An Operator's Dream
An Operator's Dream
Summary: Older West Coast grapple yarders are among the toughest machines in the bush to operate. After 12 years in R&D, a Victoria firm has the solution a computerized single-joystick control system.
By L. Ward Johnson
If youve ever had occasion to get behind the controls of an old West Coast grapple yarder, youll know that running one can take super human effort. Every time a turn is yarded in you must simultaneously heel and toe two-foot pedals with your right foot to maintain line tension, while moving a knee throttle back and forth with your right leg to control engine speed.
There are also controls to operate with your left foot, a couple of levers to pull and push, and some buttons and switches to toggle as well. Miscue any of these functions and you can quickly lose the turn or snarl the lines. In addition to coping with the complexity of the controls, you must react to radio instruc-tions from the pickup point, since you are often unable to see the logs you are attempting to grapple.
Then, once the turn is secured, you must coax the logs into the landing without breaking them or gouging the terrain. At the landing, you check to ensure that the area is clear and that no one is in danger, then you place the logs securely on the log deck. Once the logs have been positioned, you release the grapple, throw everything into reve rs e, and send it whirring back into the woods for the next turn. Depending on the show, this process might be repeated 20 or more times an hour throughout the day, as you yard in turn after turn. If all goes well, at the end of the day you have perhaps 150 turns at roadside ready for loadout.
There are a considerable number of these old grapple yarders still working on the West Coast and, while they are venerable old pro-ducers, the precision and dexterity required to run such complex equipment can levy a considerable toll on operators. Many find the work both stressful and strenuous, and often complain of chronic aches and pains after only a short time on the job. If there were such a thing as a contortionist monkey with double rubber joints and an extra prehensile appendage, he would be a prime candidate for a grapple yarder job. Within the last decade, technology has made many jobs such as grapple yarding less physically demanding.
Mechanical systems have been improved and there are better electronic and hydraulic power controls. But while these jobs are now less physical, the increasing complexity of the equipment has upped job stress levels.
One of the organizations working to simplify machine operation is RSI Research Ltd., a Victoria, BC-based engineering and man-ufacturing company specializing in telerobotic work systems and digital equipment controls. Back in the early 1980s, RSI was joined by Dr. Peter Lawrence of the electrical engineering department at the University of British Columbia. Lawrence took his sabbatical at RSI to work with engi-neers developing digital control systems for multi-function subsea manipulators. At the time, RSI was developing computer-based teler-obotic manipulator systems for unmanned submarine work vehicles used on offshore oil rigs and deep sea recovery missions.
While developing these systems, Lawrence and RSI engineers started looking at other possible applications for the technology and quickly made the connection to heavy equipment. The configuration of heavy hydraulic manipulators is very similar to that of many hydraulic excavators. Lawrence became convinced that applying the same type of digital control systems to heavy equipment would improve productivity and make the operators job easier, more accurate and less stressful.
The revelation set Lawrence and RSI on a 12-year path to bring the technology to the marketplace. Lawrence decided the best approach was a single joy stick control which, when manoeuvered in a manner that reflected the desired movement of the machine, caused the machine to react in the same way. If you wanted to extend an excavator stick downward to scoop up a bucket of dirt for instance, you would simply push the joy stick forward and down.
In reaction, the stick and bucket would automat-ically go to the appropriate digging angle, and the bucket would lower itself. The trick was to get the machine to perform in a manner intuitive to the movements of the joy stick so the operator wouldnt have to think about the indi-vidual adjustments. It had to be as natural and intu-itive as picking up a pencil off a desk. Nobody thinks about the various shoulder, elbow, arm and hand movements; they simply reach out and pick it up.
Lawrence called this concept Coordinated Motion Control, or CMC. Six patents were eventually secured to protect the idea and the name was registered as a trademark on behalf of the University of British Columbia. At UBC, Lawrence successfully demonstrated the concept on a log loader. RSI licensed the technology from the University and set out on a development project to bring it to the marketplace. It was not a simple process to adapt CMC technology to grapple yarding.
There were failures, then advances, then failures again, but slowly ideas and reality began converging. Finally, in February, 1995, after nearly eight years in development, RSI successfully installed the first production unit on a Madill 044 grapple yarder working at MacMillan Bloedels Franklin River Division, west of Duncan on Vancouver Island. This yarder was was one of the first 044s made, with a completion date of November 12, 1981. The CMC unit on this yarder consists of three major components: a keypad, a joystick and an onboard computer.
The keypad, used to set consistent operating parameters such as line tension, is located on the operators left arm rest. On the right arm rest is the joy stick, which is fitted with non-contact, Hall-effect sensors that electronically transmit movements to the computer. The computer, located under the house in a sealed black box, reads the movements of the joy stick sensors and trans-lates them into machine movements. With this system all yarding functions, including main line out and main line in, slacking and tightening the haulback to lower and raise the grapple, opening and closing the grapple to secure the turn, and machine swing to deck the logs when the turn reaches the landing, are controlled with a single joy stick. The joy stick has replaced three clutches, three brakes and the knee throttle control. It doesnt control functions such as travel to change roads or boom up and boom down.
These movements are still done with conventional controls. Operating the grapple yarder is Ed Matchett, a long-time MB employee. After nine years on the 044, Matchett is a firm convert of the CMC system. He says that after it was installed, he was able to use the system in just a few minutes, but it took him about three weeks to feel completely comfortable with it. Its a different concept to get used to the idea of intuitively moving a joy stick instead of working pedals and lever but once you catch on, theres nothing like it.
Matchett still has all the old controls in the cab and occasionally reverts back to them particularly if he is in an especially tricky sit-uation. I guess Im still learning to use the joy stick system, Matchett says, so occa-sionally Ill go back to the old controls. But the CMC system is sure a lot easier most of the time, and I wouldnt trade it with the old system for anything. With the CMC, I dont feel all beat up at the end of the day like I used to and you cant imagine how good that is.
Matchett says the computer does all the thinking while he looks after the big picture. Once you catch on to that intuitive idea, you stop thinking about all the move-ments you have to make. I can even stand up in the cab and run the machine if I have a visibility problem. As long as Ive got my hand on the joy stick, I can do all the func-tions and do them without effort. It gives me a lot more freedom and lets me keep an eye on the ent ire operation instead of attending to clutches, levers and brakes.
Thats better and safer. Matchett says productivity has gone up around 20 per cent since the yarder was equipped with the CMC sys-tem. We re getting more turns in a day and were getting more life out of our lines. Its nearly impossible to mess up the spooling and since we arent down as much, we get higher productivity. Its made this side better and more effective all around, Matchett says.
Bradley Moore is marketing director for RSI Research. He says now that the grapple yarder system is up and running, RSI is busy developing CMC systems for other heavy equipment such as log loaders, feller bunchers and processors. Think of how many different kinds of machines there are out there and that is our market, he says. Now that we have a CMC system for the grapple yarder one of the most complex machines to operate we think we can incorporate this technology into a host of other machines and applications as well.
We are refining the technology all the time thats a process that never stops and once it becomes a standard operating system for equipment, its going to ch a n ge the way we operate these machines forever. We dont know where this technology will eventually lead, but we know its just in its infancy at this point. There certainly are better things ahead for equipment operators in all industrial and construction applications.
This page and all contents
�1996-2007 Logging and Sawmilling
Journal (L&S J) and TimberWest Journal.