IOSR Journal of Electrical and Electronics Engineering (IOSR-JEEE)
e-ISSN: 2278-1676,p-ISSN: 2320-3331, Volume 11, Issue 2 Ver. III (Mar. – Apr. 2016), PP 28-34
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Output Based Input Shaping for Sway Control of a 3D Crane
System
Nura M. Tahir*, Kamal A. Abubakar, A. U. Sambo, U.I. Bature, Nasir A
Yakub, Liman Haliru
Faculty of Engineering, Abubakar Tafawa Balewa University (ATBU), Bauchi, Nigeria.
[email protected]*
Abstract: this paper presents an output-based input shaping and a proportional integral derivative (PID) for
load hoisting control of a 3D crane. Unlike conventional input shaping in which model parameters are used for
designing the filter, output-based filter is designed using the signal output of the target system thus, problem of
model uncertainties are avoided. Simulation results show that, precise payload positioning with negligible sway
is achieved. The proposed hybrid control is robust and can easily be implemented on higher order system.
Keywords: 3D crane; PID, Hoisting, sway, output-based filter, conventional input shaping.
I.
Introduction
The current trend of achievements in the modern world would have been practically impossible without
the use of Cranes. They are also known as Bridge or Overhead Cranes [1]. These are machines used for lifting
and transferring heavy loads from one point to another. The faster the load is moved the lower will be the time it
takes to reach the final desired destination [1]. But moving the load very fast will result in an unwanted sway in
its final destination. The sway can be a threat to safety, and therefore minimization of this undesirable sway as
well as the fast movement of the load for better system performance are of paramount importance. Gantry
Cranes have been used in a wide range of applications including but not limited to Constructions,
Transportation, Materials handling as well as cargo management [2].
Various techniques have been used in solving this problem, some of which are presented in this paper.
Input shaping technique has been used in [3]–[8]. Akbar Assa et. al [1] have developed a four step design
procedure for an improved fuzzy crane control. M.A Ahmad et. al [9], have conducted a comparison of active
sway control of Gantry crane system using PD Controller and Delayed feedback signal (DFS). Mahmud Iwan
Solihin et. al [10], have used kharitonov’s stability to perform robust PID anti-swing control of an automatic
Gantry crane. M.A Ahmad et. al [4], have proposed a comparative assessment of PD and PD –type fuzzy logic
controller in sway control of Gantry crane system. Ayadin Yesildirek has proposed an intelligent control of
gantry cranes using artificial neural network technique [2]. M.A Ahmad et.al [6], have proposed an anti-sway
control of Gantry Crane using sliding mode control (SMC) and Delayed feedback signal (DFS) techniques.
Yang Xia et. al [11], have conducted a research on the control of a suspension stiffness for the beams in Gantry
machining centre. Ivan Burul et. al [12], have used h–infinity (H∞) Control Theory on Gantry crane system to
solve the sway problem, a better result was presented as compared to pole placement technique. M.A Ahmad
et.al performed an experimental investigations of low pass filter techniques for sway control of a Gantry crane
system [13], the result revealed that the higher the number of order of the low pass filter the better t the sway
reduction. M.A Ahmad, Z. Zulkifely and M.A Zawawi have conducted an experimental investigations of input
shaping schemes for sway control of Gantry crane system [6], the result shows that the higher the number of
impulses the higher the sway level reduction. M.A Ahmad et.al [14], have investigated a feedforward technique
for anti-sway control of 3-D Crane system, the result revealed acceptable anti-sway capability. Masood Askari
et.al [15], have used model predictive control technique on Gantry crane system. Chuxiong Hu et. al [16],
have used adaptive robust contouring controller in designing an industrial biaxial precision on Gantry crane
system. Ning Sun and Yongchun Fang [17], have developed a new anty swing control method for underactuated cranes with un modelled uncertainties. Yang Junqing and Sui Meie [18], have proposed an automatic
identification system of real-time gantry crane (RTG) in container terminal. Z. khu, K liu et at [19], have
presented an output based input shaping for suppressing residual vibrations. J. Han, Z. khu, Y He et at [20],
have also proposed output based filter for residual vibration control and also compared with the conventional
input shaping filter.
Unlike conventional input shaping, output based input shaping has a lots of advantages among which
are, it is robust to changes in payload, the overall speed response of the system can be increase, the problem of
parameters uncertainties are avoided.
