Integrated Package
Software for Multi-copter Flight Simulation
DroneV 4.0
The Operation Windows and User Manuals are All
Described in English
DroneV is a package software for simulating flight
performance such as cruising range, acceleration and
maximum speed of drones.
While
the general-purpose 1DCAE tool builds a model by combining sub-models and
modules created using many optional product groups
for
system level simulation of drones, Drone V3 has the series functions from
creating aircraft model , flight mode file, payload
file, and wind files
required for system level simulation to output flight
results.
Wha’s
New @V4.0
DroneV4.0 supports to simulate the
flight of multi-copters that use contra-rotating rotor unit, which has two
rotors arranged in
upper and lower
stages to obtain large thrust for transporting and delivering goods. The upper
and lower rotors of each rotor set are
each driven by
independent motors to control the vehicle's pitching, rolling, and yawing
attitude, as well as altitude or velocity.
Hexa-copter with contra rotating rotors
(1) How to Model the Contra-Rotating Rotor
1.
Thrust Stand Test of the Contra-Rotating Rotor Unit
Measure the thrust , torque, and speed of the upper and lower rotor
using a commercially available or
in-house thrust stand.
Schematic of Thrust Stand Example
of Thrust Stand Test Data
2. Modeling Applying Propeller Momentum
Theory for Contra-Rotating Rotor
Referring to the thrust stand test data
entered in Excel sheet to create the aerodynamic model
of contra-rotating rotor, determine some
parameters in the model.
.
(2) Control of the Rotor Speed
1. Pitching, Rolling, and
Altitude or Velocity of the Vehicle
The
attitude angles except for yawing and altitude of the vehicle are controlled by
the relative difference
in the
total thrust of the upper and lower rotor Thn between each rotor
set.
Rotating Motion of All Rotors
in Contra-Rotating Rotor System
2. Yawing
The main purpose of using contra-rotating rotors in airplanes and
helicopters is to cancel the reaction torque of
the two rotors. However, if two rotors with a same pitch are arranged
in series and rotated at a same speed,
differences in thrust and torque between the two rotors will appear.
Therefore, a variable pitch mechanism is
required to solve this problem.
On the other hand, fixed pitch rotors are used in multi-copters in
pursuit of weight reduction and mechanical simplicity,
but the speed can be controlled by an independent motor for each rotor
instead, and Yawing torque can be controlled
by the differential speed of the upper and lower rotors.
The control target is
yawing angular velocity or yawing torque, and the manipulated variable is the
rotational speed
difference Δω between the upper and lower
rotors, and there are three control methods when the target yawing torque
is zero, as shown below.
◆Speed-Based Control
Speed difference Δω = 0, and although the reaction
torque is not balanced for the individual rotor set, the overall vehicle is
balanced.
◆Torque-Based Control
Based on torque difference Δtq=0 to balance the torque in each rotor set, but the speeds of the two rotors are
different.
◆Thrust-Based Control
Thrust difference Δth = 0, and although the
reaction torque is not balanced for the individual rotor set, the overall
vehicle is balanced.
The operating conditions (thrust, speed, and torque) of each rotor will
differ depending on the control methods above.
3. Comparison of Rotor Operating Conditions(Thrust/Speed/Torque) by Yawing Control Method
The simulation results using a Hexa-copter model are shown below.
a) Hovering
Figure a) below shows the
operational data of the #1 rotor set when the vehicle with its center of gravity on the
Z-axis is hovering
in a windless environment. Comparing the
upper and lower (U, L) rotors, it can be seen that in speed-based control, the
speed of both
rotors is the same, in torque-based control, the torque is the
same, and in thrust-based control, the thrust is the same as well.
b) Forward Flight
Figure
b) shows the operational conditions of #1 to #6 rotor set when the vehicle
of which center of gravity offset from the Z-axis
flying horizontally forward., using speed-based control or torque-based
control.
In this
case, there are differences in the thrust of each rotor set in
order to control the pitching and rolling attitudes. Then the yawing
torque
is generated due to unbalancing of *drag force acting on each rotor and
gravity acting on the forward-leaning vehicle, and the upper and lower
rotors are differentially operated to maintain the yawing angle.
It can be seen that there are differences in operating
conditions between speed-based control and torque-based control.
*Drag force:
Resistance force which is parallel to the rotor rotational plane and acts in
the opposite direction to the flight direction
a) Hovering
b) Forward Flight
(3) Comparison
of Power Consumption between Contra-Rotating Rotor and Single Rotor
The table below shows a
comparison of the power consumption of a Quad-copter
with contra-rotating rotor and a Octo-copter
with single-rotor, both of which have rotors with the same
specifications.
