This past month (June 20th, 21st, and 22nd) Sentek Dynamics along with controller company Crystal Instruments attended the European Automotive Testing Expo in Stuttgart Germany. Over 6,000 attendees came out to visit more than 300 exhibitors. There was a wide variety of testing equipment displayed at each of the exhibits; it ranged from virtual-reality driving simulators to test and measurement devices including temperature chambers, shakers, and vibration controllers. Sentek Dynamics and CI together showcased the largest of their L-Series shakers along with a Spider-81 Vibration Controller.
This year’s prominent theme was the focus vendors paid towards testing the limitations of autonomous driving instrumentation. As autonomous vehicle technology continues to develop, automotive manufacturers need to employ carefully thought out tests to ensure the reliability of the software that drives each vehicle, as well as the computers and sensing elements that provide the necessary feedback to allow the software to navigate the car down the road.
Developers of driver assisted and driverless instrumentation have many situations for which they need their hardware to perform perfectly under. One such situation that has become evident to CI and Sentek is the increased requirement for vibration and shock testing to test the sensing elements used in autonomous vehicles including lidar, video cameras, radio cameras, and GPS computers. CI and Sentek witnessed this trend first hand and are working closely with autonomous vehicle designers to provide the best vibration testing equipment to test autonomous driving instrumentation.
This year's European Automotive Testing Expo gave both CI and Sentek the perfect platform for which to discuss and share their knowledge of vibration and specifically how it relates to autonomous driving equipment. Interested folks stopped by the booth and many engineers walked away with a new understanding on how Sentek Dynamics and CI have assisted in vibration testing in the past and how they can provide their knowledge in the future.
To learn more about the mechanics of vibration and vibration-testing autonomous vehicle equipment and other developments from Sentek Dynamics, please send us an email (email@example.com), follow our blog updates (www.sentekdynamics.com), or come see us again at the upcoming Automotive Testing Expo in Novi Michigan, USA.
Recently, the Sentek Dynamics Team commissioned a Sentek Dynamics THV Series AGREE Chamber* at a major US aerospace company. An identical chamber is scheduled to be commissioned at the company’s Canadian facility in August 2017.
*Sentek Dynamics THV Series environmental test systems offers a turn-key solution for product development and reliability improvement. The THV Series chambers combine temperature, humidity, and vibration testing into one whole chamber. This method of testing, also known as The Department of Defense’s AGREE (Advisor Group on Reliability of Electronics Equipment), subjects the device under test (DUT) to a variety of simultaneous temperature, humidity, and vibration conditions that can be applied to a wide-range of military and commercial test requirements.
THV Series environmental test systems uses the Crystal Instruments’ Spider-100 controller which integrates the industry recognized Crystal Instruments EDM software for vibration control for precise control of temperature, humidity and vibration across the test regime. Chambers are offered in several sizes with shakers ranging from 22 kN (4840 lbf) to 391 kN (88,000 lbf).
Developing an efficient installation and commissioning process requires an understanding of facility requirements for electrical power, water, compressed air and laboratory layout. The Sentek Dynamics team excels at working closely with customer personnel to develop a coordinated plan. Status updates are communicated through weekly meetings and the include the discussion of:
- Identifying of pre and post-installation activities
- Documenting discussions with customer staff regarding facility requirements
- Coordinating of sub-contractors, for rigging, city permits, and electricity, water and compressed air hookup
- Shipping and receiving logistics, off-loading, unpacking, and positioning system components at their final locations.
- System start-up and final acceptance
The successful commissioning of the chamber is confirmation that the Sentek Dynamics team understands the customer’s needs. Specifically, the necessary planning to accomplish the installation and commissioning of the system in an efficient manner.
The key to the superior performance of the THV Series environmental test systems is the powerful yet practical Spider-100 controller. The Spider-100 controller supports Crystal Instruments’ versatile Environment Data Management (EDM), vibration control software (VCS), and dynamic signal analyzer (DSA) software.
The Spider-100 is specially developed for combined temperature, humidity and vibration testing where the device under test (DUT) is subjected to simultaneous temperature cycling, variable humidity, and vibration. The unique capability of simultaneous control for combined testing is made possible by the excellent control design which allows for control of a shaker, refrigeration units, electric heating elements and humidification components.
The algorithm of the temperature and humidity control is based on PID control theory. It includes a very smart, self-tuning capability that allows the software to obtain the optimum PID parameters using several iterations of self-tests. This blog briefly describes the software setting of PID control and the self-tuning capability.
