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At Dover Motion we pride ourselves on our knowledge of Engineered Motion System design. With over 50 years of experience and more than a thousand products developed we have accumulated a vast array of knowledge. Our White Papers capture a piece of this knowledge that is most often requested by our customers.

 

TitlePublication / White PaperDescription
Adjustable passive magnetic constantPublicationThis publication presents an adjustable passive magnetic system that provides constant force along its stroke. Gravity is an undesirable force in most linear stages that operate in non-horizontal and specifically in vertical directions. Active systems consume extra energy to compensate for this force. In addition, they impose complexity, heat and cost to the systems. Pneumatic counterbalance systems have been proposed for the past two decades; however they need compressed air and are not reliable. This design provides a passive, reliable and adjustable counterbalance that works based on shear magnetic force.
Slow Down to Speed UpPublicationIt may not seem logical, but you can boost the productivity of a servo system by slowing down its operation. This publication explains this paradox
A Constant Velocity Scanning Stage with Resolution of 31 PicometersPublicationThis publication describes a constant velocity scanning stage with a resolution of 31 picometers.
A High Performance X-Y Stage with a Novel Topology (Delta Stage)PublicationThis publication describes a 350 mm travel X-Y positioning system with a novel topology, high dynamic performance, and an advanced real- time controller. While the initial implementation positions a 300 mm semiconductor wafer under a stationary laser system, the design can be scaled upwards or downwards in travel to suit a wide range of potential applications. The Delta Stage described below provides substantially higher performance than traditional X-Y stages, and its advantages become even more compelling as the travel is increased.
The X-Y-Z's of Biomedical ImagingPublicationAt the heart of many biomedical instruments lies an automated digital microscope. While many of these systems employ simple brightfield imaging with epi (through the objective) illumination, variants include transmissive illumination, fluorescence microscopy, darkfield illumination, TIRF, Nomarski, confocal, etc. In all of these cases, some simple optical rules can be used to optimally configure a system for your application, and these rules in turn drive the requirements for the system’s mechanics. In this article, we’ll explore how the optics and mechanics interact, and show you some ways to optimize your imaging throughput.
Accuracy in Positioning SystemsWhite PaperThe state of the art in precision positioning sys¬tems has undergone continuing improvement, with the result that modern positioning systems can now achieve unprecedented levels of accuracy. These gains have come about due to specific technical advances (most notably, the availability of coherent light sources) as well as inexorable pressure from high-tech applications which depend on dimensional accuracy for their existence. Notwithstanding the gains that have been made, there are gaps between levels of accuracy which are perceived as achievable, and those levels which can actually (and/or affordably) be met. This paper will attempt to address the realistic accuracy levels which various positioning technologies can meet, as well as the nature of the limi¬tations which restrict accuracy.
Force Generation and MeasurementWhite PaperOur broad product offerings in miniature, high performance, air bearing linear motor stages have, by virtue of their design, some interesting secondary capabilities of particular value in photonic automation applications. In addition to their traditional roles as point-to-point motion stages and constant velocity systems, the completely non-contact nature of their three primary design elements
– motor, bearing, and encoder – permit these stages to function as both high performance generators and measurers of force. Central to this capability is the complete absence of friction in the bearing ways, the perfectly linear relationship between motor coil current and the resulting force, and the availability of high resolution optical encoder position feedback. Together, these make the creation and measurement of milliNewton-level forces a reality in your application, as an added benefit above and beyond the substantial value that they already provide in high precision movement, and short move and settle times.
Limitations of FlexuresWhite PaperWhen one surveys the field of precision positioners intended for use in photonic automation, flexural guideways show up in a substantial number of product offerings. At first glance, they seem well suited to the task; they are simple to build, low in cost, and their limited travel seems a good fit to the application. Upon closer examination, however, the weak points of flexures multiply, and their intrinsic limitations stand out. At the outset, we should point out that we have been designing and shipping very high performance flexure based systems for over ten years, and have a substantial depth of experience in flexure design. In the proper application, they can be an effective way technology, but we see many cases in which either the wrong flexure design is chosen, or where a good design is used outside its fairly narrow region of good performance.
Limitations of LeadscrewsWhite PaperLeadscrews are a very effective means of translating rotation into linear motion, and provide a popular and cost effective actuator for many positioning stages. At Dover, we ship thousands of screw-driven axes each year, and for many applications, leadscrews remain the technology of choice. Their intrinsic mechanical advantage is often of value, which allows them to support gravitational loads, and generate significant axial forces. Common variants of leadscrews include rolled, ground, and lapped threads, and their mating nuts can be provided in anti-backlash friction-nut form, ballnut, and planetary configurations. There are also “threadless” nuts which employ angled radial bearings on a plain shaft. Despite the effectiveness of leadscrews in general purpose positioning systems, they begin to run out of steam as the required resolution increases.
Limitations of PiezosWhite PaperAll translation stages require a set of ways, as well as a means of actuation to produce motion along the guideways. There are a number of actuation technologies available to choose from, and one of these makes use of the inverse piezoelectric effect. This is an effect in which the application of an electrical voltage to selected materials produces an extension or contraction in that material. Due to the very low magnitude of this expansion or contraction, all practical implementations of the piezo effect rely upon either reiteration or amplification to produce useful motion. While Piezos have their place, inherent in their design are limitations that can be overcome with the use of other technologies.
Positioning Systems OverviewWhite PaperDivide and conquer! To help in understanding positioning systems, it is useful to employ a classically reductionistic approach, breaking such systems down into their constituent assemblies. In this paper, we will divide the overall function of positioning systems into categories and discussing their attributes.
The Air Bearing Throughput EdgeWhite PaperAir bearings have an additional edge over conventional bearing systems that is not generally appreciated. When compared with rolling steel bearing systems, air bearings offer a throughput advantage of up to 10 times, which is a substantial productivity improvement

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