Design of the robot : the Robotic Arm

Description :

The prehension unit is fitted with three servomotors for the rotation and a fourth one for the tigthening of the gripper.
The connection with the base is carried out by the fixing of the first servomotor with the help of two M3 screws.
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Modeling :

Design of the arm

Draft of the robotic arm (Pdf, 246 Ko)

Calculation of mass properties :

Mass properties and center of gravity determination are very important for selection of the servomotors (model, torque), especially the lowering arm servomotor (servo 2).

Propr_masse_bras_prehenseur.xls

Note : a calculation page permits to recapitulate each part influence and to adjust if necessary properties of the elements.

Mass properties with TopSolid'Design :

1°) we attribute a specific material to the servomotor to have a mass of 17 g.
Note : select the context Attributes

, the fonction Material

and choose : Manager materials. Then create a specific material (Mat_comp_Servo) in the category Miscellaneous, with density 1.72 kg/dm³.
2°) we open the ROBOT ASSEMBLY file and we apply the fonction Analyse element

with physical informations display to the Arm Tiny-S compact D.

Note : informations display concern the arm alone. To take into account the object to deplace (8 g in our calculation page), we have to modelize it in the sub assembly document and apply an appropriate material to it.

Servomotors rotations :

The design of the arm includes angular drivers to parameter its position. We just have to select the tool Modify élément , click on the arm to accede to the menu list of the four angular position parameters.