Developing an Internet-Enabled Dyno for Remote R&D and Education

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"The CompactRIO platform has proven to be a versatile and cost-effective solution for building and supporting the engine dyno, while meeting or exceeding the requirements. The result is a win-win for both GDJ and the educational community."

- Dave Philipson, Viewpoint Systems, Inc.

The Challenge:
Developing a strong, simple, Internet-based, and cost-effective solution for controlling and monitoring an internal combustion engine for remote research and academics.

The Solution:
Integrating an NI CompactRIO system with Remote Panel technology to perform crank angle-based control and measurements at 6,000 RPM. The field-programmable gate array (FPGA) portion handles the more than 100 kHz crank encoder signals to coordinate engine timing and the CompactRIO real-time controller assures safe operations and measurements of all sensors and actuators, including fuel, pressure, air, and temperature.

Author(s):
Dave Philipson - Viewpoint Systems, Inc.
Jim Campbell - Viewpoint Systems, Inc.

NI Platinum Alliance Partner Viewpoint Systems and GDJ Background

A former educator whose main goal is to bring math and science from theory into hands-on practice founded our client, GDJ, Inc., and its subsidiary, MechNet. GDJ provides innovative, highly accurate lab equipment at practical prices. This equipment is American-made, and currently used in leading universities, NASA labs, and industrial testing facilities throughout North America.

GDJ had been developing dyno stands for educational purposes for a number of years. Although some institutions could purchase them for their programs, the equipment was expensive and required frequent maintenance, which often made it cost prohibitive. GDJ wanted to develop a cost-effective way for university and high school students to access the stands as though the equipment was in their lab, thus, effectively renting time on the stands while giving the students a real, hands-on experience. Science, technology, engineering, and math (STEM)-based initiatives motivate much of this effort to improve educational competitiveness for the U.S.

The client ultimately wanted to offer three types of stands: a single-cylinder engine dynamometer (gas/diesel/natural gas/propane), a gas turbine engine, and a wind tunnel. This paper focuses on the single-cylinder engine dynamometer. Figure 1 shows the next-generation diesel version.

Figure 1: Single-Cylinder Engine Dyno

Because users are remote and have usually not used this system before, the user requirements are centered on easy and safe operation. The system needed to be safe and versatile, easy to operate, have a Web interface with multiple-user access capability, and provide the ability to view-only or control the system.

The system requirements included the following:

  1. Accurate detection (thousands of counts per revolution) of crank-angle positioning up to 6,000 RPM
  2. High-resolution timing control based on the crank angle
  3. Ability to measure a variety of sensors with flexible signal conditioning
  4. Ability to control digital and analog actuators
  5. Diagnostics panel to display sensor readings and control actuators
  6. Real-time calculation of critical parameters, such as maximum cylinder pressure per cycle and airflow
  7. Real-time data visualization
  8. Data logging and high-speed “snapshots” for the pressure versus volume graph
  9. Closed-loop control of throttle position
  10. 0.   Closed-loop control of engine speed via variable load
  11. 1.   Closed-loop control of engine load via variable throttle

The most challenging technical requirements surrounded the need for highly accurate, angle-based timing for all cycle-based engine control and acquisition.

Our Solution

The client first attempted this project using a Windows OS and quickly realized the difficulty in attaining the responsiveness required to operate the engine properly. In addition, many items are mounted on a roll-around frame, making it challenging to find room for a PC or PXI system on the frame. Plus, given the vibrations and jolts the frame receives under normal use, the durability of a PC-based solution was questionable. Finally, the client did not have the desire or time to develop the final control and monitoring solution, because their capabilities and direction were on building and selling the product.

The client sought an external integrator with the required capabilities. Our company, Viewpoint Systems, was selected because of our expertise with the leading-edge LabVIEW Real-Time and LabVIEW FPGA technologies, tools that were ideally suited for addressing the client’s requirements.

The NI platform selected for this project was CompactRIO. This platform was perfectly suited because it offered the requisite size, channel count, signal conditioning, and LabVIEW Real-Time and LabVIEW FPGA capabilities for the real-time needs. The system developers for this project were Stuart McFarlane and David Philipson.

Using CompactRIO With LabVIEW Real-Time, LabVIEW FPGA, and Remote Panel Technology

The CompactRIO controller runs the entire application. We used LabVIEW Real-Time for the main loops and the interface with the FPGA which performs the crank angle-based control and data acquisition. We used NI Remote Panel technology to access the application on CompactRIO, giving students and instructors the ability to monitor and control the engine via Windows Remote Desktop technology.

