Balancing the Virtual Path: Influence of Amplitude, Frequency, and Input Method on VR Locomotion.

This paper investigates how sinusoidal terrain characteristics and input modalities influence locomotion performance and user experience in virtual reality (VR). Two studies were conducted using a custom-built elastic balance board (EBB). The first study (Study 1) employed a 2 (amplitude: low vs. high) × 2 (frequency: low vs. high) within-group (N = 24) design to examine how slope characteristics affect locomotion efficiency (i.e., speed and completion time), postural stability (i.e., sway velocity), and subjective experiences (i.e., motion sickness, vection, usability, fear of movement, presence, and workload). High frequency slopes in terrains increased completion time, sway velocity, motion sickness, fear of movement, and vection, whereas amplitude alone had minimal effects. The second study (Study 2) used a 2 (amplitude: low vs. high) × 2 (input: EBB vs. joystick) within-group (N = 25) design to explore amplitude effects further and compare locomotion input methods. High amplitude increased completion time, sway velocity, and fear of movement, while EBB use enhanced presence and vection but required a higher workload compared to joystick input. Across both studies, frequency emerged as the primary factor influencing locomotion demands, and amplitude effects became more pronounced when combined with embodied locomotion interfaces. These findings provide design guidelines for VR locomotion systems, emphasizing the importance of aligning terrain complexity with input modality to optimize user comfort and control accuracy.