Global Controls Design Brief : A-Arm Inspection Cart

Global Controls is here to help you integrate PLC, Motion Controls or Vision products into your machine. We are the product integration group for RSA consisting of engineers, technicians and support staff. Below is a Design Brief recently completed by Global Controls. 

Project Description: Design and manufacture of a mobile, machine vision inspection cart to provide pass-fail status of all A-arms produced. 

Design Criteria/Objectives: 

  1. Able to determine if assembly of A-arm was correct.
    1. No missing critical components.
    2. Manufactured in correct orientation.
    3. Coated with correct color.
  2. If inspection failed, show user details of failure.
  3. If inspection passed, notify user to place in shipping container.
  4. Prevent operator from testing the same part twice in a row.
  5. Able to train vision system on new parts.
  6. Be able to move to multiple locations within facility.
  7. Easy to use.
  8. Able to plug into a standard wall outlet.
  9. Create and print shipping container tag once criteria is achieved.

Project Obstacles: 

  • A-arms are produced across seven (7) different families of vehicles
  • Multiple variations within each family
  • Multiple colors within each family
  • A-arms are produced in various 3-dimensional orientation.
  • Had to print shipping container label to end-customer specifications.

The Answer: 

Designed and manufactured a cart utilizing a Teledyne Dalsa machine vision system with two (2) 9 MP area scan cameras – (1) monochrome and (1) color. The monochrome camera was trained to inspect the assembly for the correct configuration of the critical area, and the color camera was trained to verify the assembly’s orientation and color. 

A Unitronics HMI/PLC was used to control the system and provide feedback to the operator. After each part inspection, it notifies the operator if the part passed or failed. If passed, the operator is provided with further instructions. If failed, the operator is provided with reasons for the failure and further instructions. The HMI/PLC tracks and displays the number of “good” parts and upon completion of a storage bin, or the end of a job run, prints a bin sticker via an on-cart thermal transfer printer. 

Since the A-arms are in varying 3-dimensional profiles, Rockford process developed a flexible part holder. Each holder fixed the orientation of the critical portion of the assembly. This allowed for the area scan cameras to be mounted directly above the table reducing the setup time of each inspection.

Proximity sensors buried within the part holder and PLC logic prevents the operator from inspecting the same part with rapid succession.

The electrical system is designed and manufactured to NFPA 79 and UL 508a standards.

Pat Klingberg, Director Global Controls Inc. Special Thanks to Rockford Process Controls Inc for use of this application.