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PYROTECHNIC ROBOT - COSTRUCTIVE DESIGN AND COMMAND
lonel A. Staretu, Marius A. lonescu,
Transilvania University of Brasov, Product Design, Mechatronics and Medium Department, Brasov, Romania
DOI: 10.5937/vojtehg61-4035
FIELD: Mechanical Engineering ARTICLE TYPE: Original Scientific Paper
Abstract:
Pyrotechnic robots are service robots used to reduce the time for intervention of pyrotechnic troops and to diminish the danger for the operators. Pyrotechnic robots are used to inspect dangerous areas or/and to remove and to distroy explosive or suspicious devices/objects. These robots can be used to make corridors through mined battle fields, for manipulation and neutralization of unexploded ammunition, for inspection of vehicles, trains, airplanes and buildings. For these robots, a good functional activity is determined with regard to work space dimensions, robotic arm kinematics and gripper characteristics. The paper shows the structural, kinematic, static synthesis and analysis as well as the design and functional simulation of the robotic arm and the grippers attached on the pyrotechnic robot designed by the authors.
Key words: analysis, kinematics, constructive design, CAD simulation.
Introduction
Pyrotechnic robots are service robots used to reduce the time for intervention of pyrotechnic operators and to diminish the danger for them (www.salvex.com).
Pyrotechnic robots are used to inspect dangerous areas or/and to remove and to distroy explosive devices. These robots can be used to make corridors through mined battle fields, for manipulation and neutralization of unexploded ammunition, for inspection of vehicles, trains, airplanes and buildings. For these robots, a good functional activity is determined with regard to work space dimensions and robotic arm kinematics.
In the paper, the kinematic synthesis and analysis, one command scheme and a functional simulation are shown regarding the robotic arm from the pyrotechnic robot designed by the authors.
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Staretu, I. et al, Pyrotechnic robot - constructive design and command, pp. 63-71
VOJNOTEHNIČKI GLASNIK/MILITARY TECHNICAL COURIER, 2013., Vol. LXI, No. 3
Pyrotechnic robots - general aspects
A pyrotechnic robot has three main mechanical components: a mobile platform, a robotic arm (the manipulator) and a gripper (Paun, Constantin, 2002), (Staretu, Daj, 2004, pp.55-58).
The mobile platform can be equipped with wheels or crawlers, the robotic arm is a manipulator with 5 or 6 axles and the gripper is usually a gripping mechanism with jaws or, rarely, an anthropomorphic mechanical gripper, see Fig. 1. and Table 1 (www.salvex.com).
After the comparative structural analysis for more types of pyrotechnic robots (Fig. 2,a,b), for the designed robot we adopted the structural scheme of Fig. 2,c. This structure is formed of a platform with crawlers, a robotic arm and a linkage gripping mechanism with two jaws.
The platform has the degree of freedom M = 2 and each crawler is powered by an electric motor.
a b
c
d e
Figure 1 - Main types of pyrotechnic robots Slika 1 - Glavni tipovi pirotehničkih robota
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Main characteristics Glavne karakteristike
Table 1 Tabela 1
Nr. Robot Platform
length width height turret speed movement Slope
1. Vanguard MK1 915 mm 435 mm 405 mm (packed) 120° 12,33 m/min crawlers 40°
2. Teodor 1300 mm 680 mm 405 mm 420° 0-50 m/min crawlers 35a
3. MR1 1170 torn 700 mm 950 mm Wheels 40° (with crawlers)
4. Andros 1245 mm 445,5 mm 1118 mm - - crawlers 45°
5. Hobo 1468 mm 701 mm 881,4 mm - 50 m/min wheels 42 □
Nr. Robotic arm Gripping system
vertical Horizontal useful weight stroke
1. 1320 mm 965 mm S Kg (extended arm) 16 Kg (contracted arm) 0 - 20 cm
2. 2400 mm 2&00 mm 20 Kg (extended arm) 30 Kg (contracted arm) 0 - 30 cm
3. 2650 mm 1&50 mm (5150 mm) 15 Kg ( at 3,5 m) 122 Kg (at 1 ill) -
4 - - - -
5. - - - -
After the structural analysis of the robotic arm, the following conclusion can be formulated: there are 6 outside connections (L = 6) and the degree of freedom is 5 (M = 5). The gripper has M = 1.
