Real-Time Hybrid Testing (RTHT) Systems

Real-Time Hybrid Testing (RTHT) represents the cutting edge of structural dynamics and seismic simulation. By seamlessly integrating physical experimental testing with advanced computational modeling, RTHT allows engineers to evaluate the complex seismic responses of large-scale structures without needing to construct full-scale physical models. Servo Hydraulic Solutions specializes in engineering the high-fidelity control systems and zero-latency actuators required to execute these demanding simulations accurately.

How Real-Time Hybrid Simulation Works

In an RTHT setup, a structure is divided into two distinct parts: The Physical Substructure: The critical component (such as a bridge column, isolation bearing, or damping device) is physically constructed and tested in the laboratory using servo-hydraulic actuators. The Computational Substructure: The remainder of the structure (e.g., the rest of the bridge or skyscraper) is simulated numerically in real-time on a high-speed computer. During a simulated earthquake event, the computer calculates the structural response and commands the actuators to apply precise displacements to the physical component. Simultaneously, load cells measure the resisting forces from the physical component and feed that data back into the computational model—all within milliseconds.

The Engineering Challenge: Latency and Backlash

For an RTHT simulation to be valid, the time delay between the computer command and the actuator response must be near zero. Even a fraction of a millisecond of latency or a millimeter of mechanical play can inject false energy into the simulation, destabilizing the entire test. At Servo Hydraulic Solutions, we solve this by utilizing: Ultra-Low Latency Digital Controllers: Custom-configured control loops that ensure absolute synchronization between the numerical model and the physical hardware. 68/69 Series Backlash-Free Swivels: Our proprietary hydrostatic joints eliminate mechanical slop, ensuring zero phase lag during high-frequency force transmission.

Benefits of Implementing RTHT in Your Laboratory

Cost Efficiency: Test massive structural designs accurately without the exorbitant cost of building full-scale physical models. Space Optimization: Conduct comprehensive seismic evaluations even in laboratories with limited strong-floor or strong-wall space. Enhanced Data Fidelity: Observe the true dynamic interaction between specific physical components and the broader structural system under realistic seismic loading.

Upgrade Your Lab for RTHT

Is your laboratory equipped to handle the demands of Real-Time Hybrid Testing? Contact our engineering team today to discuss upgrading your current servo-hydraulic infrastructure with RTHT-capable controllers and low-latency actuators.

Frequently Asked Questions About Real-Time Hybrid Testing (RTHT)

1. What is Real-Time Hybrid Testing (RTHT) in structural dynamics?

Real-Time Hybrid Testing (RTHT) is an advanced simulation method that combines physical laboratory testing with computer-based numerical modeling in real-time. It allows engineers to test specific physical components (like a damper) while simulating the rest of the structure computationally during a seismic event.

2. How does RTHT differ from Pseudo-Dynamic Testing (PDT)?

While both combine physical and computational models, Pseudo-Dynamic Testing (PDT) runs at a slow, extended time scale. RTHT runs in actual real-time (milliseconds), making it essential for testing velocity-dependent components like viscous dampers and shock isolators.

3. Why is ultra-low latency critical for RTHT systems?

In RTHT, the computational model and the physical actuator must communicate instantly. Even a few milliseconds of latency or phase lag can introduce false energy into the system, leading to inaccurate test data or dangerous physical instability in the test rig.

4. How do backlash-free swivels improve RTHT accuracy?

Mechanical play in standard joints introduces severe errors during high-frequency RTHT. Integrating precision components like the 68/69 Series Backlash-Free Swivels ensures zero mechanical slop, transferring exact displacement commands from the actuator to the test specimen without phase delay.

5. Can you upgrade our existing servo-hydraulic shake table for RTHT?

Yes. Servo Hydraulic Solutions specializes in revitalizing legacy testing systems. We can upgrade your existing hydraulic actuators with advanced digital controllers and low-latency feedback loops required for strict Real-Time Hybrid Simulation (RTHS).

6. What are the primary applications of Real-Time Hybrid Simulation?

RTHT is widely used in civil and structural engineering for earthquake simulation, aerospace testing for vibration fatigue, and automotive engineering for active suspension system validation without needing full-scale physical prototypes.

7. What hardware is required to build a custom RTHT system?

A reliable RTHT system requires high-speed DSP (Digital Signal Processing) controllers, high-response servo valves, fatigue-rated actuators, and rigid mounting components (like zero-backlash swivels) to ensure instantaneous force transmission.

8. What are the cost benefits of using RTHT in a university laboratory?

RTHT significantly reduces research costs and space requirements. Instead of building a massive, expensive full-scale structural model, universities can physically test only the critical sub-component while the computer accurately simulates the massive superstructure.

9. Do your testing systems lock us into proprietary RTHT software?

No. We build our custom servo testing solutions using Commercial Off-The-Shelf (COTS) components and open-architecture controllers. This ensures seamless integration with standard academic and industrial computational frameworks like OpenSees or MATLAB/Simulink.

10. Who provides engineering support and installation for these systems?

Doug Weller and the expert team at Servo Hydraulic Solutions (based in Boulder, Colorado) provide comprehensive design, installation, and on-site field support for complex RTHT testing systems globally.

Servo Hydraulic Shake Tables
Universities and industries globally utilize Servo Hydraulic Solutions tables for simulating earthquake vibrations, shock, and transportation-related vibrations. These tables cater to short-term tests or durability testing and can qualify equipment to standards like IEEE-344, RIM testing, Bellcore GR-63, AC-156, and DOT vibration standards.
Public Education Shake Tables
Public education shake tables are utilized by universities, science museums, emergency planning and education organizations, and other institutions to simulate earthquake experiences for educational purposes. Alongside exhibits, videos, and lectures, these tables help prepare individuals for earthquake responses, reducing fear and enhancing safety procedures. Experiencing realistic earthquake motions enhances learning and can save lives. Additionally, these tables are used for investigating engineering issues related to earthquake safety, such as wall attachments, suspended lighting, and furniture overturning. Our philosophy is to match customer needs with the best Commercial Off-the-Shelf products, providing options for upgrades and repairs, benefiting everyone involved.

About Servo Hydraulic Systems

Led by Doug Weller, Servo Hydraulic Solutions in Boulder, Colorado specializes in custom earthquake simulators, vibration testing systems, and shake tables using commercial off-the-shelf components.

We prioritize customer input and tailor solutions to individual needs, with nearly 20 years of experience in installation and testing. We offer remote services nationally and internationally.

If your current system needs troubleshooting or upgrades, we can revitalize it with computer interfaces and updates, leveraging our expertise with analog systems.

We emphasize local labor and materials for higher-quality results and reduced service calls, ultimately aiming to save our customers money.