Mechanical

Overview

The robot is based on the idea of being simple yet effective. It has three core mechanical systems, being the grabbing mechanism, the arm reaching system (x-axis), and the arm raising system (z-axis).

Grabbing mechanism

Initially the grabbing mechanism started as a four-bar. After a few iterations, the team realized that using a servo motor is more efficient so the servo was mounted to the third iteration of the four-bar. To minimize the space the mechanism takes up, it was put on a hinge and a servo was mounted above it that uses fishing line to lift the mechanism.

Since the robot will only play horizontal blocks on one side of the tower, it needs to check for a center block to be able to play. An IR sensor was placed at the end of the mechanism as to tell if there is a center block in the jenga tower.

Arm Reaching Mechanism (X Axis)

The system starts with the dresser sliders being mounted onto an aluminium block that is bolted onto the z-axis system. From there, two aluminium brackets were mounted to the long end of the dresser sliders allowing the system to move the necessary length.

A rack and pinion system was used to move the arm mechanism in and out. The rack was mounted directly on the brackets and the gear was mounted to a stepper motor which was mounted onto the z-axis system.

Due to there being a size requirement for the robot, the dresser sliders were cut down by 6 cms to fit inside of the player area.

Arm Raising Mechanism (Z Axis)

Most of this system was scavenged from a high speed assembly robot found in the robotics lab. The main components being a threaded rod and a guide rod. The threaded rod has a threaded bearing system unique to its threading. An aluminium block was mounted to the bearing base as to allow us to mount the x-axis system. A bearing unique to the threaded rod was then zip tied to the threaded bearing base which inhibits rotation of the bearing base around the threaded rod while allowing vertical movement. Plastic mounts were manufactured and mounted onto the base board to keep the both rods vertical at all times. A DC motor with an encoder was used to turn the rod which caused the bearing base to move up and down.