Refurbished Robotic Arm (2019)

#Robotics #Solidworks #Arduino #C++ #3D-Printing

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SUMMARY

The advancement of robotics technologies over recent years has redefined what humans and machines are capable of achieving together. Over time, researchers and enthusiasts alike have worked on numerous aspects of this field to bring incredible ideas into life. One of the many branches within the domain of robotics is the use of robotic manipulators. Although first used as a means to handle dangerous tasks, manipulators have found their way into different sectors of industry and academics. Recently, the College of Engineering at the University of Nebraska - Lincoln purchased a Scorbot ER-VII robotic arm to educate students about the fundamentals of robotics. This manipulator, first manufactured in the mid-1980s, utilizes a controller and a teach pendant that can be used to execute simple commands. However, one significant drawback of the controller is its size. At the time of production, the available technologies constrained the manufacturer to build a controller that is over 1992 cubic inches in volume and weighs nearly 42 pounds. Hence, in fulfillment of the senior design project, our team was tasked with creating a new controller module using modern-day electrical components to increase the transportability of the system that is to be used as an educational tool by future students to learn the fundamentals of robotics kinematics. The approved deliverables for redesigning the controller module, along with the accompanying user interface were as follows:  

1. Case Design

  • Compact, enclosed case for all controller components

  • 50% reduction in size and weight(final volume under 996 Cu. In. & final weight less than 21 lbs)

  • Ability to support a 10lb static load
     

2. Minimum Power Requirements

  •  Provide at least 12 volts at 2 amps per motor
     

3. Command Execution

  • Software developed in C++

  • Process encoder signals from each motor

  • Allow command-line input
     

4. Functionality

  • Maintain the full range of motion outlined in Scorbot VII user manual

  • Operate the arm with a maximum payload of 4.4 lbs

  • Manipulate the robot by rotating each motor individually

The aforementioned project was done in accordance with the final project requirement for MECH 447: Mechanical Design II at the University of Nebraska-Lincoln. This group project was accomplished in a span of 15 weeks during the Fall 2019 term. Other members of the team included Drew Jerred and Connor Kaeding. Within the allocated time for this project, the design team held weekly meetings throughout the semester with the sponsor of this project, Dr. Carl Nelson, to provide updates on the progress and adjust the output result based on the specific needs of the sponsor. At the end of this period, the aforementioned deliverables were successfully met. A compact case with a volume of 154 cubic inches and an overall weight of 0.89 pounds capable of supporting 10 pounds of the external load was 3D printed. The prototype’s cost was $287.84, with a custom-designed PCB taking $67.00 of the expenses. Moreover, sufficient power was successfully provided to operate the motors. Command execution and functionality deliverables were also achieved.

 

The full report detailing the approach to accomplish the above tasks with justifications to the decisions made for each phase can be found below. 

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