Technology

Jun 21 2013

Using videos to improve operations | Part 6 – Quick simograms

Here, we finally start collecting measurements from the video, focusing on what we can collect while watching without stopping. In this mode, we can break down operator time by broad categories like  “Waiting,” “Walking,” or “Assembling,” but we don’t have the time to name each task and collect comments or improvement ideas. This will require a more detailed and time-consuming analysis. 

One method, developed by Christophe Caberlon, involves two analysts, one viewing the video and the other one filling out an electronic spreadsheet. Instead of looking for state-change events in the video, we look at it in 5-second increments. Every five seconds, the analyst viewing the video calls out the state the operator has been in since the previous call. Each 5-second. Interval is assigned one column in the spreadsheet and there is one row for each state. Based on the call, the second analyst switches the color of the cell for the state and time interval.

Counting in 5-second intervals involves aliasing, but it is not a problem for a rough-cut estimate. The rows in the spreadsheet do show the state transitions in a Gantt-chart like format called “simogram,” and can summarized into proportions of time spent in each state, as in the following example:

Simogram example

This example uses cell background color to express content, which is not generally recommended because Excel does not provide built-in tools either for quick input or for analysis. The result, however, is graphically much more attractive than filling the cells with Xs. Changing the background color of a cell requires multiple steps, which cannot be repeated every five seconds. These steps, however can be recorded as a Macro. In this example, the macro has Ctrl+q as a hot key to mark a cell and Ctrl+w to unmark it. Also, each 5-second time segment must be assigned to one and only one category. When working your way through a video, it is impossible to avoid cases where one segment will be missed and another accidentally assigned to more than one category.

To detect these errors, we need to count the gray cells by column, and to summarize the times into relevant aggregates, we need to count them by rows. While Excel provides no built-in function to do this, you can find add-on modules to do it. The modules used above are due to C. Pearson. 

This method is also restricted in the number of states to track. It is feasible for two or three but not fifteen. With the limited number of choices, it is a good idea to include an “Other” state. The states should also be clear and unambiguous, such as:

  • Walking: the operator’s legs are moving.
  • Working: the operator’s hands are moving.
  • Waiting: all the operator’s limbs are still.
  • Touching: One of the operator’s hands is touching the product.

Categories that are abstract and subject to interpretation, like “Value-added” should be avoided. Note also that an operator who is Working or Touching, may be handling the work piece or transforming it, and we don’t have enough categories at this level to make the difference. 

Timer Pro provides a method called “Non-stop timing,” in which the analyst simply clicks on a category when observing a state transition, and the time since the previous click is automatically assigned to this category. This eliminates the aliasing due to using 5-second intervals, and relieves one analyst from the task of clicking the right spreadsheet cell every 5 seconds.

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Jun 8 2013

Using videos to improve operations | Part 5 – Watch it in fast motion

Christophe Caberlon has a special way of conducting this first step: at 6X normal speed. When reviewing videos with the operators who have been recorded, he has found that accelerated motion has the effect of drawing attention to the activities that consume the most time, as the ones that do not are filtered out. If the operator spends the majority of the time walking back and forth to a shelf to pick parts, a fast-motion viewing of the recording makes it dramatically obvious and compelling, making the operator eager to help improve the process. After trying various 2X, 4X and 8X, he has found that the 6X ratio of acceleration works best for this purpose.

When Christophe  told me about this, it reminded me of a scene in the movie The Hunt for Red October, in which sound is used the same way. Jonesy, the sonar operator in the American submarine tracking the soviet submaring Red October, has just heard the sound of the propellers disappearing when the Russian boat turned on its “silent” propulsion system. But he still heard a vague rumbling. The analysis software categorizes this sound as magma displacement, but the sonar operator believes that the sound is made by the submarine. To convince his captain of that, he plays the recording at 10 times the speed, which turns the rumbling into a rythmic “tac tac tac” characteristic of a human artifact and not magma displacement.

The idea of watching the video in fast  motion is that, by filtering, it lets you see patterns you would otherwise miss. The same is true of slow motion, but fast motion has the advantage,… of being fast. You wouldn’t want to review an entire 1-hour video in slow motion, but you may do it in a few excerpts as part of the detailed analysis we will go into in a coming post.

