Two Lego Mindstorm Robots Engineering Essay

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The idea of this project is to design two Lego Mindstorm robots (Discovery and Challenger) which will collaborate with together to perform a range of task. These robots are designed to explore and perform various tasks on lunar surface. This project would be a flow along after the discovery of water molecules on moon by NASA's Lunar Crater Observation and Sensing Satellite. The idea of Discovery and Challenger is to collect samples on lunar surface as well as discover the humidity of the surface. Both the robots will communicate with each other to work on various circumstances and terrain. One of the main capabilities of one of the robot is to move through craters on lunar surface by laying a bridge to transport itself from one to another place. Meanwhile, the other robot will be able to go up or down through deep walls to carry out the experiment. Solar panel will be one of the most vital components for the robots to gain power throughout the research journey. Besides that, various sensors will be considered in both robots for communication and collaboration purposes. These include:

Touch sensors

Light sensors

Sound sensors

Ultrasonic sensors



DCP Sensor Adaptor

Human override is a major contribution in today's technology for many applications. As for in this project, a MINDROID application connecting Android Smartphone will be taken into consideration for the backup system in case of operation failure. LabVIEW programming language will be used to formulate the program and run the robots.


Robot is a mechanical device which functions automatically on its independent control devices. Robots have the ability to perform multiple tasks at various situations especially jobs that are quite boring, difficult and dangerous for people. [1] The term robot have come from a Czech word called robota which means drudgery.[2] In today's technology, robots are so advance in their job as they are taking over human's routine tasks such as welding, drilling painting automobile parts, assembling electronic circuits and making plastic containers. (Shown in Figure 1 below)

Figure 1: Robots weld car bodies at a manufacturing plant in Wixom. Michigan ranks as the leading U.S. automobile manufacturer. Image credit: Ford Motor Company

Robotics is the combined studies of science and technology in robots. There are many types of robots which are developed to enhance the performance of daily life. A robot is made up of five major components which are similar to human. Robots have a moveable physical structure, a motor, a sensor system, a power supply and a computer brain that controls all of these elements. [3] They are categorised as the basis of degree of autonomy and industrial as shown below:

Degree of Autonomy


Robots remain fixed in one place.

Robots in this category are robotic arm, computerized machines and industrial robots.


These robots are mobile where they can move around.


Robots are designed to function underwater.

They are called the Autonomous Underwater Vehicles


Known as the unmanned aerial vehicles which includes the robotic flying machines


Robots which are called rovers are designed to operate in low gravity environments.

Industry basis

Industrial robots

Robots that are practiced in many companies today for jobs that need endurance, accuracy, speed and reliability.

Agricultural robots


They are automated robots that are used for work which is risky or inaccessible to human.

Service Robot

Robots that are used outside an industry field which includes either domestic help or military use.

Humanoid Robot

An autonomous robot with its overall appearance similar to a human body.

ASIMO, Robonaut 2, Enon and Nao are the types of humanoid robot used a research tool in certain scientific areas.

Examples of various robot kinds are shown on Figure 2 below.

Figure 2: Types of Robot

The following are good reasons to invest R&D of robots: [16]

Delivering a host of benefit in a wide variety of applications.

Significant revolution in productivity and efficiency in production industry.

Reduces operating cost

Improving product quality and reliability.

Provides quality of work for employees

Increases production output rates

Reduces material waste

Increasing yield

Collaborative robots are robots which are able to communicate with each other to perform a task programmed. Today's technology has been so advanced that sources are available to build and programme a robot. A number of interface software with different type of programming languages is been used to develop the world of robotics such as:

Interface Software

Programming Language

Lego Mindstorm



C Language


Heart To Heart

RS Media

C++ Language

Table 1: Types of Robotic Software


The rapid development in robotic industry is caused by the enthusiasms of space agencies in exploring and investigating new planets. Successful missions such as the Spirit and Opportunity rovers were sent to study the geological characteristics of the Martian planet. The aim of this project is to design two robots (Discovery and Challenger) using Lego Mindstorm which will collaborate and execute a range of task. The robots will be programmed to perform task in various circumstance and terrain environment. The robots will be capable of collecting geological samples and investigating the presence of water in lunar surface. Communication between Discovery and Challenger is essential to carry out tasks. However, ways of communication will need to be considered in detail to maintain a good collaboration between the two robots. A weighted decision matrix (Shown in Table 2 below) is used to consider the possible designs for the robots.

