This invention relates generally to motion sickness and particularly to devices for counteracting motion sickness. Minimizing motion sickness is a long-felt need since it constitutes a significant detriment to all forms of human travel. Numerous studies have been conducted into the nature of motion sickness and its contributing causes and many inventions have been made in an attempt to relieve motion sickness, especially in the environment of ocean-going vessels or craft. Many of the patented devices incorporate a platform that is supported for movement relative to a vessel and which is equipped with devices to offset the vessel motion and thereby keep the platform fairly stable. Obviously, in a sea-going vessel encountering waves on the order of 10 to 20 feet, supporting such a platform so that it is isolated from movement of the vessel is a monumental, if not impossible, feat. For lesser motion amplitudes, on the order of a few feet, the offset required results in a large, unwieldy and expensive apparatus. The prior art devices have all attempted to counteract the rolling, pitching and swaying of a vessel to hold a platform steady and are limited thereby.
While the many studies of motion sickness have not revealed an indisputable single cause, or group of causes, it is clear that certain types of motion have a definite tendency to induce motion sickness. It is not known whether the movements are solely responsible or whether there are unexplained psychological factors involved. It is believed that the perception of certain motions is in itself conducive to motion sickness.
Scientific study has verified that vertical displacement of frequencies up to about 0.5 Hz causes motion sickness in humans. Human perception of other motion may also contribute to or actually cause motion sickness. Motion sickness, while more pronounced in ships and boats, is certainly not confined thereto and air and car sickness are also well known.
With computer technology and sophisticated fluid dynamic control systems, it is well within the realm of realizability to provide a completely controlled vehicle suspension system. In particular, automatically controllable suspension systems for automobiles are known. In such systems, a number of sensors yield information concerning the vehicle angular movements such as "sway," pitch, roll and longitudinal, vertical and lateral linear displacements. A microprocessor computes the necessary forces to be applied to the various suspension points to maintain the vehicle in any predetermined attitude, generally one that corresponds to a level condition. Forces at the suspension points may also be adjusted or overcompensated to, for example, have the automobile "lean in" on a turn rather than lean out in response to the natural forces involved. The speed of response of presently available hydraulic systems is sufficiently great that practically any vibration or motion disturbance can be fully compensated for.
There have been numerous attempts in sea-going vessels to provide captain's chairs and the like that are freely suspended from the vessel to maintain a stable, level position, preferably without significant other motions. It can readily be appreciated, however, that the problem of fully compensating an automotive suspension, encountering motion displacements of a few inches, is relatively simple compared with compensating a platform for a sea-going vessel that encounters waves that are many feet in height. Consequently, there has been no practical or effective anti-seasickness platform developed for use in such vessels. Even in smaller "day-sailers" or pleasure boats, the magnitude of the movements have made such stabilized platforms too large, too cumbersome and much too expensive.
The present invention is a significant departure from the prior art in which the components of motion are attempted to be cancelled or neutralized in order to provide a stable platform and thereby avoid motion sickness. Rather than attempting to offset or compensate such motions, the system of the invention simply adds a relatively small, vertical motion of different frequency that breaks up the sickness inducing motion. For example, a sickness inducing vertical motion of 0.5 Hz may be broken up by imparting a vertical motion of 2.5 Hz frequency to the platform. In a practical setting, the displacement of the platform will have an inverse relationship to the frequency of the displacement and a 2.5 Hz frequency will represent significantly less displacement of the platform. This, of course, translates directly into reduced power for actuating platform movement. The theory of the invention is that breaking up of the fundamental frequency of the vertical movement that induces motion sickness negates the tendency of such movement to induce motion sickness. This theory, in part, explains why it is that people rarely suffer from motion sickness on roller coasters, which certainly involve the particular vertical movement frequencies that have a tendency to induce motion sickness, but also involve many other movements which may effectively mask the motion sickness inducing tendency. The invention also envisions partial compensation for the gross movements of the vessel or conveyance relative to the platform for generally contributing to the comfort and stability of the person or persons supported on the platform.