Dual-axis test rate tables are key precision equipment in aerospace, inertial navigation, high-end manufacturing, and sensor research. Their primary function is to provide high-precision angular position, angular rate, and dynamic motion references for loads such as inertial devices (e.g., gyroscopes, accelerometers), seekers, and optoelectronic pods, enabling calibration, testing, and performance evaluation . Given the diverse range of products and technologies available on the market, scientifically selecting a rate table that meets specific needs becomes a complex systems engineering task. This article will systematically explain the selection methods and technical considerations for dual-axis test rate tables, focusing on three core performance dimensions: accuracy, stability, and dynamic response, and combining relevant standards and engineering practices.

1. Core Performance Dimensions Analysis: Accuracy, Stability, and Dynamic Response

Choosing a dual-axis test rate table is essentially a process of precisely matching its core performance indicators with your application requirements. These indicators are interrelated and together determine the rate table's final testing capabilities.

1.1 Precision System: A Comprehensive Consideration from Static to Dynamic Perspectives

Precision is the cornerstone of rate table performance and needs to be evaluated from both static and dynamic perspectives.

Static accuracy primarily refers to position accuracy and repeatability. Position accuracy is the maximum deviation between the actual position reached by the rate table and the commanded position, usually measured in arcseconds (″). For example, the spindle position accuracy of a certain model of rate table is ±2″, and the pitch axis is ±3″ . Repeatability is even more critical, measuring the consistency of the rate table returning to the same position multiple times, directly affecting the reliability of the test; high-performance rate tables can achieve accuracy within 1″ . These two indicators are crucial in static testing and calibration.

Dynamic accuracy refers to the accuracy performance of the rate table under continuous motion, with rate stability as the core indicator . It represents the degree of fluctuation in the actual output rate of the rate table under a constant speed command, usually measured by relative error (e.g., 5 × 10⁻⁵ ) . Stability at low speeds (e.g., 0.001°/s ) is particularly critical for simulating extremely slow motion or conducting high-resolution tests .

1.2 Stability: The foundation for ensuring long-term reliable operation

Stability determines the rate table's ability to maintain performance during long-term operation or in complex environments, and it relies on precise mechanical design and thermal management.

Mechanical stability : The core lies in the shaft system structure . Mainstream high-precision rate tables adopt a "U-T" type structure (U-shaped outer frame, T-shaped inner frame). This design has advantages such as high rigidity, good shaft orthogonality, and strong load adaptability . Secondly, load-bearing capacity must be selected based on the maximum weight and size of the load being measured (e.g., a common range is a table diameter of Φ320mm to Φ600mm ) , with sufficient safety margin .

Thermal stability and anti-interference : Temperature changes cause thermal expansion of mechanical structures, introducing errors. For highly demanding applications, the thermal control design of the rate table should be considered , or a model with an integrated temperature control chamber should be selected to provide a stable testing environment for the load . Furthermore, the equipment's vibration resistance is also an important aspect of environmental stability.

1.3 Dynamic Response: A Key Characterization of Motion Control Capability

Dynamic response metrics measure the rate table's ability to execute fast and complex motion commands.

Rate and acceleration range : Maximum angular rate and maximum angular acceleration define the motion limits of the rate table. For example, some rate tables have maximum rates ranging from ±500°/s to ±800°/s and maximum accelerations ranging from 200°/s² to 360°/s² . When selecting a rate table, ensure that it covers the maximum motion envelope required by the test outline.

Dynamic response characteristics refer to the speed and accuracy with which the rate table follows control commands, involving the bandwidth and response time of the servo control system. High dynamic response capability is essential for test scenarios that require simulating rapid maneuvers or angular vibrations (swing) .

For ease of comparison, the table below summarizes the core performance parameter ranges of a typical dual-axis test rate table:

Table 1: Typical Range of Core Performance Parameters for Dual-Axis Test Rate Table

2. Selection Process: From Requirements Definition to Technology Matching

Scientific selection should follow a systematic process to ensure that technical specifications serve practical applications.

