Design and implementation of double H’-gantry manipulator for TUT microfactory concept
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This Master of Science thesis depicts the mechanical design and physical implementa-tion of double H’-gantry manipulator called DOHMAN. The H’-gantry mechanism is belt driven, two dimensional positioning device in which the belt is arranged in capital “H” form, and enables one linear and one rotary movement. The Ball-Screw Spline, in addition, is mechanism that consists of Ball Screw Nut, Ball Spline Nut, and Lead Screw with screw and spline grooves that fit both nuts. This mechanism enables linear and rotary displacement along the same axis. The DOHMAN robot is made of two par-allel kinematic H’-gantry structures linked with a miniature Ball Screw-Spline mecha-nism. The resulting structure is capable of performing four degrees-of-freedom (DOF) displacements along the three Cartesian axes X, Y and Z as well as a rotation W around the Z axis. The size and the other geometries of the DOHMAN robot aim to fit into the microfactory concept (TUT-μF) developed at Tampere University of Technology. For position control and visual servoing of the robot, an additional module was de-signed and implemented. Custom design of mechanical parts along with the selection of off-the-shelf components was done for building the robot prototype. The chapters and the appendix of this thesis thoroughly explain the design decisions and the implementa-tion. During the design development a new innovative homing strategy for linear Z and angular W axes was suggested and later implemented. This innovative homing provides efficient use of space for mounting the limit switches, avoiding huge loss in the overall Z-axis movement, and significantly reduces the cabling issues in the moving structure. Besides the innovative homing, other advantages of DOHMAN are distributed actuation and homogeneous workspace. The distributed actuation decreases the overall mass of the moving structure and also reduces the cabling within the overall mechanical system. The consistency in the workspace eases the control of the robot because there are no regions to avoid while moving the end effector.