Motion simulation systems have included platforms for supporting and initiating physical movement for participants in film exhibitions and amusement attractions as well as simulation products. Such systems have been designed to provide physical movement to participants with film or computer simulation activities.
Motion simulators such those as for amusement attractions and flight simulators include a system that artificially recreates motions such as aircraft flight and various aspects of a flight environment. Typically, these systems include software operated algorithms that govern how a vehicle moves such as in aircraft flight, and how the vehicle reacts to vehicle controls and to external environmental factors such as air density, turbulence, and the like. By way of example, flight simulation is used for a variety of reasons, including flight training for pilots, design and development of the aircraft itself, and research regarding aircraft characteristics and control handling qualities. Further, flight simulations may employ various types of hardware, modeling detail and realism. Systems may include PC laptop-based models of a simple cockpit replica to more complex cockpit simulations, and with wide-field outside-world visual systems, all mounted on six degrees-of-freedom (DOF) motion platforms which move in response to pilot control movements and external aerodynamic factors. Yet further, 6-axis motion systems have been used for simulation in other fields such as driver training and driving research. Simpler systems with less degrees of freedom have been used for a wide variety of applications including flight cabin staff training, medical applications, and maritime training.
Early motion systems typically gave movements in pitch, roll and yaw, and the payload was limited. The use of digital computers for flight simulation typically was limited to specialist high-end computer manufacturers, but with the increasing power of the PC, arrays of high-end PCs are now also used as the primary computing medium in flight simulators.
The early models generally used TV screens in front of the replica cockpit to display an Out-The-Window (OTW) visual scene. Computer-based image generator systems also used TV screens and sometimes projected displays including collimated high end displays for pilot training.
As improvements to motion simulator systems developed with advances in technology, demand increased for full flight simulators (FFS) to duplicate relevant aspects of the aircraft and its environment, including motion. A six degrees-of-freedom (DOF) motion platform using six jacks is a modern standard, and is required for Level D flight simulator standard of civil aviation regulatory authorities such as the Federal Aviation Administration (FAA) in the US and the European Aviation Safety Agency (EASA) Europe. The FAA FFS Level D requirements are the highest level of FFS qualification currently available. The motion platform must have all six degrees of freedom, and the visual system must have an outside-world horizontal field of view of at least 150 degrees, with a collimated distant focus display and with a transport delay to conform to the FAA FFS Level D requirements. Realistic sounds in the cockpit are required, as well as a number of special motion and visual effects.
In order for a user to feel that a motion simulator is accurate, the simulator has to behave in a way that feels realistic and predictable. By way of example, if a pilot gently guides a simulated aircraft into a turn, the motion simulator shouldn't tilt at a sharp angle, which would represent a much tighter turn. Data gathered from computer models, field tests and complex algorithms are typically used to program simulator behavior. Force-feedback greatly affects the user's experience, making it seem more real and consequently a more effective training environment.
Cam driven motion systems have been used in products for the amusement and for low-end simulation in the simulation industries. Cam driven systems have been provided with a variety of geometries and axis arrangements, including 3-axis systems and 6-axis systems, such as used by E2M Technologies in the Netherlands.
Some of these systems have used induction motors controlled by variable speed drives (VSDs) using analogue control signals from a motion controller based on a PID loop. A Proportional, Integral, Derivative (PID) loop is typically used by controllers to eliminate the need for continuous operator attention. These induction motor systems experience problems with motion lag caused by slip between the field and the rotor which results in a large error between the commanded and actual position. Further, servo motor controlled systems known in the industry have also not met the requirements for Level D. Such position errors are increasingly problematic as motion systems in simulators and amusement attractions utilize higher speed computer rendering and graphics as users can sense and experience this lag, slow response time and an out-of-sync experience.
Systems have sought to achieve multi-axis motions systems such as the Stewart platform which used a 3 to 3 and 3 to 6 configuration which was difficult to produce due to the complexity of the co-joined bearings.
Known induction motor and servo motor systems also have limitations in the control of the position of the system in relation to an activity of the user such as simulation activity like flying or viewing a film or visual depiction in a simulator. These systems also experience problems induced by activities such as high frequency vibrations that affect the life and performance of the motors. Payloads have also been limited by these designs due to the power-to-size ratios of both induction motors and servo motors with currently known control systems.
There remains a need for an improved motion simulation system with improved control of the motion and synchronization between the physical motion and response time to provide a smooth motion and realistic motion experience. There is further a need for such simulation systems to be capable of supporting a high payload while maintaining the smooth and realistic motion experience. There is also a need for a motion system that can be easily reconfigured and adjusted for varying operating scenarios or applications.
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