Abstract
To improve the programming efficiency of automatic assembly system, a novel skill programming framework based on task learning is proposed for modular assembly system in this paper. In this framework, the motion sequence of assembly skills can be modeled by demonstration data. And the assembly task is represented hierarchically. A complete assembly process of a part is divided into several skills, and each skill is divided into several sequential assembly motion primitives (AMP) of multiple modules. Then, a learning method of assembly motion sequence based on Hidden Markov Model is proposed, and the maximum probability method is used to generate the optimal sequential AMP. Each AMP is input to the assembly system in the form of instruction to complete the assembly. Aiming at the problem of accurate positioning and trajectory planning, visual guidance and direct teaching method are used to settle this problem. To evaluate the viability of the proposed framework, a customized modular assembly system is used to acquire the demonstration data, and a graphical user interface (GUI) software is designed. Five assembly skills are learned. Experimental are conducted to validate the effectiveness of the proposed method.
Highlights
With the development of automatic assembly for custommade and low-volume, the automatic assembly system needs to have the ability to transfer from one task to another efficiently [1]
A new skill learning framework is presented, which regards the skill as a serial of assembly motion primitive for modular assembly system
In the aspect of high-level structured demonstration and learning, the proposed method is successfully applied in a modular assembly system for new task
Summary
With the development of automatic assembly for custommade and low-volume, the automatic assembly system needs to have the ability to transfer from one task to another efficiently [1]. Because different types of sensors have their own limitations, the modular assembly system integrating multiple sensors can meet the requirements of complex assembly tasks. In addition to trajectory teaching, the modular assembly system has functions such as image processing [2], force feedback control [3], IO control, multi-modular parallel or serial control, and collision detection [4]. The modular assembly system has the characteristics of multiinformation fusion, complex coordination, and diverse control methods [5]. In the traditional programming of automatic assembly process, writing computer code and the use of teach pendants are the predominant method.
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