Data Acquisition System for Revitalization of Aircraft EMB 312 T-27 and AT-29 Force Simulator

This article aims to describe the data acquisition system for the Revitalization of the Force Simulator (T-27 and AT-29 Aircrafts). The acquisition system consists of an HMI, a controller/acquirer (clp), 4 signal converters (LC4200), and 4 load cells. The System is supported by supervisory software that records the trials, saving them in txt files. In addition, it is possible to view the quantities graphically. This equipment was developed to measure forces and acquire data on cadets and pilots using a force simulator in a joystick format. Developed with a robust case, with detachable electrical connectors, this is ideal for measurements in the field. The “brain” of this case is the NEON Logic Controller, which reads the inputs provided by the LC4200 that converts signals from the load cells into signals suitable for the PLC. With these readings, it filters and converts the signals to known quantities, in this case force in kgf. In addition, all the information collected by the NEON can be acquired through a serial output (with the help of a serial/USB converter). For this it is necessary to use the supervisory software developed exclusively for this application.The NEON PLC works in conjunction with the MT8071iP Human Machine Interface (HMI) which locally indicates, on an LCD display, the quantities measured in numerical and graphical form to facilitate the operation and handling of the equipment and its functions. The instruments below form part of this equipment:4 load cells Model CSA/ZL-100, from MK Controls, for up to 100 kg of traction and compression.1 NEON PLC with I/O HIO140 module (4 digital inputs (pnp), 4 digital outputs, 4 12-bit analog inputs (0 to 20 mA or 4 to 20 mA), 2 analog outputs (0 to 20 mA or 4 to 20 mA). 1 Expansion module for NEON PLC HIO140, 4 digital inputs, 4 digital outputs, 4 analog inputs 4 to 20 mA or 0 to 20 mA (12 bits). 4 load cell converters, model LC4200, with inputs of -20 to 20 mV and outputs of 4 to 20 mA.


Introduction
The Air Force Simulator (SF) of the T-27 Aircraft ( Figure 1) was built between 2005 and 2008, in the Precision Workshop of the Medical Faculty of Ribeirão Preto, University of São Paulo. The objective of this equipment is to develop a simulator of forces exerted in the joystick of the aircraft EMB 312 Toucan T-27 and AT-29 Supertoucan (Figure 2), for evaluation of forces and physical training of pilots and cadets [1][2][3][4]. The equipment created simulates, through a joystick and spring system, mechanical forces very close to the actual forces applied to the joystick during the execution of a maneuvers/acrobatics. A system composed of four load cells connected to a signal logger enabled quantification of the forces as a function of time in the simulator [1][2][3][4]. This signal encoder module was responsible for filtering and digitizing signals from the load cells. Software integrated with the signal logger was able to store and provide information about the force and moment registers. The signal conditioning was able to provide the varying voltage gain steps, such that the signals from the transducers could be faithfully represented after data collection.
The signals applied to each load cell were digitized for subsequent processing in the application. The equipment captured the signals of variation of this applied voltage on the load cells connected to the springs and provided a voltage value corresponding to this action. The simulator can be used as training to strengthen muscle groups required in acrobatic flights and as a tool for physical evaluation and scientific research in Pilots and Aviator Cadets of the Brazilian Air Force during the years 2008 to 2017 [1][2][3][4].

Use of the Force Simulator for Research
The force of gravity is altered many times during an acrobatic flight. A pilot's body weight may increase by 5 to 6 times for a few seconds [5][6][7][8].
Consequently the mechanical forces performed by the pilot on the lever, pedals, and joystick are increased. Failure to prepare physically for the flight can lead to muscle and joint injuries and decrease flight safety, increasing the risk of collision with other aircraft, and falls. The force simulator aims to reduce the risk of injury and increase flight safety, by improving the muscle strength of pilots in the movement of the joystick. The principal characteristics of the force simulator are the training of specific muscle groups recruited in flights and the simulation of loads applied to the joystick during the execution of simulated maneuvers [9,10]. This equipment is extremely useful in research at the Air Force Academy. Many of the physiological alterations that pilots undergo during flight can be analyzed in the force simulator without any risk. Studies have already been performed to monitor heart rate, blood pressure, and intracranial pressure using, primarily, physical exertion in the FS [1][2][3][4].

