The following information pertains to the application of controlled area network systems (CAN) and off-highway equipment.
IEN: What are the major concerns facing motion technology, and how can they be addressed?
Hall: Personal safety is an issue sitting high on the minds of the off-highway equipment industry. Looming with the power of this equipment is the costly threat from accidents that can occur from distracted or foolish operation. So are the heavy price tags for the liability insurance equipment owners are carrying to protect their business.
Related to safety is the damage the vehicle can cause to itself when, for example, a boom swings into the chassis of the machine or punches out a window.
Designing out danger can be a tall order when taking into account the randomness of these acts and of equipment operation. To put any single piece of apparatus or operating function on one of these machines into motion often calls for a complex array of mechanical and hydraulic systems for power or direction. For standard electrical component systems, a large volume of gear needed to implant this intelligence would have to be stuffed into a vehicle''s chassis. In short, the mission of maximizing vehicle safety could be limited.
Solutions are within reach for equipment manufacturers thanks to the use of the SAE J1939 protocol implemented by the (CAN) concept to manage and monitor vehicle functions so designers can enter new frontiers of safer operation. The job performed by switches, fuses, relays, and other devices are compressed into compact microprocessors housed in a construction-rugged case. Rather than the jumble of wiring that can typically comprise a system, multiplexed communications between these modules takes place over a twisted pair of wires. Safety interlock algorithms programmed into the system now enable the equipment to limit its operation when the microprocessor decides the equipment is working outside of its limitations or as sequences are occurring that can lead to risk for the operator.
Designers can provide a network of these controller modules to coordinate the many functions present on very large machines, or use just a single box when necessary. Even a small mini-dozer using a single-board controller can prevent its scraper from operating or the ignition from sparking if the operator is not safely sitting in the driver''s seat. (Photos: Small vehicles and machines weighing over a 100 tons can utilize the sophisticated motion control capabilities provided by CAN technology.)
Datalogging functions accumulating the information flowing through the system using the SAE J1939 protocol builds an operating profile for diagnosis of machine performance, should a malfunction occur, to enable the development of corrective designs.
Another advantage of the CAN approach is that with simple reprogramming, attachments can be added onto the machine. The operation of the option can be coordinated into the system and incorporated into the safety interlock scheme.
IEN: What are the R & D hotspots?
Hall: The tractor is the agricultural workhorse. For the last few years CAN has controlled agricultural machinery functions. Inherent in the design of it and other farming equipment is the versatility that comes from available attachments.
The recent introduction of the ISO 11783 standard has brought further advancements for control of the array of available implements. Based on the CAN standard, this serial communications protocol can traffic information on such functions as power management, speed, hoisting gear, the power take-off shaft, rate of spray, and lighting control.
Imagine the initial fear of all the information from these electronically controlled functions coming into the cab, resulting in a confusing array of dials, gauges, and displays.
The prime feature of the 11783 is the Virtual Terminal (VT), which provides the operator interface inside the cab on a single screen that can be easily configurable to match up with what the operator needs to know, against what the system, off of the implement, can provide. Consequently, applications are arising for this technology outside the agricultural area for those vehicles also controlled by CAN systems.
Along with the capability to display the status of any of the implements that may be operating on the machine, the VT is highly versatile. Sealed in a weathertight case, the VT can accept the output information for each implement. This data can be defined and presented by a mask, which tracks a specific attachment.
A Softkey Area provides labeling for assigned softkeys. The display can be in either black and white or output in a 16- or a 255-color palette. Alarm masks, which require acknowledgment by the driver, can be defined to pop-up automatically in the VT foreground.
The VT is ready for auxiliary input devices, such as a joystick on the armrest, or a screen button. Regardless of where the devices are positioned on the machine, the VT automatically detects the auxiliary inputs when they are brought online. In addition, the VT can accept video inputs, giving the operator "eyes" all over the machinery to, for example, safely position a crane or back up a machine.
IEN: How much progress has been made in preventing software and hardware debugging issues? Installation challenges?
Hall: Immediately apparent -- as the software comprising CAN systems is replacing many of the functions performed by electrical hardware components, this is leading to a decrease in the time devoted to QA/QC. Equipped with laptops, technicians verify operation of the machine per design specs and quickly trace down any problems. No longer having to prowl around the inside of the machine, the technician can hook up the computer to an R232 port and, from the comfort of the cab, run diagnostics. Only if the software isolates a problem having to do with a hard-wired electrical component does the tech need to access the guts of the equipment.
