This entry concludes the final blog entry for our Animatronic Turtle Project! With the presentation taking place on Tuesday morning in the MEM Conference Room at 10:45 am, our device and presentation requirements have been completed!
System Integration: The animatronic turtle is finished! Both videos below provide an overview of the completed device, as Video 1 is the completed turtle, and Video 2 is with the shell removed. The final steps this week have included a lot of final cosmetic touch ups to the device, for the shell was cut in different places to have it completely cover the mechanical four bar linkage system, as well as the wires connecting all of the hard ware components. Further steps were taken to have the device appear visually pleasing, as green ribbon was placed on the "underbelly" of the device to make it look authentic from the audience's viewpoint. All coding in MATLAB is completed, as both the accelerometer and sensor fully interact with the environment. Human users who come in contact with the device or appear within 20 cm of the nose sensor, the device will retract into its shell. The animal does not fully retract, as real sea turtles in teh wild are unable to do so.
Presentation: For the presentation, a pet litter box has been transformed into a mock ocean with sand and rocks to make the device appear in its natural habitat. Aside from that, a presentation has been uploaded this blog site which is how we will relay our project to Drexel faculty and peers. The final report detailing the entire module progress of our group has also been uploaded. We hope you have enjoyed following the progress of our team this term bringing an Animatronic Turtle to life!
Video 1: Turtle Overview w/Retraction Movements
Video 2: Mechanical System Overview
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Figure 1: Completed Turtle
This week we completed our major goal of continuing to integrate all of the system components, and finally got to test our device for the first time!
Mechanical System: For the mechanical system, the only remaining part was integrating the four bar linkage into the outer design of the turtle. It was investigated and concluded that chicken wire was going to be too weak for our needs, so we found an alternative solution by taking something very common, a metal coat hanger! Hangers are very rigid and can be bent to the specifications we need, so we found this to be an effective way of connecting the outer stuffed legs into the mechanical system.
Programming: Continuing with the programming of the device, the group has received an accelerometer intended to give the turtle more interactivity with an audience. While the sensor will detect movement within range, the accelrometer will be placed in the head of the creature so that it will cause the device to retract when it is touched. Code is being made to have the Arduino send the input from the accelerometer back to MATLAB.
Aesthetic Design: Loose ends are beginning to be resolved on the aesthetic end, as the turtle has been completely destuffed and the limbs detached in order to connect them to our mechanical and electrical systems. The process of paper macheing a new shell has taken place, as the new shell is thinner and taller to meet the height requirements to cover the entire system. Paint and polyurethane were used to give the shell a glossy and realistic look. Our own designs were replicated on the shell to give it a very sleek and appealing feel.
System Integration: The first run through of our full system between the mechanical, electrical, and aesthetic systems took place. The video details our device in action:
Video 1: Testing of Turtle
Figure 1: System Integration Taking Place
Figure 2: Destuffed Turtle
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Figure 3: Turtle Assembled
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Figure 4: New Shell Under Construction
Figure 5: Completed Shell
Week 7 Update:
Building upon the progress made during week 6, this week we continued testing of our electrical and mechanical systems, and are working towards an improvement on the aesthetic design.
Mechanical Design: On the mechanical side, both four bar linkage systems for the front and rear limbs have been attached to the wood base, and are able to move freely. To make this happen, some adjustments to the wood bases to allow the mechanism to continuously move in straight path while operating. This was done by going back to the machine shop and creating a central canal in the wood bases so that the parts could move unobstructed. The servos themselves have been attached to wood pieces to mount them to the acrylic base, as full system integration is beginning to take place.
Programming: On the programming end of things an infrared distance sensor was obtained and will be placed onto the device. The infrared distance sensor is being characterized and tested so that we can accurately know the distance an object is away from the sensor. A graph below details the output of the senor and how far of a distance we can have before telling the turtle to contract.
Aesthetic Design: For the outer design of the turtle itself, the group has opted to purchase a stuffed animal to make the device more visually pleasing. While the shell will still be constructed out of paper mache and customized, the limbs and the head will be extracted from the stuffed animal and integrated into the system. This will be done through using chicken-wire, or some knd of mesh to attach the cloth to the four-bar linkage system.
