Motion Control System Includes Solid-State, Embedded PC
August 27, 2010 by admin
Filed under Featured Mechatronic Articles, Motion Control, Technology
Siemens announced that an embedded PC is now available for its Simotion® P320-3 motion control applications. Providing maintenance-free controls, the Simotion P320-3 brings the power and simplicity of a PC to motion control.
The embedded PC, which features a DDR3 memory and an Intel Core2 processor, is free of wear from moving parts, such as hard disks and fans. This compact motion control system provides maximum flexibility and accommodates centralized or decentralized machine concepts for PC-based applications or for applications that require a compact size.
It is designed for many different motion control applications with its multiple onboard interfaces. They support communication over Profinet, the open industrial Ethernet standard, as well as Ethernet interfaces that run at 10 / 100 / 1000 megabit speeds. Four USB interfaces make it simple to connect a keyboard, USB stick, printer or other devices. A DVI port rounds out the links so users can attach a display or monitor. The Simotion P320-3 can also be used in a “headless” configuration without a display, monitor or front panel.
LEDs on the front indicate the operating states, making self-diagnosis easy. The integrated power supply bridges temporary power failures. In the buffered SRAM memory, the process data is saved securely even in the event of a sudden voltage drop. Monitoring functions for the batteries, temperature and program execution are also included. The Windows Embedded Standard 2009 operating system, which increases the reliability of the system, is pre-installed. Additionally, the Simotion runtime system comes installed on the Simotion P320-3.
Top 5 Electrical Considerations for Mechanical Engineers
August 10, 2010 by admin
Filed under Commentary, Design, Featured Mechatronic Articles
Previously, we covered mechanical considerations for electrical engineers. Now, we give the other side a chance to speak. Here are five targeted pieces of advice for mechanical engineers responsible for electromechanical systems, from the perspective of an electrical engineer.
Mechatronics systems intelligently integrate mechanical and electrical elements to perform increasingly complex and demanding functions. When designing electromechanical systems, mechanical engineers and electrical engineers may tend to emphasize the technologies, components, and design principles from their single area of expertise—which can lead to systems with higher operating costs, increased maintenance demands, and less than optimal performance. As an electrical engineer involved in helping OEMs and manufacturers design and build mechatronic systems, I’ve seen how inefficiencies and unnecessary complexity can be unintentionally designed into machines.
A clean design balances mass and motion: sturdy, durable framing withstands years of vibration and shock, combined with lighter-weight components helps to reduce mass and enable the use of smaller motor/drive components.
Better mechatronic systems can be created when mechanical engineers consider five crucial concepts while designing manufacturing systems, to derive the greatest value and efficiency electronics systems can offer to the manufacturing process.
1: Create a clean design
Good mechatronics design starts with good mechanical design – the best electronics and electrical systems cannot compensate for poor mechanical design. The most successful designs are “clean.” They feature a strong, rigid frame, using materials and structural principles to ensure that, whatever motion the machine undergoes, its long-term stability is “engineered” in.
Make sure that rigid bearings and support are used where motors are mounted on machines; this helps prevent shafts from being sheared off due to microfractures that occur because the motor shaft is mounted out of alignment with a pillow block bearing or gearbox input planetary gear. Place motors on the machine in the best location so that operators aren’t accidentally stepping on cables and connectors and causing damage; and design machine guarding with easy access points to get to motors mounted under the wing base of the machine while still protecting them against harsh environments.
Most importantly, a clean design balances mass and motion: sturdy, durable framing that withstands years of vibration and shock, combined with lighter-weight components for the moving parts of the machine. This combination helps reduce mass, delivers more energy-efficient motion, and makes it easier to size-up smaller motor/drive components for the machine. We’ve seen a lot of very innovative mechanical machine designs over the years, and a clean design makes the largest contribution to a machine’s longevity, robustness, and lowest overall cost of ownership.
2: Directly couple the motor to the load
Effective mechatronics starts with a “clean slate” design. In the past, machines were often built around a single ac motor powering a machine line shaft, to which were attached gearboxes, pulleys, sprockets, chain drives and other mechanical devices for moving individual areas of the machine in synchronization – an approach to powering manufacturing that literally can be traced back to the dawn of the Industrial Revolution.
