Construction Robot Position Sensing for Fast, Precise End-Effector Control
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Solution Overview
Problem
Construction robots face challenges in achieving high-speed and precise positioning of end effectors due to conflicts between speed and precision, with existing methods like using external total stations being slow and requiring continuous line of sight, and kinematic models being prone to errors from mechanical inaccuracies and vibrations.
Innovation Solution
Incorporating first and second position sensors on the lifting device and base, respectively, to measure actual positional data, and calibrating the kinematic model using these sensors to reduce errors, combined with temperature compensation and strategic use of external position measuring devices for calibration at discrete intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external total station is used to continuously measure end effector position, then position measurement is achieved, but measurement speed is very slow and positioning speed is reduced
Solution Approach 1:
The measurement system is segmented into two parts: a first position sensor on the lifting device for continuous high-speed measurement of lifting movements, and an external total station for periodic calibration. This segmentation allows each sensor to operate in its optimal performance range, resolving the contradiction between continuous measurement and measurement speed.
Solution Approach 2:
The first position sensor acts as an intermediary between the lifting device and the external total station. It continuously tracks lifting device position at high speed, while the total station periodically calibrates the sensor's reference frame. This intermediary approach enables high-speed positioning while maintaining measurement accuracy through periodic external validation.
2Measurement precision
If external total station is used for continuous measurement, then position data is obtained, but continuous line of sight is required which limits accessibility to all construction site positions
Solution Approach 1:
The first position sensor on the lifting device performs self-measurement of position without requiring external line of sight. It autonomously tracks its own position relative to the base, enabling measurement in positions where external total station cannot establish line of sight, thus improving adaptability while maintaining measurement capability.
3Productivity
If kinematic model with pre-calibrated solid model is used for position calculation, then positioning is achieved, but mechanical inaccuracies and vibrations cause significant positioning errors especially when lifting device is extended
Solution Approach 1:
The first position sensor provides real-time feedback on the actual position of the lifting device, which is used to continuously update and correct the kinematic model. This feedback mechanism compensates for mechanical inaccuracies and vibrations by comparing actual position measurements with model predictions, significantly improving positioning accuracy especially when the lifting device is extended.
Solution Approach 2:
The patent replaces reliance on purely mechanical kinematic model calculations with sensor-based measurement. Instead of calculating position based on mechanical linkages and pre-calibrated models prone to mechanical errors, the system directly measures position using the first position sensor, substituting mechanical computation with optical/electronic measurement to eliminate mechanical inaccuracies.
4Manufacturing precision
If first position sensor is added to measure lifting device position, then positioning accuracy is improved, but device complexity increases
Solution Approach 1:
The first position sensor is merged with the lifting device structure itself, using the device's existing movement and positioning mechanisms. The sensor leverages the lifting device's own position information rather than requiring completely independent measurement, reducing overall system complexity while improving positioning accuracy through the combination of mechanical positioning and sensor measurement.
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a construction robot (10) comprising a chassis (14), a base (12) arranged on the chassis (14), a lifting device (16) arranged on the base (12), and a robot arm (18) arranged on the lifting device (16) and equipped with an end effector (20), preferably multi-axis. It is characterized in that the construction robot (10) has a first position sensor (24, 26) configured to measure position data of the lifting device (16). The invention further relates to a method (1000) for controlling such a construction robot (10). The invention enables the robot to quickly and precisely reach working positions with the end effector (20).