Application Notes for Linear Position Sensors and Supporting Electronics. Provided by Alliance Sensors Group H. G. Schaevitz LLC. Would you like to discuss an application? Call us today 856-727-0250
Most snow plows utilize hydraulic actuators to raise and lower the plow blade, change the blade’s left-to-right surface contact angle, and adjust the plow blade’s front-to-back tilt angle. Typically, these plow positioning functions are under the plow operator’s control. However, the operator’s productivity can be improved and plow maintenance reduced if plow position feedback is made available to the operator in the vehicle’s cab. A further benefit to plow fleet operators is that the position sensors’ output could be transmitted along with the GPS location of the plow vehicles to a remote site, where the plow operating parameters can be logged and evaluated for productivity and maintenance analysis. In addition, there can be electronic systems on board the plow vehicle that utilize various sensors to evaluate snow pack compaction and related factors to automatically control the most important plow position parameters.
There has been a revolution in the position sensor market with the development of low cost, high precision, inductive LVIT Technology developed by H. G. Schaevitz LLC dba Alliance Sensors Group in Moorestown, NJ.
LVIT Technology (Linear Variable Inductive Transducer) has significant advantages over LVDTs and Potentiometers having an excellent stroke-to-length ratio and using contactless, inductive technology; giving you best of all worlds at a cost-effective price. The LRS-18 series are designed for dimension or position measuring applications in factory automation and in various industrial and commercial applications such as automotive testing, mil/aero test stands, robotic arms, and packaging equipment.
Under the right conditions, an S1A module can be "hot swapped" with another module having the same internal DIP switch settings and loaded with values in certain EEPROM locations that match those in the original module. If S1As are connected in a multi-module array, this process will take the selected module off-line, but if done carefully, will allow the remaining modules in the array to operate normally.
To prepare the replacement module for a hot swap, the configuration data of the original module, which should have been obtained previously and saved for a possible hot swap, is needed. If this data is not available, connect to the RS-485 port of the original module with a PC and terminal program, and use the Config command to get it. Using that data, set the internal DIP switches and jumpers of the new module to match, then power it up and use its RS-485 port as noted above to load the values of ADC HI, ADC Lo, In Pot, Gain, and, if needed, FOP, FD, and LF using the Set command for each value.
Alliance Sensors Group, a division of H.G. Schaevitz, LLC, has developed a linear position sensing technology called LVIT that offers an excellent price-to-performance ratio compared to other linear position sensing technologies such as LVDTs, linear potentiometers, and magnetostrictive devices. Furthermore, LVITs can offer the best stroke-to-length ratio of any contactless linear position sensor, because their overall length only increases by a relatively small percentage beyond their stroke.
Mechanical installation: An ASG ME-7 in-cylinder position sensors is embedded into a 48 mm diameter
cavity in the rear endcap of a hydraulic cylinder. It may be inserted from the front of an unassembled
cylinder or from the rear of a cylinder with a two-piece endcap with a separate end cover.
Mechanical installation: MR-7 in-cylinder position sensors are designed to be inserted into an o-ring port machined into the rear endcap of the hydraulic cylinder. Standard MR-7s use an SAE J1926-1 -8 port with a 3/4-16 UNF thread. Metric threaded versions use an ISO 1649-1 port with a M18 x 1.5 thread. Both ports are Illustrated below. For either size port, the sensor's male thread comes with a Viton o-ring installed.
SAE J1926-1 -8 Port
How they work and how to use them with a third-party LVDT signal conditioner designed specifically for Power Gen Applications
LVDTs (Linear Variable Differential Transformers) are very commonly used as position sensors in power plants throughout the world. Working from AC voltages and frequencies not available from power lines, LVDTs require a signal conditioner to provide the necessary operating power. Alliance Sensors Group's model S1A module, designed specifically to be used in power gen applications, is considered by many power gen users be the most advanced and easy to use single channel LVDT signal conditioner on the market today. It can operate practically any inductive or LVDT-type position sensor currently in use.
