This document summarizes a study that used MATLAB to simulate an eight-wheeled rocker bogie suspension system for a rover. The study involved modeling the rover system in SolidWorks, importing it into MATLAB using a SolidWorks translator tool, and simulating it moving in MATLAB. The simulation analyzed slippage of the wheels at different speeds and showed that slip decreases over time, and higher speeds result in more initial slip but less slip overall. The study concluded the simulation helped analyze the stress levels and motions of the rover components and confirmed the design could withstand loading.

1. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 2, March - April (2013) © IAEME
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SIMULATION OF EIGHT WHEELED ROCKER BOGIE SUSPENSION
SYSTEM USING MATLAB
Alok Kumar Pandey*; Dr R. P. Sharma **
* ME (Student) Dept. of Mechanical Engineering, Birla Institute of Technology,
Mesra, Ranchi, 835215 India.
** Dept. of Mechanical Engineering, Birla Institute of Technology, Mesra, Ranchi,
835215 India.
ABSTRACT
Rovers are important vehicles of today’s solar system exploration. Most of the rover
designs have been developed for Mars and Moon surface in order to understand the
geological history of the soil and rocks. Several mechanisms have been suggested in recent
years for suspensions of rovers on rough terrain. Our design of eight wheeled rocker-bogie
suspension system has advantage of linear bogie motion which protects the whole system
from getting rollover during high speed operations. This improvement increases the reliability
of structure on rough terrain and also enables its higher speed exploration with same obstacle
height capacity as diameter of wheel.
In this paper we simulate rover to find slip and its deviation from desired path and
express the complete process of importing SolidWorks file into MATLAB. We use eight
wheeled rocker bogie suspension mechanism for our simulation. For this purpose we made
component in SolidWorks. In SolidWorks each and every parts are analyzed and simulated
using SimulationXpress. A Simulink diagram is generated by importing SolidWorks
assembly file into MATLAB followed by simulation.
Keyword- MATLAB, SolidWorks, Rocker Bogie,
1. INTRODUCTION & LITERATURES SURVEY
In recent years almost all exploration mission uses rocker bogie mechanisms due to its
great obstacle climb capacity. Rover’s faces slip problem on uneven terrain. This slip reduces
rovers speed and leads to power loss. In loose soil rover deviates from its intended path and
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2. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
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can stick with soil, which also increases power loss. Power loss reduces mission time by
discharging batteries. Since we cannot control the availability of solar energy, as this is only
power source on the other planet, we have to control power loss. We can extend mission time
by controlling slip and reducing rover sinking into loose soil which gives more time to our
rover for exploration.
A. Winterholler, et -al [1] (2005) “Design Of A High-Mobility Low-Weight Lunar
Rover” have reported a set of experiments using a new highly mobile rover prototype that
was tested under lunar-like operational conditions in the lava fields of the Mojave desert near
Amboy, CA.
Thomas Thueer, Pierre Lemon [2] (2006) “Carb –Exploration Rover with Advanced
Obstacle Negotiation Capabilities” have introduced locomotion concept CRAB, and
compared it with other rovers regarding obstacle negotiation capabilities.
Jan Danek, et –al [3] (2007) “Simulation and Animation of Mechanical Systems” has
discussed a process for simulating and animating mechanical components in the context of a
larger system and also described how a dynamic model created from the CAD assembly can
be integrated into the larger model of the overall flight vehicle.
Robert Bauer, et -al [4] (2008) “Dynamic Simulation Tool Development for Planetary
Rovers” have developed a dynamic computer simulator for step-obstacle negotiation by
comparing simulation results with a quasi-static analysis of a rocker bogie suspension.
Hrishi Shah, Sourish Chakravarty [5] (2009) “HW6-Wheeled Mobile Manipulator” (2009)
wrote a MATLAB programme for non-linear feedback linearization to reduce the equations
of motion to a second order dynamic equation for the error of position of the wheeled robot.
LI Yunwang, et -al [6] (2010) “Mobile platform of rocker-type coal mine rescue
robot” have discussed the flameproof design of the rocker assembly, as well as provide the
operational principles and mechanical structure of the bevel gear differential.
Harjinder Singh, et -al [7] (2011) “Design and Experimentation of a Six Wheel Lunar
Rover for Motion on Uneven Terrain” have described the design, development and
experimentation of a six-wheel mobile robot (rover) for motion on uneven lunar like terrain.
The suspension mechanism of the rover was designed using a rocker-bogie mechanism.
DongmokKim, et -al [8] (2012) “Optimal design of hand & carrying rocker & bogie
mechanism for stair climbing” have proposed a stair climbing hand-carrying cart based on the
rocker-bogie mechanism. They conduct experiments to find an optimal design of the
kinematic variables of the rocker-bogie mechanism for stable stair climbing.
2. SYSTEM SIMULATION
For simulation purpose of our robot we assemble each and every part in proper place,
give direction of each component, and apply mate instructions of SolidWorks. Then we try to
import our model in MATLAB but there is no direct option in SolidWorks. So to create a
SimMechanics model from assembly we download and install SolidWorks-to-SimMechanics
Translator. One can download it directly from SimMechanics Link download website at
http://www.mathworks.com/products/simmechanics/download_smlink.html. On this website
there are many versions but only the same version of installed MATLAB is working. After
downloading the zip file we need to write command in MATLAB to install this file without
extracting it. In the MATLAB command window write: path(path,
'<installation_file_folder>') then again write install_addon('<zip_file_name>.zip'). Now in
command window of MATLAB write smlink_linksw this will complete integration process

3. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
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with SolidWorks. This time open SolidWorks, go to tool, open Add-Ins and check the
SimMechanics Link in both Active Add-ins and start up boxes.
Figure 2.1: Shows von-mises stess on the Rocker
Figure 2.2: Shows the displacement of Rocker
After installation of this free software, it was possible to generate a textual description
of the assembly that lists the mass properties for each body and the characteristics of each
joint defined in the SolidWorks assembly. This description was saved to a SimMechanics
XML file. After saving the SolidWorks assembly as a SimMechanics XML file, we can
easily convert it into SimMechanics model. It should be noted that only CAD assembaly files
can be converted into Simulink model.

4. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
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Figure 2.3: Shows the von-misses stress on wheel
Figure 2.4: The von-misses stress on wheel
For importing this model into MATLAB set/browse working directory as current
folder, double click to open xml file or write mech_import ('filename.xml') in the MATLAB
command window. MATLAB®
automatically creates a SimMechanics model from .xml file
(as Figure no. 2.5 shown). The resulting SimMechanics model can be rearranged and add
background colours for easier understanding. It was noted that all CAD assemblies are not
exported into SimMechanics models.

5. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
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Figure 2.5: Simulink model of our rover generated by MATLAB
This is due to SolidWorks mates. SolidWorks-to-SimMechanics Translator attempts to find a
SimMechanics joint corresponding to each mate in SolidWorks assembly. As there is no one-
to-one correspondence between SolidWorks mates and SimMechanics joints, the conversion
is not always possible, or it does not translate as intended. In this case we need to update
manually SimMechanics diagram and change Simulink blocks with correspondence
SolidWorks mates and after final simulation through MATLAB we get figure no.2.6
Figure 2.6: simulation of rover in MATLAB

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3. RESULTS AND DISCUSSION
We simulate our rover on a fixed elliptical path. Ellipse major axis is 3.5 m and minor
axis is 2.5 m. Centre of ellipse is lies in x plane at x =2 and y =0. Angle subtended between
major axis and horizontal is 450
. We are generating total 540 points in our simulation and
running it for 10 seconds. We are tried to figure out slip behaviour for our wheel design. For
this purpose we simulate with different linear velocity and angular velocity. In each
simulation rover follow same path and generate 540 points, which is analyzed to find best
driving speed and exact slip of the wheel.
3.1 Simulation at V= 1 m/s and ω = 1.17 rad/ s2
Figure 3.1(a): Trace point variations Figure 3.1(b): percentage of slip vs. time
3.2 Simulation at V= 0.5 m/s and ω = 1.75 rad/ s2
Figure 3.2(a): Trace point variations Figure 3.2(b): percentage of slip vs. time

7. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
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3.3 Simulation at V= 0.25 m/s and ω = 1.75 rad/ s2
Figure 3.3(a): Trace point variations Figure 3.3(b): percentage of slip vs. time
The above figures-3.1a, 3.2a and 3.3a show that as velocity increases with constant ω,
means less slip cases, the bubbles are shifting towards outer periphery of ellipse. It means the
rover is more tend to follow desired path in the case of less slip.
The above figures also shows that as velocity of rover increases all curve shifted towards
right.
The above figure-3.1b, 3.2b and 3.3b shows that the slip vs. time curve become
steeper as velocity increases. The curve is shifting towards origin which shows that at high
velocity initial slip is high and as time passes slip value goes down.
4. CONCLUSIONS
Following are vital conclusions drawn from paper:
• Slip diminishes as time passes.
• Initially slip is very high.
• We cannot eliminate slip completely it can reduce to some extent only.
• Path traced by rover is depends on velocity, as velocity changes path missing
increases.
• The load simulation of different components shows the stress and deflection
behaviour of components.
• The simulation in SimulationXpress shows that our design is enough strong and it can
sustain in adverse condition of loading.
• Simulations of rover in MATLAB confirm movability of linkage and their relative
motion with each other.
• Simulation of rover on elliptical path gives us visual representation of rover motion.

8. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
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REFERENCES
1. A. Winterholler, et -al (2005) “Design Of A High-Mobility Low-Weight Lunar Rover”
Proceedings of iSAIRAS 2005. Munich Germany. September 2005.
2. Thomas Thueer, pierre Lemon (2006) “Carb –Exploration Rover with Advanced Obstacle
Negotiation Capabilities” In proceeding of the 9th
ESA workshop on Advanced Space
Technologies for Robotics and Automation ‘ASTRA 2006’ ESTEC, Noordwijk, The
Netherlands, November 28-30, 2006
3. Jan Danek, et -al (2007) “Simulation and Animation of Mechanical Systems” American
Institute of Aeronautics and Astronautics 2007.
4. Robert Bauer, et -al (2008) “Dynamic Simulation Tool Development for Planetary Rovers”
International Journal of Advanced Robotic Systems, Vol. 5, No. 3 (2008)
5. Hrishi Shah, SourishChakravarty (2009) “HW6-Wheeled Mobile Manipulator” (2009)
University At Buffalo, http://www.mathworks.in/matlabcentral/fileexchange/23962-dynamic-
control-of-a-wheeled-mobile-robot/content/HW6_MAIN_1.m
6. LI Yunwang, et -al, (2010) “Mobile platform of rocker-type coal mine rescue robot”
ScienceDirect, Mining Science and Technology 20 (2010) 0466–0471
7. Harjinder Singh, et -al (2011) “Design and Experimentation of a Six Wheel Lunar Rover
for Motion on Uneven Terrain” International Journal for Engineering and Technology, Issue
1, Volume 2, December 2011.
8. DongmokKim, et -al (2012), “Optimal design of hand & carrying rocker & bogie
mechanism for stair climbing” Journal of Mechanical Science and Technology 27 (1) (2012)
125~132.
9. Gopichand Allaka, Prasad Raju Kalidindi, Koteswara Rao S, Manibabu Daadi and Abhay
Patnala, “Design of Solid Shafts using MATLAB”, International Journal of Mechanical
Engineering & Technology (IJMET), Volume 3, Issue 3, 2012, pp. 645 - 653, ISSN Print:
0976 – 6340, ISSN Online: 0976 – 6359.
10. Flt Lt Dinesh Kumar Gupta, “Linear Programming in MATLAB”, International Journal
of Industrial Engineering Research and Development (IJIERD), Volume 4, Issue 1, 2013,
pp. 19 - 24, ISSN Online: 0976 - 6979, ISSN Print: 0976 – 6987.