Kinesthetic Cues that Lead the Way

Wayfinding is of vital importance to pedestrians walking in unfamiliar areas. Generally, pedestrians rely on directional information, street names, and landmarks [Bradley & Dunlop, 2005]. Recently, many mobile devices, such as mobile smart phones, can provide us with detailed digital maps, global positioning information, and navigational information. These location-based data and services are usually presented on visual displays. However, the visual displays in mobile devices are very small, which makes it hard to see and use the data. With the increasing complexity of information, and the variety of contexts of its use, it becomes important to consider how other non-visual sensory channels, such as audition and touch, can be used to communicate necessary and timely information to users. Additionally, there are a number of user groups, such as visually impaired people and the emergency services, who also require non-visual access to geographical data. Kinesthetic stimulation, such as that for pulling or pushing the hand, has the potential to be more intuitive and expressive than cutaneous stimulation, such as rumbling vibration, in conveying direction information because force feedback devices can indicate a onedimension direction directly. Although a substantial number of force feedback devices have been developed in the last twenty years, most of them use either mechanical linkage to establish a fulcrum relative to the ground (Massie & Salisbury, 1994), use a huge air compressor (Suzuki et al., 2002; Gurocak et al., 2003), or require wearing a heavy device (Hirose et al., 2001). Physical constraints mean that none of them can be used in portable information devices. Some portable “torque” displays have been proposed, based on the gyro effect (Yano et al., 2003) or angular momentum change (Tanaka et al., 2001) have been proposed; however, they can produce neither a constant force nor a translational force without also producing a reaction force; they can generate only a transient rotational force since they use a change in angular momentum. Recently, there have been a number of proposals for generating both constant and directional forces without an external fulcrum by using two oblique motors whose velocity and phase are controlled (Nakamura & Fukui, 2007), by shifting the center-of-mass of a device dynamically to simulate kinesthetic inertia (Swindells et al., 2003), and by producing an air pressure field with airborne ultrasound (Iwamoto et al., 2008). In contrast, our idea is to exploit the characteristics of human perception to devise a new force perception method for portable information devices that can generate a translation force sensation with a long duration (Amemiya et al. 2005; Amemiya and Maeda 2009). The method uses an asymmetric oscillation, where brief intense pulses of acceleration alternate