VR locomotion is a tricky topic to tackle as considerations for how the user feels is important. It must be intuitive and at the same time, not cause sickness.

An idea that I can think of is to perhaps create a type of controller that sense the grip strength of the player. Then, combined with the eye tracking to get where the player is looking in the scene, there can be a gestured input that requires the player to exert some grip strength and a pulling motion before the player is quickly moved to their desired position based on the gaze with the peripheral blacked out.

I think that this will be intuitive and interesting as it will feel that you are exerting some sort of power with the grip strength requirement to pull yourself towards to location that is far away. With the blacking out of the player’s peripheral, the player will also be less likely to feel motion sickness.

Locomotion in VR is hard to be implemented correctly due to the fact that a wrong implementation could cause motion sickness. Most locomotion is implemented by having physical movement from the player or limited movement from the player. I feel that a good way to do this might be allowing the player to lie on a bed and he can move the in-game character by using motion tracking devices with his hand. Hence when the in-game character is moving in VR, the player would not feel too sick as he is resting his head on the bed and can be more relaxed as compared to standing upright to play the game. This might help in reducing motion sickness as the player senses are more relaxed and the locomotion in VR would not be too drastic for the player who is lying on the bed. Furthermore, the player can only move a little while lying on the bed and this might help the player to not overthink the complicated movement introduced by the VR game, allowing the player to feel secure and less likely to feel motion sickness.

One of the big problems with motion sickness in VR comes from the player’s movement being different from what the brain expects. There was this multi-directional treadmill device I saw a few years back that moved the user in the opposite direction of where they walked in the XY axis. If I recall correctly it did not allow for vertical movement as the harness is attached to a fixed point around the waist. I think an improvement would be to have the harness attached to the ceiling by 3 or 4 ropes. Then the tension of these ropes can be used to determine the player’s movement in all 3 dimensions (if the player crouches then the ropes will be pulled downwards, etc). All other parts of the setup would remain the same including the treadmill. With this setup the player can probably jump and crouch similar to in real life.

When considering the implementation of VR locomotion, there are two main obstacles to overcome: tracking movement and constraint of physical space.

To properly track movement, I feel that a system using cameras and predictive movements can be employed. We’ve had the Kinect and Wii for decades now, and detection of a player’s movements without the excessive use of wearables should be more than possible with today’s technology. Multiple cameras can be set up across a room to detect a player’s movements within a three-dimensional space. However, there still may be issues with over-detection or a disconnect between the player’s physical movements and that of the avatar. Sometimes a player may just be adjusting themselves slightly, but their movement may prompt the avatar to move forward as well. To reduce such issues, or to prevent ‘unnatural’ feeling movements, predictive analytics can be adapted to predict the player’s movements.

A larger issue with seamless VR locomotion would be the constraint of physical space. While the virtual environment can be as large as the developer wants, the player will be constrained by the size of the physical space they are in. I feel that VR treadmills are a good way to overcome this limitation. Though they may get in the way of how ‘realistic’ movement feels, keeping the player physically in the same spot may be the only way to overcome physical space constraints.

That being said, these are very niche and expensive ways of employing VR locomotion and it may need years of research and development before it can be accessible to the everyday consumer.

Locomotion is the medium that allows users to navigate through a virtual environment. When space is limited, games often rely on buttons or directional pads to displace the user from their original position within the 3-Dimensional area.

We see many games try to work around locomotion by NOT giving movement control to the player. Such games are “Beatsaber” and “VR the Diner”, not requiring user movement. Even for 3D painting, movement can be overcome by rotating the sculpture, rather than having to move around it. There are also some shooting games that focuses on the shooting action scenes in a car or in a building, automatically advancing players when they clear a stage. This reduces the need for the player to move.

There are definitely times where movement is necessary for an immersive experience. The main workaround we see nowadays are 360 degree threadmills that keep players in place. Just be careful to let players play in a safe manner in case things go south like this: https://www.reddit.com/r/funny/comments/pkuzli/vr_workout_with_added_heart_attack/

Locomotion based on In-Place Motion Sensing

When the user wants to move in the VR landscape, he or she will need to execute a specific physical action on the spot to do so. This could be something simple like a small movement of the right arm forward to move the right leg forward. This is pertaining to the Sensory Conflict Theory, where the aim is to try and minimize the conflict since now both the user’s mental model which knows that the arm moved, is matched by the movement in the VR landscape.

Reduce Motion Sickness using Sensory outputs

Since in the Sensory Conflict Theory, the user experiences motion sickness due to a mismatch in the senses and/ or mental model of the user, we could try to output some form of sensory feedback to the user when they walk, to try and fill in the gap.

For example, when the user moves a joystick to move the player in the VR landscape, whenever the player in the VR landscape steps on the ground, a small vibration could be sent to the user through the joystick, to simulate the feeling of actually stepping on the ground. This can be the attempt to bridge the gap in the sensory cues.

Reduce Motion Sickness using User Interface as a REST Frame

In usual 2D/ 3D games, the User Interface is usually fixed to the game screen.

In VR, we can try to do the same thing by having the User Interface fixed onto the user’s vision just like how it would usually be in a regular 2D/ 3D game. The User Interface can then act as a REST Frame for the user, since the User Interface elements can act as fixation points for the user during actual locomotion.

Assume that we have 2 handles attached to the ceiling in front. Each hand can reach a handle and pull it to you. When your left hand pull the handle your right foot will move forward a grid. If you release a handle it will go back to its origin position pending for the next operation. So by pulling a handle, release it while pulling the other, you can move forward. And if you pull the 2 handles together, you will jump for one grid.

Perhaps one way we can address the issue of Virtual Reality locomotion would be to implement a type of shoe that removes all forms of movement forward. As the player moves their legs forward, the shoes will automatically roll the player’s feet backwards, acting as a form of wearable treadmill. However, one possible disadvantage of using these shoes would be that the player might not be able to take fast steps.