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Figure 1: The Stuffed Animal Purchased for Aesthetics
Figure 2: Infrared Sensor being used
Figure 3: Sensor Data Output Graph
Figure 4: Inserting Canal in Wood Base
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Figure 5: Completed Mechanical 4-Bar Linkage System
This week the group has made many strides in the development of the mechanical and electrical systems for the turtle.
Mechanical Design: Several trips were made to the machine shop to cut pieces for the four bar linkage mechanism and wood base, and the group was introduced to using different machines in the shop including a bandsaw and drill press. The four-bar linkage itself has been attached to the wood base, and going forward into next week, the group is planning on integrating the servo programming systems with the mechanical system. Pictured below are different components being constructed, and system assembly beginning to take place.
Aesthetic Design: The other major development this week included the first step in the aesthetic design phase, as the first mold for our turtle shell was constructed using paper-mache. This was done using simple materials including newspaper, flour, and salt to make the bonding substance, and the shell was constructed on the face of a balloon to give it the familiar shape of a turtle shell.
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Figure 1: Paper-Mache Shell
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Figure 2: Four Bar Linkage Assembly
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Figure 3: Paper-Mache Workshop
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Figure 4: Cutting Wood in the Machine Shop
Week 5 Update:
This week our project is beginning to come to life, as we have our first physical parts that are going to be used in the development of the turtle.
Mechanical Fabrication: This week our group made the first major physical advancement of our project…a trip to the Drexel machine shop! With the designs for the base and four bar linkage finalized, a piece of sheet 12” by 24” acrylic was obtained in the shop to laser cut these parts and begin the process of assembly. All of our Creo files were reproduced on an AutoCAD spreadsheet (pictured below), and a dsxl file was created to have the machine precisely cut the components we designed. Going forward into next week, it is our collective goal to get the mechanical portion up and running, as well as begin to incorporate the programming to the linkage.
Programming: On the programming side of things, more functions were added to the MATLAB class file for the servo controller. This includes functions to set speed and acceleration of servos, gather input of analog and digital devices and obtain information about a servo's position and moving state. The next pieces of code that will be done will be for the sensors that are going to be used for the turtle.
Mechanical Fabrication: This week our group made the first major physical advancement of our project…a trip to the Drexel machine shop! With the designs for the base and four bar linkage finalized, a piece of sheet 12” by 24” acrylic was obtained in the shop to laser cut these parts and begin the process of assembly. All of our Creo files were reproduced on an AutoCAD spreadsheet (pictured below), and a dsxl file was created to have the machine precisely cut the components we designed. Going forward into next week, it is our collective goal to get the mechanical portion up and running, as well as begin to incorporate the programming to the linkage.
Programming: On the programming side of things, more functions were added to the MATLAB class file for the servo controller. This includes functions to set speed and acceleration of servos, gather input of analog and digital devices and obtain information about a servo's position and moving state. The next pieces of code that will be done will be for the sensors that are going to be used for the turtle.
Figure 1: AutoCAD Laser Cutting File
Figure 2: Acrylic Cut in the Shop
Week 4 Update:
Over the course of this week the group has reached the final steps in the design of the mechanical system for the turtle, as well as started the process of coding on MATLAB to eventually bring the device to life.
Mechanical
System: The mechanical system had various imperfections following
the last weekly update, as several things had to be changed to account for elevation
issues with the base. Due to the full movement of the arms (featured in the video
below) and the size restrictions of the servo motors, it was soon realized that
we would need to elevate the mechanism about a 1.3” above the surface of the acrylic
give it the freedom of degrees desired for movement. To solve this issue, wood
is going to be glued above the base surface, and the mechanism itself will be
placed on the wood, above the servos to resolve this issue.
Programming: MATLAB code was made to represent the Pololu Servo Controller
as a MATLAB object. A function/method has been made to control a servo when
given the specified port and target movement value. This code takes these
specified values and translates it to bytes which get sent over the COM port to
the servo controller. Future versions of this code will include more
functions/methods that are specified in the Pololu Servo Controller's user
manual such as setting a servo's velocity and acceleration as well as a
more user friendly interface. This interface will be able to search for COM
ports on your computer and let you choose from ports that have been found
rather than simply inputting a port number.
Moving forward this
week, the group plans on receiving the raw materials necessary to begin
construction, and time will be spent in the machine shop to begin cutting and
welding the components together. Included below are some CAD images of our base, head, and the metal joint for the device.