A clean design makes the largest contribution to a machine’s longevity, robustness and lowest overall cost of ownership.
Consider replacing this architecture with individual servomotors coupled directly to the load you are moving. There are multiple design, machine cost, and operational advantages to this idea (which a surprising number of machine designs do not use). First, consider cost: every time you add a gearbox, you add multiple costs: it’s an additional point of failure, it has to be lubricated, and it needs spare parts. Plus, you add mechanical backlash that must be compensated for during machine commissioning every time you have a product changeover – motion and axes synchronization complexity that today’s intelligent drives and servomotors eliminate.
When you strategically locate servomotors as close as possible to the area of motion they are serving, the incremental cost of electric drive components is almost completely offset by eliminating the cost of mechanical components and labor that must be purchased, machined, assembled and configured. In particular, not having to stock multiple sets of sprockets, gears and cams, as well as the time involved in changeovers with mechanical drives, can really drive down the total cost of ownership for the machine.
Ultimately, this design approach greatly reduces windup and backlash, as well as improves machine commissioning time; and current state-of-the-art direct drives, direct motors, and linear motors let you run higher gains and improve the machine’s performance.
Consideration #3: Use electronic gearing and camming
Today’s electronic drives and motion control platforms give mechanical engineers, a powerful, flexible tool to improve the accuracy and performance of the machines you design. This technology lets you create a virtual “electronic line shaft” that can electronically synchronize all the drives and motors on the machine, eliminating the mechanical line shaft. In the process, you can dramatically improve axes synchronization and accuracy – from 1/16th or 1/32nd of an inch typical with mechanical line shafts, down to motion precision closer to hundredths or even thousandths of an inch with electronic line shafting.
And this synchronization can be accomplished with zero mechanical backlash – and fewer product jams. It also eliminates a host of mechanical adjustments to bring the machine online, as well as the operator adjustments each time the machine is stopped and restarted.
Electronic gearing and camming makes machine changeover completely programmable: For example, the use of FlexProfile technology lets operators load machine recipes with the touch of a button on the HMI screen, and the changes are made in the control and servo system to run the next product.
The FlexProfile camming technology makes it possible to build multisegmented cam profiles based on position, velocity, or time-based motion profiles. When you change a section of the electronic cam with a recipe change through the HMI, the control platform will automatically optimize the rest of the cam profile across all of the machine’s motion elements. This enables the machine to run a shorter cycle time, or provide smoother dynamics for the machine, even though a change has occurred such as a different bag seal time or flap tucking cam position on a cartoning machine.
Consideration #4: Incorporate energy-efficient technology
One of the fastest growing costs for any manufacturing operation is energy – and good mechatronic design can help control these costs through the application of electric drive and motor systems designed to save energy.
In machines that use servomotors directly coupled to critical axes of motion, and that also use electronic synchronization and camming, the proper sizing of the servo system can create a highly energy efficient machine.
Proper sizing requires an accurate assessment of several motion factors (motor by motor): How fast the axis needs to accelerate, the size of the mass you’re trying to move, and how precise the acceleration and deceleration needs to be. Undersizing will lead to strains on the drives and motors; oversizing will draw too much power to do too little work.
Some of today’s most cutting edge systems, such as the Rexroth IndraDrive Mi integrated drive/motor systems, include a highly energy efficient feature: bus sharing. Multiple drives are daisy-chained together and share power from the same bus; in many multi-axis machines, as some motors are accelerating up to speed (drawing power), others are decelerating (regeneration power). With bus sharing, rather than having to deliver maximum power to the accelerating motors and bleed off the decelerating motors into heat across a bleeder resister, power is shared, so the machine’s power consumption is significantly reduced.
A further energy-efficient technology is called regenerative power supplies. In many machines, multiple servomotors will decelerate at the same time, boosting the voltage to excess levels on the power bus. Older generation electrical drives would bleed that excess electrical energy as heat – wasting the power, and adding to the factory floor’s heat production, requiring additional cabinet cooling. With regenerative power supplies coupled to a shared bus system, what was once wasted power can now be fed back through the shared bus and sold back to the electric company.
