This project is 4 dof robot arm controlledby Arduino mega 2560. The frame of the arm can be 3d printed. All joints are module designed so you can easily change the number of joints.
Step 1: Hardware Joints
The arm uses 4 deceleration stepper motors as effector. The original design was a 7 DOF robot, yet the motor can’t generate enough torque to drive the whole system. So the number of joints was reduced to 4.
The structure of the arm was designed as hollow structures to reduce the weight. All joints share the same module. 6 ball bearings are placed in joint module and tangent the shell to reduce the vibration while rotating.
Step motor is a kind of open loop component, which means it can’t feedback state of the arm. In order to control the arm with target angel of each joint , a micro switch was placed in each joint to detect the Initial point of each arm. Then the arm can controlled based on the Initial point (0 degree).
The CAD file is attched.
Step 2: Eletronic
The arm uses a Arduino Mega 2560 as central controller. The driver of step motor was designed with ULN2003A (Darlington tube), directly connected to digital IO of the Arduino.
Step 3: Control
The software of the arm is still under developing. I’m planning to use the computer control the arm via serial communction.
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