VR- and AR (augmented reality)-powered products have been envisioned as the next major platform for human communication after mobile phones. Facebook is building out the immersive digital worlds it calls the “metaverse,” taking the immersive technology to unprecedented heights, expecting to reach a billion people within the next decade. Advances in 5G technologies and consumer VR hardware in recent years (e.g., Oculus Quest 2 and HTC Vive Cosmos Elite) open up infinite possibilities for AR and VR application developments. There is thus a pressing need to provide a more realistic sensation in the humans’ virtual interaction process, such as to simulate the shape, size, weight, compliance, temperature, and texture in object manipulation.  

Despite the advancements in technology, simulating the real sense of weight in a virtual environment is still a massive challenge. This is due to the absence of real gravitational forces and the complex nature of humans in determining the heaviness of an object.  Weight is perceived through the combination of multiple sensory systems, and a wide range of factors – including touch, visual, and force senses – can influence the perception of heaviness. 

The needs for weight perception in VR are most apparent in the training field, where precision in manual tasks is crucial. For instance, in a micro-surgery training simulation, a surgeon may need precise feedback to perceive the weight of his/her tool to ascertain how to adjust the force applied to an affected area. This applies to assembly line simulations where fragile objects are produced. If the objects do not reflect the real world, then the skills acquired in VR won’t be transferable. VR gaming has garnered massive popularity by providing the players with a truly immersive, first-person perspective of game action. Without the weight feedback, all game objects have the same equivalent weight as a remote controller. Having different weight perspectives can further enhance the gaming realism experience. Players can feel the different weights of the ball in bowling or feel the weight of the falcon standing on their hand in the falconry training.  

Direct haptic is the major stream of weight perception research focusing on the innovation of haptic devices that can generate direct proprioceptive force sensations in grasping, holding, or lifting an object. Indirect haptic focuses on simulating the feeling of weight by generating non-gravitational haptic forces through tactile sensations such as skin deformation at the fingertips. Haptic interfaces could create a real sense of weight by rendering tactile and proprioceptive sensations; however, they suffer from physical limitations in weight perception rendering to balance the maximum throughput over the size and weight of the actuators.  

From the reviews of literature studies of weight perception in VR (Lim et al., 2021), it is observed that most weight simulation methods were designed and applied to specific application scenarios and setups. The shortcomings of techniques and approaches in the studies indicate that there is still a gap towards building a robust multi-gesture weight perception simulation that is adaptable to different application needs.  

At Sunway University, Lim Woan Ning and her students are working on an innovative model to create the weight sensation without the actual matching haptic stimulus, known as pseudo-haptics. The model relies on human cognitive characteristics to induce haptic illusions in weight perception by combining the visual feedback and the voluntary-exerted force to create the sense of weight. 

This research involves the technological challenge in capturing the hand pressure during the interaction, and the design challenge in simulating the objects’ behaviour according to the pressure to create the pseudo-weight illusion. As the model requires relatively simple hardware compared to active haptic devices, it is less costly, has better mobility and faces fewer hardware problems of heavy device weight and weak motor output.  

Further reading is available in the review paper from the IEEE Access Journal: https://ieeexplore.ieee.org/document/9628093  

Lim Woan Ning
School of Engineering and Technology
Email: @email