In mid-2013, Komatsu introduced its D61i-23 crawler dozers, the standard-track EX and low-ground-pressure PX. The inconspicuous “i” in the designation stands for “intelligent” and means that these models incorporate Komatsu’s Intelligent Machine Control (IMC) system, which sets them apart from their conventional D61 counterparts with an ability to automate blade control from first rough cut to final grade. The net result, says Komatsu, is a significant productivity increase for both experienced and less-experienced operators, compared with machines running with conventional automated grade-control systems.
Construction Equipment had the opportunity to observe the IMC system in use when working with Komatsu to place a D61PXi-23 with the dozer specialists at Local 150’s (International Union of Operating Engineers) training center in Wilmington, Ill. Komatsu trained Local 150’s Chris Yanos and Kevin “Zip” Ackert on the IMC system, and then left the machine in their competent hands for more than a month. On a mild day in mid-April, CE editors spent the day with the operators as they worked the D61i and offered their comments on the machine’s design and performance.
Komatsu’s product marketing manager for Intelligent Machine Control, Derek Morris, who joined us at Wilmington, gave us a quick review of the D61i’s design features and the capabilities of the IMC system.
With conventional automated blade-control systems, Morris told us, the operator typically shuts off the system and dozes with manual control until approaching finish grade. If the system were switched on and the finish grade were at depth unattainable in a single pass, the machine likely would stall or slip its tracks in an effort to dive to final grade. An alternative approach, he said, would be to manually program in progressive offsets, digitally altering the depth of the final grade to make the tractor work in small bites.
The IMC system, however, Morris told us, has the “intelligence” to sense the load on the blade, and then to react to a given resistance by automatically adjusting the blade to sufficiently reduce the load, allowing the tractor to keep moving productively without tearing up the ground or wearing out the undercarriage.
“This is where the real intelligence of the new machine-control system resides,” said Morris. “The net result is that system will operate in its automatic mode from the first pass at the top of the existing elevation to the last pass at finish grade, assisting the operator to cut all the way down to the target design surface. An after-market system typically is used to cut only the final few tenths [of a foot].”
D61i design details
Yanos mentioned during our initial walk-around of the D61i that one of his first observations was that the blade-mounted antenna and the cables that connect the antenna to the machine, typical for conventional automated grade-control systems, were missing on the D61i.
“With all the hardware integrated into the machine, there’s less you have to carry out to the machine in the morning,” said Yanos, “plus, there’s the safety factor of not having to climb on the blade when it’s wet or covered with snow to connect the hardware.”
As Yanos observed, the external components required for a typical aftermarket automated blade-control system, including the blade-mounted GNSS (Global Navigation Satellite System) antenna—along with its mast, cables, and brackets—as well as blade-mounted orientation sensors, are absent on the IMC-equipped dozers.
Morris explained that the capability of all that hardware is packaged into IMC machines via a roof-mounted antenna (a cube about 4 inches square), chassis-mounted Enhanced Inertia Measurement Unit (which determines machine orientation 100 times per second, including mainfall, direction of travel, and crossfall), and Komatsu-designed, stroke-sensing hydraulic cylinders (raise, tilt, and angle) that precisely report blade position.
Integrating the hardware, said Morris, has a number of advantages. By placing the antenna on the roof, he says, “as-built” information (the present contour of the site) can be accurately measured at the tracks, no matter the actual location of the blade, and dozing progress can be transferred to the operator accurately in real time. And, reinforcing Yanos’ observation, the blade-mounted antenna and vulnerable cables are eliminated, he says, along with the need to remove these components at night to protect against theft and vandalism.
Another intelligent aspect of Komatsu’s IMC system, Morris told us, is that of dozing modes—“cutting and carry,” “cutting,” “spreading,” and “grading.” Cutting and carry accommodates the dozing technique of starting at the beginning of the cut and pushing to the end, allowing the machine to optimally load the blade, and then elevate the blade slightly to a carry position as it moves to the end of the cut.
The cutting mode is designed for operators who prefer to start the cut a few machine lengths from the end, and then to progressively reverse, taking short, aggressive passes in the process. In this mode, the blade raises and lowers as needed during the cut to retain an optimum load.
The spreading mode can be used, for example, when placing aggregate from a stockpile, and the simple grading mode reacts essentially as would a conventional aftermarket blade-control system.
“The system has control logic for determining how the blade loads and how the tracks react in different operating situations,” said Morris. “This lets operators customize the system to how they prefer to run the machine.”
In addition, the IMC system incorporates load modes—light, normal, and heavy—which are akin, said Morris, to the work modes on excavators and allow the machine to be further tailored to the material and application.
On site with Komatsu IMC
Local 150’s Ackert and Yanos are well-versed in automated grade control systems and teach the fundamentals of these systems to operators in the Local’s Apprenticeship and Skill Improvement Program—without neglecting, of course, the fundamentals of manual blade control. Operating the D61i, however, was the operators’ first exposure to Komatsu’s IMC system.
The IMC system, Morris told us, can work from a digital terrain model (which can be wirelessly updated) or can generate its own plan for a flat plane, sloping plane, or crown. When we were on site with the D61i, we worked with both, establishing a 1-foot offset for an area that Local 150 had previously mapped and also using the IMC system to create a sloping-plane surface on a large stockpile of material.
