Lab 5:Locomotion technique Implementation

Hybrid Biometric Locomotion: Ground-Walk＋Sky-Flight

In this experiment, I designed a system called “Hybrid Dynamics” to provide an immersive and comfortable VR experience using natural body movements.

Walk Mode: “Walking” Players use the Index Trigger and alternate swinging their arms up and down to move. The system mimics human walking, from slow walking to running.
Flight Mode: “Avian Flight” To address vertical challenges (like high coins), I added a “bird flight” metaphor. Players can spread their arms and look up to seamlessly transition from walking to flying.
Stop mechanism: I designed the trigger as a “clutch” for movement. The user only moves while holding it, and the system stops the user instantly the moment it is released. This “emergency brake” prevents accidental drifting and allows for precise landings, significantly reducing motion sickness.

Goal: To use body movement and visual feedback to improve immersion and reduce motion sickness.

2. Technical Implementation

The core logic of my code converts physical movements into 3D space vectors.

A. Core Logic: Gaze-directed Steering

I didn’t write complex mode-switching code. Instead, I used a mathematical approach that tracks the HMD’s forward vector.

Explanation:
- When players look straight ahead, the movement is walking.
- When they look up and swing their arms, they fly towards their target.

B. Parameter Tuning

To balance feel and comfort, I set fine-tuned dynamic parameters:

speedCurveExponent = 2.0f: A quadratic curve, filtering out minor controller shakes, making only intentional swings noticeable.
damping = 5.0f: Simulates inertia to prevent sudden stop effects, avoiding visual tearing. I removed the Locomotion Technique (Script) that was included in the template file and rewrote the Arm Swing Locomotion (Script).

C. Walking & Running Mode

How it works: This mode focuses on horizontal movement. The system calculates the combined speed of both controllers in real-time and projects it onto the ground plane (XZ plane).

Direction Lock: To prevent up-and-down shaking when walking due to arm movement, the system forces the Y-axis of the movement vector to be 0.

Speed Curve: A quadratic curve is introduced, This means small movements cause tiny shifts, while strong, fast walking generates rapid speed, accurately simulating the feeling of moving from walking to running.

D. Avian Flight Mode

How it works: When the player looks up and flaps their arms like a bird, the system switches to 3D movement.

Omnidirectional Navigation: The Y-axis is no longer locked. The direction of the headset (HMD) forward vector becomes the direction of the flight engine’s thrust.

Gaze-Directed: This helps reduce motion sickness. Players dive down by looking down and take off by looking up.

3. Process & Problems

Challenges:

Script Conflicts:

Unity projects come with default movement scripts that interfered with my custom Arm-Swing logic. Solution: I created an automatic tool to disable conflicting components during startup.
From “Coordinate Displacement” to “Speed Mapping”:

Initially, I tried using positional changes to move the player but it felt unnatural. Solution: I switched to using the velocity of the controller, making movement feel smoother and more realistic.
Motion Sickness from High-Speed Movement:

High-speed arm swings caused a “teleporting” visual effect, leading to motion sickness. Solution: I introduced a speed curve and a speed cap to smooth the transition between low and high speeds.

4. Lessons Learned

Comfort First: It’s better to limit maximum speed than to allow players to experience uncomfortable acceleration.
Automation is Key: Automated scripts like FixBannerPhysics save a lot of debugging time.
Focus on Gaze Direction: When designing flight modes, using “head orientation” for movement is more natural and reduces directional errors caused by hand movements.