I equipped my robot with gripper for moving the objests. Based on questions I will try to explain the construction and operation.
This gripper is intended to hold and move objects from one place to another. For this purpose it is enough to lift the object several milimeters from the floor. This simplifies the construction.
Maximum width of the object is 60mm at fully open jaws. Jaws are parallel at any position. It is done using 2 pairs of arms. The distance between arms in pair is 4 mm which allows to move them by 45° . Servo is connected using screwing sticks and ball joints. It is possible to use only 90° of the servo movement.
On the internal side of jaws there is thin neoprene to hold objects safely without excessive force.
Both parts are attached to aluminium plate. This plate is mointed to robot chasis on two plastic hinges (black pieces. Up/down motion is driven by microservo without fix connection to the plate. Servojust pulls the plate forward and this lifts the tips of jaws 1 cm up. Down it goes by gravity when the servo turns away.
The material used for all parts is aluminium. This you can cut and drill using simple tools even on kitchen table. Pieces are glued with metalic epoxy and screwed.
It is possible to use different materials and profiles.
I used squared 10x10 mm profiles and 12x10 U-shape profiles
I took advantage of these specific shapes. square profile fits inside the U profile which makes the construction robust.
.... will be ammended based on questions