Taking the COTS route with ATS 2.0 was undoubtedly the right decision, and when we started searching for PXI chassis and modules suppliers, the usual considerations came into play – cost, lead times and reliability. That presented us with a fairly level playing field, but it was Pickering’s guaranteed long-term product availability and support that really stood out and was one of the key factors in choosing them over their competitors.
Curtis Instruments, a Kohler company, is an original equipment manufacturer (OEM) of high-tech motor speed controllers and
vehicle control systems used extensively in materials handling trucks and equipment. For example, the company’s AC F2A
motor controller features dual high-performance ARM Cortex microprocessors and is optimized for use as a traction controller
on 1- to 2-ton Class III pedestrian-operated powered pallet trucks. The controller is also suitable for hydraulic pump
control.
As part of the company’s rigorous QA processes, all motor controllers (and the F2A is just one of 33 different motor controllers in the company’s portfolio) are subjected to thorough functional verification checks. For performing these, Curtis has several identical automated test systems (ATS).
The ATS was introduced in 1998 and comprised of:
The system is universal in that it can be used to test every motor controller (i.e., all Series, SepEx, PM, and AC models) in Curtis’ product portfolio. This versatility is thanks to:
Much of the ATS’s functionality is achieved using custom cards designed by Curtis. These include differential cards (with four circuits that measure voltages, currents, duty cycles, and speed), a multifunction card (for certain measurements and console control signals), relay cards to monitor signals from the device under test (DUT) and to drive control signals to the battery cabinet and motor stands. There are also throttle cards to drive the motor stand and DUT motors, plus communication cards to talk with the DUT and the motor stands.
To optimize serviceability and eliminate downtime, Curtis took great care to ensure that as many ATS components as possible could be removed for bench-top servicing or replacement.
Richard Allred, Senior Test Engineering Group Leader at Curtis Instruments, comments: “Interchanging most subassemblies does not require re-calibration of the ATS, and if one of the units does develop a fault, we can repair it quickly as we keep spare components on hand - although that is becoming increasingly challenging.”
As mentioned, the original ATS entered service in 1998 – and has served Curtis well. However, its continued use has been put at risk by obsolescence issues that include:
Allred continues: “Discussions about an ATS version 2 started as early as 2014. We like the functionality we have with the original ATS as a great deal of thought went into it, but we needed to protect ourselves against escalating obsolescence issues. An ATS 2.0 made sense. It was also an opportunity to try and reduce the test time. ATS 1.0 takes an average of 5 minutes to perform a test cycle. We wanted to reduce that by at least a minute.”
Curtis recognized that the solution to component obsolescence was to move away from custom cards and to use commercial-off-the-shelf (COTS) products and, by extension, let the OEMs of those cards manage component obsolescence.
It was also decided to move away from using a motor stand and actual motors. Instead, simulated loads would be used. The benefits of doing so include:
Core to embracing COTS was the selection of a modular card and chassis format, and Curtis decided on PXI.
“When the design work for ATS 2.0 started in earnest, in 2018, Pickering Interfaces was identified as the best provider of many of the cards we would need,” recalls Allred, “and their load simulation capabilities are renowned in the industry.”
The following Pickering Interface PXI switch and simulation modules are used:
Also, whereas ATS 1.0’s fixture interface contains relays and custom PCBAs that route the generic signals and measurements from the console to the motor controller, ATS 2.0 uses Pickering’s matrix cards as above.
Allred explains: “The matrix cards make for more simplified fixture interface wiring and signal routing to the DMM for duty-cycle, voltage and current measurement, and to the encoder measurement hardware.”
An NI card is used for isolated DIO requirements, and a Peak 4-CH Isolated CAN card is used for communications. Also, the host processor OS is Windows 10.
ATS 2.0 was released for use within Curtis in 2018, and at the time of writing, there are 16 systems in use at the following locations:
…and another five systems are scheduled for build before the end of 2023.
The planned service life for ATS 2.0 is a minimum of 10 years. “Though shorter than the circa century of service ATS 1.0 provided, today’s electronics industry supply chain is very different from how it was in the 1990s,” adds Allred. “ATS 3.0 is likely to be an evolution of ATS 2.0, possibly capable of testing multiple products at the same time. Also, Curtis makes far more than just motor controllers, and we’re becoming increasingly responsible for electrification within the Kohler group.”
As for reducing average test time, that goal has been met, with ATS 2.0 taking 3.5 minutes compared to 5 minutes on ATS 1.0 - a 30% reduction.
In its ATS 2.0, Curtis Instruments has a versatile test system. Functionally, it is the same as their long-serving ATS 1.0 - but it is faster and more reliable. It is also easier to inject faults and monitor load conditions, both benefits coming from the use of simulated loads.
Above all else, Curtis has protected itself from component obsolescence. Although the current thinking is that the service life of ATS 2.0 might only be ten years, this can easily be extended as Curtis has complete peace of mind that Pickering Interfaces will ensure the availability of appropriate PXI cards and modules, which was why the company was selected.
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