Design and implementation of a cost-effective 4-DOF robot manipulator

Abstract

As an alternative to buying an expensive robot manipulator, this thesis has the goal of designing and implementing one from scratch. Specifically, a moderately large, cost-effective, yet accurate robot is to be implemented, that can be used in pick-and-place tasks. Costs are to be kept low wherever possible, and the implementation accomplishable even at home. Fully completing the project involves making numerous design choices in the design process. To accomplish the goal, there are multiple aspects to consider: materials, motors and drivers, arm segments and gearboxes, end-effector, frame of the robot, robot control, and electrical design. Some parts of the process are left out of scope of this thesis, but they will be completed myself.

As a result of the design process the final implementation will include: a structure of a SCARA robot arm, 4 degrees of freedom, NEMA 17 stepper motors, TMC2209 stepper motor drivers, a servo motor, limit switches, 3D-printed PLA and PETG parts, steel parts, pulleys, timing belts, ESP32 development boards, along other electrical- and more miscellaneous components. The robot is then 3D-modeled and implemented based on the design.

The finished robot is tested in a 1-hour long pick-and-place task, where it performs reliably. In addition, its repeatability and positional accuracy is measured. The repeatability is measured to be ±0.007 millimeters in horizontal movement, and ±0.0205 millimeters in vertical movement. The positional accuracy, in a task of placing two pieces 30cm apart, is found to be 1.5mm. The total estimated price, when counting parts used on the robot adds up to 382.09€. Therefore, the finished robot manipulator is found to adequately fulfill the requirements set in the beginning.

In the scope of this thesis the manipulator is tested and designed specifically for pick-and-place applications, but it could be easily developed further to fulfill its full potential. It could be integrated with advanced control software, which could include for example using computer vision to track objects, or it could be fully transformed into a laser engraver, CNC mill, or many other CNC machines by redesigning the end-effector and software.