Precision Control in Non-Linear Motion Base Platforms: How Servos & Simulation Solved the Challenge

Controlling a motion base platform with precision is no small feat—especially when the system is non-linear by design. Recently, Servos & Simulation’s engineering team was tasked with solving a complex problem: how to precisely control a six-axis motion base, track its position in space, and dynamically redefine the centroid of the moving platform’s coordinate system.

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The Challenge: Non-Linearity and Spatial Awareness

Unlike linear systems, Servos & Simulation’s motion base platforms use non-linear crank and pushrod mechanisms, which introduce significant complexity into the system’s mathematical modeling. Traditional closed-form solutions don’t apply here—so our engineers developed a custom software solution from the ground up.

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The Solution: Precision Control Software

To address this challenge, our team designed, programmed, and tested a Precision Control Software package capable of:

• Accepting roll, pitch, yaw, X, Y, and Z commands from a host computer
• Translating those commands into precise actuator movements
• Compensating for all non-linearities in the mechanical system
• Allowing the coordinate system’s center to be moved anywhere in space

For example, the system can redefine the center of rotation to a point 20 inches above the platform, enabling roll and pitch to occur around that new point. This is critical for applications like pilot feel realism or missile testing, where the reference point must be offset from the platform’s physical center.

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Dynamic Evaluator: Real-Time Position Tracking

To complement the control system, our engineers developed a Dynamic Software Evaluator that:

• Reads feedback potentiometers from each actuator
• Calculates the platform’s real-time position in roll, pitch, yaw, X, Y, and Z
• Sends this data to the host computer at rates from 200 Hz to 1 kHz

This allows the host system to know exactly where the platform is at any given moment—essential for synchronized simulation, testing, or visualization.

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System Architecture: Modular and Scalable

The software architecture includes three key components:

1. Precision Controller – Handles motion commands and actuator control
2. Dynamic Evaluator – Tracks and reports real-time platform position
3. Server Module – Manages communication between the host and both software modules

These components are memory-mapped for seamless integration but can also operate independently. The Server Module handles all communication, allowing the control and evaluator software to remain focused on their core tasks.

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Real-World Results

In the accompanying video, you can see the system in action. Despite the platform’s non-linear mechanics, each axis moves independently and precisely, with no cross-axis interference. At the 55-second mark, the video shifts perspective to show how the center of rotation has been moved—approximately 44 inches from the platform’s center—demonstrating the software’s ability to redefine spatial reference points dynamically.

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Why This Matters

For customers with demanding simulation or testing requirements—such as antenna tracking, pilot training, or vehicle dynamics—this level of control and flexibility is essential. Servos & Simulation’s software not only removes the complexity of non-linear mechanics but also empowers users to customize and control motion with unmatched precision.

If your application requires this level of control, we’re ready to help. For more information or to discuss your specific needs, please contact our engineering team.

For more information on our entire product and this software package, please check out our web site at www.servos.com or email us at info@servos.com.