In this paper, we proposed an algorithm that can move robot manipulator with constant velocity in robust stability. The moving velocity of arm is controlled by an algorithm of the adaptive impedance control, which increases operation efficiency and keeps the advantages of the impedance control. This control algorithm will satisfy practical and efficient applications, such as manipulator control that assist safely in feeding impaired patients. The manipulator is firstly based on 1 DOF robot arm which rotates in the vertical plane. The effect of gravity was eliminated by robust control. The algorithm of robust adaptive impedance control increases operation efficiency and operation stability. Furthermore, the impedance with the robust control design eliminates the steady state error which is caused by the static friction, and the reaction torque observer reduces the ripple of torque and smoothes the output of velocity.
The objective of this paper is to present the development of 3D digital manufacturing through synchronous 5-axes printing for greatly enhancing the strength of the printed parts. In traditional fused deposition manufacturing (FDM), which is one of the digital manufacturing technologies, the melted material is required to be extruded from the nozzle on the workspace platform with a fixed direction. The strength is restricted in the direction of perpendicular to the layers since the printing way is layer by layer. The poor adhesion between the layers becomes a weakness to resist external force, especially when the force exerted from different directions. In this paper, algorithms for synchronous five axes printing based on the surface printing trajectory has been proposed to overcome the lack of strength issue. A five axes synchronous 3D printing machine developed in our NTU Intelligent Robotics and Automation Lab enhances the strength of the printed parts by adding additional materials to the surface of the parts. Five axes printing can achieve the goal of printing in different orientations so that the strength of the printed parts is greatly enhanced in comparison with the printing in a fixed direction only. The five axes synchronous 3D printing has been successfully demonstrated in physical printing. The strength analysis of printed parts is also performed under the three-point bending test and the tensile test. It shows that the strength of the five axes printed sample is increased by nearly three times in the bending test and nearly two times stronger in the tensile test.
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