The S1A LVDT signal conditioner module offers an open-collector failure warning output signal which is available at J2-2 on the blue terminal block connector. This output is a connection to the collector of an internal transistor switch, whose factory default mode of operation is Normally Open (NO). In NO mode a device connected between the +24 V DC supply and J2-2 will have no current flow when the module is operating without error, producing a logic High (+24 V) at J2-2, but if a failure occurs, current will flow producing a logic Low (0) at J2-2.
Recommendations for DC power supplies and USB-based data acquisition hardware for use with ASG's signal conditioners and DC-operated sensors
DC Power Supplies
There are two distinct types of DC power supplies that convert the AC power line voltage into
An ongoing challenge in the USA is that our transportation infrastructure is aging, as attested to by the increasing traffic and the resulting load limits being placed on bridges. In the present technological world, bridge monitoring does not have to rely on periodic human inspections, but could rely instead on electronically monitoring a bridge’s health, so it can be maintained and repaired well before any structural integrity problem could develop.
Bridge expansion and contraction due to seasonal heating and cooling is a common problem found in civil engineering. To combat this problem, engineers put expansion joints in the bridge to absorb these changes. This problem is compounded with railway bridges, where the expansion of a mile long section of rail could be as much as 4 ft over a temperature change in some climates of 100 degrees F. This could lead to rail buckling, known in the industry as “sun kink”, as shown below, and the derailment of a train.
ME Series Linear Position Sensor Installed in a Hydraulic Cylinder
Alliance Sensors Group offers in-cylinder position sensors to replace magnetostrictive technology at a lower installed and ownership costs. The LVIT ME series embedded sensor is placed in the same location as the other technologies as shown above. The sensor uses the gun drilled hole in the rod and piston assembly as the target. Typically a 10mm dia. hole is drilled but other sizes can be sensed. The unit is provided with a cable outlet for the electrical connections.
Alliance Sensors' LVIT Linear Position Sensors offer SenSet™ Field Programmability. SenSet™ allows the installer to very simply and quickly exactly match the full scale electrical output of a sensor to the actual mechanical movement range of the device in which the sensor is installed
1. Connect a 2-wire RS-485 port converter to the computer on which this GUI is to run and connect the converter's output terminals to the RS-485 bus connections on the LVDT module(s), Data A (D-) connects to terminal J3-2 and Data B (D+) connects to terminal J3-1, but always follow the data polarity (D) indicated above, regardless of the letters used for the data lines.
Operating an ASG LVDT signal conditioner using its RS-485 communication port
ASG LVDT signal conditioners incorporate an RS-485 two-wire multi-drop serial communications interface for up to 16 devices. This port enables half-duplex serial communication by which a module can be set up and calibrated remotely and system data can be read or stored on a PC running a terminal program like Hyper Terminal with a 2-wire RS-485 converter for the computer's serial port or USB port connected to terminals J3-1 and J3-2 of the signal conditioner. The communication parameters are: 9600 bps, no parity, 8 data bits, and 1 stop bit (9600, NP, 8, 1), with echo on. Be sure that the RS-485 connection for Data A (D-) is connected to J3-2 and Data B (D+) is connected to J3-1.
By: Ed Herceg Chief Technology Officer
The Alliance Sensors Group model S1A module is the most advanced single channel LVDT signal conditioner available today. It will operate practically any LVDT currently on the market, but occasionally users can be confused by unusual LVDT configurations,
Find data sheets for Alliance Sensors Group LVDTs LVIT and LVDT Signal Conditioning by product.
An established but disruptive technology is now displacing older technologies being used for in-cylinder hydraulic actuator position feedback. LVIT Technology™ is an inductive technology which has been replacing both magnetostrictive sensors that use time-of-flight measurement technology and resistive potentiometers to offer a very rugged sensor that does not wear out.
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