Force Feedback Haptics

As Stone posits: “it is only quite recently that haptic technologies have appeared that are capable of delivering believable sensory stimuli at a reasonable cost, using human interface devices of a practical size” (Stone, 2001, p. 1). The digital haptic Teleportation of touch (tele- touch) is relatively recent as well. The HAPTEX Project, a 36-month research project from 2004 to 2007, conducted by Dr. Nadia Magnenat-Thalmann at the MIRALab at the University of Geneva, is an example of the development of a tele-touch device aimed at the development of a “complete virtual reality system for visuo-haptic interaction with virtual textiles” (Biomedical

Physics at Exeter: HAPTEX Project, n.d.), to serve the textile and fashion industry. HAPTEX is

an example that works by virtually teleporting haptic material sensations (of textiles). The haptic interactions and exemplify tele-touch mediation because haptics are used to interact with a simulated computer environment. It is a real world practical example where designers can touch their materials ‘virtually’ using haptic interactions.

The pneumatically controlled SHIRI robotic buttocks give a creative example of haptic force-feedback, using a unique tele-touch device that consists of ‘a pair of mechanical buttocks that quiver when you spank them.’ Nobuhiro Takahashi and a team at the Tokyo University of Electro-Communications developed Shiri, which means buttocks in Japanese. The buttocks move and twitch via inflatable air bags that react with force felt haptics. Two large puffed up pneumatic pouches attempt to (visually? physically?) simulate the reaction of the gluteus maximus muscle when spanked. This innovative robot conveys physiological responses to tactile interaction and is centered on human engagement. The dynamics of physical interaction have been considered at the level of social interface, and this increases the requirement for complex

tacit understanding of phantom remote presence. Eduardo Kac has stated that “freer forms of communications can emerge out of interactive artistic practices that make the process of symbolic exchange the very realm of its experience” (Kac, 2005, p. 3).

‘Servo Motor Torque Controlled Force Feedback’ is a commonly used and a relatively accurate force feedback system. As described, pneumatic controls have also been developed to facilitate force feedback haptic communication. Force feedback is a technology that facilitates a kind of hand-holding experience, which restricts or guides the user’s hand towards or away from certain movements physically. Current force feedback devices, such as the ‘entact W6D Haptic Device’ (W6D Haptic Device, n.d.), ‘The Geomagic® Touch™ Haptic Device‘, and the ‘Novint Falcon® Force Feedback Controller’ (Novint Falcon with Novint/Sandia 3-D Touch Software, 2008), are all designed to perform universal or generic, ‘one size fits all’ force feedback. Both devices are intended to replace the standard mouse when interacting with computer programs and games. Most force feedback devices are designed to act like interactive computer accessories, capable of facilitating touch for a wide variety of environments and/or applications. However, there are dynamics in physical events that are not present in the computer simulations of 3D models and video games. Physical dynamics are specific to scale and freedom of movement. A computer mouse, stylus, touchpad and keyboard have been sufficient for most of the physical interactions we have with computers since representations on a computer screen do not have to respond to the dynamics of material events in the physical world. When sculpting as actual events in the physical world, however, there are significantly more complex physical dynamics at play because the materials are real and require constant dynamic interaction. As such, no universal device can facilitate universal haptic control unless it envelops the entire human body or is tapped directly into our central nervous system (both only theoretical possibilities at this point in time).

In order to avoid trying to simulate all physical dynamics involved in a force feedback haptic interaction, we can simply ensure that the robotic controller has the same level of articulation (degrees of freedom) as the tele-operated robot. What I discovered in search of the haptics technology I needed is that the manipulator and the robot work better when they have the same joint, axis and freedom of movement or flexibility dynamics. Touchbot #2 has force feedback at every axis of motion on the manipulator and controllers. In this way, the controller, and the controlled robotic arm share the same dynamic range of movement and so are capable of

enacting the commands in unison. Tien Chang, H. McGee, Eric Wong and Sai-Kai Cheng and Jason Tsai have an industrial application patent on a multiple robot arm tracking via what is known as a ‘mirror jog.’ They describe their work in this way:

A user interface allows a user to jog the arm of the leader and to program movement of the arms for automatic execution such that the end effector reaches predetermined positions. A controller, operatively connected to the servo motors and the user interface, controls the operation of the servo motors, moves the arm of the leader in accordance with the programmed movement, and moves the arm of the follower such that it tracks or mirrors movement of the leader. (Chang et al., 2009)

What I did is take this idea and expand it with bi-directional haptic (and vibrotactile) force feedback. I discovered that this method can provide a sculptor with a controller that has more accurate dynamics of physical resistance. Touchbots use a hybridization of current force feedback haptics, supported by Dr. Howe, who believes that “one of the most important points in tactile sensing and robotic manipulation is the absolute necessity of good control of forces and fine motions” (Howe, 1993, p. 21).