wireless-controlled animatronic hand

1
Project Name : WIRELESS-CONTROLLED ANIMATRONIC HAND Students Name : Ahmad Moharib, Mohammad Arar Razan Hijazeen, Alia Ghunaim, Saja Abu Naseer, Supervisor Name: Dr. Sulieman BaniHani Abstract Introduction Methodology Result Discussions & Conclusions References HASHEMITE UNIVERSITY FACLTY OF ENGINEERING SCIENTIFIC DAY 30 APR 2015 [1] Arduino Uno microcontroller: <http://arduino.cc/en/Main/ArduinoBoardUno>. [2] Animatronics: <https://littlebits.cc/projects/animatronic- hand>. [3] Similar structure: <http://www.sparkfun.com/news/580>. [4] Spectra Symbol flex sensors datasheet: <https://www.sparkfun.com/datasheets/Sensors/Fl ex.pdf >. <https://www.imagesco.com/sensors/flex- sensor.html>. [5] Servo motors: <https://www.jameco.com/jameco/workshop/howitwo rks/how- servo-motors-work.html>. <https://arduino.cc/en/reference/servo> . Animatronics is the use of mechatronics to create machines which seem animate rather than robotic. Animatronic creations include animals, plants and even mythical creatures. Animatronics was developed by Walt Disney in the early sixties. Essentially, an animatronic puppet is a figure that is animated by means of electromechanical devices. Animatronics is the cross between the animation and the electronics. Basically, Animatronics is the mechanized puppet. It can be remotely controlled or pre-programmed. The abbreviated term originally coined by the Walt Disney as Audio. Animatronics is a subset of anthropomorphic robots which are designed drawing inspiration from nature. The humanoid robots will be equipped with anthropomorphic multi-fingered hands very much like the human hand. We call this a humanoid hand robot. Humanoid hand robots will eventually supplant human labour in the execution of intricate and dangerous tasks in areas such as manufacturing, space, the seabed, and so on. Further, the anthropomorphic hand will be provided as a prosthetic application for handicapped individuals[2]. Many multi-fingered robot hands have been developed. These robot hands are driven by actuators that are located in a place remote from the robot hand frame and connected by tendon cables. The elasticity of the tendon cable causes A mechanical arm is robotic, usually programmable, with similar functions to a human arm. The links of such a manipulator are connected by joints allowing either rotational motion or translational (linear) displacement. The links of the manipulator can be considered to form a kinematic chain. The business end of the kinematic chain of the manipulator is called the end effecter and it is analogous to the human hand. The end effecter can be designed to perform any desired task such as welding, gripping, spinning etc., depending on the application. However, these hands present a problem in that their movement is unlike that of the human hand because the number of fingers and the number of joints in the fingers are insufficient. The animatronics hand has a thumb and four fingers[2]. In this project we are working on an animatronic hand and a wireless control unit for it as a regular glove that can be worn in human hand with flex sensors on each finger. The hand will make the same movement of fingers as the operator moves his fingers. All of that is controlled using an Arduino microcontroller[1]. In this project, we have create a simple mechanical design, the electrical piping tubes will be used to make a prototype of the human hand, they will be implemented in a certain way to make the most flexible mechanical design for the hand. Each tube (finger) will have a returning spring on its back that will return the finger to its original position when the tension force is removed[3]. Inside each finger there will be a string that will pull the top of the finger so that the whole finger will be bended when the string is pulled. What are the flex sensors? Flex sensors are sensors that change in resistance depending on the amount of bend on the sensor. They convert the change in bend to electrical resistance change, the more the bend, the more resistance value. They are usually in the form of a thin strip, 1-5 inch long that varies in resistance[4]. They can be made uni-directional or by- directional Servos are controlled by sending an electrical pulse of variable width, or pulse width modulation (PWM), through the control wire. There is a minimum pulse, a maximum pulse, and a repetition rate. Servo motors can usually only turn 90 degrees in either direction for a total of 180 degree movement. The motor's neutral position is defined as the position where the servo has the same amount of potential rotation in the both the clockwise or counter-clockwise direction[5]. The PWM sent to the motor determines position of the shaft, and based on the duration of the pulse sent via the control wire; the rotor will turn to the desired position. The servo motor expects to see a pulse every 20 milliseconds (ms) and the length of the pulse will determine how far the motor turns[5]. Connection wirelessly between the control glove and the mechanical design of animatronic hand for elaboration was realized using XBee transceiver and XBee shield, which support the ZigBee protocol for Wireless Personal Area Network (WPAN) development[6]. Upon conductions of the experiment, using the variables finger, angle, sensor value and position, the following results were produced. During the first test we measured the angle relationship between human finger and the corresponding finger on the animatronic hand. we found that the index finger, middle finger, ring finger, and pinky all had about the same sensor value from the flex sensors. The thumb on the other hand was limited in movement compared to the other fingers, and therefore the sensor data was in a smaller range. then we came up with three positions to test, fully extended, half extended, and unextended. From here we created a video of all fingers at these different positions. then we analyzed the videos through the use of editing software and found the angle of each finger at each position. Then we conducted the same procedure for the animatronic hand, finding the angle of each finger at each position in the process. we found that at the fully extended position the relationship between human finger and the corresponding finger on the animatronic hand was about a 20° difference. At half extended the relationship was the closest at about a 10° difference. At unextended we noticed the most difference with human fingers bending almost 30° more than the animatronic hand. The thumb was the most consistent finger with only about 10° difference on all three tests. Overall, the comparison of my hand compared to the animatronic hand was greater than we thought. The position with the greatest difference was fully flexed. What all this means is that the animatronic hand has a relationship with my hand. The Problem of Flex Sensors Non-identity. Solution consists in calibrating the device in extreme points; open hand (0 degrees), clenched hand (180 degrees), and then calculating the linear function slope coefficient of every sensor. Eventually the sensor's angle of flex is computed using the altered linear function. The calibration consists in pushing a button while fingers are in position described on a serial monitor screen, which significantly improves the quality of projecting the fingers motion. The chart above shows the differences between particular sensors. For proper calculation of the rotation angle a calibration consisting of

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Page 1: Wireless-Controlled Animatronic Hand

Project Name : WIRELESS-CONTROLLED ANIMATRONIC HAND

Students Name : Ahmad Moharib, Mohammad Arar Razan Hijazeen, Alia Ghunaim, Saja Abu Naseer,

Supervisor Name: Dr. Sulieman BaniHani

Abstract

IntroductionMethodology

Result

Discussions & Conclusions

References

HASHEMITE UNIVERSITYFACLTY OF ENGINEERING

SCIENTIFIC DAY 30 APR 2015

[1] Arduino Uno microcontroller: <http://arduino.cc/en/Main/ArduinoBoardUno>.

[2] Animatronics: <https://littlebits.cc/projects/animatronic-hand>. [3] Similar structure: <http://www.sparkfun.com/news/580>.

[4] Spectra Symbol flex sensors datasheet: <https://www.sparkfun.com/datasheets/Sensors/Flex.pdf >. <https://www.imagesco.com/sensors/flex-sensor.html>.

[5] Servo motors: <https://www.jameco.com/jameco/workshop/howitworks/how- servo-motors-work.html>. <https://arduino.cc/en/reference/servo>.

[6] XBee Communication Module: <https://arduino.cc/en/Main/ArduinoXbeeShield>.

Animatronics is the use of mechatronics to create machines which seem animate rather than robotic. Animatronic creations include animals, plants and even mythical creatures. Animatronics was developed by Walt Disney in the early sixties. Essentially, an animatronic puppet is a figure that is animated by means of electromechanical devices. Animatronics is the cross between the animation and the electronics. Basically, Animatronics is the mechanized puppet. It can be remotely controlled or pre-programmed. The abbreviated term originally coined by the Walt Disney as Audio.

Animatronics is a subset of anthropomorphic robots which are designed drawing inspiration from nature. The humanoid robots will be equipped with anthropomorphic multi-fingered hands very much like the human hand. We call this a humanoid hand robot. Humanoid hand robots will eventually supplant human labour in the execution of intricate and dangerous tasks in areas such as manufacturing, space, the seabed, and so on. Further, the anthropomorphic hand will be provided as a prosthetic application for handicapped individuals[2].

Many multi-fingered robot hands have been developed. These robot hands are driven by actuators that are located in a place remote from the robot hand frame and connected by tendon cables.

The elasticity of the tendon cable causes inaccurate joint angle control, and the long wiring of tendon cables may obstruct the robot motion when the hand is attached to the tip of the robot arm.Moreover, these hands have been problematic commercial products, particularly in terms of maintenance, due to their mechanical complexity.

A mechanical arm is robotic, usually programmable, with similar functions to a human arm. The links of such a manipulator are connected by joints allowing either rotational motion or translational (linear) displacement. The links of the manipulator can be considered to form a kinematic chain. The business end of the kinematic chain of the manipulator is called the end effecter and it is analogous to the human hand. The end effecter can be designed to perform any desired task such as welding, gripping, spinning etc., depending on the application. However, these hands present a problem in that their movement is unlike that of the human hand because the number of fingers and the number of joints in the fingers are insufficient. The animatronics hand has a thumb and four fingers[2].

In this project we are working on an animatronic hand and a wireless control unit for it as a regular glove that can be worn in human hand with flex sensors on each finger. The hand will make the same movement of fingers as the operator moves his fingers. All of that is controlled using an Arduino microcontroller[1].

In this project, we have create a simple mechanical design, the electrical piping tubes will be used to make a prototype of the human hand, they will be implemented in a certain way to make the most flexible mechanical design for the hand. Each tube (finger) will have a returning spring on its back that will return the finger to its original position when the tension force is removed[3].

Inside each finger there will be a string that will pull the top of the finger so that the whole finger will be bended when the string is pulled.

What are the flex sensors?Flex sensors are sensors that change in resistance depending onthe amount of bend on the sensor.They convert the change in bend to electrical resistance change,the more the bend, the more resistance value.They are usually in the form of a thin strip, 1-5 inch long thatvaries in resistance[4]. They can be made uni-directional or by-directionalThey are available in three resistance changes:

-Low resistance range, nominal resistance between 1KΩ-20KΩ.-Medium resistance range, nominal resistance between 20KΩ -50KΩ.

-High resistance range, nominal resistance between 50KΩ-200KΩ.

Servos are controlled by sending an electrical pulse of variable width, or pulse width modulation (PWM), through the control wire. There is a minimum pulse, a maximum pulse, and a repetition rate. Servo motors can usually only turn 90 degrees in either direction for a total of 180 degree movement. The motor's neutral position is defined as the position where the servo has the same amount of potential rotation in the both the clockwise or counter-clockwise direction[5].

The PWM sent to the motor determinesposition of the shaft, and based on theduration of the pulse sent via the controlwire; the rotor will turn to the desiredposition. The servo motor expects tosee a pulse every 20 milliseconds (ms)and the length of the pulse will determine how far the motor turns[5].

Connection wirelessly between the control glove and the mechanical design of animatronic hand for elaboration was realized using XBee transceiver and XBee shield, which support the ZigBee protocol for Wireless Personal Area Network (WPAN) development[6].

Upon conductions of the experiment, using the variables finger, angle, sensor value and position, the following results were produced. During the first test we measured the angle relationship between human finger and the corresponding finger on the animatronic hand. we found that the index finger, middle finger, ring finger, and pinky all had about the same sensor value from the flex sensors. The thumb on the other hand was limited in movement compared to the other fingers, and therefore the sensor data was in a smaller range. then we came up with three positions to test, fully extended, half extended, and unextended. From here we created a video of all fingers at these different positions. then we analyzed the videos through the use of editing software and found the angle of each finger at each position.

Then we conducted the same procedure for the animatronic hand, finding the angle of each finger at each position in the process. we found that at the fully extended position the relationship between human finger and the corresponding finger on the animatronic hand was about a 20° difference. At half extended the relationship was the closest at about a 10° difference. At unextended we noticed the most difference with human fingers bending almost 30° more than the animatronic hand. The thumb was the most consistent finger with only about 10° difference on all three tests. Overall, the comparison of my hand compared to the animatronic hand was greater than we thought. The position with the greatest difference was fully flexed. What all this means is that the animatronic hand has a relationship with my hand.

The Problem of Flex Sensors Non-identity. Solution consists in calibrating the device in extreme points; open hand (0 degrees), clenched hand (180 degrees), and then calculating the linear function slope coefficient of every sensor. Eventually the sensor's angle of flex is computed using the altered linear function. The calibration consists in pushing a button while fingers are in position described on a serial monitor screen, which significantly improves the quality of projecting the fingers motion.

The chart above shows the differences between particular sensors. For proper calculation of the rotation angle a calibration consisting of measuring extreme points of the characteristics is required[4].