Of course, the idea of reviewing a video in fast motion is more interesting if you can actually do it, and the most common video players around don’t let you run at 6X. I tried the following:

  • Quicktime V. 7.7 through “A/V controls” lets you run videos at speeds up to 3X.
  • Windows Media Player does not let you change the speed.
  • Real Player lets you change speed by powers of two by pressing Ctrl-Shift-F4, but the resulting accelerated videos are not watchable.
  • VLC media player lets you use any speed up to 4X, and powers of two beyond, up to 32X.

Among video editors, Windows Live Movie Maker lets you change speeds, but Google’s Picasa 3 doesn’t. For Windows Live Movie Maker, it is again in powers of 2.

In video annotation software, ANVIL doesn’t do fast-motion, but Timer Pro does. To view a video in 6X in Timer Pro, you click on the Video tab and set the speed to 12. The video then plays at the right speed but the a wrong aspect ratio. If, however, you click on the Comparison tab, you can view at 6X normal speed and with the correct aspect ratio, albeit in a small window that you cannot adjust.

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May 31 2013

Using videos to improve operations | Part 3 – Shooting shop floor videos

Following are a few recommendations on the art of taking shop floor videos:

  1. Special requirements on shop floor videos. We have already seen that the requirements for shop floor videos differ from those of other uses of this technology. If you shoot a family or sports event, you will naturally want the highest resolution you can get, which would be counterproductive here. Likewise, shooting a video for the purpose of data collection is different from doing it for art or entertainment.For example, the Youtube video of a NASCAR pit stop looks somewhat like a shop floor video but isn’t one. It is entertaining and dramatically shot, but not usable for analysis. In fact, a shop floor video that captures everything that is needed for analysis is likely to bore anyone who is not directly involved with the target process.

    This needs to be considered when deciding who will be holding the camera. You will naturally prefer someone who is already handy with it, and that is likely to be from experience capturing family occasions, sports, or from making movies as an amateur. The ability to keep a camera steady and pay attention to lighting, composition and focus is valuable, but the camera operator will have to be coached on the specific objectives of shop floor videos.

  2. Applications to setup time reduction or to the improvement of a work station. the camera needs to be looking down at the operator’s hands. In short operations, it can be done by holding the camera with a raised arm, and using the swiveling LCD screen for control. This gets tiring quickly and requires standing in such close proximity to the operator as to possibly interfere with his or her movements.
    Many plants have mezzanines or catwalks that provide a view from above. Being observed from such a place, however, may be uncomfortable for the operators, as well as too far to zoom in on the hands and capture any voice comments. The middle ground is to shoot from the top of a stepladder located within zooming and hearing range of the operator station, just far enough to avoid any kind of interference

    Amin recording operation
    Shooting a video from a stepladder.

    This works, until the operator leaves the station to walk beyond the reach of the zoom, at which point getting down off the stepladder to follow the operator while recording causes a few seconds of the action to be lots. A better solution is to hand over the camera to another team member on the ground, or even to involve more than one camera. In any case, this needs to be planned. Image stability is not an issue on the stepladder, but it is when following an operator’s movement across the floor, and you do not want a video that will make participants sea-sick during review. While professional tracking shots require equipment that is not available in a factory, some amateurs have supplemented the camera’s own image stabilization by shooting from a wheelchair.