Robot 1 - Discovery

Act as the Master robot

Discovery will give instruction to Challenger (Robot 2) to perform certain tasks

Places a bridge when there are craters on Lunar surface to transport itself as well as Challenger to an even surface

Measures the humidity of the Lunar surface

Logs data discovered on lunar surface

Designs that are to be considered (shown in Figure 6 and Figure 7). However, more designs combining solar panel are shown in Appendix 1.

Figure 3: Bridge-Laying Mindstorm Robot

Figure 4: Stilzkin Bridge Laying Mindstorm Robot

Robot 2 - Challenger

Acts as the Slave robot

Follows the instruction of Discovery

Ability to go up and down walls deep walls to collect samples

Collects specimens for further research

Stores the specimens in a basket on its body

Designs that are to be considered (Shown in Figure 5 and Figure 9)

There are more designs combining solar panel in Appendix 1 below

Figure 5: Lego Mindstorm Chimney Climber

Figure 6: Lego Technic 8479 Code Pilot (Truck)



Design 1

Design 2

Design 3

Design 4

Design 5

Design 6














































































Table 2: Weighted Decision Matrix

The design for the robots follows as in Appendix 1.


The manufacturing and system configuration of the robots are time and resource consuming process. Futile and near zero gravity environment on Lunar surface add the complexity to produce such robots. Some of the constraints omitted during the project timeline are as following:

Building robots

Mobility on uneven surface

Lasting on hazardous and futile environment

Structural strength

Robotic components

2.1 Limited sensors available in a robot

2.2 Solar panel as the power source for the robots

2.3 Data storage

2.4 Camera connectivity


Mass of the robots

The ability of a robot to sustain the weight of the partner robot


Minimal conditions essential for successful IR transmission

Distance apart between two robots

Angle between both robots

Level of ambient light can be tolerated


Multiple robots commence challenges


Determination of which robot moves first

How does a robot know whose turn it is?

Motion Planning

The ability of a robot to move to a target without knowing the location of the other robot

Cost of the Project

Additional sensors

Additional bricks and components

Solar panel as the power source



The key component of a Lego Mindstorm is the NXT which is the programmable brick that renovates models into robots, hence control their action. NXT is known as the brain of the robot as the software to write the program is downloaded into it via infrared. These robots are sovereign as they are programmed to run the mission without any input or interference from the control station. They explore and interact with the surroundings and decides based on the input from their atmosphere through sensors. Communication between two robots can be performed by using these NXT bricks as well as infrared eyes. Besides that, another way of communication is through sound. The NXT consist of a piezoelectric speaker which generates 6 distinct tones and can also carry a tune. [5] A detailed research has been carried out to decide on the design of the robots using Lego Mindstorm NXT 2.0.

Design Configuration

The design of the robots needs to meet certain requirement where they will need to lift specimens, store samples, travel on craters ( as shown in Figure 3) as well as climb on walls or deep holes. However, the two robots will have different designs and functions. A variety of Lego model designs will be considered for Discovery and Challenger. The designs are shown in Appendix 1.

Figure 7: Craters on Moon surface [4]

The source of power for the robots will be generated from the Sun. The use of solar panel is becoming extensive in the industry as it is more cost efficient and reliable. The good part of it is the ability to equip solar panel to the robots as the main source for power. However, the power consumption of the motor, size, capacity and cost needs to be considered. The solar system comprises of one 9V solar panel, providing approximately 250mA which would be sufficient to power the NXT and a single motor in direct sunlight. [6]


Table 3: Basic Sensors [7]Sensors are the most fundamental aspect of a robot which is equivalent to the five sense of human's personality. There are various sensors programmed in a robot depending on the type of task undertaken. These include the basic sensors and additional advance sensors.




Reacts to touch and release


Distinguish between light and dark

Determine the light intensity in a room and light intensity of various colours


Measure noise level in dB and dBA

Identify sound pattern and recognize tone differences


Judge distance

Detecting object and measuring its proximity in centimetres or inches


Measures the Earth's magnetic field

Notify the robot's facing direction by calculating the magnetic heading

Built in calibration which help reduce other magnetic interference


Measures acceleration which will also help to measure the g forces

Notify the position of the robot


To protect the program

Use multiple transponders to run multiple program paths




Ability to record up to 30 frames per second

Consist of a microphone for recording sound for videos

GP2D12 distance sensor

Able to read distance between 10 and 80 cm

Wire Guidance sensor

To guide the robots reliably along a wire track

Laser Target Finder sensor

Detecting reflecting targets several meters away

DCP sensor adaptor

To log data such as humidity, temperature, pH values and sounds

Table 4: Advanced Additional Sensors [7]


Communication is one of the most vital elements in this project as it determines the successiveness of the robotic collaboration. Lego Mindstorm NXT unit consist of an IR communication port which will be considered in this project as a method of interaction. Accurate transmission is essential as there should not be obstacles between the robots to guarantee communication. On the other hand, synchronization is equally significant as this determines which robot moves first and whose turn it is in a task undertaken.