The use of direct drive, direct motors and linear motors versus mechanical couplings lets you design a system to run higher gains.
Consideration #5: Use HMI’s for better troubleshooting
User-friendly intelligence is now available through today’s touchscreen HMIs. Machine layout drawings and schematics can be incorporated into control menus and diagnostic tools, to better manage the machine’s day-to-day operation and troubleshooting. Drawings and interactive instructional tools can not only show the precise point where a problem is – they can also step the operator through the tasks to restart production.
Advanced graphics like this can be combined with the distributed intelligence inherent in servomotor-driven machines, to prevent machine failures or faults before they happen. With such predictive maintenance, this capability lets you or machine designers set fault tolerance bands in drives and then monitor drive performance. Electric drives and motors allow a broad range of conditions to be monitored – conditions that are directly associated with mechanical performance; variations in load, temperature, vibration, torque, belt tightness, gear meshing are all mechanical events that generate changes in the torque profile of an electric drive and motor moving those machine elements. Mechanical engineers can set tolerance bands for these components, and if they exceed them, then predictive maintenance alerts can be clearly and intelligently displayed through the HMI to operators, along with specific advice about next steps to take to correct the issue before it becomes a serious production problem or something that can damage the machine.
With Rexroth’s IndraDrive Mi integrated motor/drive system, multiple drives are daisy-chained together and share power from the same bus, significantly reducing energy consumption.
Blending technologies for optimal value
Every electromechanical system should perform its designed function with the minimal use of energy, motion and components required to get the job done – that’s the fundamental goal of any engineer. Electrical drive and servomotor systems now offer a wealth of reliable, energy-efficient, digitally intelligent platforms to power the integrated vision of mechatronics to greater value and more innovative manufacturing and automation solutions.
Hopefully, the five considerations described here demonstrate the advantages that today’s electric drives and controls offer, helping you simplify certain mechanical design and engineering challenges and provide new resources for driving innovation and creativity in machine design.
Mechatronics and Economics
August 8, 2010 by Steve Meyer
Filed under Automation, Commentary, Featured Mechatronic Articles, Green Energy, Industry, Manufacturing Trends, Technology
Recently, I did some industry analysis on jobs and revenue. How many dollars of sales are required to “create or save” a job in a given industry. I only looked at a couple of industries and found that it ranged from $219,000 to $275,000 in sales for certain types of processed materials to employ a worker in that industry.
Obviously, this type of metric will vary wildly depending on how highly automated a particular industry is. The beverage industry is highly automated and doesn’t have a large employee staff to generate finished products. But interestingly, the companies that build machinery for the beverage industry have fairly high employment because it takes a combination of technically trained skilled workers to make the machinery that makes the beverage products.
The agricultural economy has grown dramatically with the introduction of machinery to assist in the process. Complex machines have been developed for many applications to increase productivity. The latest round of enhancements are tilling and planting equipment that uses Global Positioning Satellite information to keep the tractors in a straight line and computer plots of the land to maximize the planting area per acre. Pretty amazing stuff.
In the automotive area, there are some interesting statistics. In the ten year period from 1998 to 2008 the industry increased its gross output per employee by 33%. This is a huge statistic and represents the long term impact of automation on the manufacture of vehicles. The other interesting statistic is that the average internal price of a car today is the same as that ten years ago. Given that the US industry has pushed it’s quality to compete with the Japanese cars that were perceived as superior to US in quality, this is an amazing feat.
Of greater interest is the comparison of total vehicle shipments. The most cars and light trucks ever shipped by the US Auto makers was in the year 2000 when we shipped 17.8 million units according to Ward’s Auto which reports on the car industry. This feat was almost duplicated in 2005 when 17.4 mil units were shipped.
A relatively stable manufacturing base over the years, the US auto industry hit a disastrous slide in 2008 shipping an anemic 13.49 mil units followed by an even worse 2009 when we shipped 10.6 mil cars and trucks. This was the year in which the Chinese automakers topped the US manufacturing rate for the first time ever. A point that the Chinese press made with great vigor in spite of the fact that the majority of Chinese automakers are actually joint ventures with foreign companies, the single original Chinese auto maker being in great difficulties due to poor product quality.