Equipment Characteristics
The picture below shows the equipment with the case open ( Figure 3): 1) MHI: Interface and display to accompany trials.
2) Serial Connection: Output connection for USB converter that will be connected to the PC.   ance differential with noise filters, maintaining a quick response to input variations. The minimum possible impedance to be connected to the equipment input is 100 Ω , resulting, for example, from the impedance of a single cell or from the association of cells in parallel. The LC4200 can be conditioned on a DIN rail that guarantees mechanical protection, facilitates installation, and makes direct access to electronic circuit components difficult.

NEON PLC:
The NEON PLC ( Figure 4) has the role of treating the signals of the load cell converters, converting these signals to kgf and making them available to the HMI and software. The PLC has its own application (software), developed in a Ladder environment. This application was developed in a dedicated and exclusive way for the Force Simulation system. It consists of a single rack with capacity for up to 2 I/O modules, HIO140. Load cell: Load cells are the sensor element for measuring force. The load cells consist of a measuring element where the strain-gages are attached. This element is made of aluminum, meaning that it is very resistant, but also has some elasticity, although minimal. Aluminum steel is slightly deformed under load, but then returns to its initial position, with an elastic response to each load. These extremely small changes (micro-deformations) can be measured by strain-gages. Due to its "S" shape, the cell allows deformation by tensing and compressing. These deformations in the strain-gage are converted to electrical signals. These electrical signals are converted and amplified by the LC4200 load cell converter (described later).

LC4200
The LC4200 is an interface used to convert load cell signals to signals that the PLC can use, in this case, 4 to 20 mA current signals. The equipment has excellent precision and stability, with built-in excitation voltage (10 V) and the presence of external adjustments of zero and span, which allows greater flexibility to adapt to the desired application, and also accuracy, since the adjustments can be carried out in the field. The LC4200 input is a high imped-  The "Tara" routine works in a similar way to normal scales (butchers, for example). When active, it takes the current value of force (weighing) and considers it to be "zero" for all other measurements.

Operation
Operating the case is very simple. First it needs to be turned on by connecting it to the mains (127 or 220 V). Connect the cables to each load cell. cation between the PC (through supervisory software) and the PLC.

Description of Neon Plc Operation Software PLC Software details
The software in the PLC (controller) treats each signal input and transforms it into an engineering unit (kg). The way this is done is described by the equation below: Y = m X + n + tara  be saved is configured and the rate of acquisition of the trials is configured.

Communication: Buttons to connect or discon-
nect software from the case.
2. Serial port opened correctly. If this LED does not light up, make sure that the USB/serial converter has been connected correctly. Also make sure that the converter driver has been installed and that the COM port has been configured correctly (see chapter 5.2 COM file format: Choose the format in which the trial will be saved (.txt or .xls).
3. The two options are .txt and xls (Excell).

Acquisition
Interval: Sets the frequency with which the points will be saved during the trials, that is, the rate of acquisition of the points in the trial.

Trial: Start trial.
This key is only enabled if the software is connected to the instrument case.
6. Stop: Ends trial. This will only be enabled when a trial is in progress.
7. Save: Saves trial on the computer. This will only be enabled after starting a trial and stopping it.
8. Discard: Discard trial started. This will only be enabled after stopping a trial.
Then activate the on/off switch. It is possible to operate the instrument without the software just by observing the force values on the display. If you want to operate with the help of the software, connect the converter to the PC and the cable to the instrument case. For more information on using the software, read chapter 5 below. The case display is touch screen (Figure 6), with no physical buttons. 3. Tara key makes the current value "zero". It needs to be pressed for 2 seconds to activate. To disable, press for 2 seconds.

Status LED:
Indicates HMI and controller working.

Supervisory Software
When you run the software, it has the following initial screen: This is the screen (Figure 7) where the user connects the software to the equipment. This is also the screen where the format in which the trials will to the device. If this LED does not light up, make sure the serial cable is correctly connected to the case, the case is on, and the serial port is opened correctly (item above). Once connected, the software will automatically jump to the indicators screen ( Figure 9, Figure 10, Figure  11, Figure 12 and Figure 13).
The configuration screen has the following features and functions:

Conclusions
The T-27 simulator, developed in 2008, and its revitalization completed in 2020, is projects for the physical training of pilots and aviation cadets of the Brazilian Air Force. The new version of the force sim-   ulator, in addition to inserting the new system for collecting and evaluating force data, also includes the possibility of simulating the force applied to the stick of the AT-29 Supertouncan aircraft.