Product category:
Linear Position Sensors
News Release from: Penny + Giles | Subject: Vehicle sensing and control systems
Edited by the Engineeringtalk Editorial
Team on 05 September 2006
Advances in vehicle sensing and control
Sensing and control systems are playing an important role in improving efficiency of the vehicle/operator partnership: Cliff Durling and Les Metcalfe explain.
New industrial vehicle sensing and control systems are playing an important role in improving efficiency of the vehicle/operator partnership They are rugged, and sophisticated, and they are being used to make significant improvements in vehicle efficiency
This article was originally published on Engineeringtalk on 12 Mar 2001 at 8.00am (UK)
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Everyone wants to increase efficiency - of systems, processes, machinery and people - and the industrial vehicle market is no exception.
Improved control systems bring better productivity through easier and safer operation, and lower cost of ownership by reducing wear and tear.
Great progress has been made in this area over the past 10 years.
Electronic joystick control, the biggest single development in this market in recent years, offers huge improvements over the all-manual hydraulic controls that are still common today.
They are much safer, quieter and cleaner because high-pressure hydraulics are no longer in the cab and the effort required by the operator is much reduced.
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Aberdeen based Sub-Atlantic Limited are using two different Penny and Giles joysticks for motion control on their Apache and Cherokee ROVs.
In-cylinder VRVTs improve undersea operations
VRVT transducers from Penny and Giles Controls have been incorporated in special aluminium subsea cylinders that are used to disconnect offshore oil pipeline bundles from towing vessel wires.
Sensors give accuracy on web tensioning
Penny and Giles HLP190s (Hybrid Linear Potentiometers) are specified by Valmet Atlas-Winders for the web tensioning systems on their range of paper, film and textile unwind and rewind machines.
This means that operators can work longer and are less likely to make mistakes.
As a result, joystick control makes considerable improvements in productivity of hydraulic action vehicles such as a loaders and excavators.
Even more recently, the increasing use of the SAE J1939 Controller Area Network standard (known as CANbus) in industrial vehicles from agriculture to materials handling opens up a wide range of control options and possibilities.
Communication systems designed according to J1939 standards are EMI/RFI tolerant, free of multiple connection wires, easy to install, and feature remote access and self-diagnosis capabilities.
Penny + Giles' latest joystick designs offer J1939 CANbus with additional input pins so enabling nonCANbus features to be connected to the bus network without an extra node being required making for a smaller, neater joystick interface.
This is an advantage not only for the operator but also for the system integrator as components are smaller, lighter and easier to mount in an optimised position.
However clever the electronics, old habits die-hard and it is only natural for an operator, keen to get the job done and possibly more used to a heavier control action, to move the joystick fast and hard.
The instinct is to push the joystick right to the limit of its movement every time, in order to complete the action more quickly and so work more 'efficiently'.
In reality of course, this 'slamming' of the joystick is not the most efficient method at all - it just puts increased stress and wear on the equipment and does not make it move any quicker.
That is why vehicle manufacturers are now looking for sensing and control systems that do more than just carry out an operator's instructions, they actually improve on them using information collected from other parts of the vehicle sensing system.
For example, Penny + Giles is working with a leading vehicle manufacturer on an integrated sensing and control system that takes the joystick operator commands and combines it with flow control valve information and feedback from the motion sensor to provide a smooth, closed loop control action.
This innovative system eliminates the 'judder' effect of slamming the joystick to its limit, with considerable benefits for the long-term health of the vehicle, and therefore for cost of ownership, through reduced wear and maintenance frequency.
The system is also more comfortable for the operator, as the response to the joystick movement is still quick but the uptake of the hydraulics is smoother.
The comfort of the operator is a very important factor in the design of control systems.
The compact design and flexibility of electronic joysticks means that the chair armrests can be made adjustable to suit individual users, unlike mechanically operated hydraulic systems that need to be rigid-mounted to prevent hose flex and to carry the weight of the installation.
But while there is a move away from mechanical controls to electro-hydraulic systems, it is important that the users are able to make the transition with a minimum retraining or reorientation as to the function of the joysticks.
Penny + Giles has responded to this need with mechanical features designed into the joystick to simulate the feel of a hydraulic system.
These features include the use of a mechanical lock in the small joystick space envelope that holds the operating lever at an extreme of travel.
Other customers are looking at smart systems with the capability to 'learn' a set of actions that can then be repeated automatically - for example to dig a series of trenches or load a dump truck.
This not only improves the consistency of the results, but also helps with operator fatigue and can be designed so that the system smoothes the control action as the instructions are repeated.
Similarly, 'return-to dig' or 'return -to-load' functions that automatically return the digger arm or lift forks of a vehicle back to a known point at the touch of a button - are increasingly popular.
These functions allow the driver to focus on manoeuvring the vehicle into place for the next run without being distracted by the equipment controls, again saving time and effort and improving safety.
Manoeuvring a bulldozer or digger vehicle over uneven ground, it can be tricky for the driver to prevent the blade or bucket scraping on the ground.
Penny + Giles helped a customer avoid this problem with a clever CANbus-based system that uses the joystick controls to automatically 'float' the hydraulics just above the ground, again allowing the driver to concentrate on driving without fear of damage to the equipment.
Future generations of off-highway vehicles are likely to have enhanced chassis/suspension systems that allow faster travel over rough terrain.
The US military is developing all-terrain-levelling systems on various types of military vehicles, allowing them to move more quickly over uneven ground.
These vehicles use a combination of position feedback sensors on fast-acting hydraulic suspension systems that absorb the rough terrain, keeping the vehicle platform stable and level.
This assists the control of heavily-laden support vehicles and personnel carriers, as well as armament platforms that can fire weapons on the move.
Despite all the benefits, the increasing use of CANbus and electronics makes some manufactures nervous.
More used to the mechanical world of engines and hydraulics, not all industrial vehicle manufacturers are comfortable with the increasingly important role of electronics in their products.
Some have started to employ electronics designers in house, but others continue to rely on specialist systems integrators to supply them with the complete systems.
Either way, Penny + Giles, as the only player with specialist capability in both joysticks and motion control sensors, is uniquely placed to provide support for this market.
As the following examples show, it is only with a detailed understanding of the business needs of the customer and the technical details of the application that the best sensing and control solution can be arrived at.
The need to increase the efficiency of refuse collection is what brought one of our longstanding customers - a leading US manufacturer - to see us recently.
The company set itself a target to find ways of increasing the lifting capacity of its trucks by more than 30%, from 1100 to 1600 bins a day.
The in-house design team came up with a new side-loading lift mechanism that was able to pick up and empty the bin from the pavement with no need for the operator to position it on the forks, as in previous designs.
This is quicker for the refuse collection team and requires fewer operatives, increasing the overall efficiency of the operation.
However, the increased number of lifts in any one shift puts additional wear and tear on the truck's lifting mechanism, and the danger was that the cost of ownership would be increased by a greater maintenance requirement.
Understanding this problem, Penny + Giles recommended its noncontact in-cylinder position sensor, to be used in conjunction with system integration electronics to provide shock-free cushioning.
This programmable and variable electronic cushioning effect at each end of the stroke significantly reduces wear on the lifting mechanism and stress on the vehicle.
As a result, the one million-cycle life expectancy is likely to be increased by about 300% to three million cycles.
But there are times when a 'kick' or 'shudder' is required - to shake the last of the refuse from the bin (or, equally, the sand from the bucket etc) - and these sophisticated control systems allow for that too.
The new refuse truck system has a smooth-action override facility or a 'shake' button that the driver can use as required, for complete control of the emptying action.
For vehicles operating in the most extreme environments, reliability is key to optimisation of productivity.
Innovative solutions may be required to overcome specific challenges of agricultural or construction vehicles for example.
The familiar and commonly quoted IP (ingress protection) ratings, which indicate sealing of the component against the ingress of water and dust are specified for a static environment and may not offer an adequate specification for moving vehicles and their equipment.
Penny + Giles routinely tests and specifies equipment to the toughest IP standards and is the only supplier to rate a rotary motion control sensor to IP68M for moving equipment.
This very demanding water resistance standard is for equipment that is moving through water, submersed at a depth of up to two meters, for anything up to 30 minutes at a time.
It is ideal for any vehicle that may have to drive through a river ford, or cope with larges puddles on a muddy construction site for example.
In another example of coping with harsh conditions, one Penny + Giles customer experienced problems with potentiometric linear sensors on agricultural machinery being used in Southern Europe.
The effect of wet mud and chaff collecting on the polished shaft of the sensor, then drying in the sun when the shaft was stationary, eventually led to catastrophic seal failure.
Drawing on experience in aerospace, motorsport and other harsh outdoor applications, Penny + Giles was able to offer two solutions; a linear position sensor with an aluminium protective sleeve for external mounting, or a fully integrated and immersed in-cylinder linear position sensor.
The customer acted on our recommendations and the problem has been solved.
This is a fine example of how experience in the design laboratory is just not enough on its own - you need to get out and get your hands dirty.
Although not strictly speaking on a vehicle, our experience in another agricultural equipment application gives a good example of why understanding the specifics of harsh environments is so important.
A fully integrated in-cylinder immersed solution was found to be the best solution on this milking robot after external sensors started to corrode from the effects of cow urine.
Because the robot was sold worldwide, the customer accepted our suggestion of contactless technology, and this has proved extremely successful.
The customer has gained from improved product reliability, elimination of costly maintenance, and his product has become a market leader in this industry.
Australian farmers increased efficiency of a tractor-based Lateral Irrigator system by more than 90%, and yield by an extra US $90,000 per crop when they installed a new control system with sealed linear sensors and a high speed industrial communications network.
The new system gave operators the ability to control the steering of the entire machine - which has a massive 56m span - to within just 75mm, over a distance of several kilometres.
In addition, because of the repeatability of the control system, precious water is distributed uniformly and an even water profile is maintained throughout the entire crop.
The need for manoeuvrability and maximum coverage with minimum crop damage is what prompted another customer to make use of our rotary sensors in an innovative "steer-by-wire" system for specialist crop-spraying tractor vehicles.
Positioned on the pivot-point of the steering axel, the sensor monitors the exact position of the wheels.
The system uses these data to ensure that the front and back wheels constantly track each other so crop damage is kept to a minimum especially when turning.
A clever crab steering facility uses individual wheel marking and is very useful where the incline could cause the machine to sideslip, and to avoid soil compaction.
Developments in control system technology are bringing a new level of sophistication to vehicle controls, which is resulting in more efficient operation.
High reliability signals from the latest sensor and joystick designs, combined with intuitive control system software means that vehicles and their equipment can be tuned to optimise performance to individual applications.
At the touch of a few buttons, routine operations can be performed at high speed with minimal fatigue, for considerably better productivity from vehicle and operator. Request a free brochure from Penny + Giles ...
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