Getting machines to do more while using less fuel are two of the most important factors on a work site. Once the equipment is selected and the site layout planned, the main variable affecting the success of the overall operation is operator behavior.
With the massive difference between an experienced and novice operator—and an equally massive difference in the cost/benefit ratio—Volvo Construction Equipment (Volvo CE) is researching a system which will help less skilled operators work as efficiently and productively as the best and most experienced operators in the industry.
“The operator has a great influence over a machine’s productivity and fuel efficiency,” said Bobbie Frank, alternative drivetrain research engineer at Volvo CE. “In the future we will see advanced systems develop that are less dependent on operator skills. Currently this technology is still in its infancy but there will come a time when Volvo machines actively guide operators, and even control the primary functions.”
Measuring Operator Deviation
Recently in Eskilstuna, Sweden, 80 operators took part in a Volvo study whose aim was to discover the differences in fuel efficiency and productivity between different operators performing identical tasks in the same Volvo L220F wheel loader. The operators were grouped into four categories—novice (with two to 10 hours of wheel loader operating experience), occasional (with machine knowledge but not frequent use), test operators (Volvo employees who operate wheel loaders regularly but not professionally) and professional operators (those who work with wheel loaders on a daily basis).
Each operator performed the same tasks in three different simulated work sites: a short loading cycle in rehandling material with a load receiver, a load and carry up-hill cycle onto a conveyor belt in rehandling material and a short loading cycle loading shot rock onto a load receiver. All parameters were isolated—except the operator. Data such as bucket load, vehicle speed, use of accelerator and brake pedal was recorded along with fuel consumption. From this data, fuel efficiency in ton/liter and productivity in mt/h were calculated.
“This study focused on how operator behavior affects the fuel efficiency and productivity of wheel loaders working in bucket applications in production chains,” said Frank. “The results showed an enormous difference between fuel efficiency and productivity between operators of differing expertise. Between the novice and the professional operator, productivity increased up to 700% and fuel efficiency increased by up to 200%. When novice operators are excluded from the results, there is still an increase of up to 300% in productivity and 150% in fuel efficiency.”
Increased Machine Intelligence
“The results from this investigation highlight the opportunity to reduce costs through optimized operator behavior,” said Frank. “We can see that the operator has a great margin of influence over the fuel efficiency and productivity of the machine. If we could raise the efficiency and productivity of all the operators in this study to the same level as the operator with the best results, it would add up to a big saving for our customers.
“By developing an advanced control system that assists the operator, we should be able to decrease human influence and actively help operators work more efficiently without reducing productivity,” said Frank.
“Volvo cabs of the future will assist the operator by presenting information in heads-up displays and other innovative approaches. Through haptic controls (technology which takes advantage of the sense of touch by applying forces, vibrations or motions to the user) we will see the machine interacting with the operator and giving feedback.”
What the Future Holds
At Volvo CE, the company’s engineers are looking ahead and developing innovative technology for future machine designs. “This study is only really the beginning of this research and it will be developed further and used in a number of different ways,” said Frank.
“The next stage is to find—using virtual simulations—the optimum way of operating a machine. It will be interesting to see how this compares with the top operator from our investigation. There is a lot of potential to develop an advanced operator assist system and training tool with these results and, with more data from different machines in other applications, managers could use this information to set the pace of production and optimize the overall efficiency of the entire job site.”
GE Energy Offers Complete AC Power Solution
Surface mine operators are finding it harder to deliver the same amount of minerals in the same time with existing technologies, according to GE Energy—the ore being uncovered has lower concentrations of minerals as existing sites become more mature. As a result, mining companies are increasingly under pressure to find more energy-efficient and reliable solutions. In response, GE Energy has introduced a new alternating current (AC) excavator solution which consists of drives, controls and motors designed specifically for challenging surface mine applications and environments.
The AC system is a complete motion solution comprising an integrated family of power delivery elements, Variable Frequency Drives (VFD), AC motors and controls. Each system is designed for the specific application using motors of various frame sizes and mounting orientations (horizontal and vertical) and drives tailored to the platform. The system is designed to use a master PLC to control system functions, maintaining commonality of equipment and control algorithms with existing DC excavator systems.
GE Energy said its newly designed air-cooled AC KD800 series motors are mechanically interchangeable with its existing DC MD800 series Mill Duty motors, down to the mounting configurations and shaft heights. This gives prospective users the flexibility to select either AC or DC, whether retrofitting existing excavators or engineering an all new design.
Main features of the AC system include:
- Active front ends capable of regenerative operation from the interface to the utility.
- Dedicated inverters, sized to motor requirements, control each of the motors.
- Insulation is designed for 20-year winding life under normal excavator operation.
- AC systems are designed for higher productivity by providing higher peak and continuous power ratings.
- Anti-friction bearing life exceeds major excavator overhaul intervals.
- Internal shaft grounding brush is field replaceable.
- Field replaceable speed sensors are used to ensure accurate rotor position and rotational direction while providing precise torque control.
- Bearings and stators are equipped with factory-installed RTDs.
The company said its new family of AC VFDs have been developed using a modular approach designed to meet customer specifications using a common set of modules and passive components, thus improving availability and reliability. The product line features:
- Four-quadrant control of all motor functions with active power factor correction.
- An air-cooled drive system designed for minimal maintenance with extended filter change intervals.
- AFEs and inverters configured as master/slave with an automatic fail-over feature, which allows for reduced-capability operation until maintenance can be scheduled.
- System communication networks that use standard bus protocols.
The Active Front End (AFE) in the VFDs provides high energy efficiency with Power Factor management to minimize line transients and disruptions at the Point of Common Connection (PCC) to the utility. The inverters are designed and rated to support the severe duty of excavator motor applications.
Mining operators look to uptime and cycle time as two measurements that provide the most meaningful indication of lower cost per material ton moved ($/mtm). GE said its AC excavator solutions, based on an advanced AC drive, control and motor system technology, will help deliver the reliability and productivity necessary to help mining operators meet their goals.
GE Energy created GE Mining Solutions to collaboratively develop with mining clients the technologies needed to continue their success. GE Mining Solutions is part of GE Global Industries, GE Energy’s new cross-business that interconnects technologies from across GE Energy’s diverse portfolio to increase efficiency and results for customers in critical business sectors.
