Abstract
To tackle the jittering of a robot arm-tip, a novel method of the jittering mitigation is proposed. The key idea is to transmit the jittering to vibration of a mass block nested inside the jittering-mitigator. This method only requires the frequency of the jittering at the arm-tip. To verify the practicability of the method, a practical robot was applied through simulations and physical experiments. The jittering mitigator device can be directly attached to or detached from the arm-tip. The jittering at the arm-tip was first measured through experiments using accelerometers connected to the vibration and noise testing system. Then, the dominant frequency was identified through fast Fourier transform analysis. The theoretical parameters of the jittering mitigator were calculated accordingly. A model was established to simulate the jitter reduction effect of the mitigator. The results revealed a 68% reduction in the average amplitude of the jittering vibration at the arm-tip, which is corroborated by the experiment results. The proposed method could be applicable to all types of robots theoretically because it only requires computing the frequency of jitter.
Highlights
Trajectory accuracy and kinematic stability are the most important indicators of precision for a robotic arm [1,2,3,4,5,6]
Previous studies found that the arm-tip jittering of a robot can seriously affect its trajectory accuracy and kinematic stability under typical working conditions
The step motors in the joints of a robot substantially may contribute to the jittering vibration, which complicates the equation of motion
Summary
Trajectory accuracy and kinematic stability are the most important indicators of precision for a robotic arm [1,2,3,4,5,6]. All these methods require sophisticated real-time sensors and feedback systems, as well as control algorithms This challenge has limited the practical industrial applications of robot arms [10]. It is because passive vibration absorption methods ignore all the complicated and interrelated non-linearities to dissipate the vibration energy Such a simple damping system will require a substantial amount of additional mass, for the frequency range of a typical jittering vibration. The equations of jittering vibration at the arm-tip of a robot are much more complex than the simple resonance. In theory, it is applicable to any type of robot It integrates vibration transmission and damping into one system, which sets it apart from the existing active and passive control systems.
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