The 2009 US auto showing is particularly dismal when you consider the “cash for clunkers” incentive which spent $1.4 billion taxpayer dollars to generate 200,000 additional unit sales. A small showing in the scheme of things even if the market was 10 million units.
Will the US auto market pick back up? Certainly, but not to the former highs of 2000 and 2005. 2009 shipments were off by 40% from the 2005 high, and that is too much of a gap to be easily recovered. Especially when unemployment continues to be running in the 10% range and higher.
Is there hope? Yes. Serious electric hybrids and battery manufacturing for the US automakers will create tens of thousands of jobs in the next couple of years. Demand for foreign hybrids has been running at over 400,000 units per year, and will likely increase once there are quality US made products available.
States that pay attention to the needs of the industries they provide locations for are States that will thrive with low unemployment and low deficits.
Caterpillar’s Crawl May Hold Clues To Future Robotics
July 26, 2010 by admin
Filed under Design, Featured Mechatronic Articles, Robotics, Technology
Caterpillars have a unique “two-body” system of movement that may have implications for robotics and human biomechanics, U.S. researchers say.
The scientists found that the gut of the crawling hawkmoth caterpillar moves forward independently of and in advance of the surrounding body wall and legs, instead of moving with them. This is the first time this type of movement has been reported in an animal, the study authors noted.
“Understanding this novel motion system may help efforts to design soft-bodied robots. It may also prompt re-examination of the potential role soft tissues play in biomechanical performance of humans and other animals,” study senior author Barry Trimmer, a professor of biology and of natural sciences at Tufts University, said in a university news release.
The findings are published online July 22 in the journal Current Biology.
Hawkmoth Caterpillar That may look like a snake, but it’s actually a hawkmoth caterpillar
“Although internal tissue movement caused by locomotion has been identified in many organisms, the caterpillars seemed to be propelling themselves by means of a two-body system — the body wall container and the gut it contained. This may contribute to the extraordinary freedom of movement seen in these soft-bodied crawlers,” first author Michael Simon said in the news release.
Further research is needed to determine if this type of movement offers caterpillars an evolutionary advantage, and how this finding may prove valuable in robotics, added Simon, who conducted the study as part of his doctoral research in Trimmer’s lab.
“The focus to date has been on robots’ external design, but we also have to look at how it’s most advantageous to arrange the inside of the robot and any payload. Would motion be enhanced, for example, by packing more mass toward the rear, as these caterpillars seem to do?”
A grant from the U.S. National Science Foundation funded the research.
U.S. Army Developing Snake Robotics
July 26, 2010 by admin
Filed under Featured Mechatronic Articles, Robotics, Technology
Development of snake-like technology underway at the U.S. Army Research Laboratory is moving the military toward sending more autonomous systems instead of Soldiers on search-and-rescue missions, a top priority in the most dangerous mission areas.
Army researchers call it the Robotic Tentacle Manipulator, a developmental project that expands on snake robotics research introduced at Carnegie Mellon University’s Robotics Institute, an ARL-funded effort through its robotics Collaborative Technology Alliance initiative.
This new work has resulted in the arrangement of the bases of several snakes in a circular array that functions like a team using multiple parts of their bodies to manipulate an object, scan a room or handle improvised explosive devices.
This snake-robot is scalable; it can be built however large or small as a subsystem to a larger platform like iRobot’s rugged system Warrior, which travels over rough terrain and climbs stairs. The number of tentacles or snakes determines the breadth or scope of its search capabilities. The number of links on each of those tentacles supports each snake’s length or reach into an area, as well as its ability to crawl, swim, climb or shimmy through narrow spaces all while transmitting images to the Soldier who is operating the system.
The subsystem comes equipped with sophisticated electronic sensors, among them laser detection and ranging, or LADAR, to render 3-D representations of object shapes and physical properties like faces, mass and center of mass.
“The technology is leading to more than just the very tip of the snake being used in the object manipulation effect,” said Derek Scherer, a researcher who works within ARL’s Vehicle Technology Directorate. “Consider that snakes push off rocks or roots to propel their bodies. We are using this same concept in development.”
