Robot Arm Vibration Control via Posture-Dependent Weighting
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Solution Overview
Problem
Robot arms with elastic links and torque transmission mechanisms experience vibrations during operation, leading to instability when the arm is in specific postures, as existing vibration control methods increase feedback and destabilize the system.
Innovation Solution
A robot control device with an inertia sensor and angle sensors that calculates and weights vibration information across multiple coordinate systems to adjust drive commands, reducing correction values and stabilizing the robot arm's operation even when close to specific postures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If vibration control is implemented by increasing feedback correction values to motors, then vibration of the robot arm is reduced, but the robot control becomes unstable when the arm is in specific postures
Solution Approach 1:
The patent changes the parameter of feedback correction values by introducing posture-dependent weighting. The correction values are dynamically adjusted based on the robot arm's posture, using weighting coefficients that reduce the feedback gain when the arm approaches specific postures (e.g., fully stretched positions). This prevents control instability while maintaining vibration suppression effectiveness in safe postures.
2Ease of operation
If the robot arm operates near specific postures (stretched positions), then the distribution of correction values to motors increases, but this causes control instability
Solution Approach 1:
The patent implements dynamic adjustment of feedback weighting coefficients based on real-time robot arm posture. As the arm approaches critical postures (detected via joint angle sensors), the weighting coefficients are automatically reduced, making the feedback control less aggressive. This dynamic adaptation allows the system to maintain stability across the full operational range while preventing instability near singular configurations.
Data Source
AI summary
A robot control device controls the operation of a robot including a base; a robot arm that has at least three links, at least three joint portions, and at least three drive sources; an inertia sensor; and at least three angle sensors. The robot control device includes a first coordinate system vibration calculation unit; a second coordinate system vibration calculation unit; a weighting unit; a third coordinate system vibration calculation unit; a correction value calculation unit that obtains correction values for correcting the respective drive commands of the drive sources based on vibration information in a third coordinate system, and the respective detected results of the angle sensors; and a drive source control unit that controls the operations of the drive sources based on the respective drive commands of the drive sources, the correction values, and the respective detected results of the angle sensors.