  3. Fixed position on a tripod for time-lapse videos. Setting the camera on a tripod in a fixed position is not appropriate for this kind of analysis, but is when taking time-lapse videos of a large area for purposes of work sampling.
  4. Recording the position and orientation of the camera. It is also necessary to record on a layout of the shop floor the position and orientation from which the video is shot. The point is to return to the same location to shoot another video to document the improvements once implemented.
  5. Number of repetitions. Traditional time studies involve taking measurements on the same operation 6 to 10 times, for the purpose of improving precision when setting standards of operator performance. But our purpose in recording operations is not to set standards but to change processes to make the work simultaneously easier, safer, less error-prone, and faster.
    All we need for this purpose is one representative execution, and the operator can tell us if there is anything special or abnormal about it. If possible, we just take it into account during the analysis; otherwise, we make another recording. To make sure we have one complete execution, we start recording a few seconds before the operation starts and stop a few seconds after it ends.
  6. Scale. The presence of people in the videos gives us at least a rough sense of scale, but sometimes we would like more precision, for example to know how far an operator has to reach for a part, or how fast a cart is rolling. The following shots show the extreme measures the Gilbreths took for this purpose, with a gridded background. The picture also shows a large and precise timer, which was necessary because they used imprecise hand-cranked cameras.
  7. No editing. We do not edit the shop floor video, except possibly to add a title and administrative data at the beginning, Otherwise, we use it in the analysis exactly as shot. It is raw data, and we want to keep it that way.

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May 29 2013

Using videos to improve operations | Part 2 – Management Preparation

Whether on the shop floor or elsewhere, starring in a video makes people nervous, particularly when they don’t know how it will be used and when it is done by strangers. On the shop floor, particularly when unions are present, operators fear that the videos recordings will simply be used against them and to  justify layoffs. Unless these fears are put to rest before the shoot, it will be tense and, if it happens at all, the quality of the data will be affected.

Following are key steps to follow:

    1. Have a clear objective. Videos can be used for many purposes:
      • Setup time reduction. This is the most common current use in Lean implementation.
      • Work Sampling. A time-lapse video of a work area can be used as a series of snapshots on which to count the people and machines by category of activity, providing rough estimates of proportions of time spent walking, waiting, carrying parts, processing work pieces, etc.
      • Analysis of team coordination. You record from a distance the movements and state changes of multiple people and machines. You don’t see the details of what each one does, but you identify situations where they:
        • Walk long distances, empty-handed or carrying heavy parts,
        • Cause others to wait,
        • Deadlock each other,
        • Fix the work done by others,
        • …
      • Details of work done at an individual station. You focus on the hands of one operator through a sequence of steps at a work station, with the goal improving both individual steps and their sequencing.
      • …

      This is necessary not only to plan the shoot so that the video supports the objective, but also to identify the people who will be recorded and the ways in which the analysis may affect them.

    2. Secure the consent of the participants. The people recorded in the video are not the object of a project but participants in it. It should only be done if they and their management agree. This entails the following:
      • Review the project with the direct supervisor of the area first, and proceed only if he or she supports it. The supervisor needs to agree to let operators participate in video analysis sessions, during work hours if they can be temporarily replaced in production, and in overtime otherwise.
      • If the plant is unionized, review the project with the union leadership. Unless prevented from doing so be constraints external to the plant, unions support the project once they are reassured that:
        • The purpose is not to make people work harder.
        • It is no threat to job security.
        • It usually improves safety.
      • Review the project with the operators, in the presence of their supervisor and a union representative if applicable.
      • There must be a clear policy on the handling and dissemination of videos after the analysis. The principle to follow is that what happens on the shop floor stays on the shop floor. The videos are not to be shared with any outsider to the project. VHS cassettes were easy to safeguard; MPEG files on hard disks are a different challenge. They need to be organized in a video database with proper indexing and safeguards, which is a whole other subject.

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May 24 2013

Using videos to improve operations | Part 1 – Overview and Motivation

This is the first in a series of posts about  the use of video technology to improve operations. This technology is now so pervasive that it is nearly impossible to buy a phone that does not include a camera capable or recording footage that is good enough for broadcast news. Journalists use amateur videos to show storm damage or expose human brutality. We use it to identify improvement opportunities in operations.

For long-time followers of this blog, this is closely based on comments I posted 18 months ago about a news article on the application of a sports video analysis package to manufacturing. The forthcoming installments, on the other hand, are completely new. 

Contents:

Frank and Lillian Gilbreth did it 100 years ago

Motion pictures have a long history in manufacturing. In 1895, the first film ever publicly projected onto a screen showed women leaving the Lumière Brothers factory in Lyon. In 1904, the American Mutoscope and Biograph Company shot several scenes in Westinghouse factories. In 1913, Frank and Lillian Gilbreth were probably the first to use this new technology to analyze operations, and a compilation of their films is available on line, which shows that, from the very beginning, the camera was much more than a substitute for the stopwatches used by Taylor. As is obvious from watching the Gilbreth films, where Taylor measured in order to control, the Gilbreths observed in order to improve. Taylor’s greater fame or notoriety, however, obscured this fundamental difference in the public mind, and made workers as wary of cameras as of stopwatches.

