Keigo Matsumoto

Unlimited corridor: redirected walking techniques using visuo haptic interaction

The main contribution is to realize an efficient redirected working (RDW) technique by utilizing haptic cues for strongly modifying our spatial perception. Some research has shown that users can be redirected on a circular arc with a radius of at least 22 m without being able to detect the inconsistency by showing a straight path in the virtual world. However, this is still too large to enable the presentation of a demonstration in a restricted space. Although most of RDW techniques only used visual stimuli, we recognize space with multi-modalities. Therefore, we propose an RDW method using the visuo-haptic interaction, and develop the system, which displays a visual representation of a flat wall and users virtually walk straight along it, although, in reality, users walk along a convex surface wall with touching it. For the demonstration, we develop the algorithm, with which we can modify the amount of distortion dynamically to make a user walk straight infinity and turn a branch freely. With this system, multiple users can walk an endless corridor in a virtual environment at the same time.

Curvature manipulation techniques in redirection using haptic cues

This paper proposes a method for improving the effects of redirected walking (RDW) by using haptic cues, particularly for the discrimination of path curvature. Some research has shown that users can be redirected on a circular arc with a radius of at least 22 m without being able to detect the inconsistency by showing a straight path in the virtual world. However, this is still too large to enable the presentation of a demonstration in a restricted space. We develop an RDW system, which displays a visual representation of a flat wall and users virtually walk straight along it although, in reality, users walk along a convex surface wall with touching it. Using this system, we conduct an experiment, and the results show that our method reduced the amount of perceived curvature in RDW down to 62% as compared to an only visual method.

Ascending and Descending in Virtual Reality: Simple and Safe System Using Passive Haptics

This paper presents a novel interactive system that provides users with virtual reality (VR) experiences, wherein users feel as if they are ascending/descending stairs through passive haptic feedback. The passive haptic stimuli are provided by small bumps under the feet of users; these stimuli are provided to represent the edges of the stairs in the virtual environment. The visual stimuli of the stairs and shoes, provided by head-mounted displays, evoke a visuo-haptic interaction that modifies a users perception of the floor shape. Our system enables users to experience all types of stairs, such as half-turn and spiral stairs, in a VR setting. We conducted a preliminary user study and two experiments to evaluate the proposed technique. The preliminary user study investigated the effectiveness of the basic idea associated with the proposed technique for the case of a user ascending stairs. The results demonstrated that the passive haptic feedback produced by the small bumps enhanced the users feeling of presence and sense of ascending. We subsequently performed an experiment to investigate an improved viewpoint manipulation method and the interaction of the manipulation and haptics for both the ascending and descending cases. The experimental results demonstrated that the participants had a feeling of presence and felt a steep stair gradient under the condition of haptic feedback and viewpoint manipulation based on the characteristics of actual stair walking data. However, these results also indicated that the proposed system may not be as effective in providing a sense of descending stairs without an optimization of the haptic stimuli. We then redesigned the shape of the small bumps, and evaluated the design in a second experiment. The results indicated that the best shape to present haptic stimuli is a right triangle cross section in both the ascending and descending cases. Although it is necessary to install small protrusions in the determined direction, by using this optimized shape the users feeling of presence of the stairs and the sensation of walking up and down was enhanced.

Turn physically curved paths into virtual curved paths

Redirected walking allows users to explore a large virtual environment while there is a limitation of the room size. Previous works tried to present users straight path in a virtual environment while they walked on a curved path in reality. We expand a previous technique to present users a various curved path in a virtual environment while they walked on a particular curved path or a straight path with/without haptics. Furthermore, we propose a novel estimation methodology to quantify walking paths which user has thought he walked in reality. The data from our experiment shows that users feel walking a various curved path in VR as same as one-to-one mapping condition.

Magic table: deformable props using visuo haptic redirection

We developed a novel virtual reality (VR) system that can transform objects using visuo-haptic redirected walking techniques. By using rotational manipulation and body warping techniques we can change the shape of objects. In the proposed system, it is possible to transform a square table into an equilateral triangle or a regular pentagonal table. Users can check the change in the shape by touching the edge of the table while walking around it.

Walking uphill and downhill: redirected walking in the vertical direction

This paper proposes a novel redirected walking technique that creates the feeling of walking uphill and downhill in the virtual environment while actually walking on a flat floor in the real world. We focus on the amount of energy consumed while walking uphill and downhill. Previous studies show that walking uphill takes three times as much energy as walking on a flat ground while walking downhill takes only half as much energy. We believe that the walking feeling in the virtual environment could be improved by changing the walking distance according to the gradient and bringing it closer to the energy consumption at the actual ascending and descending walk. We conducted a preliminary experiment to confirm that the proposed method is effective and the experimental results imply that our method is efficient for walking uphill.

Walking up virtual stairs based on visuo-haptic interaction

In the field of virtual reality, a few methods exist that allow a user to walk up and down the stairs in a virtual environment (VE); however, most of them are based on a complicated device system that generates physical steps using actuators (e.g., [Iwata et al. 2005; Schmidt et al. 2015]). Because it is difficult for users wearing head mounted displays (HMDs) to keep track of the surrounding environment, walking on physical steps could prove to be very dangerous and lead to injuries. Further, these systems have disadvantages in that the user cannot walk naturally. Therefore, a simple and low-cost system that allows users to walk safely and freely in the vertical direction in a VE is highly desirable.

Mobius walker: pitch and roll redirected walking

A redirected walking (RDW) techniques enable users to walk around infinite virtual environments (VEs) in a finite physical space. In previous studies on RDW, many researchers have discussed manipulations in the yaw direction, but few have tackled with redirection in pitch and roll directions. We propose a novel VR system, which realizes pitch and roll redirections and allows users to experience walking on the 3D model of Mobius Strip in the VE.