Scherer said that with increased manipulator dexterity, Soldiers can offload more tasks to the robotic platform. “When the platform is tasked with inspecting a potential IED threat, the extreme adaptability of the tentacle manipulator will allow the platform to rummage with precision,” he said.
Its ‘touch sensitivity’ allows the snake-robot to balance objects and feel where forces are being applied as it rotates devices.
“It allows it to lift and reposition objects, including IEDs, for examination, and do so in a controlled fashion that is unlikely to detonate any ordnance.” Scherer noted. “These same capabilities would improve inspections during cargo and checkpoint missions.”
Researchers predict the technology may one day solve the “opening a door” problem, which has been a consistent obstacle in robotics, Scherer said. High levels of articulation in the manipulator could prove to be effective for grasping and rotating different types of door handles using knobs, handles, levers and bars.
“Solving the door problem would greatly improve indoor robot missions,” Scherer added.
The developmental hardware includes a large-screen laptop, which presents a simple user interface. Each 24-centimeter tentacle is directed by a master controller system, which communicates with the motors that are embedded in each of the links found on the tentacles. The motors essentially direct individual tentacle movement and the master controller directs the entire amalgamation of snakes, or tentacles.
“This is a distributed intelligence framework that permits advanced manipulation algorithms to run on a complex but affordable hardware platform,” Scherer said.
Top-Secret Robotic Legs Helping The Paraplegic Walk Again
July 24, 2010 by admin
Filed under Featured Mechatronic Articles, Robotics, Technology
Bionic legs are a new top-secret invention that is helping a paralyzed man walk again. The demonstrated was unveiled in New Zealand, who can now stand up and walk across the room to shake hands with Prime Minister John Key. This new invention is being called “Rex”, which is short for “robotic exoskeleton.” The battery-powered robotic legs strap on around the legs and waist of the user to support their weight.
Using a joystick and a small keypad, Allen demonstrated how to operate the legs to stand, walk, and even go up and down steps. The Rex has to be custom fitted to each user, it took about three days for Allen to get the hang of it. However, now he is capable of strapping the device on himself, without any assistance.
The inventors of Rex are Richard Little and Robert Irving. They are two childhood friends originally from Scotland. Seven years ago after Irving was diagnosed with multiple sclerosis, the duo came up with the idea. Over the next few years, they refined Rex into a 38kg (84lb) device. All their work was top secret; even Allen, who agreed to be the Rex test pilot, kept his family in the dark about the project until the launch.
“It was all top secret and what we didn’t know, we didn’t need to know anyway. But seeing him here today, it’s just blown us away. It’s brought tears to our eyes really,” Allen’s father said in a statement. Allen has been in a wheelchair since injuring his spinal cord in a motorcycle accident five year ago. When he heard what Little and Irving were planning, he jumped on board. “They brought me in and I said ‘I want to be part of that.’ I couldn’t walk away — or roll away — from that,” he stated.
The investors in the venture capital company put up the $7.5 million which was needed to create the prototypes. The device is expected to be on the market worldwide by mid-2011. The cost of the custom made device will cost around $150,000 each. However, it is priceless for people who never thought they would walk again.
Out Of The Gait: Robot Sets Untethered ‘Walking’ Record
July 21, 2010 by llangnau
Filed under Featured Mechatronic Articles, Mechanical, Motion Control, Robotics
The loneliness of the long-distance robot: A Cornell University robot named Ranger walked 14.3 miles in about 11 hours, setting an unofficial world record at Cornell’s Barton Hall early on July 6. A human – armed with nothing more than a standard remote control for toys – steered the untethered robot. Ranger navigated 108.5 times around the indoor track in Cornell’s Barton Hall – about 212 meters per lap, and made about 70,000 steps before it had to stop and recharge its battery. The 14.3-mile record beats the former world record set by Boston Dynamics’ BigDog, which had claimed the record at 12.8 miles.
A group of engineering students, led by Andy Ruina, Cornell professor of theoretical and applied mechanics, announced the robotic record at the Dynamic Walking 2010 meeting on July 9, in Cambridge, Mass. Ruina leads the Biorobotics and Locomotion Laboratory at Cornell. The National Science Foundation funds this research.
