The document summarizes an internship report on developing a graphical user interface in LabVIEW to control a vertical take-off and landing (VTOL) system. The summary describes LabVIEW and its dataflow programming approach. It then provides an overview of the VTOL hardware, including a fan motor, position encoder, and interfaces to control voltage, current and position. The intern developed front panel controls and indicators in LabVIEW to monitor and adjust the VTOL system in real-time.

1. Internship Report
A graphical user interface (in LabVIEW) for
controlling a Vertical Take Off and Landing system
(VTOL)
A project by
Rishabh Prakash
Department of Electronics and Communication Engineering
Haldia Institute of Technology
At Indian Institute of Engineering Science and Technology
Shibpur
________________________________________________
Dr. Subhasis Bhaumik
Professor and Head,
Aerospace Engineering & Applied Mechanics
Coordinator
School of Mechatronics and Robotics
IIEST Shibpur

3. Index:

4. Introduction:
Labview
LabVIEW is a highly productive development environment for creating custom applications that interact with real-
world data or signals in fields such as science and engineering.
The programming language used in LabVIEW, also referred to as G, is a dataflow programming
language. Execution is determined by the structure of a graphical block diagram (the LabVIEW-
source code) on which the programmer connects different function-nodes by drawing wires. These
wires propagate variables and any node can execute as soon as all its input data become available.
Since this might be the case for multiple nodes simultaneously, G is inherently capable of parallel
execution. Multi-processing and multi-threading hardware is automatically exploited by the built-in
scheduler, which multiplexes multiple OS threads over the nodes ready for execution.
LabVIEW ties the creation of user interfaces (called front panels) into the development cycle.
LabVIEW programs/subroutines are called virtual instruments (VIs). Each VI has three components: a
block diagram, a front panel and a connector panel. The last is used to represent the VI in the block
diagrams of other, calling VIs. The front panel is built using controls and indicators. Controls are
inputs – they allow a user to supply information to the VI. Indicators are outputs – they indicate, or
display, the results based on the inputs given to the VI. The back panel, which is a block diagram,
contains the graphical source code. All of the objects placed on the front panel will appear on the
back panel as terminals. The back panel also contains structures and functions which perform
operations on controls and supply data to indicators. The structures and functions are found on the
Functions palette and can be placed on the back panel. Collectively controls, indicators, structures
and functions will be referred to as nodes. Nodes are connected to one another using wires – e.g. two
controls and an indicator can be wired to the addition function so that the indicator displays the sum of
the two controls. Thus a virtual instrument can either be run as a program, with the front panel serving
as a user interface, or, when dropped as a node onto the block diagram, the front panel defines the
inputs and outputs for the given node through the connector pane. This implies each VI can be easily
tested before being embedded as a subroutine into a larger program.
The graphical approach also allows non-programmers to build programs by dragging and
dropping virtual representations of lab equipment with which they are already familiar. The LabVIEW
programming environment, with the included examples and documentation, makes it simple to create
small applications. This is a benefit on one side, but there is also a certain danger of underestimating
the expertise needed for high-quality G programming. For complex algorithms or large-scale code, it
is important that the programmer possess an extensive knowledge of the special LabVIEW syntax
and the topology of its memory management. The most advanced LabVIEW development systems
offer the possibility of building stand-alone applications. Furthermore, it is possible to create
distributed applications, which communicate by a client/server scheme, and are therefore easier to
implement due to the inherently parallel nature of G.
Benefits:
1. Interfacing to Devices
2. Code compilation
3. Large Libraries
4. Code re-use
5. Parallel Programming
6. User Community

5. Hardware (VTOL System):
The QNET vertical take-off and landing (VTOL) system consists of a variable speed fan with a safety
guard mounted on an arm. At the other end of the arm, an adjustable counterweight is attached. This
allows the position of the weight to be changed, which in turn affects the dynamics of the system.
The arm assembly pivots about a rotary encoder shaft. The VTOL pitch position can be acquired from
this setup.
Some examples of real-world VTOL devices are helicopters, rockets, balloons, and harrier jets.
Aerospace devices are typically more difficult to model. Usually this will involve using software system
identification tools to determine parameters or actual dynamics. Due to their inherent complexity, flight
systems are usually broken down into different subsystems to make it more manageable. These
subsystems can be dealt with individually and then integrated to provide an overall solution.
QNET Vertical Take-off and Landing (VTOL) system

