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Tornado-S Missile Inertial Measurement Unit (IMU) Teardown and Analysis
0:00:04 Introduction: The video focuses on the Inertial Measurement Unit (IMU) of a Tornado-S missile, specifically the fiber optic gyro and accelerometers.
0:00:12 Initial Problem: The presenter initially acquired a fiber optic gyro, FPGA board, and power supply board separately from eBay, but discovered the fiber optic cable was cut.
0:00:40 Functional Unit: A second, complete fiber optic gyro unit was obtained, which is believed to be fully functional.
0:00:57 IMU Components: The IMU measures angular velocity on each axis and contains two electronic modules, including two DC-DC converters.
0:01:31 Teardown of DC-DC Converter: A separate, identical module (reference BP-006) is taken apart, revealing resistors and likely a switched-mode DC-DC converter.
0:01:59 Connectors: The presenter also found matching connectors that are usefull for further testing.
0:02:35 Accelerometers: The IMU also includes three accelerometers, each with an associated ADC board to convert the accelerometer's current output into a digital value for the guidance computer.
0:03:19 Additional Board Assembly: Another board assembly is shown, which includes a power supply with toroidal transformers.
0:03:46 Accelerometer Variations: Two different types of accelerometers are identified (TSE 1940M and DK 15 3), with the DK 15 3 likely being a newer model.
0:05:07 Strap-down Inertial Navigation: The system uses strap-down inertial navigation, employing Euler equations to determine the missile's position based on integrated angular velocity and acceleration data.
0:06:12 DC-DC Converter Analysis: The DC-DC converter module (PNSK and BP-006) is examined, revealing multiple converters: Traco Power 0505, TEN 8-2421 (Β±5V output), TEN 15-2411 (5V output), and an additional 5V to 5V 1W converter of unknown use.
0:08:30 Power Supply for Fiber Optic Gyro: The analyzed module provides power to the fiber optic gyro.
0:08:44 Temperature Sensitivity of Fiber Optics: The speed of light in fiber optics varies with temperature, affecting measurement accuracy.
0:09:02 Temperature Compensation: Two solutions exist: software correction based on temperature measurement or maintaining a constant temperature. The Tornado-S uses the latter.
0:09:20 Heaters: Flat resistors within the assembly act as heaters to maintain a constant temperature.
0:09:28 Temperature Controller: A separate board assembly acts as the temperature controller, not the power supply as initially thought.
0:09:35 Heater Resistances: Two heaters are present: 90 ohms (likely constantly powered) and 6 ohms (controlled by the controller board).
0:10:01 Temperature Sensor: A three-wire temperature sensor (reference A7) is located within a hole in the assembly.
0:10:28 Temperature Controller Schematics: The temperature controller circuit uses a PNP transistor (2T877) to drive the 6-ohm heater, controlled by a driver transistor and a comparator circuit that responds to temperature variations detected by the sensor.
0:11:52 Power Supply Requirements: Testing the temperature control system requires two power supplies: one (around 12V) and another (around 28V, simulating a missile thermal battery).
0:12:20 Thermal Batteries: The presenter shows a set of three thermal batteries (reference 9B 287) weighing approximately 4 kg.
0:13:00 Initial Test: Connecting the unit to 25V and 12V power supplies shows no current draw on the 25V line, indicating the regulation temperature is below the ambient temperature.
0:13:42 Voltage Measurements: Voltage measurements at the op-amp inputs confirm the ambient temperature is above the regulation temperature.
0:14:08 Adjusting regulation temperature: In order to test the system, the presenter must adjust the temperature regulation set point.
0:14:10 Modification for Testing: To trigger the heater, the presenter plans to remove resistors to increase the voltage on the op-amp's non-inverting input or add a resistor to decrease the voltage on the inverting input.
0:14:57 Resistor Modification: Removing a resistor is insufficient, so a resistor decade box is added in parallel to the sensor to simulate a lower temperature.
0:15:21 Successful Test: With the resistor decade box set to 8 kilo-ohms, the heater activates (drawing approximately 5 amps), and the temperature begins to rise.