Z-Height Feedback End-Effector
The motivation behind this project was to add redundancy into the can grabbing process to correct for the unlevel surface the gantry sits on. In order to achieve this goal of z-height feedback, a limit switch was added to a rigid outer casing with the gripper mechanism attached to the inner housing. This inner housing moves separately from the outer housing, but is attached through four guide rails with springs. The guide rails help guide the motion of the inner casing straight up when a collision occurs while the springs work to restore the limit switch to it’s open state upon the can leaving the grip of the end-effector.
Side by side view of both end-effectors without the finger attachments.
Overall view of the final end-effector design.
Bottom view of the fully assembled end-effector. Shown is a view of the rack and pinion gear actuation method used for opening and closing the gripper fingers.
Top view of the cable routing opening.
Overall view of the installed end-effector. Also shown is the power distribution mount and the communication management mount.
Close-up of the installed end-effector. Shown are the two fingers used for gripping cans and the two pegs used for triggering the limit switch upon contact with a can.
Close up of the communication management mount. This mount includes a U2D2 board for dynamixel communication and a Maestro servo controller for reading the limit switch outputs.
Demos
This is a demo of the general control sequence for grabbing cans. As shown, the end-effector travels down until it makes contact with the can at which point it closes the gripper fingers. From here, it raises to a certain height to take the can to its placement position, and then repeats the previous process but instead opening the gripper fingers.
Full demo of the new end-effector being used to build a pyramid structure.