Previously, students in Ruina’s lab set a record for an untethered walking robot in April 2008, when Ranger strode about 5.6 miles around the Barton Hall. Boston Dynamics’ BigDog subsequently beat that record.
One goal for robotic research is to show off the machine’s energy efficiency. Unlike other walking robots that use motors to control every movement, the Ranger appears more relaxed and in a way emulates human walking, using gravity and momentum to help swing its legs forward.
Standing still, the robot looks a bit like a tall sawhorse and its gait suggests a human on crutches, alternately swinging forward two outside legs and then two inside ones. There are no knees, but its feet can flip up – and out of the way, while it swings its legs – so that the robot can finish its step.
Ruina says that this record not only advances robotics, but helps undergraduate students learn about the mechanics of walking. The information could be applied to rehabilitation, prosthetics for humans and improving athletic performance.
Cornell University
www.cornell.edu
Robotic Vehicle Assists Soldiers in Missions
July 15, 2010 by admin
Filed under Featured Mechatronic Articles, Robotics, Technology
The U.S. Army’s Autonomous Platform Demonstrator (APD) will assist soldiers in payload missions and keep them safe in the process. Developed by the Tank Automotive Research, Development and Engineering Center, (TARDEC), the APD is a 9.6-ton, six-wheeled, hybrid-electric robotic vehicle used by the Robotic Vehicle Control Architecture, or RVCA Army Technology Objective, also out of TARDEC. Working with the Army’s Program Executive Office Integration, RVCA has integrated a suite of system control, display, and sensing hardware and software onto the robotic vehicle to enable a soldier to control it in real-time, or operate it in an autonomous mode.
“It uses a variety of sensors and LADAR (laser/radar scanning radar) to detect moving objects at distances,” said Dr. Jim Overholt, senior research scientist in robotics, TARDEC. Additionally, RVCA provides Reconnaissance Surveillance and Target Acquisition capabilities.
“It has a four-meter mast with a sensor ball on top so it goes up pretty high and can see out quite a ways,” said Chris Ostrowski, associate director for Vehicle Electronics and Architectures at TARDEC.
“When you combine the autonomy and control capabilities provided by RVCA with the mobility characteristics of APD, it allows the soldier operator to quickly deploy a mission payload precisely where he wants it, and over some very tough terrain,” said Andrew Kerbrat, APD project manager, TARDEC.
The robotic vehicle is currently undergoing mobility testing at Aberdeen Proving Ground, Md. With its advanced hybrid-electric drive train, the 15-foot-long vehicle can achieve speeds of more than 50 mph. High-speed maneuverability tests include lane changing. “This is a challenging controls problem with a skid steer vehicle. We want the robot to be stable when performing maneuvers like this, but we also want it to retain the other mobility characteristics that it possesses at lower speeds,” said Ostrowski. Those characteristics include the ability to climb a one-meter step, navigate a 60% slope, and pivot turn in place.
When equipped with its autonomous navigation system (it is configured with GPS waypoint technology, an inertial measurement unit and computer algorithms) it avoids obstacles in its path. The mobility testing is aimed at advancing and developing the robot’s ability to maneuver at higher speeds while maintaining extreme terrain-ability at lower speeds.
As a series hybrid-electric vehicle, the APD is propelled by six in-hub electric motors and has a diesel generator that charges its lithium ion batteries.
“The state-of-the-art hybrid-electric drive train is just one of the mobility technologies we are demonstrating with this platform,” said Kerbrat. Other technologies being demonstrated include advanced suspension systems, thermal and power management systems, robotic safety systems, and lightweight hull technologies.
“We’ve made a lot of progress with this platform in a short time period. From concept to wheels on the ground was just a shade over two years, and in the eight months since then, we’ve driven almost 3,000 kilometers and have demonstrated 95 percent of the metrics that we were trying to show with this platform,” said Kerbrat.
3-D Video Gaming On Rain Becomes A Reality
July 14, 2010 by admin
Filed under Featured Mechatronic Articles, Robotics, Technology
A new 3-D projection technology that floats video and images on falling water may have entertainment value for theme parks and gaming in the future. It also might help drivers to navigate more safely at night through torrential downpours.
