111.3.3 - Systems Approach

EMI/PWC Analysis

What is an "EMI/PWC" Chart?

- A Power-Work-Control (PWC) or Energy-Material-Information (EMI) Chart is an informal way to visually illustrate the relationships between how things flow through and connect within a system
  - By "things", we mean:
    - Power/Energy - Power input into the module, that (is typically) transformed/transduced to perform the work
      - Examples: Electrical Power, Pneumatic Power, Hydraulic Power, Mechanical Power, etc.
    - Work/Material - Result/Output of the power/energy input into the module (the work being done)
      - Examples: A gripper grabbing a part, a CNC machine moving an end mill into a part, a 3D-printer depositing material, etc.
    - Control/Information - Signals to and from the module (inputs & outputs)
      - Examples: An (input) sensor detecting whether or not a pneumatic piston is extended or retracted, an (output) 24V signal that opens and closes a pneumatic valve
  - EMI charts can help to identify potential problems or areas for improvement in the system, such as energy loss, material wastage, or inefficient information flow. They also facilitate the design and implementation of automation systems by specifying the interactions between the components of the system in a logical and comprehensive manner.

Making an EMI/PWC Chart

Because EMI's/PWC's are informal, there is not any "official" standard or format for PWC/EMI Charts, but the method shown below is recommended, as it is scalable for both simple (single-module) and complicated (many-module) Mechatronic Systems:
- Purple Arrows (from Control → Power) represent Outputs
- Orange Arrows (from Power → Work) represent Transformation/Transduction
- Green Arrows (from Work → Control) represent Inputs

Troubleshooting with an EMI/PWC Chart

An operator can use an Energy-Material-Information (EMI) chart to troubleshoot a mechatronics system in several ways:
- Identify the problem: By reviewing the EMI chart, the operator can identify where in the system the problem is occurring. For example, if there is a problem with the flow of energy, the operator can look for a break in the energy flow arrows on the EMI chart.
- Isolate the problem: Once the operator has identified where the problem is occurring, they can use the EMI chart to isolate the problem to a specific component or group of components. This can help the operator to focus their troubleshooting efforts on the specific component or group of components that are causing the problem.
- Identify the cause of the problem: By reviewing the EMI chart, the operator can identify the cause of the problem. For example, if there is a problem with the flow of material, the operator can look for a blockage in the material flow arrows on the EMI chart. This can help the operator to understand why the problem is occurring and what steps need to be taken to fix it.
- Check the control signals: By looking at the EMI chart, the operator can check the flow of control signals and see if there is a problem with the control system. This can help the operator to identify if the problem is caused by a malfunctioning sensor, actuator, or controller.
- Identify potential solutions: By reviewing the EMI chart, the operator can identify potential solutions to the problem. For example, if there is a problem with the flow of energy, the operator can look for ways to increase the flow of energy, such as increasing the size of the energy source or adding a new energy source.

3.3✔ CHECKPOINT

EMI/PWC - Dispenser System

For the Dispenser System pictured here & physically available in the IMO Lab (Room 114 in Building 24):
- Operate the system in both Auto & Manual mode
- Hint: Make use of the lights on the PLC & various sensors to help provide further context
Create an Energy-Material-Information (EMI) / Power-Work-Control (PWC) Chart for the "Dispenser" system
- Note: Look to the example EMI/PWC Chart of the "Pick 'N Place" System (pictured below & physically next to the Dispenser System)
Once done, upload documentation of your progress (text/pictures/gifs/videos) to your previously-created "Systems Approach Tools" project page on your portfolio website, including:
- Your EMI/PWC, compared side-by-side to the physical modules & components of the system
- Descriptions/summaries of what you did/learned

Sample EMI/PWC of "Pick 'N Place" System (Example Only) - Requires instructor action

"Pick 'N Place" System (Example Only, DO NOT Analyze)

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