Abstract: Solving actual high-precision rotation axes of revolute pairs is one of significant initiatives to improve running-precision of a set of equipment. As a classical approach, least square method is difficult to obtain appropriate fitting straight line when measured spatial points are intensive. It was found, through the study on the problem, that least square method causes a 90° deflection easily, that is, straight line after deflection locates in a vertical plane of the ideal straight line, and that the reason resulted in deflection is that distance function of least square method is not a single extreme value function, the occurrence of deflection reaches only one of the minimums rather than the extreme minimum in fact. In order to prevent the deflection, a production system based-on fitting method was proposed for spatial straight line fitting. First, the proposed method specifies a basic direction for the fitting line, and then sets the differential change, at last, through limited iteration, the ideal fitting straight line can be found. The proposed method can effectively avoid the deflection of adopting least square method of straight line fitting, and has been proved with a high value of application in practice through the real joint axes measurement of a robot.
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Received: 10 March 2009
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