b
a
c
Figure 2 - Structural schemes Slika 2 - Strukturalne šeme
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Staretu, I. et al, Pyrotechnic robot - constructive design and command, pp. 63-71
VOJNOTEHNIČKI GLASNIK/MILITARY TECHNICAL COURIER, 2013., Vol. LXI, No. 3
Designed robot - main characteristics
Structural synthesis of the robotic arm
For the first time, the kinematic synthesis is used to obtain the main dimensions (Fig. 3) for optimum workspace.
a
Figure 3 - Kinematic scheme: the main dimensions (a) and extrem positions of the robotic arm (b) Slika 3 - Kinematička šema: glavne dimenzije (a) i krajnji položaji robotičke ruke (b)
Kinematic analysis of the robotic arm
The direct kinematics is used to determine the position of the K characteristic point. In this situation, the movements of the joints are known. The kinematic scheme is shown in Fig. 4
Regarding this kinematic scheme, the homogeneous rotative and translational matrices have the following form (Dudita, 1989):
Rx :
Rz :
1 0 0 0 ' "1 0 0 0
0 1 0 0 , Ry := 0 cos( y) 0 sin( y)
0 0 cos( x) - sin( x) 0 0 1 0
0 0 sin( x) cos( x) 0 - sin( y ) 0 cos( y)
(1)
1 0 0 0" "1 0 0 0
0 cos( z) - sin(z) 0 , T := x 1 0 0
0 sin(z) cos(z) 0 y 0 1 0
0 0 0 1 z 0 0 1
With the rotative matrices from the joints and the translational matrices between the joints, the direct model of the finite movements can be obtained as a compound homogeneous operator E06. We used the MAPLE soft for this. For example:
E05:=simplify(multiply(E01,E12,E23,E34,E45)) and
E35:=multiply(E34,E45);
" 1 0 0 0
E 35:= b4 cos( fi54) 0 sin( fi54)
0 sin( fi 43)sin( fi54) cos( fi 43) - sin( fi 43)cos( fi54)
0 - cos(fi 43) sin( fi54) sin( fi43) cos(fi 43) cos( fi54)
E25:=simplify(multiply(E23,E34,E45));
E15:=simplify(multiply(E12,E23,E34,E45));
This is verified with numerical values in the following form:
L1:=[fi10=Pi/3,fi21=Pi/6,fi32=Pi/3,fi43=Pi/4,fi54=Pi/12];
LI :
f10 = —n,fi21 = — n,f32 = —n,fi43 = — n,fi54 = — n , 3 6 3 4 12
L2:=[b1 = 100,a2=600,b2=200,b3=500,b4=90];
L2 := [b1 = 100, a2 = 600, b2 = 200, b3 = 500, b4 = 90],
Staretu, I. et al, Pyrotechnic robot - constructive design and command, pp. 63-71
VOJNOTEHNIČKI GLASNIK/MILITARY TECHNICAL COURIER, 2013., Vol. LXI, No. 3
E05s:=evalm(Msubs(L1,L2,E05));
E 05s::
1
154.8076212
14.54482663
1219.615242
0
.3244692642
.9280226547
.1830127019
0
.6123724358
.3535533909
.7071067812
0
.7209158735
-.1173624830
-.6830127020
The position of the K characteristic point will be: x = 154.8 mm; y = 14.544 mm; z = 1219.61 mm.
Static analysis
Static calculations aim at determining external forces acting on the inner mechanism and forces acting on the kinematic elements. Forces, masses, and centers of gravity of the elements necessary to calculate the time necessary to driving the couplings were determined using the CATIA software (Doc. 1, 2005). Fig. 5 shows two schemes for computing the static momentum for couplings C and B of the robotic arm.
a b
Figure 5 - Computation model for momentum in couplings C(a) and B(b) Slika 5 - Računarski model za moment sile u spojevima C(a) i B(b)
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Constructive design
Based on the results of the kinetic-static analysis, dimension calculations were made (strength calculations) of the component parts (elements) and then we realized the technological project of the robot mechanical parts. The technical drawing of the assembly in some specific positions is shown in Fig. 6.