1. Clearly define testing requirements and standards : This is the starting point for selection. First, the type of the object under test ( gyroscope , inertial navigation system, seeker, etc.), its physical parameters (size, weight), testing objectives (calibration, functional testing, lifespan testing), and the testing standards or specifications to be followed must be clearly defined . For example, in high-standard fields such as aerospace, GJB 2426A-2015 "Test Methods for Fiber Optic Gyroscopes" is a guiding document that provides unified regulations on the performance, environmental adaptability, and testing methods of fiber optic gyroscopes . Clearly defining standards is the foundation for all subsequent negotiations and acceptance of technical parameters.

2. Quantify core performance indicators : Based on the requirements of the first step, the accuracy, stability, and dynamic response requirements are specified into numerical indicators. For example, if a certain type of fiber optic gyroscope needs to be calibrated, based on the test requirements for its threshold and scaling factor nonlinear error, it may be deduced that the rate table needs a minimum rate of 0.001°/s and a rate stability of 1×10⁻⁵ .

3. Evaluate the auxiliary systems and interfaces :

Slip rings : used to supply power and transmit signals to the load on the rate table. The number of rings (such as 55 rings or 60 rings) must meet the needs of all power and signal channels .

Control & Software: Modern rate tables are equipped with computer-controlled measurement and control systems. The software should be evaluated to determine whether it supports the required control modes (position, rate, swing), programming flexibility, data acquisition and analysis functions, and whether external interfaces (such as RS422) are compatible with existing test systems .

4. Comprehensive consideration and vendor research : While meeting core performance indicators, weigh costs, delivery time, after-sales service, and technical support capabilities. Prioritize vendors with extensive case studies and a strong reputation in the target application area (e.g., inertial navigation testing).

3. Application-Scenario-Oriented Selection Focus

Different testing applications may have different focuses on the three core performance metrics.

Inertial device calibration and testing : This is the most classic application of a dual-axis rate table. Accuracy (especially rate stability and low-rate performance) is the primary consideration , because key parameters such as the gyroscope's threshold, scaling factor, and linearity are extremely sensitive to the accuracy of the input reference . Good position accuracy is also required for multi-point positioning tests.

Inertial navigation system simulation and testing : focuses on dynamic response and motion range . The rate table needs to be able to simulate various angular motions of an aircraft or vehicle (high-speed turns, maneuvers), thus requiring high maximum angular rate and angular acceleration. Simultaneously, multi-axis position combination capabilities are also used to simulate complex attitude changes .

Testing of photoelectric tracking equipment : A balance between dynamic response and low-speed stability is required . The rate table needs to simulate smooth line-of-sight scanning motion (requiring high stability) and rapid target acquisition and tracking (requiring high dynamic response).

For tests involving environmental testing : If calibration and testing are required to be carried out under different temperature conditions , a rate table model that can be structurally integrated with the temperature control chamber must be selected, or an integrated dual-axis rate table with a temperature control chamber can be directly selected to ensure the reliability of the test reference under temperature change conditions .

4. System Integration and Future Considerations

Choosing a rate table is not just about selecting a standalone device, but also about planning a testing subsystem. Its ease of integration with the existing laboratory environment (foundation, vibration isolation), data acquisition system, and central control software should be considered. Furthermore, as testing tasks become increasingly complex, attention should be paid to whether the rate table possesses modular expansion potential (e.g., future upgrades to a three-axis system) and intelligent functions (e.g., model-based adaptive control, predictive maintenance support).

In summary , selecting a dual-axis test rate table is a systematic project guided by standards and specifications (such as GJB 5878-2006 General Specification for Dual-Axis Test Rate Tables and GJB 1801-1993 Main Performance Test Methods for Inertial Technology Testing Equipment ) , with precision as its backbone, stability as its reinforcement, and dynamic response as its core. Only by translating clear application requirements into specific technical indicators through a scientific process and accurately matching them with reliable products can one ultimately invest in a powerful testing tool that can serve scientific research and production tasks stably and accurately over the long term.