For the latter, Ackert first took a position measurement (a 3-second tap on the monitor) to establish the blade’s position, which the system reported in northing, easting, and Z-elevation values. He then moved the tractor to the end of the proposed grade and took another measurement. Through this process, the IMC system established direction of travel and mainfall. Ackert then entered a crossfall value of 4-to-1 for the slope.
“I like the aspect of this system that automatically gives the percent of mainfall after you take the second reading,” said Ackert. “With some systems, after you shoot the second point, you have to go into a text menu and select the mainfall option. The system Komatsu uses, however, is somewhat more involved if you want to edit the elevation.”
Overall impressions of the D61i
While the operators alternated in the seat working the slope with the IMC system activated (controlled by tapping the blade lever forward at the start of the cut and rearward at the end of the cut), we had opportunity to solicit from each general impressions of the D61i.
“Komatsu has always built a nice dozer—very well balanced.” said Ackert. “These machines are relatively easy for apprentices to get used to, because Komatsu moves the operator a bit farther forward, and it’s easier for newer guys to catch on to the breaking point of the tractor—where it balances.”
Although most of the dozers in the Local’s fleet have a torque-converter/power-shift-transmission drive train, Ackert likes hydrostatic drive and gives Komatsu credit for designing the drive system to accommodate operator preferences. (The system has a “variable” mode with 20 incremental speed settings and a “customizable” mode with three speed settings.)
“The two transmission modes let you set it up like a three-speed power-shift, or you can select the variable mode and set the speed with the thumb wheel on the joystick,” said Ackert. “I usually load the blade in first gear and carry it in second with a conventional drive train, so this system lets me work that way if I choose.”
Yanos seemed to appreciate the variable mode.
“The hydrostatic is nice, because you can adjust the speed depending on the material you’re working with. The load is always changing, and the hydrostatic lets you easily adjust for this, rather than just staying in one gear with a conventional transmission.”
Visibility and control placement were also high on the D61i’s list of accommodating features.
“Visibility is excellent behind you and to the sides,” said Yanos, “and with the cooling package in the rear of the machine, the slanted hood lets you see down to the corners of the blade. I also like the design of the controls—everything is pretty much at your fingertips for transmission and blade control.”
Ackert agreed about the controls, but with one exception.
“I’d like to see a different location for the increment switch for adjusting the GPS offset. It’s on the cab wall; I’d like to see it on the blade lever, so when you’re cutting and want to lose a little material, it’s right there.”
Both concurred, however, that the D61i was extremely quiet—“both inside the cab as well as outside the machine,” said Yanos.
Assessing the IMC system
Yanos summed up the overall impression he and Ackert had from working with the IMC system switched on from top to bottom of the cut when working on the slope programmed into the system on site.
“The system takes much of the effort and repetition out of the dozing task. When you’re not constantly having to adjust the blade to keep the tractor moving and to keep the tracks from slipping, the work becomes much easier.”
Ackert added a qualifier. “I agree that the system is easier on the operator, but the basics still apply. You still have to know where to start the cut so that the blade loads in the proper distance, and you have to know where to place the material and how far to come back to start the next pass. The operator still has to think through the process.
“I noticed that when I was cutting at the bottom and pushing up the slope in the cut-and-carry mode, it was very easy to maintain grade. And when the machine crested the top of the slope in the auto mode, as soon as you touch the stick you have manual control and can do what you want. It’s a nice feature; you don’t have to turn off the system to get control.”
In an additional exercise, Ackert opened a cut 15 feet wide, 30 feet long, and 1 foot deep in extremely stubborn material, first with the D61i’s IMC system switched off. He then opened an identical cut, adjacent to the first, with the IMC system activated and working from the Local’s modified digital terrain model.
“This was a tough test for the intelligent system,” he said, “because of the type of material we were working in. The heavy clay we have here in northern Illinois, once it gets hard, is extremely difficult to penetrate.”
Proof of the material’s obstinate resistance was evident when Ackert initiated successive cuts with the IMC system turned off, having to apply down pressure on the blade until the front of the D61i’s tracks were off the ground. But that said, the machine pushed strongly to excavate the foot of material from the designated area.
When working in this material with the IMC system active, Ackert programmed the system in its cutting-and-carry and heavy-material modes. Talking with him afterwards, he said that the system seemed to need time to initiate the cut in the hard material, but then would dig in strongly and push aggressively.
“I decided that if I were on a real job site with this machine and using the IMC system in this material,” he said, “I’d first use the corner of the blade to quickly rip through the hard surface.”
Which he did, making what he called “corn rows” along the length of the area. Once done, he said that the IMC system worked well and kept the machine moving steadily through the cut, top to bottom, with no track spin. We unofficially timed the D61i working in both its manual and automated modes during this exercise and determined that it completed the task significantly faster in the IMC mode—approaching 15 percent faster—even after having taken time to pre-rip the material.
“In all fairness,” said Ackert, “the automated system would probably have handled the situation just fine—it would just have taken a bit more time to establish the surface cuts. It was a judgment call, but it seemed easier to me to quickly rip the surface of the material, and then let the system take over. In most materials, I’m sure the system would work precisely—but this stuff is a special case.”
Yanos suggested that in material such as that encountered at Local 150, it might make sense to program in a shallow offset to initiate surface cuts. Ackert agreed that would be a practical way to proceed, but added that “the whole point of the IMC system is to start at the top and use it all the way down. Maybe it’s a situation where human intelligence and machine intelligence come together to work most effectively.”
Taking the long view of the day’s events, Ackert summed up. “It’s a nice product—you really can’t say anything bad about it.”