Transcript DESIGN OF WIRELESS PROSTHETIC HAND

DESIGN OF WIRELESS PROSTHETIC HAND
Contents
Introduction
Why Wireless robotic arm
System Description
Block Diagram
System Operation
Conclusion
References
Photographs
Introduction
 Prosthetic arms which are available in the market are classified as
 Mechanical Arm
 Electrical driven arm
 Myo-electric arm
 Mechanical arm operates using body power with the use of Bowden
cables. That cable is attached to the soldier with a string. When
the movement of the soldier occurs, the cable is stretched hence
opening & closing of plum takes place.
 Electrically driven arm operates using relays & switches, no harness
cable is required.
 With the advent of new technology arm prosthesis reached to a new
dimension results a new prosthetic arm , where the features of grip
force has been implemented & the whole system operates using EMG
signal (Signal from muscle)
Why Wireless Robotic arm
 It has been seen that the signal strength from amputee stump decreases as the
years of amputation increases.
 It is because the muscle slowly lost its elasticity, if it is unused for a number of
years
 For the amputation above 20 years, the muscles permanently lost its
elasticity and comes under a permanent fatigue state.
 EMG signal lost forever in that situation. So our state-of-the-art technology
(Myo Electric arm) will be of no use.
 In this situation it is indeed a very challengeable task for rehabilitation.
 Amputee needs all types of features like Myo electric arm but the feed signal
should not be EMG.
 As a solution of the above stated problem, we have developed one wireless
robotic arm, in CSIO where all the features are present but the input feed is not
an EMG signal, It operates using wireless switch.
System Description
Total System
RF Transmitter
RF Receiver
RF Transmitter
Four
Switches
Antenna for
Signal
Transmission
RF
Transmitter
RF
Transmission
Module
Encoder
Block Diagram of RF Transmitter
Figure 1. Block diagram of RF transmitter
Contd..
 Switches
 All the switches are of Micro switch type
 They are connected with four input data pins of Encoder
 The switches are marked as “STOP”; “OPEN”; “CLOSE
WITH LOW GRIP”; “CLOSE WITH HIGH GRIP” (Right to
left)
 Encoder
 The encoder has 8 bit address bus, four bit data bus
 One Transmission enable port pin, denotes whether the
transmission is successful or not
 The address bus is grounded as no another device
except switches are connected
 One internal crystal which provides the clock for data
transmission
Contd..
 RF Transmission module
 This module is used for data modulation & transmission
 The modulation type is AM
 Carrier frequency is 434 MHz
 Antenna for RF communication
 It is a simple wire
 It is stripped at another end, which acts as a simple wire
radiator antenna
RF Receiver
Receiving
Antenna
Microcontroller
with Motor
Driver
RF Receiver
Decoder
RF Receiving
Module
Block Diagram of RF Receiver
Figure 2. Block diagram of RF receiver with grip controlled circuitry
Contd..
 Antenna for RF Receiver
 It is same as described in Transmitter section
 RF Receiving module
 This module is used for data demodulation & re shaping
 The Demodulation type is AM
 Carrier frequency is 434 MHz
 Decoder
 The decoder is synchronized with encoders in all prospect
 The decoder has same 8 bit address bus, four bit data output.
All the data output pins are connected to the microcontroller
pins
 One Valid Transmission port pin, denotes whether the
transmission is valid or not
 The address bus is grounded
 One internal crystal which provides the clock for data receiving
Contd..
 Microcontroller With Motor Driver
 It is the heart of the whole system
 All Four output pins from decoder and the Motor driver pins’
are connected with microcontroller as shown in the block
diagram of receiver
 The two limit switches measures the maximum extent of
opening & closing of Plum
 The Opto Switches are used as a Limit Switch
 Microcontroller drives the DC motor through Driver circuitry
as the signal (Low to High ) received from the Decoder output
pins.
 External Pulse shaping circuit is used to control the duty cycle
of the pulses generates to control the speed of DC motor
 The software written based on speed control of DC motor
System Operation
Total Operation
Close Arm
Close with Low Grip
Open Arm
Close with High Grip
Contd..
• Video of wireless prosthetic hand
Conclusion
 The arm has been developed & Tested with 2 different level of grip
forces in CSIO
 The wrist is not automatic, it is manually controlled Rachett based.
 Level of the grip forces can be increased if the number of the
switches are increased in transmitter section.
 Wrist rotation can be controlled electronically if the mechanical
arrangement can be modified and attached with motor shaft.
Photograph
Figure: Transmitter & Receiver along with Hand
References
[1] Ferguson, G Reg Dunlop, “Grasp Recognition from Myo electric
Signal”, Proc. Australasian Conference on Robotics and Automation,
27-29, Nov 2002, Auckland
[2] Andres Herrera, Andres Bernal, David Isaza and Malek Adjouadi,
“Design of a Electrical Prosthetic Gripper using EMG and Linear
Motion Approach”, the National Science Foundation grants EIA9906600 and HRD-0317692
[3] Edwin Iversen, Harold H. Sears, and Stephen C. Jacobsen,
“APPLICATIONS OF CONTROL”, IEEE Control Systems Magazine, pp
16-20, 2005 (doi: 10.1109/MCS.2005.1388792)
Thank you !