PID Control Parameters and Self-tuning
PID control parameters can be based on temperature/humidity ranges or temperature ramp rates and can be configured in the self-tuning section. Due to the non-linearity of the control system, P, I, and D parameters have different optimal values in different ranges. Please use the PID self-tuning function to ensure optimum values in different test regimes. Currently, the self-tuning region is automatically calculated based on the run schedule. If the temperature/humidity parameters in a certain range need to be tuned, the self-tuning feature inside the self-tuning region can be turned on.
Click the Manual Edit Value link as shown below to edit temperature and humidity value ranges then configure the PID parameters which affect the control characteristics directly. Because the control system is non-linear, the optimal values of P, I, and D parameters are most likely not the same. The values can be optimized via PID self-tuning. The self-tuning region has various colors to represent the status of each range block. If the block color is light yellow it indicates heating, cooling, humidifying, and dehumidifying is not complete. If the block color is bright yellow, it indicates at least one action of heating, cooling, humidifying, or dehumidifying is complete. If the block color is green, it indicates all heating, cooling, humidifying, and dehumidifying actions are complete.
Click the PID Self-tuning button to open the self-tuning page where there are 5 options.
- All Self-tuning
- Heat Self-tuning
- Cool Self-tuning
- Humidification Self-tuning
- De-humidification Self-tuning
P, I, D parameters can also be manually set. Click any region inside of Self-tuning region, the PID parameters corresponding to that region will show below it. Click Manually edit the value, the P, I, D values of the current region can then be modified. Hover the mouse over How to set P, I and D and a detailed explanation about P, I, and D parameters and their suggested regions will be displayed.
Click Reset all to return all PID parameters in all regions to the manufacturer’s default settings. Click Show all values to see a detailed list of PID settings showing the PID parameters in each region. Altogether there are 18 cells consisting of one 9-cell region based on values, and one 9-cell region based on ramp rates. Each cell has 4 groups of PID parameters covering heating, cooling, humidification, and dehumidification for a total of 72 groups of PID parameters.
The self-tuned PID parameters can be saved so that they can be loaded from the library in other tests with the same temperature/humidity profile, without another self-tuning.
If the control is not optimized during testing, the PID parameters can be modified during the control process. After the modification click Apply all to save the updated parameters in the library, and the updated parameters will take effect immediately.
The PID parameter settings contain information about the PID control algorithm and specific PID input settings. Input temperature and humidity values or input humidity values with temperature ramp rates are used as part of the PID control algorithm. These settings are configured during factory acceptance testing of the system and are not recommended to be adjusted without assistance and or approval from Crystal Instruments. For advanced operations, PID parameters can be exported to a local drive and imported from previously saved settings if adjustments are needed for control optimization.
The PID control settings involve adjustments to the control interval durations and selection of various cooling methods (compressor, liquid nitrogen and liquid nitrogen with compressor).
The Control interval specifies the duration of time the compressor, heater or humidifier will turn on to control the temperature and/or humidity of the system.
The Range of temperature control initiates refrigeration when the temperature lowers to the target value specified.
The Nitrogen control interval is only relevant when choosing the “liquid nitrogen” or “liquid nitrogen and compressor” option for the cooling method.
The Compressor control interval controls the duration the compressor is turned on for cooling and dehumidification control.
The Heat dead band and Cool dead band specify the temperature range outside of which the “I” (Integral) control will not be activated. Once the specified temperature is surpassed, only “P” (Proportional) and “D” (Derivative) control are active.
The Temperature AVG (average) and the Current channel AVG (average) are the average number of temperature and current channel readings used for control, respectively.
The Self-tune function is used when automatic calculation of the specific PID settings is desired.
The Big temperature rate limit is an option valid only when the cooling method is set as “liquid nitrogen and compressor”. If the temperature changes at a rate less than this specified value, the compressor will be used for cooling. Otherwise, Nitrogen will be used for cooling.
The Humidify dead band and Dehumidify dead band specify the humidity range outside of which the “I” (Integral) control will not be activated. Once the specified humidity is surpassed, only “P” (Proportional) and “D” (Derivative) control are active.
Reference channel control is applied when the temperature difference from the sensor on the UUT to the chamber temperature is known. This known temperature difference assists in overall temperature control.
ASTM transportation tests (such as ASTM D4169) are commonly used to simulate vibrations induced by the shipping of containers via truck, air, and rail. Often times these tests require very low level random vibration profiles which can be hard to run and control. On top of that, many of the profiles begin as low as 1 Hz, which can cause problems as well.