Video 1: 4-Bar Linkage Mechanical System Simulation
Figure 1: Turtle Head CAD Rendering
Figure 2: Bar Designed in Creo
Figure 3: Base Outline w/Servos and Wood Components
Week 3 Update:
This week the group has made many strides in developing the mechanical
system designs as well as finalizing the initial list of materials needed to
start construction. To control the movements of the turtle’s hands and head, the
group has decided to develop a four bar linkage system that will be able to
propel the arms outward of the shell to give it the ability to move. Throughout
the week, the four bar linkage has been redesigned multiple times by the group
in order to get the most potential out of the mechanism. As featured below in
the video, the latest design calls for a linear motion four bar mechanism,
where the head and arm movements are all controlled in one cycle of the device.
With the basic movement controls in mind, the process of finding the right
materials has begun to begin construction. The early bill of materials sheet
below details the initial supplies being ordered, including sheets of aluminum,
acrylic, and slotted screws, enabling us to begin cutting and welding in the
machine shop next week. Going forward, the group is investigating if it would
be possible to incorporate a linear slide system into the device, or turn to a
rack and gear design to be able to make this design feasible.
Figure 1: Bill of Materials to Order
I
Figure 2: Simulation for Mechanical 4-Bar Linkage
Week 2 Update:
Submitted this week was the design proposal for our project. Our project goals have been defined in this brief, as well as our plan of action in completing this project.
ENGR 103-077/092- Spring
2013
Freshman Engineering Design Lab
Freshman Engineering Design Lab
“Animatronic
Turtle”
Project Design
Proposal
Date
Submitted: April 9th, 2013
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Submitted
to:
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Group
Members:
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Nicholas Philips, nwp25@drexel.edu
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Eric Lam, el438@drexel.edu
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Harshit Aggarwal, ha398@drexel.edu
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Chengyang Andy Mo, cm963@drexel.edu
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Judy Tran, jt585@drexel.edu
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Abstract:
The idea behind the development of an
animatronic turtle is to expose the various group members involved in the
project to hands on engineering techniques, and using the module as a teaching
resource to introduce a wide scope of practices when it comes to developing a
feasible design and working fabrication. The main goal is to produce a working
animatronic turtle robot in ten weeks, and present a device that is composed of
many features and elements in order to fully mimic a turtle that is familiarly
known in the wild. Some of the basic functions of the device will be creating a
full working mechanism, where the turtle’s hands, legs, head, and neck are all
able to move, and the body parts are given the ability to contract within its
shell. The electrical components of the device will be incorporated into a
system of servos and sensors, as well as an accelerometer to give the device
the ability to freely move. The final step is incorporating everything into a
complete software system, where all movements and actions can be controlled to
make the creature fully interactive with its surroundings. The project is
expected to be a very challenging task, as several members will be learning for
the first time technical skills from welding to sawing, and others expanding
their knowledge of computer programming, 3D rendering software and robotic
design. The major task will be learning, and applying these skills all in time
for an interactive presentation to share with fellow Drexel students and staff.
1 Background
The major goal of this project is to design and construct an animatronic device that will further the understanding and technical knowledge of the engineering group members, and produce a feasible working prototype. The main learning objectives of this module is to gain a general understanding of the workings of robotics, from the mechanical and electrical design, and ultimately being able to bring the device to life through computer programming techniques. The motivation behind developing an animatronic turtle is that all of these goals can be fulfilled where a basic working mechanical and electrical system can be designed and created, and the familiar movements of a turtle can be mirrored through the use of servos, a controller, and programming software. Since there is a high emphasis on using animatronics and computers to interact with humans, the goal is to make the turtle interactive where different sensors can be placed on the device to read human movement or facial expressions, or an accelerometer can be used to move the turtle towards a group of people. A common example would be having the turtle contract when a sensor picks up movement ahead, or using an accelerometer to control its movement. These objectives are all attainable in the ten week timetable in this module, as group members are anticipating and pledging sizeable amounts of time commitments and will power to ensure the project gets completed and to tackle the technical challenges that are bound to happen with any project. Some of those challenges include becoming proficient and knowledgeable in the necessary computer programming software such as MATLAB coding, or developing a properly working mechanism within the tight ten week timespan. This project will also introduce familiarization with different engineering tools such as those found in the machine shop, as several group members will have to learn how to weld, solder, and be able to put the device together. The group will also be introduced to different types of machines, from a 3D rapid prototyping machine, band saw, metal sheers, and grinders in order to complete the device. The necessary skills and knowledge will be is one of the main goals of this project, as the group members are being introduced to the necessary skills that are required in engineering, and this a very heavy group project where deadlines and cooperation are critical to the success of the project.
