. From the article: "Firstly, what is “Haptics?" This term means “of or relating to the sense of touch”. Haptic technology, or haptics, refers to the technology that connects the user to a computerized system via the sense of touch by applying forces, vibrations and/or motions to the user. Perhaps people do not realize it, but haptic technology is already in our lives.