DOI: 10.9790/1676-1102032834
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Output Based Input Shaping for Sway Control of a 3D Crane System
II.
Model Description
3D crane system is an industrial machine which is normally used to transport loads from one place to
another in construction industries, nuclear plant, house wire, seaport, heavy machine installations, etc. In this
paper, two degrees of freedom (2D) motion is considered. The main components of the system hardware are: a
cart, a rail and a pendulum as shown in Figure 1.
Figure 1: system description
With XYZ as the coordinates of the system, α is the angle of lift-line with Y axis and β is the angle
between the negative part of Z axis and the projection of the payload cable onto the XZ plane. T is a reaction
force in the payload cable acting on the trolley, Fx and Fy are the forces driving the rail and trolley respectively,
Fz is a force lifting the payload and fx, fy and fz are corresponding frictional forces. These are defined as:
1
mp
mt
, 2
mp
mt m r
Fy
Fx
F
, u2
, u3 z
mp
mt
mt mr
fy
f
f
f1 x , f 2
, f3 z
mt mr
mp
mt
u1
K 1 u1 f 1 , K 2 u 2 f 2 , K 3 u 3 f 3
In which; m p ,
m t and m r are the payload mass, trolley mass and moving rail respectively. l is the length of
the lift-line. The dynamic equations of motion of the crane can be obtained as [15].
xt K 2 2 K 3 sin sin
(1)
yt K1 1 K 3 cos
(2)
xp xt (l l 2 l 2 ) sin sin 2l cos c
(2l l) cos sin (2l l) sin cos
y p yt (l l 2 ) cos (2l l) sin
zp (l l 2 l 2 ) sin cos 2l cos
(2l l) cos cos (2l l) sin sin
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(3)
(4)
(5)
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Output Based Input Shaping for Sway Control of a 3D Crane System
Where, x p , y p and z p are position of payload in X, Y and Z axes respectively.
x t and y t are positions of trolley
in X and Y axes respectively. The Dots are the derivative of the respective quantities.
The parameters of the system are shown in Table 1.
Table 1. System parameter
Variables
Mass of trolley,
Values
1 kg
mp
Mass of payload,
1.155 kg
mt
Mass of moving rail,
2.2 kg
mr
Cable length, l
Gravitational constant, g
Corresponding friction forces,
III.
fx, fy, fz
0.72 m
9.8 m/s2
100, 82, 75 Ns/m
Logarithmic Decrement
For the simplicity of design, logarithmic decrement techniques as in [21], [22], is used to determine the
damping ratio and natural frequency of the system, so as to reduce the order of the system. This technique can
be explain using an under damped system as shown in Figure 2. And these parameters are determined using the
following relations;
4
2
;
2
(6)
Where
ln(
y1 and t 2 t1
)
y2
IV.
(7)
Output Based Input Shaping
In this technique, the filter is design using the signal output of the target system, reference system is
designed based on the dynamic response of the system then Filter gains are obtained using MATLAB program.
1. Basic principle
To explain the basic principles of this technique, a second order system is considered as in [19].
G s
Kwn2
s 2 2 wn s wn2
(8)
Let the reference system be design as follows;
M s
km wm2
s 2 2 m wm s wm2
(9)
If the filter is designed as;
km wm2 s 2 2 wn s wn2
FO S
(10)
Kwn2 s 2 2 m wm s wm2
Hence, the product of G ( s ) and F0 ( s ) will gives M (s) thus adequate static gain, damping ratio and
bandwidth can be achieved by choosing km , m , wm respectively.
Thus;
s 2 a2 a1 s a0
(11)
s 2 2 m wm s wm2
The aim is to obtain the values of ao , a1 , a2 so that zeros of F ( s ) will cancel the poles of G ( s ) , as
F ( s) F0 ( s) and poles of G ( s) are identical.
F s
DOI: 10.9790/1676-1102032834
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Output Based Input Shaping for Sway Control of a 3D Crane System
2.
Designing output-based filter
The filter is designed by first designing the reference system, in which a critically damped system is
normally considered, which can be realized as;
w2 c
Gr ( s )
( s wc ) 2
(12)
Where wc is the bandwidth of the system, and is selected based on the time response of the system.
This system has little or zero vibration. The cost function is used to minimize the difference between the output
of the reference system and that of the target system [19], [20].