According to psychologist Arlie Belliveau:

“The Gilbreths used workers’ interest in film to their advantage, and encouraged employees to participate in the production and study of work through film. Participants could learn to use the equipment, star in a film, and evaluate any resulting changes to work practices by viewing the projected films in the labs or at foremen’s meetings. Time measurements were made public, and decisions regarding best methods were negotiated. By engaging the workers as participants, the Gilbreths overcame some of the doubt that followed Taylor’s time studies.”

In other words, these pioneers already understood that, unlike the stopwatch, this technology enabled the operators to participate in the analysis and improvement of their own operations.

Until recently, however, the process of recording motion was too cumbersome and expensive, and required too much skill, to be massively practiced either in manufacturing or in other types of business operations. In addition, most managements failed to use it in as enlightened a way as the Gilbreths, and manufacturing workers had a frequently well-founded fear that recordings would be used against them. As a consequence, they were less than enthusiastic in their support of such efforts.

Use in Setup Time Reduction

Setup time reduction is probably the first type of project in which it was systematically used, first because the high stakes justified the cost, even in the 1950s and second because its objective was clearly to make drastic changes in activities that were not production and not to nibble a few seconds out of a repetitive task by pressuring a worker to move faster.

The Vanishing Cost of Shooting Videos

Technically, the cost of shooting videos has not been an issue since the advent of the VCR in the 1980s. Analyzing a video by moving forward and backwards on a cassette tape, while it appears cumbersome today, was far easier than dealing with film. The collection of data on electronic spreadsheets also eliminated the need to use counterintuitive time units like “decimal minutes.” Adding columns of times in hours, minutes and seconds was impractical manually but not a problem for the electronic spreadsheet.

With videos now recorded on and played back from flash memory, and free media-players as software, not only is moving back and forth in a video recording is easier, but the software maps video frames to the time elapsed since the beginning. We could manually transfer timestamps read from the bottom of the video player software window into electronic spreadsheets and have the spreadsheet software automatically calculate task times as the differences between consecutive timestamps.

Analyzing Data in Video Form

While this approach has been a common practice for the past 15 years, video annotation software is available today, which helps break down the video into segments for steps, label them, categorize them, and analyze them.

You can also use it to structure the data and generate a variety of analytics to drive improvements or document the improved process through, for example, work instructions. Over the previous approach, video annotation has the following advantages:It automates the collection of timestamps. Reading times on the video screen and typing hem into an Excel spreadsheet is tedious and error-prone. Plowing through the details of a 30-minute is tedious enough already.

  1. Within the annotation software, each video segment remains attached to the text, numeric or categorical data you attach to it. One click on the data brings up the matching video segment.
  2. Using parallel tracks, you can simultaneously record what several people and machines do. Of course, you can do that without annotation software too, but it is more difficult.
  3. You can still export the data you collect and analyze it in Excel, but you can also take advantage of the software’s built-in analytics.

“Video time studies” is too restrictive a name for what we do with videos. It implies that they are just a replacement for a stopwatch in setting time standards. But what we really do with videos is analyze processes for the purpose of improving them, and this involves more than just capturing times. The primary pupose of the measurements is to quantify the improvement potential to justify changes, and to validate that they have actually occurred.

Remaining Challenges

Putting this technology to use is not without challenges. Video files are larger than just about any other type we may use, be they rich text, databases, or photographs. And they come in a variety of formats and compression methods that make the old VHS versus Betamax dilemma of the VCR age look simple. More standardization would help, and will eventually come but, in the meantime, we have to learn more than we want to know about these issues. Functionally, the next technical challenge is the organization of libraries or databases for storage and retrieval of data captured in the form of videos. The human issues of video recording and analysis of business operations, on the other hand, remain as thorny as ever.

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