In
order to eliminate
the effects of losses in the motor and ESC, the total power consumed by the
eight rotor is shown instead of
electric
power consumption in the comparison.
In the
table, it can be noticed that the single rotor consumes about 13-14% less power
in both hovering and forward flight.
Like
this example, if the total rotor rotating area is the same, the rotor
efficiency (N/kW) will generally be higher for a single rotor.
So,
when using contra-rotating rotors, it can be said that consideration on rotor
efficiency by simulations should be made advance.
＜Comparison of Power between Contra Rotating and Single＞
|
Vehicle
Type |
Num.
of Rotor |
Rotor
Dia. |
Differential
Control Method |
Hovering |
Forward
Flight(10m/s) |
|
Quad-copter |
(Dual)
x (4) =8 |
0.51m |
Speed Base |
5.853kW |
5.423kW |
|
Torque Base |
5.86kW |
5.454kW |
|||
|
Octo-copter |
(Single) x(8)=8 |
0.51m |
− |
5.084kW |
4.655kW |
Wha’s
New @V3.3
The fault tolerance of the vehicle can be evaluated.
Please
watch!
↑
↑ ↑ ↑
Click pictures above to watch the movie
・It is possible to predict whether the vehicle
can fly stably at the target speed (X, Y, Z direction) maintaining the
appropriate yaw, pitch,
and roll
angles by reconstructing the thrust distribution of each rotor, when either
rotor is damaged and lost the thrust.
・Up to 2 damaged rotors can be selected by GUI.
◆Features Fault Tolerance Prediction Method of DroneV
・In general, Dynamic Modeling and differential equation solvers such
as Matlab/Simulink are used for motion analysis of
drones.
On the other hand, DroneV uses Kinematic Modeling and inverse analysis with a
non-linear simultaneous equation solver
to find the solution of
the rotor thrust distribution for the vehicle to maintain the dynamic balance
at each time step.
・Expressing the difference between the two methods in simple manner,
Dynamic Modeling reproduces the process of controlling
the thrust distribution of each rotor sensing the response of
flight speed and attitude, while DroneV determines directly
the thrust distribution to enable the vehicle to maintain a stable
attitude in target speed, and if no solution is found, it is determined
that the stable flight is impossible.
・Therefore, DroneV is suitable for
applications that require many case studies, such as fault tolerance
prediction, because it does not
require creating a control program ,
moreover the computational load is small.
Wha’s
New @V3.2
◆ Support
vehicle models equipped with variable pitch propeller (VPP)
Fixed pitch propeller (FPP: Fixed Pitch
Propeller) and variable pitch propeller (VPP: Variable Pitch Propeller) can be
selected.
Currently,
many drones use FPP, but in the future, especially large drones and sky cars
will be expected to have VPP’s for higher propeller efficiency
over a
wide flight speed range than conventional FPP.
V3.2
provides the simulation of the flight of an aircraft equipped with VPP in
addition to the conventional FPP.
◆Support
centrally-powered models installed a power source in the center of the aircraft
Since
VPP-equipped models are available, a ‘centrally-powered’ model mounting a power
source(engine or a motor) in the center, and drives
propellers
via
power transmission system Is added to vehicle configuration options.
What’s
New @V3.1
(1)
Motor drive system option
Sine
wave drive , voltage phase vector control, and field
weakening control in high speed area was assumed.
↓
Support
a square wave drive, fixed voltage advance control, and without field weakening
control in high speed area.
(2)
Support motor efficiency map input
Both motor and inverter efficiency maps can be
created by MS-Excel in a vehicle model.
＜Basic Features of the Product＞
◆Possible to fly a three-dimensional flight
course while changing the attitude (yaw, pitch, and roll).
-The
flight of vehicle even with complicated flight patterns can be simulated
without detailed programming
such as a motor control, because of applying
an inverse analysis method
◆An impact of the crosswinds defined with a
three-dimensional vector can be predicted.
◆3D coordinates of the center of gravity and
aerodynamic center can be defined, and the allowable center of
gravity position range for safety flight can
be predicted.
◆Flight course can be defined by either time to
X, Y, Z direction velocity component or time to X, Y, Z spatial position.
-In the
case of the course by position input, the specified points can be connected
with spline curves, corner R and straight lines, or straight
lines.
Moreover,
the flight speed is automatically determined for each route to pass the
specified position point at the specified time.
Technical
Report
◆Technical
Report: High Power & Low
Emission Engine for Next Generation Hybrid Drone