Human Override

Lego Mindstorm is advanced by an external future application which involves human override. A free application (MINDroid) turns an Android Smartphone to a wireless remote control device to control these Lego Mindstorm robots. The presence of this application had carried out successful experiments on Lego Mindstorm robots. This application is connected to the NXT robot over a standard Bluetooth connection. The Smartphone transmits directional control to the brain of the robot via accelerometer. The magnificence of the application is the way it controls the robot which is by tilting the phone. This action will stimulate motors on the robot to move left, right, forward and back. However, there are enhanced functions in this software where other motor based activities can be carried out such as shooting out an object from the robot or closing a gripper hand. [8] This Smartphone software would be a great remote controlling intelligent device to be applied to this project.


A timeline for the whole project lifetime is produced in Microsoft Project giving the details of the tasks to be done.


The idea of this project is to design two Lego Mindstorm robots called Discovery and Challenger which will collaborate with each other to perform a range of task. The robots will be exploring Lunar surface and carrying out tasks such as collecting adequate specimens for experiments and also determining the humidity of the surface. Each robot will have their own functions to perform the tasks as they are going to be building in two different designs. The cooperation concept between the two robots will be a master-slave relationship. In this case, Discovery being the master and Challenger being the slave. A remote controlling device using Android Smartphone application will also take into consideration to control the direction of the robots in case of system failure. In overall, there are restrictions that need to be analysed in order to achieve this project successfully.


[1][2] Kazerounian, K."Robot." World Book Online Reference Center. 2005. World Book, Inc. Available at: (Accessed 5 November 2010).

[3] Harris, T. (2002) How Robots Work [Internet], Available at: (Accessed 2 November 2010).

[4] NASA's New Moon Missions. (2009) NASA Blogs [Internet], Available at: (Accessed 15 November 2010).

[5] What is NXT? Lego Mindstorm [Internet], Available at: (Accessed 10 November 2010).

[6] Power your Lego Mindstorm NXT Robot using nothing but the Sun. Greendiary [Internet], Available at: (Accessed 29 October 2010).

[7] Sensors. Lego Mindstorm [Internet], Available at: (Accessed 3 November 2010).

[8] Tofel, K.C. (2010) Lego Launches Robot-Controlling Android Application [Internet], Gigaom. Available at: (Accessed 3 November 2010).

[9] Figure 4: Lego Mindstorm Barrel Collector, Available at:

[10] Figure 5: Lego Mindstorm Chimney Climber, Available at:

[11] Figure 6: Bridge-Laying Mindstorm Robot, Available at:

[12] Figure 8: Stilzkin Bridge Laying Mindstorm Robot, Available at:

[13] Figure 9: Spike (Scorpian) Lego Mindstorm, Available at:

[14] Figure 10: Lego Technic 8479 Code Pilot (Truck), Available at:

[15] Figure 11: Lego Mindstorm Powered with Solar Panels, Available at:

[16] ABB, 10 Good Reasons to Invest in Robots [Internet], Available at: (Accessed 30 September 2010).

Knudsen, J.B. (1999) The Unofficial Guide to Lego Mindstorm Robots [Internet], Sebastopol, O'Reilly. Available at:'Reilly/(EBooks)%20-%20O'Reilly%20-%20The%20Unofficial%20Guide%20to%20Lego%20Mindstorms%20Robots.pdf (Accessed 10 November 2010)

Junghans, A. (2001) Collaborative Robotics with Lego Mindstorms [Internet], Germany, Karlsruhe University of Applied Science. Available at: (Accessed 15 November 2010).

Gockley, R. (2002) Multi-Robot Communication with Lego Mindstorm [Internet], Available at: (Accessed 20 November 2010).

Sharma, A. (2010) ABB Opens Robotics Application Center to Increase Productivity [Internet], Available at: (Accessed 3 November 2010).