Ergonomics MURI & EMMURI Supported Assessments Within Proplanner

MURI or EMMURI

MURI comes from the Japanese concept for actions beyond one’s power. Standardization of the MURI ergonomics concepts originated from an Italian University. While Standard and Empowered MURI are largely similar in use Standard MURI, scores are based more on frequency, whereas EMMURI is more based on checkboxes.

Available in Assembly Planner as the preferred and default ergonomics system.
Available for BMOST and MTMUAS Calculated Time Study standards or Observed Time Studies.
Calculated time standards can be linked to default EMMURI codes.
Typically used for entire body movements.
User will get a score for each activity based on the individual work steps

Operation Level

Standard MURI

The picture below shows the sheet view in the standard MURI format. It is based on the counting of different actions. As you can see, there are numbers entered into the sheet that corresponds to the number of times an ergonomic motion must be performed within an Assembly Planner Activity.

For example, in the 'Bend' motion type for activity 220, there is a two, indicating that within activity 220 a level 1 Bend is performed twice. These numbers are then multiplied by the weighting factor set in the Ergonomics Tab in Options to come up with an overall score for the activity and for the sum of the type of Muri (Bend, Twist, etc.). There are nine types of Muri within the Standard Ergonomics setup.

You can also set the time-standard rank for ergonomics in the Ergo Options tab. You can specify whether the software first looks to observed or calculated ergonomic data when generating reports. The Time Standard Rank can be changed by clicking one-time standard and using the arrows on the right to move it up or down the list.

The defaults for 'Dominant Arm Factor' and 'Idle Time Coefficient' can also be set for use throughout Assembly Planner:

Dominant Arm Factor indicates the percentage of work to be performed by the dominant arm, as that is what is accounted for when doing an ergonomic study. For example, if the Dominant Arm Factor was .75 as shown above, and the worker performed 100 total actions, only 75 of them would count toward the ergonomic score.

Idle Time Coefficient is used to set a universal utilization rating within the ergonomics studies. If the Idle Time Coefficient is set to .8 as shown above, the worker is said to be working at the utilization of 80%. For example, if a worker performs 100 actions in the 8 minutes he is observed, but he has 2 minutes of rest due to the coefficient, the frequency would actually end up being 10 actions per minute.

Time Standard Rank is used during ergonomics rollups. If an observed time study and a calculated time study are present for a given activity, whichever one at the top of this list will be used in the ergonomics rollups.

EMMURI

In contrast to the frequency driven Standard MURI, EMMURI is largely checkbox based. Rather than count the amounts of time that a Type of Motion happens, the Empowered MURI uses checkboxes to see if the type of motion occurred within a Work Step. The frequency of the entire work step is automatically set by the number of times it is recorded in the activity during the calculated or observed time study.

In Operation Editor, a summary of the study is displayed. Notice that the value of the Motion is shown rather than the frequency (this can be seen in 00000027 Bend and Twist). There are seventeen types of MURI in the Empowered Ergonomics Setup.

Activity and Time Study Level

While the principle is the same, this is the level where the information is put into the system, so the changes are more evident. The Standard Ergonomics sheet looks the same, but now the fields are editable, and the IDs are the work steps within the activity and not the activities within the operation.

The boxes can be filled with numbers signifying frequency and these frequencies are used, along with the weights set in the Ergonomics Tab, to create a full study and reports.

The real difference is in the simple nature of the checkbox format. This format is shown throughout the Ergonomics Time Study section and is most commonly used as it is more user friendly, and contains more fields. Rather than count the frequency of occurrences manually, all work steps are automatically counted and the frequency is updated. This allows a user to simply check a box to show the level of the motion type.

Standard MURI Report – summarizes motion count by type for a given Activity, Operation, or Routing

Empowered MURI Report– summarizes motion count by type for a given Activity, Operation, or Routing. The Revised OCRA index is based on the frequency of repetitive motion and the severity of arm and hand-related scores in the EMMURI study.