Motion Drive Algorithm

OverTilt Motion Drive Algorithm

OverTilt is RTI’s Motion Drive Algorithm (MDA), designed to generate an optimal set of motion cues while keeping the motion system within its physical limits. We use a tuning file to select the parameters for the MDA.

Simulator Features

OverTilt® provides an advanced form of tilt coordination. It fully coordinates the linear and angular movement of the motion base, providing optimum specific force cues, and high frequency and sustained specific force cues. Using OverTilt , we’ve achieved “adaptive” type algorithm performance without running into complex tuning requirements or the instabilities you usually encounter when using such algorithms.

Classical Mode

A Classical Mode, which RTI’s MDA also includes, filters the three channels of angular velocity and three channels of specific force using a set of six 2 pole, 2 zero filters. In addition, a set of two low pass filters, with tunable break frequencies, are used to control tilt coordination. All filter parameters are adjustable in the tuning file.

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Shared Tuning Parameter Characteristics

In both the Classical and OverTilt Modes, tuning parameters control several additional features:

Offset of the tilt coordination axis to move from motion centroid to operator’s head.
Independent gravity scaling and limiting, which provides greater stability when used in aircraft or
entertainment simulation.
Direct correlation of vehicle orientation to motion base orientation, which provides increased performance when used in ground vehicle simulation.

OverTilt has been used in conjunction with motion bases from MTS, Burke Porter, McFadden, Moog, Motionbase PLC and Tsunami Visual Technologies.

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Benefits

Requires only three parameters to tune for each linear channel including tilt coordination.
Maintains maximum position parameter keeping you from hitting limits.
Limits Tilt Rate and Tilt Acceleration, eliminating false rotational cues.
Prepositions based on the current input acceleration effectively doubling the motion envelope, fully integrated with the maximum position parameter.
Tracks the position, velocity, tilt, and acceleration of the motion base, selecting the optimum tilt angle and cue to be represented.
Reduces filter reference frame effects that are common in the Classical Algorithm.
Allows you to rapidly manipulate the algorithm because it is based on SimCreator technology.

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The OverTilt algorithm

The OverTilt algorithm can be quickly configured for a variety of motion bases, both large and small. For linear specific force, only three parameters must be configured: maximum specific force, maximum position and maximum tilt rate. OverTilt performs motion base pre-positioning as determined by the current input acceleration. It also provides smooth adjustments in the commanded specific force, avoiding large false cues which can occur when the motion base reaches its excursion limits.