Abstract
A vision-based three degree-of-freedom translational parallel manipulator (TPM) was developed. The developed TPM has the following characteristics. First, the TPM is driven by three rodless pneumatic actuators and is designed as a horizontal structure to enlarge its horizontal working space to cover a conveyor. Then, a robot-vision system (including a webcam mounted on the TPM) collects images of objects on the conveyor and transfers them through the LabVIEW application programming interface for image processing. Since it is very difficult to achieve precise position control of the TPM due to the nonlinear couplings among the robot axes, feedback linearization is utilized to design an adaptive interval type-2 fuzzy controller with self-tuning fuzzy sliding-mode compensation (AIT2FC-STFSMC) for each rodless pneumatic actuator to attenuate nonlinearities, function approximation errors, and external disturbances. Finally, experiments proved that the vision-based three degree-of-freedom TPM was capable of accurately tracking desired trajectories and precisely executing pick-and-place movement in real time.
Highlights
Robotic manipulators are efficient at picking, placing, and assembling objects and at tracking movements
Motivated by the previous discussions, this paper presents an intelligent model-free control system for rodless pneumatic actuator (RPA)
The presented adaptive interval type-2 fuzzy controller with self-tuning fuzzy sliding-mode compensation (AIT2FC-self-tuning fuzzy sliding-mode compensator (STFSMC)) effectively attenuates the nonlinearities in the translational parallel manipulator (TPM), which come from two parts: (1) the pneumatic cylinder leads to its low stiffness and compressibility of air and large friction forces; and (2) the use of the valve leads to dead zones and varying rates of air flow through servo valves
Summary
Robotic manipulators are efficient at picking, placing, and assembling objects and at tracking movements. The third purpose is to develop robot vision and implement pick-and-place operations for the 3-DOF PM For these purposes, a 3-DOF TPM, driven by three horizontal-axial RPAs with the associated proportional directional control valve (PDCV), was developed for three-dimensional (3D) path tracking control. The presented adaptive interval type-2 fuzzy controller with self-tuning fuzzy sliding-mode compensation (AIT2FC-STFSMC) effectively attenuates the nonlinearities in the TPM, which come from two parts: (1) the pneumatic cylinder leads to its low stiffness and compressibility of air and large friction forces; and (2) the use of the valve leads to dead zones and varying rates of air flow through servo valves.
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