We used the following tools for this project:

The module I/O list is detailed below:

  • NI 9211 thermocouple analog input module for measuring temperatures for the engine intake air, exhaust, the cylinder head, and oil
  • NI 9472 digital output module for controlling the engine power, the starter, and fuel selection – gasoline /natural gas /propane
  • NI 9474 digital output module for stepper motor control of the throttle position
  • NI 9411 digital input module for the crankshaft encoder and throttle position stepper motor position
  • NI 9263 analog output module for load control of the eddy current brake control
  • NI 9201 analog input module for the status of the fuel flow for liquid gasoline and natural gas/propane gas, airflow, oxygen sensors, cylinder pressure, and load cells

Technical Highlights

Pressure Signal Capture for P-V Calculations

The most important aspect of this system lies in the ability to capture data that is accurately correlated with the crankshaft position. A quadrature encoder attached to the crankshaft indicates the angle of the crank, as well as TDC via the Z index. The large number of pulses per revolution and the high RPMs pose a significant challenge without the use of FPGA technology. Using the FPGA for the acquisition, we can accurately take “snapshots” of the cylinder’s pressure-volume (P-V) data. This data is captured and passed to the real-time application through a direct memory access (DMA) first-in, first-out (FIFO) for processing and display.

Remote Access

Rather than build a user interface (UI) on the host computer, we designed the complete UI to be part of the real-time application running on CompactRIO. To access the application’s functionality, we used NI Remote Panel technology. A thin, LabVIEW client application is installed on the user’s host computer and, by specifying the remote IP address and port of CompactRIO in the host location, the user can connect to the system and “drive” it as though he or she were in the lab.

The user’s client interface shown in Figure 2 provides access to the system.

Figure 2: User Client Interface

We designed the system to support simultaneous access by multiple users through proper licensing of the Remote Panel technology.

Engine Control

All aspects of engine control are exposed on the application’s main panel, including operation and measurement of throttle position, remote engine start/stop, and operation of the dynamometer. A number of safety features are in place to prevent improper operation. For instance, dyno control is not possible until the engine is above 500 RPM. There are two versions of the system available. One allows remote start and stop of the engine while the other does not.

In addition to manual control, the system supports two active control modes: RPM control and torque control. Simple feedback algorithms with adjustable gains manipulate the throttle and dyno to run at either a set RPM with a fixed load applied or vice versa. Figure 3 shows the main control panel.

Figure 3: Main Control Panel

The screen is divided into sections allowing control of the dyno and the throttle, data logging to support post-acquisition analysis of performance, and overall system configuration.

Heads-Up Display of System Information

The application includes a diagnostic panel where indicators display all critical engine information such as RPM, torque, fuel flow, cylinder pressure, and a number of temperature sensors.

Figure 4: Performance Monitoring Panel

Data Graphs

In addition to the P-V data, all other analog signals can be captured using the same “snapshot” methodology. This provides the ability to view the specified channel against the crank angle.

Figure 5: P-V Review Graph (Diesel Engine)

System Benefits

In short, this effort’s primary goal was twofold. First, we wanted to develop software that was capable of integrating the existing engine/sensor package to provide accurate and correct data collection while also allowing system control. Second, we wanted to provide remote access to the UI so that users could benefit from using the system without actually owning the physical machinery. Providing multiple users simultaneous access to the system was also part of the later goal. 

By combining the powerful feature-set of CompactRIO and FPGA technology and the NI Remote Panel capability, the system met all of the stated goals. Educators and students from all over the world can now log on to an engine stand and deliver classroom instruction with real-time data and presentation of an actual operating engine without the hassle of owning and maintaining an engine dyno. Additionally, if modifications and enhancements are made to a system, all users that subscribe to the service can stay current without expensive replacement hardware or software maintenance costs.

The CompactRIO platform has proven to be a versatile and cost-effective solution for building and supporting the engine dyno, while meeting or exceeding the requirements. The result is a win-win for both GDJ and the educational community.

Author Information:
Dave Philipson
Viewpoint Systems, Inc.
800 West Metro Park
Rochester, NY 14623
Tel: (585) 475-9555
marketing@viewpointusa.com

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