IMU Thermal Stabilization for Drone Calibration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Quadcopter drones equipped with low-cost MEMS-based inertial measurement units (IMUs) face significant temperature-related sensitivity issues, leading to drift in gyrometric and accelerometric signals, which are not adequately corrected by existing calibration methods, particularly in mass production contexts where faster calibration is needed and recalibration without special instrumentation is desirable.
Innovation Solution
Incorporation of a heating component and thermal guide on the circuit board near the IMU, along with a thermal regulation circuit using PWM control, to rapidly stabilize the IMU temperature and store a polynomial bias/temperature characteristic for real-time corrections, allowing for both factory calibration and user-recalibration in a few minutes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional ambient temperature calibration is used, then calibration accuracy is improved, but calibration time becomes excessively long (around 3 hours)
Solution Approach 1:
The patent applies preliminary action by pre-heating the IMU chip to the target temperature (e.g., 50°C or 60°C) using a heating element integrated into the circuit board before calibration begins. This eliminates the need to wait for natural temperature stabilization during calibration, reducing calibration time from hours to minutes while maintaining accuracy by ensuring the IMU is already at the correct temperature when measurements start.
Solution Approach 2:
The patent changes the temperature parameter dynamically during calibration by using a heating element to rapidly adjust the IMU chip temperature to predetermined values (50°C, 60°C, etc.). This active temperature control allows the system to skip the long natural warming period and directly perform calibration at the required temperatures, significantly reducing total calibration time while maintaining measurement precision.
2Productivity
If fast calibration methods are used, then calibration time is reduced, but calibration accuracy deteriorates due to insufficient temperature stabilization
Solution Approach 1:
The patent implements feedback by continuously monitoring the IMU chip temperature during calibration and comparing it to the target temperature. Based on this temperature feedback, the system adjusts the heating element's power output to maintain the chip at the precise target temperature, ensuring accurate calibration measurements are taken only when the temperature is properly stabilized, thus maintaining accuracy while enabling fast calibration.
Solution Approach 2:
The system performs preliminary temperature stabilization by heating the IMU chip to the target temperature and maintaining it there for a brief predetermined period before taking calibration measurements. This ensures the temperature is fully stabilized and the IMU is ready for accurate measurements, achieving both speed and precision by eliminating unnecessary waiting time while ensuring proper thermal equilibrium.
3Device complexity
If heat-generating components are mounted on the same circuit board as the IMU, then device integration is improved, but temperature control becomes difficult due to heat diffusion
Solution Approach 1:
The patent applies local quality by creating a dedicated thermal zone around the IMU chip on the circuit board, isolated from other heat-generating components. This localized thermal management allows the IMU to be heated and temperature-controlled independently, ensuring stable temperature conditions for accurate calibration even when integrated with other components on the same board, thus resolving the conflict between integration and temperature control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces calibration time to under 3 minutes, enhances IMU bias correction accuracy, and allows for efficient recalibration without specialized equipment, improving attitude measurement quality by minimizing temperature fluctuations during flight.
Implementation Method 1
a heating component (28) capable of producing heat in a controlled manner is provided close to said IMU (26)
Implementation Method 2
a thermal guide (30) incorporated in said circuit board and extending between said heating component and said IMU so as to allow transfer to said IMU of the heat produced by said heating component
Implementation Method 3
a thermal regulation circuit, receiving as input said chip temperature signal and a predetermined set point temperature signal, and delivering as output a signal for controlling said heating component, so as to control the supply of heat to the IMU by function of the difference between chip temperature and setpoint temperature
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The drone's inertial measurement unit (IMU) is mounted on a main circuit board. The IMU (26) includes an internal temperature sensor that outputs a chip temperature signal (θ°chip). A heating element (36) is mounted on the circuit board near the IMU, and a thermal guide, incorporated into the circuit board, extends between the heating element and the IMU to allow heat generated by the heating element to be transferred to the IMU. This thermal guide may be, in particular, a flat metallic layer incorporated into the board, such as a ground plane. A thermal control circuit (44-62) receives the chip temperature signal (θ°chip) and a setpoint temperature signal (θ°ref) as input and outputs a control signal (TH_PWM) to the heating element to control the heat input to the IMU.This rapid temperature rise can be used to perform a complete IMU calibration in a few minutes.