QCM: A Curvature Manipulation Method to Suppress Discomfort in Redirected Walking

Research Background and Problem

• Identified Problem or Challenge: Redirected Walking (RDW) technology enables users to explore large virtual environments within limited physical spaces by introducing subtle discrepancies between virtual and physical paths. However, sudden shifts between virtual and physical paths during consecutive routes may cause user discomfort and reduce the sense of presence.
• Importance of the Problem: RDW is widely applied in virtual reality scenarios (e.g., virtual museum exploration and rehabilitation training), and user discomfort directly impacts the quality of immersive experiences. Therefore, reducing discomfort caused by path shifts is crucial for enhancing the user experience in virtual reality.
• Research Motivation and Related Work: Dynamic curvature changes (e.g., linear curvature changes) are one approach to addressing the above issue. Previous studies (e.g., Sakono et al.) have partially mitigated the problem of abrupt changes, but linear curvature changes fail to fully optimize users' initial reactions. This study aims to introduce more effective curvature change patterns to further reduce user discomfort.

Solution

• Proposed Method or Solution: The study proposes the Quadratic Curvature Manipulation (QCM) method and further designs the Segmented Curvature Change (SCC) model, optimizing the curvature change process through a combination of quadratic and linear functions.
• Innovations:
  1. QCM dynamically adjusts path curvature using quadratic functions, aligning better with users' perception of curvature changes.
  2. The SCC model combines QCM and linear curvature changes (LCM) in a segmented dynamic pattern, further reducing user discomfort and making curvature changes smoother.
  3. The study conducts theoretical analysis based on the "habituation" mechanism, systematically applying it to RDW technology for the first time to suppress users' perception of curvature changes.
• Implementation Steps and Key Techniques:
  • Implement QCM to achieve quadratic function curvature adjustments (path curvature changes quadratically with walking distance).
  • Design the SCC model to begin with slow quadratic changes during the initial phase, transitioning smoothly to linear changes.
  • Validate the effectiveness of QCM and SCC models through two experiments, measuring curvature gain at discomfort points and overall discomfort ratings.

Research Results

• Specific Achievements:
  • Experiment 1 showed that as the rate of second-order curvature change increased, the range of curvature gain perceived as uncomfortable by users expanded; the optimal range of second-order curvature change rates in the QCM model was identified.
  • Experiment 2 confirmed the significant advantage of the SCC model in suppressing discomfort, with users' average discomfort ratings significantly lower than other models (e.g., ACC and GCC models).
• Comparative Advantages Over Existing Solutions: Compared to traditional abrupt curvature changes (ACC) and linear curvature change models (GCC), the SCC model's refined segmented change design suppresses discomfort caused by curvature changes with lower user reaction intensity.
• Experimental or Evaluation Results:
  • The SCC model significantly reduced user discomfort ratings, especially at higher curvature gain values (e.g., 0.4 rad/m and 5.0 bending gain).
  • Simulated sickness scores (SSQ) under different experimental conditions remained in the "mild range," indicating improved comfort in immersive experiences with the new model.
• Limitations and Future Directions:
  1. Applicability: The study primarily focuses on curvature gain and bending gain, without extending to other RDW techniques (e.g., translation gain and rotation gain). Future research should validate its applicability.
  2. Expansion of curvature change models: The study only explores combinations of quadratic and linear functions; future work could investigate more complex curvature change functions (e.g., higher-order polynomials).
  3. Diversity of user groups and scenarios: Participants were predominantly university students; future studies should verify the method's effectiveness across different ages, genders, and levels of VR familiarity.

Conclusion

The QCM and SCC models provide new directions for curvature change design in RDW technology. By integrating habituation mechanisms and segmented change patterns, they significantly reduce user discomfort. This study not only supplements the theoretical foundation of dynamic curvature changes in RDW technology but also offers practical support for optimizing user experiences in virtual reality, enhancing RDW's application potential in complex scenarios.