What Ergonomic Assessments and Time Study Measurements Does Proplanner Support?
Proplanner supports live and video-based Observed time measurement as well as the largest selection of Predetermined time standards available in any commercially available application. Additionally, Proplanner supports over five ergonomics assessment standards which also represents the broadest selection in the market.
More importantly, Proplanner also provides extensive integration between Time Study and Ergonomic elements in order to semi-automate and simplify the concurrent evaluation of human motion. Together with Proplanner’s extensive MUDA (waste) analysis feature, an engineer can define a sequence of human motion that can simultaneously be evaluated with respect to Time, Ergonomics, and LEAN.
While every time measurement method can be evaluated with Proplanner’s extensive MUDA feature, each time measurement method has unique attributes that lends itself to different ergonomics assessments.
The following table shows the current list of ergonomics assessment methods available for each time measurement standard along with if the ergonomics score calculation and reporting are performed internal to Proplanner or if it is exported to a user-definable MSExcel spreadsheet template.
Ergonomics standards are often changing so Proplanner often adds, and sometimes even modifies support for ergonomics and time standard integrations based on client or industry requirements, so it is important to keep Proplanner aware of any standards you are using or would like to use.
Time measurement methods in Proplanner are covered more extensively in their own Blog. As a quick overview, users can always determine Observed time from videos or by watching a process live. Additionally, users can select a single specific predetermined time standard from the seven publicly available standards or even work with Proplanner to provide support for their own internal custom standard.
Proplanner adheres to time standard rules as recently defined by their respective organizations, however, many of the commercial standards have features that can be modified by our customers, or even Proplanner, in order to meet specific corporate requirements.
While time measurement standards are typically fairly static, Proplanner has found greater dynamic evolution of Ergonomics Assessment methods. As such, while Proplanner has implemented the REBA, Standard-MURI, and EM-MURI methods input, calculation, and reporting internally, the EAWS and OCRA standards currently only have their posture input within Proplanner which is then exported to a user-provided MS Excel template so that calculation and reporting can be performed as desired by the client. This approach allows for maximum flexibility as those standards are currently rarer and tend to be changed more frequently. The following paragraphs will provide a quick overview of how Proplanner has implemented and integrated these various ergonomics assessment standards.
When the ergonomics tab is selected within the observed time study mode, the elements of the activity (ID, Description, Frequency, Time, RTT) previously entered in the observed time tab are automatically referenced in the ergonomics tab. The following sections detail how this task information is used for each of the supported ergonomics methods.
REBA
REBA (Rapid Entire Body Assessment) ergonomics studies within the Activity Editor through the observed time tab. When a specific task in the Ergonomics tab is selected, a score can be assigned to each category. The scoring reference guide is shown in the Ergonomics Motions tab above the editing sheet. Notes about the task's analysis can be added within the sheet.
Total A Score, Total B Score, Score A, Score B, Total C Score, and Total REBA Score are automatically calculated based on the REBA standard. The colors for the Total REBA Score are associated with varying levels of risk: red is a high risk, yellow is medium risk and green is low risk. The risk associated with each Total REBA Score can be changed in the Ergo Preferences window.
MURI
MURI (Standard or Empowered) is the dominant ergonomics assessment method developed within Assembly Planner and thus it offers both the greatest support for time standards as well as the most robust set of internally generated calculations and reports. MURI comes from the Japanese concept for actions beyond one’s power.
While in the Observed time mode, a video may be uploaded and used in both Observed and Calculated time modes. In order to complete an ergonomic study, elements must be created within the Time tab of the Time Study first.
Ergonomic Motions
As a posture is selected, the Ergonomics Posture tab will update with an image of the posture. Below are a few examples. These postures can be matched to the person’s posture in the video.
Posture Display 1
Posture Display 2
In this tab, a time standard must be selected (BMOST or MTMUAS) and activities must be present in the time tab or time study. Once the activities are present, an ergonomic study can be performed. With a video playing, the plus buttons can be clicked to record a start time and end time. The weights of objects, a force that must be applied, and walk steps that must be taken within activities are added to the sheet along with any notes.
