PD control - Siggraph 2016

Straightening Walking Path Using Redirected Walking
Ayaka Nishi, Keisuke Hoshino, Hiroyuki Kajimoto
Technique
（The University of Electro-Communications, Japan）
Abstract
Virtually infinite space is a holy grail of immersive virtual environment (IVE), and numerous approaches have been
proposed, yet there still is a hardware and spatial cost. We propose a novel low-cost locomotion interface that combines a
1-DoF treadmill and a head mounted display (HMD), in which displayed image is rotated to induce straightened trajectory
for the treadmill, similar to the technique known as Redirected Walking. We conducted an experiment using the proposed
method, and showed that by using PD control algorithm, the walking path became straightened.
Related work
Purpose
The problem of
using
realistic
Two-dimensional treadmill
walking in a VRE
Two-dimensional treadmills
[1] to let users walk around a  Unnatural walking
wide VR space.
 A certain size of physical space
 High cost
Redirected Walking
 Dedicated instrument
technique
The Redirected Walking
⇨It is difficult to spread
technique [2] has also been
used, and allow users the
subjective experience of
walking straight, whereas in
reality their walking path is
controlled by visual stimuli.
Method
The contribution of this paper
 Actual walking
 Low-cost
 Space-saving
A new locomotion interface
1-DoF treadmill
+
Redirected Walking
technique
to make the walking path
straight
Users experiment
without
path control
With
path
control
Experiment 1 : Induction of Straight Walking
Algorithms
P control（d : the displacement along the x-axis）
Rotate[degree/s] = 𝐾𝑝[degree/s/m]×𝑑[m]
PD control（ d : the displacement along the x-axis,
𝑉𝑥 : the velocity along the x-axis）
Rotate = 𝐾𝑝×𝑑+ 𝐾𝑑[degree/m]×𝑉𝑥[m/s]
Physical Path
Result
• possible to induce straight line walking
• PD control gave smaller deflection
• the path became more stable as the 𝐾𝑝 value increased
Experiment 2 : Verification of Magnitude of Inducible Curvature Radius
Result
• When the radius of curvature is 2m or more,
the walking path can be confined to a 1 m width
⇨These results indicate that the method can be applied to
normal
treadmill
Reference
[1] Hiro Iwata, “The Torus Treadmill: Realizing Locomotion in VEs.” Computer Graphics and Applications, IEEE, Volume: 19, Issue: 6, pag
[2] Sharif Razzaque, Zachariah Kohn, Mary C. Whitton. “Redirected Walking.” Eurographics 2001.