AquaLux 3D, developed at Carnegie Mellon University’s Robotics Institute, targets light and images onto and between individual water droplets. The initial hope was to use the technology to develop an LED headlight system that helps drivers navigate through night storms, explains Srinivasa Narasimhan, associate professor of robotics.
“The beauty of water drops is that they refract most incident light, so they serve as excellent wide-angle lenses that can be among the brightest elements of an environment,” said Narasimhan. The research team includes Takeo Kanade, professor of computer science and robotics, and Peter Barnum, a Ph.D. student in robotics.
By carefully generating several layers of drops so that no two occupy the same line-of-sight from the projector, the drops can be used as a voxel, a sort of 3-D pixel, that are illuminated to create a 3-D image, he explains. By synchronizing the water drops, the effect can be achieved. The team is also working on a headlight that hopes to illuminate while missing as many water drops as possible to give drivers better visibility.
Source: Srinivasa Narasimhan, Carnegie Mellon University
Electric Car Prequel
July 9, 2010 by Steve Meyer
Filed under Commentary, Design, Featured Mechatronic Articles, Green Energy, Green Engineering
The electric car, hybrid or plug in, continues to be an elusive goal.
One model sports optional 2 wheel or 4 wheel in-hub mounted drive motors. With a large battery pack and a curb weight of 3300 pounds, it’s a bit ponderous. But it has a 50 mile drive radius and rarely requires any maintenance. What year will this vehicle be ready? 1899. It’s the Lohner-Porsche.
Recognizing that the weight the battery pack was a major obstacle, Ferdinand Porsche, still working for the Lohner Coachworks, came up with a hybrid model. The vehicle used a small gasoline engine to power a generator and a single motor mounted on the rear axle of the vehicle. Porsche raced the car himself in the Semmerling competition near Vienna, and with top speeds of 75 miles per hour, won against a very competitive field which included Benz gasoline powered cars. The 75 mile per hour top speed was unprecedented, especially from an electric hybrid. The year? 1900!
So all things old are made new again. If the 2200 pound weight of the Lohner Porsche battery pack could be reduced by 4:1 by using Lithium batteries, then a curb weight around 1500 pounds should be feasible. The reduced weight of the vehicle leads to significantly greater driving range. The Smart Car electric model is expected to have a range of 120 miles per charge. Which, actually, is enough for a lot of vehicle applications.
In wheel drive motors are not my favorite solution, but if the weight can be reduced, then problems relating to suspension dynamics can be managed. And that’s exactly what the folks at Protean Electric are doing. They have produced a number of conversion vehicles as demonstrations of their electric motor technology. And if the motors perform as expected, they will carve out a niche in the plug-in and hybrid electric vehicle world.
There are a couple of important points that need to made here.
#1) based on the “Absolute Value of Technology”, the only thing that matters is the vehicle costs per transportation mile. That is made up to two components, the purchase price and the expected cost per mile driven. Admittedly, if you can run an electric vehicle at $.04/mile, it is cost effective to own, even if the car costs more up front, because over the life of the vehicle, the low operating cost will overtake the purchase price.
The IRS deduction for vehicle operation is $.50/mile. Electric hybrids and especially plug-in electrics are not expected to have any major maintenance costs. Even if you add insurance, the cost per operating mile will be significantly lower.
But the higher price of the vehicle will be an obstacle from a pure economics standpoint. For this reason, some manufacturers have considered the option of the local power utility company supplying the battery pack and maintaining it. Since this is the single largest expense, leasing it to the vehicle owner in the monthly power bill is a good deal.
The second major point to be considered is plug in electrics, even with limited drive range, are the biggest contributor to American energy independence. These vehicles will directly reduce oil imports every day they are operated. Because almost none of the electricity in the United States is generated using fuel. It’s either coal, natural gas or nuclear.
So if we really want to get after the issue of energy independence and stop funding governments that support terrorist activity, the electric car is the path forward. As are 40+ mpg gasoline cars, and drilling and refining of oil in the US.
Let’s get after it!