Thus;
T
E (s) w(t ) ( y t yr t )dt
(13)
0
y(t ) is the output of the target system, and yr (t ) is the output of the
Where w(t ) is the weighting factor,
reference system.
Thus;
T
m
0
i 0
E (a1, a2 ,....an ) w t (( ai yi t ) yr (t ))2 (14)
In which;
a1 a2 ...an are the filter gains and a0 wc 2
To achieve the minimum value of E, the derivative of (14) is set to zero as;
E
0, k 1, 2,3..m
ak
(15)
And
T
m
0
i 0
w t yk t (( ai yi t ) yr (t ))dt 0
(16)
Thus, it is further simplifying as;
T
S , w t y t y (t )
(17)
0
Where
0,1, 2,3...m
0,1, 2,3,...m
And
T
S ,r w t y t yr (t )
(18)
0
In which
0,1,2,3...m
Simplifying (16), (17) and (18) yield;
m
a S
k
i 0
Where
k ,i
Sk ,r 0
(19)
K 0,1,2,3....m
In this paper, the gantry crane is reduced to second order for simplicity of design. Reference system was
designed by selecting wc 2 , it is selected based on the response time of the gantry crane.
Thus;
DOI: 10.9790/1676-1102032834
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Output Based Input Shaping for Sway Control of a 3D Crane System
Gr ( s )
4
s 4s 4
(20)
2
Hence, software (which software) was used to calculate the filter gains in the following forms;
a1 S11 S12 S1r
a S
2 21 S22 S2 r
(21)
Therefore, the gains are obtained as;
a0 4, a1 0.0144, and a2 0.1916
Hence, simplifying in (11), the filter was obtained as;
F ( s)
0.1916s 2 0.0144s 4
s 2 4s 4
V.
Result And Discussion
(22)
In this section, results and hybrid control actions are discussed. The Second order system is obtained
from the nonlinear model of the gantry crane system, using logarithmic decrement. An output-based filter was
designed using the output signal of the system to suppress payload sways. The filter was then incorporated with
PID for precise positioning of payload. The filter and PID gains were obtained as
a0 4, a1 0.0144, a2 0.1916
and p 2, I 2.5, D 0.5 respectively. This hybrid control was simulated, and sways in both x and y
direction was suppressed as in Figure 3 and Figure 4. In addition, the precise payload position was achieved as
shown in Figure 5 and Figure 6. Using the time response analyses, the trolley and rail position has a settling
time of 2.3sec; overshoot 0, rise time 1.8 sec. Hence, simulation results show that an output-based filter is one
of the best techniques in controlling residual vibrations.
1.6
1.4
y1
1.2
Oscillation (rad)
y2
1
0.8
0.6
0.4
t2
t1
0.2
0
0
1
2
3
4
5
6
7
8
9
10
Time (s)
Figure 2. Logarithmic decrement process
6
without shaping
with output input shaping
x direction sway (deg)
4
2
0
-2
-4
-6
0
1
2
3
4
5
time(s)
6
7
8
9
10
Figure 3. Trolley payload sways
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Output Based Input Shaping for Sway Control of a 3D Crane System
6
with output input shaping
without shaping
y dierection sway (deg)
4
2
0
-2
-4
-6
0
1
2
3
4
5
time(s)
6
7
8
9
10
Figure 4. Rail payload sways
1.4
1.2
Trolley position(m)
1
0.8
0.6
0.4
0.2
0
0
2
4
6
8
10
Time(s)
Figure 5. Trolley position
1.4
1.2
Rail position(m)
1
0.8
0.6
0.4
0.2
0
0
2
4
6
8
10
Time(s)
Figure 6. Rail position
VI.
Conclusion
An output-based filter incorporates with PID for residual vibration suppression and precise payload
positioning was presented. The filter was designed to suppress residual vibrations while PID was used for
position control. The hybrid control was simulated and analyzed, and the control performance has been
investigated. Simulation results show that, residual vibration suppression and precise positioning of payload was
achieved.
DOI: 10.9790/1676-1102032834
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Output Based Input Shaping for Sway Control of a 3D Crane System
Acknowledgment
The authors are grateful to Abubakar Tafawa Balewa University (ATBU) Bauchi, Nigeria and Assoc.
Professor Zaharuddin Mohamed of Universiti of Teknologi Malaysia (UTM) for providing research resources and
financial assistants.
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