At the end of the module in ten weeks, it is the goal to produce a working animatronic turtle that will have the basic mechanisms to properly move its body and parts, and the necessary programing to move and interact with the surrounding it is placed in. The physical prototype with have a mechanical mechanism with servos that can cause the device to move, and these movements will all be controlled through a servo controller. The electrical software and necessary parts will be planted within the device to transmit power and movement from the servos. The accompanying programming software will be executed through a program such as MATLAB, where numerous codes can be written to ensure that the turtle can do several things, such as move in several directions, contract its arms and legs, move its head and tail, and connect the device with various sensors and accelerometer that will cause interaction. Several of these sensors that could be implemented include a ultrasound, motion, or light sensor. It is the goal to have the device to interact under various scenarios, such as when a moving component gets close to the turtle, the surrounding sound is too loud, or when the surrounding lighting changes causing the turtle to retract.
3.1 Mechanical Activities
The contract motion is one of the main tasks. A turtle has four legs, one head and a tail. They are all contracted into the shell when potential danger is sensed by the turtle. The contract motion will be archived by one motor for each part of the body. The technical challenge in this part is how to transfer the rotating motion of the servo to the contract motion of the legs, head and tail.
3.1.2 Structure Design:
Structure Design is another mechanical
main task. Metal plate will be used to construct the body of the turtle. The
technical challenge here is how to design the parts to construct the body of
the turtle. It needs to have a shape of turtle which can be covered by a turtle
shell. The use of servo will be the most challenging part in the design as
well.
3.2 Electrical Activity:
The wire will be connected from the controller to all
the servos and sensors that need to be connected. The wire will be attached on
the metal plate.
3.3 Programming Activity:
The controller will be programmed through Matlab. The
controllers can control the degree of rotation by Matlab code.
3.3.2 Sensor Controls:
The sensor will input the signal to the controller.
The reaction of the servos can be programmed through Matlab according to the
input. The challenge will be how to program the input of sensors through
Matlab.
3.3.3 Accelerometer Controls:
The accelerometer will also be connected to the signal
input in the micro controller. The movement of the Animatronic can be mimicked
through an accelerometer device, which can be programmed through Matlab
according to the input. The challenge will be to write additional programming
in Matlab to integrate the sensor and accelerometer controls together in one
software package.
4 Project Timeline
Week
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||||||||||
Task
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1
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2
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3
|
4
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5
|
6
|
7
|
8
|
9
|
10
|
Robotics Background Study
|
x
|
x
|
||||||||
Creo Parametric Shell Design
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x
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x
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||||||||
Shell 3-D Printing
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x
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|||||||||
Material Purchasing
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x
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x
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||||||||
Machine Shop Cutting/Welding (4-6 Hours)
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x
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x
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||||||||
Mechanical System Design
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x
|
x
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x
|
x
|
x
|
|||||
Servos/Controller System Design
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x
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x
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x
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x
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||||||
Animatronic System Assembly
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x
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x
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x
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x
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||||||
Aesthetic Design
|
x
|
x
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||||||||
Animatronic Testing
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x
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x
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x
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x
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||||||
Final report preparation
|
x
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x
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||||||||
Table 1: Animatronic Turtle
Construction Timeline
5 Facilities and Resources
The project requires tools and materials that might not be
readily available, as these include the shell, the rubber skin of the turtle, sheet
metal, servos, controller, wiring, and other electrical equipment required to
make the robot. A servo controller and several servos are being provided in lab
in order to give the device power to move. Access to the machine shop will be
necessary throughout the course of the module to use the machinery required to cut
the metal pieces for the mechanism and weld them together. The group initially
decided to buy a turtle shell to try to incorporate a mechanical design into it,
but has been advised against it. The group is now exploring the idea of forming
a 3-D drawing of the shell component in Creo Parametric and producing it using
a rapid prototyping machine. Additionally, trips to hardware stores such as
Home Depot and Lowes will be required to purchase the critical components such
as the nuts, bolts, wiring, and metal. Additional trips may also be necessary
to hobby stores where specific servos or electrical equipment might need to be purchased
to meet the requirements of the animatronic turtle. The group has several
options for workspace available, primarily in the form of keycard access to
workspaces in the Drexel ExCITe Center where it is easy to convene and work on
the project.