6. System Schematic:

7. Component Description:
Rotor Actuator: There is a EM150 DC Motor and EP2245X6 Rotor.
Pulse-Width Modulated Power Amplifier : A PWM power amplifier is used to drive the VTOL DC
motor. The input to the amplifier is the output of the Digital to Analog converter (i.e. D/A) of channel
#0 on the DAQ. The maximum output voltage of the amplifier is 24 V. Its maximum peak current is 5 A
and the maximum continuous current is 4 A. The amplifier gain is 2.3 V/V.
Analog Current Measurement: Current Sense Resistor:
A series load resistor of 0.1 Ohms is connected to the output of the PWM amplifier. The signal is
amplified internally to result in a sensitivity of 1.0 V/A. The obtained current measurement signal is
available at the Analog-to-Digital (i.e. A/D) of channel #0. The current measurement can be used to
monitor the current running in the motor.
6
Analog Voltage Measurement: Voltage Sense
The analog signal proportional to the voltage output of the PWM amplifier is available at the Analog-
to-Digital (i.e.A/D) channel #4 of the DAQ. The voltage sensor sensitivity is 3.33 V/V.
Digital Position Measurement: Optical Encoder
Digital position measurement is obtained by using a high-resolution quadrature optical encoder. This
optical encoder is mounted near the top of the VTOL support arm. The encoder shaft is used as the
pivot of the VTOL body. The encoder count measurement is available at Digital Input (i.e. DI) channel
#0 of the DAQ.
Fuse
The QNET power amplifier has a 250 V, 3 A fuse.
2.1.7 QNET Power Supply
The DCMCT module has a 24-Volt DC power jack to power the on-board PWM amplifier. It is called
the QNET power supply. The +B LED on the QNET board turns bright green when the amplifier is
powered.
Encoder

8. Specifications:

9. The Forces Acting:
Free-body diagram of 1-DOF VTOL
Torques acting on the rigid body system can be described by the equation:
The thrust force, Ft, is generated by the propeller and acts perpendicular to the fan assembly. The
thrust torque is given by:
Where l1 is the length between the pivot and center of the propeller, as depicted in Figure 3.1. In
terms of the current, the thrust torque equals:
where Kt is the thrust current-torque constant. With respect to current, the torque equation becomes
The torque generated the propeller and the gravitational torque acting of the counter-weight act in the
same direction and oppose the gravitational torques on the helicopter body and propeller assembly.
We define the VTOL as being in equilibrium when the thrust is adjusted until the VTOL is horizontal
and parallel to the ground. At equilibrium, the torques acting on the system are described by the
equation:
where Ieq is the current required to reach equilibrium.

10. Equation of Motion:
The angular motions of the VTOL trainer with respect to a thrust torque, _t, can be expressed by the
equation:
where θ is the pitch angle, J is the equivalent moment of inertia acting about the pitch axis, B is the
viscous damping, and K is the stiffness. With respect to current, this becomes
As opposed to finding the moment of inertia by integrating over a continuous body, when finding the
moment of inertia of a composite body with n point masses its easiest to use the formula:
The Front Panel:

11. Power Button:
This button is used to switch on the whole Panel.
Power Indicator:
Indicates the power in the panel. It glows when power is on.
Device Selector:
This is used to select the hardware device.
Samplinng rate:
It lets us chose the extent of precision. The more the sampling rate, the accurate is the data.
Digital Scopes:
The digital scopes measure the actual value of position of the arm (in degrees), current flowing
through the motor (in Amperes) and Voltage in the motor. The position is acquired from the
quadrature encoder which sends digital values to the computer in form of pulse-width modulated
wave. The Voltage and Current value is measured through encoder in the fan motor.
Meter:
The meters operate on the basis of data acquired by the digital scopes. It displays the same data as
the digital scopes.
Voltage Slide:
This slide is used to vary the voltage to the Motor.

12. The Block Diagram: