In virtual reality, haptic feedback is normally limited to controller vibrations. While this certainly enhances realism, simulating the constant weight of an object and its offset position is beyond such a setup. For this purpose, researchers have designed Aero-plane, a handheld force feedback device that "renders weight motion illusion on a virtual 2D plane."
What this means is that the Aero-plane can reproduce scenarios like cooking something in a frying pan, where the position of your food varies in both the X and Y directions, or a game where you balance a ball on a plane. The system takes the form of a handle with two electric ducted fans on the end. As the fans ramp up, the controller's weight is offset or even transformed into the upwards direction, mimicking a mass sliding across a surface. Two propellers are used, one on each side of the handle in order to vary the relative force applied on either side.
Response time of each fan is 0.3 seconds to ramp up to 7 N (~1.6 pounds), giving a total force output of 14 N (3.2 pounds) for the system. This low response time enables it to simulate rapid-fire effects as well, such as the muzzle rise of repeating gunshots. Aero-plane is controlled with the help of an Arduino board and VR applications were developed for it in Unity3D.
Those wishing to learn more can find the entire research paper here.