6 Expertise
Coming into this project, several group members have
numerous skills and expertise pertaining to robotics and engineering design,
while others will learn the necessary skills as the module progresses. For the computer
programming aspects of the project, basic knowledge of programming languages
such as functions, conditionals and loops are needed in order to give the
turtle basic mobility and to ensure it is able to work with different sensors
and servos. Knowledge of serial communications is needed to communicate with
the servo controller to be able to manipulate devices attached to it. Electrical
wiring experience is needed to wire servo motors and sensors to a servo
controller, and ultimately run the circuitry throughout the entire device. Mechanical
knowledge in designing is needed to ensure properly working mechanisms can be
developed for the inner workings of the turtle, as well as knowledge of
materials to use in these mechanisms. Biological knowledge in the movement of
turtles is needed to help design the mechanisms of the turtle. The group as a whole
will be introduced to the techniques of using the equipment available in the
machine shop such as a rapid prototyping printer, band saws, metal
sheers, and grinders.
7 Budget
Category
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Projected Cost
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Raw Material
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$40.00
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Servos
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$90.00
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Micro Controller
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$40.00
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Sensors
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$50.00
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TOTAL
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$220.00
|
Table 2: General Budget Chart for
Animatronic Turtle
7.1
Raw Material
The basic mechanical components of the project include sheet
metal, nuts, bolts, rods and rubber. These materials are necessary to make the
shell, legs, tail and head of the turtle, as well as the mechanism design of
the animatronic. Additional raw materials will be required later in the module
for the aesthetic design of the turtle, such as material for the artificial
skin and the frame of the turtle. Some early ideas for the outside covering and
character of the turtle animatronic are rubber or amigurumi crochet.
7.2 Servo Motors
The animatronic will be requiring many servo motors in order
to fulfill the necessary movements and actions of the device. The servos that
are being recommended in laboratory should suffice for the device, as they
should be strong and powerful enough to perform the basic movements for the
arms, legs, head, and neck of the turtle. The exact model being suggested is a
Tower Hobbies TS-53 for the heavier movements or a TS-6 for lighter movements.
The heavier movements are going to included movement of the arms, legs, and
perhaps head, while the lighter servo may be used for any minor movements that
are decided to be mimicked on the device. It is anticipated that at least eight
servo motors will be required to fully complete the movements in the device.
7.3 Micro-Controller
Since there will be at least twelve channels needed for the
sensors and servos in the device, a different micro controller will be need to
be purchased for the animatronic. The servo controller that is being provided
in laboratory is a Micro-Maestro Six Channel Controller provided from the
distributer Pololu. The company has several other options available for
covering more channels, as a twelve channel device is available for $29.95, and
an eighteen channel device for $39.95. Depending on the finalized design for
the animatronic, several options are available for purchasing a suitable micro
controller.
7.4 Sensors/Accelerometer
In order to allow the turtle to interact with its
environment, several sensors are going to be placed on the device in order to
give it a personal interaction with an audience or surrounding. An ultrasonic
sensor, sound sensor, and a light sensor are some of the early proposals for
giving the turtle the ability to engage with its environment. An accelerometer
will be used on the robot in order to control the movements of the turtle. It
is the goal to be able to move the turtle in various directions, and using the
device to change direction.
Week 1 Update:
In our first day of lab, today we formed our group for our Engineering Freshmen Design Project. Our group has a vast range interests and skills which are going to be necessary to complete this animatronic, as our team is composed of mechanical, electrical, and computer engineering students. The original idea for the project started off with an animatronic Pikachu, but quickly our ideas ventured into the Pokemon world, as the next idea became a water squirting Squirtle. Eventually, our group settled on an animatronic turtle that would be able to retract into its shell. We feel that we can encompass many goals with a turtle, and that we can customize the design and workings of it specifically to that of a turtle on land. Our advisor, Dr. Primerano has emphasized the importance of human-robot interaction. To fulfill this aspect, we are planning to install various sensors within the device including an ultrasonic sensor into the turtle so it will retract when approached too closely or anything of the sort. Its going be to an exciting and challenging adventure, and our group eager to get started.
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