Ergonomics Sheet View 1
Ergonomics Sheet View 2
RTT – Stands for Real Task Time and is the time adjusted based on the average utilization of the plant:
RTT = Time / Idle Time Coefficient
Keep in mind Idle Time Coefficient is set in Tools > Preferences > Ergonomics Tab
Static – Checking this box indicates that the operator is in a non-moving posture
Posture – The drop-down in this field is filled with the standard EMMURI postures and weighted postures. Selecting a posture will automatically fill in the following fields:
- X (mm)
- Y (mm)
- Z (mm)
- Weight (Lb)
If any of the above values are adjusted, then the Posture field will update automatically.
Actions – Number of Actions per minute on that task. The calculation is below.
Actions = Frequency * (Dominant Arm Factor / RTT (converted to Minutes))
Impacts on Score
Changing the fields below will have their corresponding impacts on the score for that task.
The boxes can be manually checked in most columns to represent the ergonomic impact. The impact is judged by standards that are automatically uploaded into the Code Lookup section as an ergonomics code.
Code Lookup Section
When these boxes are checked, the bars under the rows automatically change as a visual representation of the ergonomic impact in that particular area of study.
Aggregate Bars
Notice that some checkboxes are automatically filled as a result of the information filled in the weights of objects, a force that must be applied, and steps that must be taken within activities. These sections have certain criteria and the box checked can only be changed by altering the data that it references. They are grayed out to show that they are not directly able to be changed.
Auto-Checked Boxes
On the right side of the spreadsheet, the total score for the activity is added up and a visual representation of the severity of the activity is created.
Total Score
There are ways to control what data is shown by the spreadsheet using checkboxes located directly above the sheet. When "Hide Score Columns" is checked, the numerical values are not shown for each box.
Hide Score Columns
When "Use Standard (MURI) Score" is checked, only scores relevant to the calculation of the standard score are displayed. This also reduces the overall scores, as some of the categories have been removed.
Here are the fields that are removed from view:
- Forearm
- Frequency
- Force
- WristPosture
- Grasp
- Other
- Neck
- PushPull
Use Standard Score Box Checked
Reporting works very similarly for the various time standards. Reports can be generated for an Activity (i.e. one task that the operator performs which may involve many elements and postures), or for an Operation that represents a group of Activities performed by an Operator during a work cycle on a particular unit. When reporting ergonomics on an Operation you need to consider that not all activities in that Operation would be performed during a particular work cycle because some of those operations are optional while others are mutually exclusive. As such, you will want to select a particular vehicle model and options set when generating your report, or you will want the software to apply a probability percentage (i.e. take rate) on the ergonomic scores for each Activity in order to represent an “average” amount of ergonomic stress which might occur on a typical day.
Additionally, it is important to remember that both Observed and Predetermined time standards are documented in Assembly Planner concurrently. As such, it is possible that both studies exist for your activities and therefore their ergonomics assessments may have been conducted differently. Typically a company will decide to perform their ergonomics studies on EITHER their Observed or Calculated Time standards, however, Assembly Planner does provide the flexibility for both standards to be defined concurrently.
OCRA
OCRA (Occupational Repetitive Actions) Ergonomics Assessment is an ISO Metric ergonomic standard, popular in Italy, that calculates a total score on the routing level based on the ergonomic data within activities.
The first thing to do is populate the calculated time tab with time codes. With the ergonomic tab selected the task/activity highlighted in green shows which task/activity is being shown in the detailed view (within the activity module, it is always the activity that has been selected). The detailed view is shown with the descriptions and times recorded in the Time.
Like with MURI, the engineer simply checks the postures appropriate for the operator for each element in the activity.
EAWS
EAWS European Assembly Worksheet or EAWS is a tool used to identify ergonomic risk factors. This standard is often used in Germany and is closely supported by some of the MTM standards.
Proplanner has implemented this assessment as tables within the Element editor for Activities. This implementation is very similar to how the fields appear and are edited with MURI. Users can provide this attribute data for elements and then extract this information (for an Activity or an Operation) to an Excel template file for subsequent user-defined calculation and reporting. If interest in the EAWS standard grows and the standard's calculation rules and report formatting stabilize, Proplanner will be supporting internal calculation and reporting as well.
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