Earthquake Simulation Using Single or Dual-Axis Linear Motion Stages


With the goal of safer buildings and saving lives, scientists and engineers, through the simulation of many recent earthquakes, need to test building materials and structural designs. Using either a one or two-axis high force linear positioning stage from H2W Technologies, they can simulate the effects of earthquakes as large as the largest recorded earthquake in history, the 9.5 magnitude quake on the open ended Richter scale, in May of 1960 in Chile.

To generate the high forces accelerations necessary to simulate different types of earthquakes, including a transform plate boundary quake (a destructive type of earthquake), H2W uses three-phase brushless motors with Hall Effects guided by linear ball bearings.

In addition, accurately simulating the destructive forces of an earthquake requires precise linear positioning. One-micron resolution linear encoders provide positional accuracies to ± 20 µm and repeatability better than ± 5µm.

The standard high speed, high acceleration two-axis linear positioning gantry has a stroke of 8 inches [0.2 meters] (in both the X and Y axes. The force in the X axis is 400 lbs [1780 N] continuous (1200 lb [5340 N] peak) and the force in the Y axis is 200 lbs [890 N] continuous (600 lb [2670 N] peak), although longer strokes and higher forces are available.

To simulate the shaking from an earthquake you can send the signal directly from the motion controller to the amplifier, or from the data, available from the web, you can use LabView and a DAQ card (available from National Instruments) to produce an analog voltage signal from the data file to output to the amplifier.

H2W also manufactures a line of high force linear positioning stages that have single-axis operation. This stage has a standard continuous force of 84 pounds [374 N], and a stroke of 8 inches [0.2 meters], although longer strokes and higher forces (up to 250 pounds [1113 N] continuous) are readily available. H2W will design a customized stage to meet a customer's specific needs

Key features

o Linear motors for reliable and quiet operation

o Extensive data acquisition and control capability

o Easy integration of your structures, sensors, and actuators

o Fully documented system models and parameters

o Supports scaling and playback of earthquake data

o Synchronize motion profiles with multiple tables and/or other data acquisition systems

o Integrated safety features and limits

About the Technology

The DR stage is a low profile, wider footprint, enclosed positioning stage. It is used
in closed loop positioning applications that require high speed and high
accelerations of heavier loads.

The iron core coil assembly is magnetically attracted to the stationary magnet
assembly, which provides a preload for the bearing system. The dual parallel linear
bearing rails with 4 linear recirculating ball bushing guides provide a much higher
load carrying capacity. The wide low profile of the stage ensures a stable platform
for the payload or as the bottom axis (X axis) of a stacked multi-axis system.
The larger size of the stage allows for the mounting of a larger, higher force linear
motor.

The DR positioning stage incorporates the latest in linear motion technology:

o Motors: Non-contact 3 phase brushless, low cogging, iron core linear motor,
commutated either sinusoidally or trapezoidally with Hall Effects. The
encapsulated laminated coil assembly moves and the multi-pole single sided
permanent magnet assembly is stationary. There is a large magnetic attractive
force which provides a preload for the bearing system.

o Bearings: Linear guidance is achieved by using a 2 parallel linear rail with 4
linear recirculating ball bearing guides. The bearing guides are sealed with
wipers to contain the lubrication and to keep out debris. Periodic lubrication of
the guides is recommended.

o Encoders: Non-contact optical or magnetic linear encoders with a reference
mark for homing. Multiple reference marks are available and are spaced every
50 mm down the length of the scale. Typical encoder output is A and B square
wave signals but sinusoidal output is available as an option.

o Limit Switches: End of travel limit switches are included at each end of the
stroke. The switches can be either active high (5V to 24V) or active low. The
switches can be used to shut down the amplifier or to signal the controller that
an error has occurred. The limit switches are typically an integral part of the
encoder, but can be mounted separately if required.

o Cable Carriers: Cable guidance is achieved by using a cable carrier. Cable
carriers are oversized to allow for routing of customers hoses and cables.
o Bellows: The DR comes with optional neoprene / nylon bellows with Mylar
stiffeners.

o Hard Stops: Hard stops are incorporated into the ends of the stage to prevent
over travel damage in the event of servo system failure.

Integration of Drive Electronics

As well as providing the stage or gantry to meet your needs, H2W has the
expertise to provide the necessary drive electronics, and the capability to integrate
the motion control electronics with the motion control stage in one to several axes,
and having the ability to mix and match motor and drive types. These systems can
operate in either open or closed loop applications, and every closed loop system is
provided with startup programming. In addition, H2W will provide training and
support to learn and successfully operate the motion control software.
From design to implementation, H2W provides the additional value that gets you
started using your motion control device.

About H2W

H2W Technologies, Inc. is dedicated to the design and manufacture of linear and
rotary motion products that are used in the motion control industry. We are
committed to providing every customer with the optimal solution for their motion
application in the shortest possible time, at the lowest possible cost using only the
highest quality products.

We offer a complete line of linear electric motors including; single and dual axis
linear steppers, DC brush and brushless linear motors, voice coil actuators, and AC
induction motors.

Our high speed and high precision linear motor driven positioning stages are ideal
for both single and multi-axis closed loop servo applications. We also offer a
complete line of ball screw, lead screw and belt driven positioning stages. We can
provide you either a standard or custom designed positioning stage by itself or as
a complete turnkey solution with a servo amplifier, power supply and
programmable motion controller.

Other motion control products include; limited angle torque motors for compact,
limited angular excursion rotary servo applications, 3-phase brushless rotary servo
motors with matching digital servo amplifiers and permanent magnet linear
brakes for failsafe, zero power braking for baggage handling and people moving
applications as well as amusement park rides.

New products are constantly being developed, so please check our web
site www.h2wtech.com for the latest developments and new product offerings.
H2W Technologies, Inc. has developed and implemented a quality management
system to demonstrate its ability to provide consistently product that meets or
exceeds customer requirements. Our quality Assurance procedures address
customer satisfaction through the effective application of the quality system,
including continual improvement and the prevention of nonconformity. The quality
system complies with the international standard ISO 9001 (2000). H2W
Technologies is approved for the Military Specifications MIL-I45208A Inspection
System.

With over 75 years combined experience in the linear and rotary motion field, our
team of engineers can offer you the optimal solution to your most demanding
motion control, requirements.

Other Industries Served:

Semiconductor, Medical, Aerospace, Material Handling, People Moving, Amusement
Park Rides Packaging, Automotive, and Clean Room

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