For these reasons, selecting the appropriate equipment can be tricky. A Sentek Dynamics shaker with the proper isolation options can reduce the resonance of a system at low levels, and when combined with a Crystal Instruments Spider controller and a PCB high sensitivity accelerometer (for example: model number J353B34) the system will excel when running the required profiles. Look no further if you are in search of the best equipment for the job!
Electro-dynamic shakers are by nature robust and durable pieces of testing equipment. Frequently, they are not given much thought until a problem arises. When these problems do happen, they can be costly; not only monetarily but also in lost labor hours and downtime. Regularly scheduled preventative maintenance programs can help prevent unexpected problems and maintain peak testing performance.
With the continued growth of Sentek Dynamics, increased numbers of systems in the field, and length of time these units have been productive in labs worldwide, it became clear the Sentek Team would need to grow to accommodate the preventative service and repair requirements of our clients. Sentek Dynamics is proud to offer a dedicated Field Service team. Our team is available to perform preventative maintenance, repair, installation, and relocation services for not only Sentek Dynamics equipment but the equipment of several other manufacturers as well.
The phrase “Good things come in small packages” is true! Small satellites, also known as CubeSats, are being launched at a record pace with the successful February 15, 2017 launch of 104 satellites of which 88 were Planet Labs’ Dove satellites collectively known as Flock‐3p, aboard an Indian Space Research Organization (ISRO) Polar Satellite Launch Vehicle (PSLV) rocket from the Satish Dhawan Space Center in Sriharikota, India. This amazing launch followed the successful June 22, 2016 launch of 12 Planet Labs’ Flock‐2p satellites from the Satish Dhawan Space Center. These spacecraft are shoebox‐sized satellites placed into lower Earth orbit to provide imaging data.
Using space to help life on earth Planet Labs is using their satellites for: mapping, resource extraction, maritime monitoring, weather response and agriculture to name just a few applications. The small satellite industry is becoming big business and Sentek Dynamics and Crystal Instruments are playing a supporting role in the development and commercialization of these small, cost‐effective satellites.
Sentek Dynamics and Crystal Instruments’ Role To ensure survivability during launch and reliability in orbit Planet Labs used the Sentek Dynamics’ vibration testing system at the Sentek Dynamics facility in Santa Clara, CA for initial testing of the 12 Flock‐2p units. Seeing the advantages of an in‐house vibration test capability they subsequently purchased a turnkey vibration testing system from Sentek Dynamics consisting of a 65 kN (14,600 lbf) air‐cooled vibration testing system and 16‐channel Crystal Instruments modular Spider‐80X vibration controller with a suite of EDM software.
What are CubeSats? CubeSats are a class of small satellites that use a standard size and form factor. The standard CubeSat size uses a "one unit" or "1U" measuring 10x10x10 cm and is extendable to larger sizes; 1.5, 2, 3, 6, and even 12U. Originally developed in 1999 by California Polytechnic State University at San Luis Obispo (Cal Poly) and Stanford University to provide a platform for education and space exploration. The development of CubeSats has advanced into its own industry with government, industry and academia collaborating for ever increasing capabilities. CubeSats now provide a cost effective platform for science investigations, new technology demonstrations and advanced mission concepts using constellations (swarms disaggregated systems).
Deployment P‐PODs were designed to provide a common platform for deploying CubeSats. Multiple P‐PODs can be mounted to a launch vehicle to carry CubeSats into orbit and deploy them using an internal spring mechanism into low Earth orbit once the proper signal is received from the launch vehicle. The P‐POD Mk III has capacity for three 1U CubeSats, or combinations of 0.5U, 1U, 1.5U, 2U, or 3U CubeSats up to a maximum volume of 3U.
The Future CubeSats like Planet Labs’ Dove continue to push the boundaries of what commercial small satellite technology looks like today. Small satellites have been accepted as a means to the end. Sentek Dynamics and Crystal Instruments will continue to support this effort by providing proven, high quality test equipment to the growing number of companies and organizations offering alternatives to terrestrial solutions connecting the world.
February 15, 2017 ISRO India Rocket PSLV C37 releasing 104 satellites of which 88 were Planet Labs video – https://www.youtube.com/watch?v=aYf_uyHQN5o
The Sentek Dynamics team enjoyed meeting attendees at the 2016 Automotive Testing Expo in Novi, Michigan. Visitors stopping by the booth were able to preview a complete vibration test system provided by Sentek Dynamics.
To learn more: