Nx 7 5 Motion Simulation Pdf Free
Macabeo Eastman
A motion simulator or motion platform is a mechanism that creates the feelings of being in a real motion environment.[1] In a simulator, the movement is synchronised with a visual display of the outside world (OTW) scene. Motion platforms can provide movement in all of the six degrees of freedom (DOF) that can be experienced by an object that is free to move, such as an aircraft or spacecraft:.[1] These are the three rotational degrees of freedom (roll, pitch, yaw) and three translational or linear degrees of freedom (surge, heave, sway).
Motion simulators can be classified according to whether the occupant is controlling the vehicle(such as in a Flight Simulator for training pilots), or whether the occupant is a passive rider, such as in a simulator ride or motion theater.[2]
Motion platforms for aircraft simulators are at the high end, plus some of the more expensive amusement park rides that use a simulator-type motion base; arcade amusement devices are in the middle, and motion platforms for home use are low-cost but not as capable of the higher-level devices.
One of the first motion platforms, the Sanders Teacher, was created in 1910. This was a model aircraft connected to the ground by a universal joint. When wind was present, the pilot in training was able to use the aircraft's control surfaces to move the model in the three rotational degrees of freedom pitch, roll and yaw.
In 1929 a significant advance in motion platform technology was made with the patent by Edwin Link for what became known as the "Link Trainer". This used the pilot's control stick and rudder controls to control organ-type bellows under the simulator cockpit. The bellows could inflate or deflate, giving movement in pitch, roll, and yaw.
Simulator motion platforms today use 6 jacks ("Hexapods") giving all six degrees-of-freedom, the three rotations pitch, roll and yaw, plus the three translational movements heave (up and down), sway (sideways) and surge (longitudinal).
6 Dof motions are powerful cues when combined with outside-world (OTW) imagery. Motion platforms together with OTW imagery are used in : flight simulation, driving simulation, amusement rides, and small home-based simulators.
The motion platform is used in military and commercial flight instruction training applications. Also in entertainment devices in theme parks, with users from single people to many, seated in rows in front of screens in which pictures are projected, synchronised with motions from the platform under the simulator cab.
A typical high-end motion system is the Stewart platform, which provides full 6 degrees of freedom (3 translation and 3 rotation) and employs sophisticated algorithms to provide high-fidelity motions and accelerations. These are used in a number of applications, including flight simulators for training pilots.
The middle of the spectrum includes motion platforms in arcade amusement games, rides, and other arrangements. These systems fall into a price range from $10,000 to US$99,000. Typically the space requirements for such a platform are modest requiring only a portion of an arcade room and a smaller range of motion is provided via similar, less expensive, control systems than the high-end platforms.
In the 1980s, it became a trend for arcade video games to use hydraulic motion simulator arcade cabinets.[5][6] The trend was sparked by Sega's "taikan" games, with "taikan" meaning "body sensation" in Japanese.[6] Sega's first game to use a motion simulator cabinet was Space Tactics (1981), a space combat simulator that had a cockpit cabinet where the screen moved in sync with the on-screen action.[5] The "taikan" trend later began when Yu Suzuki's team at Sega (later known as Sega AM2) developed Hang-On (1985), a racing video game where the player sits on and moves a motorbike replica to control the in-game actions.[7] Suzuki's team at Sega followed it with hydraulic motion simulator cockpit cabinets for rail shooters such as Space Harrier (1985), racing games such as Out Run (1986), and arcade combat flight simulators such as After Burner (1987) and G-LOC: Air Battle (1990). One of the most sophisticated motion simulator cabinets in arcades was Sega's R360 (1990), which simulated the full 360-degree rotation of an aircraft.[5][8] Sega have since continued to manufacture motion simulator cabinets for arcade games through to the 2010s.[5]
The lower-cost systems include home-based motion platforms, which have recently become a more common device used to enhance video games, simulation, and virtual reality. These systems fall into a price range from $1,000 to US$9,000. Within the 2000s (decade), several individuals and business entities have developed these smaller, more affordable motion systems. Most of these systems were developed mainly by flight simulation enthusiasts, were sold as do it yourself projects, and could be assembled in the home from common components for around one thousand US dollars ($1,000).[9] Recently, there has been increased market interest in motion platforms for more personal, in-home, use. The application of these motion systems extends beyond just flight training simulation into a larger market of more generalized "craft-oriented" simulation, entertainment, and virtual reality systems.[10]
Motion platforms are commonly used in the field of engineering for analysis and verification of vehicle performance and design. The ability to link a computer-based dynamic model of a particular system to physical motion gives the user the ability to feel how the vehicle would respond to control inputs without the need to construct expensive prototypes. For example, an engineer designing an external fuel tank for an aircraft could have a pilot determine the effect on flying qualities or a mechanical engineer could feel the effects of a new brake system without building any hardware, saving time and money.
Flight simulators are also used by aircraft manufacturers to test new hardware. By connecting a simulated cockpit with visual screen to a real flight control system in a laboratory, integrating the pilot with the electrical, mechanical, and hydraulic components that exist on the real aircraft, a complete system evaluation can be conducted prior to initial flight testing. This type of testing allows the simulation of "seeded faults" (i.e. an intentional hydraulic leak, software error, or computer shutdown) which serve to validate that an aircraft's redundant design features work as intended. A test pilot can also help identify system deficiencies such as inadequate or missing warning indicators, or even unintended control stick motion. This testing is necessary to simulate extremely high risk events that cannot be conducted in flight but nonetheless must be demonstrated. While 6 degree-of-freedom motion is not necessary for this type of testing, the visual screen allows the pilot to "fly" the aircraft while the faults are simultaneously triggered.
Some driving and flying simulation games allow the use of specialized controllers such as steering wheels, foot pedals or joysticks. Certain game controllers designed in recent years have employed haptic technology to provide realtime, tactile feedback to the user in the form of vibration from the controller. A motion simulator takes the next step by providing the player full-body tactile feedback. Motion gaming chairs can roll to the left and right and pitch forward and backward to simulate turning corners, accelerations and decelerations. Motion platforms permit a more stimulative and potentially realistic gaming experience, and allow for even greater physical correlation to sight and sound in game play.
Postural stability is maintained through the vestibular reflexes acting on the neck and limbs. These reflexes, which are key to successful motion synchronization, are under the control of three classes of sensory input:
These are all sensors of acceleration, and do not respond when a constant speed or velocity is reached. At constant speed, visual cues give cues of motion until another acceleration takes place and the body's motion sensors once more send signals to the brain.
In simulator motion platforms, after an initial acceleration is produced, the platform is re-set to a neutral position at a rate below human motion threshold so that the subject does not detect the so-called "wash out" phase of simulator motion cueing. The motion system is then ready to make the next acceleration which will be detected by the subject, as in the real world. This so-called "acceleration onset cueing" is an important aspect in simulators with motion platforms and models the way humans feel motions in the real world.
The human eye is an important source of information in motion simulation where a high resolution picture is available such as by day in good visibility. The eye relays information to the brain about the craft's position, velocity, and attitude relative to the ground. As a result, it is essential for realistic simulation that cues from a motion platform (if fitted) works in synchronization to the external visual scene. As discussed above, in the real world motion cues are processed by the brain before visual changes, and this must be followed in a simulator or dizziness and even nausea can occur in some people, so called "simulator sickness".
For example, if the occupant commands the vehicle to roll to the left, the visual displays must also roll by the same magnitude and at the same rate. Simultaneously, the cab tilts the occupant to imitate the motion. The occupant's proprioceptors and vestibular system sense this motion. The motion and change in the visual inputs must align well enough such that any discrepancy is below the occupant's threshold to detect the differences in motion.
It is physically impossible with most existing systems to correctly simulate large-scale motion in the limited space available in a simulator. The standard approach is to simulate cues of initial acceleration as closely as possible.[16]
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