A diagnostic software tool cuts down considerably on troubleshooting time. Take the example of a truck that has a pushbutton to raise or lower the engine rpm''s. If the switch fails to respond, the diagnostic tool tests the circuit to see if the program is seeing that switch. The laptop screen depicts whether the module recognizes the activation of the button. If the module doesn''t see the input or the output, a wire might be loose either on the button or on the wire harness. The button may not be working. The problem gets picked up much more quickly than older systems diagnosed with tools such as continuity testers.
Or, the tech can "force" the operation to see if the operating algorithm is operating correctly. The diagnostic tool can "fool" the system as someone works the toggle switch or turns the ignition key to see if the system is correctly programmed. Introduction of the laptop onto the factory floor represents a major change for most of the plant employees, particularly older workers. In some cases trainers conduct two classes: one for the long-timers who are shaky with the idea of using a computer and don''t want to look incompetent; and another for the video-game generation.
The key for the design engineer who is responsible for conveying manufacturing techniques to the production crew is to not get enthralled with the complexity of the CAN modules, but rather to sell the greater ease of assembling and troubleshooting. Turns out, after the originally hesitant employees have run their first few routines, the laptop cannot be pried out of their hands.
For product upgrades and the addition of features, the laptop becomes the tool of choice as well. Configurator software tools allow changes to be programmed into the system, either during manufacturing or later in the field. This software also enables vehicle attachments to merge operation into the vehicle''s overall system.
The decision of which part of the CAN system code may be changed using configurator software can be made when the program is originally written, either as hard code or in the configurator. If written using the configurator, the code can be changed by a field service rep, or the customer, at some point.
All else being equal, many manufacturers would prefer to do the initial code using the configurator. But smaller operations don''t have the resources to do this open source code. Generally companies having three to four electrical engineers, either on staff or on contract, with a volume of 500-1000 machines a year, working on about eight different models, can take on this task.
Base software design can also depend on the alteration possibilities a manufacturer wishes to offer to its customers. A manufacturer could be turning out, for example, 50 machines a year, with each one unique. In this case each machine has a load controller on it to be in command of the different-sized roller fitted on each one, depending upon the different environmental demands on the machines.
Each roller has a different radius with a different tooth count and has a different operating profile. For example, the machine would not be run at 900 rpm''s because its roller has huge teeth on it, so the operation is slowed down to 200 rpm to meet maximum operating efficiency. Through the configurator or diagnostic service tool, a manufacturer can reprogram the machine to be the exact unit the application calls for. The choice can be up to the manufacturer to configure through an interactive operator''s display, or in the base application, rather than always adjusting the operating profile.
Using configurator software, features can be easily added or subtracted from the unit. For example, a fire truck manufacturer might want to add lights. The feature could be written into the base code, and the system would recognize whether or not the light option is on the vehicle.
Or a tech can go into the configurator, reconfigure, say, output No. 9 on the CAN control module, and operate these lights at a set frequency or a PWM signal. If the light has a unique characteristic where it works at different amperage or a different PWM frequency from the light they used last time, they can program the specs in, making a simple change through the configurator. Now, the changes that used to be done by bringing on new parts can happen by hitting a few keys on a keyboard.
The CAN system is upgradeable and expandable, in regard to both system software and hardware components. Though a typical module offers an abundance of inputs/outputs, if extra contacts are needed, another module can be dropped into the machine. The new inputs and outputs will now work together through the configurator.
This coordination is possible by writing conditional statements that can be as easy as specifying that if input button No. 1 is pressed, output No. 7 goes off. Or output No. 7 can be tied into the operating algorithms of another 10 inputs for the condition to make this output go on to create, for example, a safety interlock.
This configuration gives the engineer an opportunity to look at the existing I/Os and come up with new ways to use them. Basically what happens now for many machines is, if the customer wants to be up to date, typically he has to go out and buy a new vehicle. Now all that is needed is an upgrade package. The user benefits from technology that comes down the line later on.
For marketing purposes, a manufacturer can offer vehicles with a longer operating life by virtue of its adaptability to changing safety requirements, in the way the machine is used or in response to the imaginations of designers and users, without being concerned about the nuts and bolts of hardware upgrades.