Figure 6 - Technical project of the pyrotechnic robot Slika 6 - Tehnički projekat pirotehničkog robota
Functional simulation
The kinematic dimensions and the forces between the constructive elements were used for the calculation of strength and then a 3D model was obtained with the CATIA software (Doc.1, 2005). This model was used at a functional simulation for the robotic arm (Fig.7).
a b1 b2
Figure 7 - Functional simulation: without object(a) and with an object(b1,b2)
Slika 7 - Simulacija funkcije: bez objekta (a) i s objektom (b1, b2)
The functional simulation is used to obtain an optimum version of the robotic arm and of the pyrotechnic robot as well.
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Staretu, I. et al, Pyrotechnic robot - constructive design and command, pp. 63-71
VOJNOTEHNIČKI GLASNIK/MILITARY TECHNICAL COURIER, 2013., Vol. LXI, No. 3
Command scheme
The general scheme for the command and control subsystem is shown in Fig. 8. The control scheme enables the remote control of the pyrotechnic robot via a cable or wireless. The command is carried out through a laptop on whose screen images from robot-mounted cameras are projected. In Fig. 8 we can identify the main electronic components of the control scheme.
Figure 8 - Command scheme Slika 8 - Šema upravljanja
Prototype of the gripper
Based on the technical project in CATIA (Fig. 9a) the gripper prototype was made, Fig. 9b. The useful weight is 6 kg and the stroke is 0-26 cm.
a
b
Figure 9 - CATIA project of the gripper (a) and prototype of the gripper (b) Slika 9 - Projekat hvataljke pomoću softvera CATIA (a) i prototip hvataljke (b)
Conclusions
The following conclusions can be formulated in accordance with the considerations presented:
1. The main kinematic mechanical component of the pyrotechnic robot is the robotic arm.
2. The dimensions of the robotic arm are essential for local work space of the pyrotechnic robot.
3. The kinematic models (direct and reverse too) are very important for finding the position of the characteristic point of the robotic arm.
4. A functional simulation using a 3D model is very important for obtaining an optimum version of the robotic arm and for the pyrotechnic robot.
References
Documentation, CATIA 5 2005.
Dudita, F.L., & et al., 1989. Articulated Mechanisms. Inventics-Kinematics (in Romanian).Bucharest, Romania: Tehnica Publishing House.
Paun, A., & Constantin, G. 2002. Types of Robots used to Handling and Determining Unexploded Ammunition. Robotics & Management Journal, 1.
Staretu, I., & Daj, I. 2004. Intervention Robots in Dangerous Places-Constructive and Functional Features. AGIR Bulletin, Bucharest, Romania, 9(1-2), pp. 55-58.
www.salvex.com/media/.../Robot_ Ma. pdf, technet. idnes. cz/robot-teodor-pyrotechnika...-/vojenstv, en.wikipedia. org/wiki/ANDROS, etc
ANALIZA, PROJEKTOVANJE KONSTRUKCIJE I UPRAVLJANJE PIROTEHNIČKIM ROBOTOM
OBLAST: mašinstvo
VRSTA ČLANKA: originalni naučni članak Sažetak:
Pirotehnički robot je uslužni robot koji se koristi za brže intervenisanje pirotehničkih jedinica kojim se smanjuje izlaganje opasnosti rukovaoca. Pi-rotehnički roboti koriste se za ispitivanje opasnih zona i/ili za uklanjanje i uništavanje eksplozivnih ili sumnjivih uređaja/predmeta. Mogu da se koriste za izradu prolaza kroz minska polja, za rukovanje neeksplodiranom munici-jom i njeno uništavanje, za pregledanje vozila, vozova, aviona i građevina. Dobra funkcionalna aktivnost ovih robota određena je dimenzijama njihovog radnog prostora, kinematikom robotske ruke i karakteristikama hvataljke. U ovom radu prikazane su strukturalna, kinematička i statička sinteza i analiza, kao i projekat i simulacija funkcije robotičke ruke i hvataljki na piro-tehničkom robotu koji je projektovao autor ovog rada.
Ključne reči: analiza, kinematika, projekat konstrukcije, CAD simulacija
Paper received on: 17. 06. 2013.
Manuscript corrections submitted on: 21.06. 2013.
Paper accepted for publishing on: 23. 06. 2013.
Staretu, I. et al, Pyrotechnic robot - constructive design and command, pp. 63-71
