Mobile Robot Pose Measurement Using Accelerometer and Camera
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Solution Overview
Problem
Existing methods for measuring the pose and position of mobile robots using cameras, inertia sensors, and encoders are prone to errors due to incorrect camera pose and unreliable encoder signals, especially when the robot is not parallel to the floor, leading to increased sensing errors and low position-calculating performance at low speeds.
Innovation Solution
A method and apparatus that utilize an accelerometer to calculate the pitch and roll of a mobile robot without a pitch or roll gyrosensor, combined with a camera and encoder, to accurately measure the pose and position by determining uniform motion sections and compensating feature point coordinates, thereby improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If encoder signals are used to calculate feature point height and measure displacement, then position measurement can be performed, but sensing errors increase considerably when the robot pose is incorrect or not parallel to the floor
Solution Approach 1:
The patent introduces an accelerometer as an intermediary device to measure the robot's pose (pitch and roll angles) independently of the encoder system. This intermediary measurement allows the system to detect and compensate for pose variations that would otherwise cause errors in the encoder-based displacement calculation, thereby maintaining measurement reliability under pose variation
Solution Approach 2:
The patent replaces the purely mechanical encoder-based height calculation with a hybrid approach that uses inertial measurement from the accelerometer. By substituting the mechanical encoder signals with inertial data for pose measurement, the system eliminates the coupling between mechanical alignment and measurement accuracy, improving reliability when the robot is not parallel to the floor
2Measurement precision
If feature point registration is performed using camera and encoder, then absolute position can be calculated, but it takes a lot of time to register feature points
Solution Approach 1:
The patent performs preliminary pose measurement using the accelerometer before feature point registration. By pre-measuring the robot's pitch and roll angles, the system can compensate for pose variations during the image processing stage, enabling faster and more accurate feature point registration without requiring multiple adjustment iterations
Solution Approach 2:
The patent implements a feedback mechanism where the accelerometer continuously provides pose information that is used to adjust and refine the feature point registration process. This real-time feedback allows the system to maintain accurate position calculation while reducing the time needed for registration by avoiding repeated trial-and-error adjustments
3Measurement precision
If pitch gyrosensor and roll gyrosensor are used to measure pose, then pose measurement can be performed, but the device complexity increases
Solution Approach 1:
The patent makes the accelerometer perform multiple functions: it not only measures linear acceleration for motion detection but also derives pitch and roll angles by analyzing acceleration components during uniform motion. This multi-functionality eliminates the need for dedicated pitch and roll gyrosensors, reducing device complexity while maintaining pose measurement capability
Solution Approach 2:
The patent changes the operational parameters of the accelerometer by utilizing its acceleration measurement capability during specific motion states (uniform motion) to infer rotational pose information. By changing how the sensor data is interpreted and used, the system achieves pose measurement without adding dedicated rotational sensors, thereby reducing device complexity
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 reduces errors in displacement measurement and enhances the accuracy of position calculation by using the accelerometer to determine pitch and roll, and compensating for camera pose variations, allowing for reliable real-time displacement calculation and position tracking.
Implementation Method 1
an accelerometer measuring acceleration of the mobile robot in a forward direction
Implementation Method 2
a uniform-motion-determining unit determining whether the mobile robot belongs to a uniform motion section, an acceleration section, or a deceleration section
Implementation Method 3
calculating a pitch and a roll of the mobile robot in the uniform motion section, using the relationship between the measured acceleration in the forward direction and the acceleration due to gravity
Data Source
AI summary
A method of measuring pose of mobile robot, and method and apparatus for measuring for measuring position of mobile robot using the same are provided. The apparatus for measuring the pose of a mobile robot includes an accelerometer measuring acceleration of the mobile robot in a forward direction, a uniform-motion-determining unit determining whether the mobile robot belongs to a uniform motion section, an acceleration section, or a deceleration section, and a pose-calculating unit calculating a pitch and a roll of the mobile robot in the uniform motion section, using the relationship between the measured acceleration in the forward direction and the acceleration due to gravity.