Robotic Arm and Dexterous Hand

Critical Design ReviewFebruary 18, 2005

The Team

DavidParrett

Wen JiaWang

KenPeters

JustinTubiolo

JeremyAmidon

Overview

Needs and Objectives Requirements and SpecificationsDesign Analysis and Synthesis

User Input Device Mechanical Operation Mechanical Power PC and Microcontroller Programs Electrical Output Circuit

Feasibility AssessmentFuture Plans

Schedule and Budget

Project Needs & Objectives

Maximum exhibit life span and durability.

Intuitive navigation and operation by users.

Robotics theme an exceptionally inviting "attractor factor."

Accessibility to many users of different age and physical ability.

Provide maintenance information and details.

The robotics exhibit becomes an extension of the human arm.

Test the display in its target environment to ensure success.

Project Specifications

The Input Device detects four movements of the hand and the fingers

The Robotic Arm moves with 4 large muscles The wrist operates as a hinge, moving the hand up and down approx. 45o

The elbow operates as a hinge, moving the hand and arm up and down approx. 45o

The shoulder rotates the entire arm around approx 180o

The upper arm lengthens and contracts a distance of at least 1 foot (0.3 m)

The Robotic Hand contains five fingers, 4 of which can move separately The thumb, index, and pinky fingers are able to move separately The middle and ring fingers move together The fingertips contract from open position to 90o partly closed

Design Analysis

User Input Device

Mechanical Operation

Mechanical Power

PC and Microcontroller Program

Electrical Output Circuit

Concept Block DiagramGlove Controller

Personal Computer

Microcontroller

Extension CylinderRotational Motor

Limiting Sensor Air Valves

Air MuscleTable Touch Sensor

Movement Cables

Air Pressure Supply

Wrist Joint Elbow JointFinger Joints

User Input Device

Sensor Laced Glove & Fighter Joystick

Utilize Flex Sensors in the Glove

Sensor Glove with Motion Track Glove has Flex Sensors in the Fingers Infrared Receptor Senses Motion in 6 Degrees

Courtesy of http://devices.sapp.org/component/flex/

P5 Data Glove

Courtesy of Essential Reality

Arm Concept

Arm With Wrist, Elbow & Rotating Cylinder 4 Degrees of Freedom Maximum Reach

Mechanical Power

Power Source Concepts

Electric 24 Volt DC Motors For the cylinder a high speed

and high current DC Servo Motor is used

For the rotation of the arm a motor with a gearbox is used for higher torque and slower speed

Power Source Concepts

Pneumatics Utilize air muscles Power-to-Weight Ratio up to 400:1 Apply Forces up to 140 lbs. Very Flexible

Photo courtesy of Shadow Robot Company

Pneumatics

Air muscles are controlled by 24 volt solenoid valves

Valve Lifespan

Valves are rated for 200 million cyclesValve Lifespan

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

50.0

0 50 100 150 200 250

Cycles Per Minute

Yea

rs

Finger Curl Problem

Linear motion of muscles was inadequate

Design Images

Design Pictures

Project Pictures

Electrical Input/Output

Inputs to PC USB signal from glove controller

Output from PC RS-232 serial output to MDB

Inputs to MDB Serial input to the UART from the PC Magnetic field sensors from arm cylinder and rotating gear Touch sensor to detect when the hand touches the display table

Output from MDB Digital signal to each valve to control pressure in air muscle Extension cylinder motor control lines

Serial port

9 PIN RS-232 serial port is used to send motion control data to the microprocessor

Serial Port Encoding

Motion ID bit 3

Motion ID bit 2

Motion ID bit 1

Speed bit 1

Speed bit 2

Speed bit 3

Speed bit 4

Direction

bit

7 6 5 4 3 2 1 0

Bit Value Motion ID

000 Thumb

001 Index

010 Middle Or Ring

011 Pinky

100 Elbow

101 Wrist

110 Up/Down

111 Left/Right

Each clock cycle the serial port transfers 8 bits of data:

Bit Valu

eSpeed

00000 stop

00010 reverse

00011 forward

8051 Development Kit

Control Concept

Arm Motion Control When the glove is moving, then the arm moves in the

same direction controlled by these signals from the glove: ‘x’ Axis controls rotional motor ‘y’ Axis controls elbow motion ‘z’ Axis controls extension cylinder ‘pitch’ Axis controls the wrist motion

Finger Motion Control Motion control theory for the fingers is same as for the arm Each robotic finger is controlled by each finger sensor on

the glove

PC Program

Initialize the P5 GloveInitialize the Serial PortBegin Main Loop Update Glove Variables with current data Filter Incoming Data to detect motion above

a certain threshold Convert Filtered Data to an 8-bit serial output Send output byte to the serial port Loop forever

Microprocessor Program

Setup the UART for serial transmission with interruptsSetup the ports for correct I/OBegin Main Loop Look at the most recent incoming serial

data Check the first 3 bits for motion ID Check the last 2 bits for desired motion If the sensor feedback allows this motion,

execute this motion and send output to port Loop forever

Theoretical Power Circuit

24V DC

BJT

microprocessor

3V DCLED 1.8K omes

RelayMotors

Control CircuitFan resister

Out put from BJT(3V)

Input from microprocessor

Motor control relays

Air musclevalves

Control relays

Connect to motor

Power switches

Connect to Motor(24V)

Low Signal Relay

Max. operating voltage 125 VAC, 60 VDC carry current 1 ARated voltage (VDC) 3Rated current (mA) 33.0Coil resistance (Ω) 91

BJT AMP board Input from microprocessor

(3.3V 25mA)

Output to relays (3v 50mA)

Power supply

Voltage output of 24 V

Maximum current of 2.5 A

Over voltage protection

Over current protection

Final Circuits

Controlcircuit

BJTboard

PowerSupply

(24V 5A)Microprocessor

Output to air valves and motors

Schedule

Cost Worksheetpart Quantity Unit cost Estimated Cost Actual Cost

Sensor Gloves 1 $80 $80 $30

Air Muscles large 5 $50 $250 $250

Air Muscles small 6 $26 $26 $156

Valve Manifold 1 $160 $160 $160

Valves 4 $70 $280 $280

Regulator 2 $50 $100 $100

Air Line 3 $15 $45 $45

High Tensile String 1 $12 $12 $12

Ait Filter 1 $75 $75 $75

Hand and Forearm 1 $500 $500 $383

Electric Cylinder 1 $200 $200 $65

Enclosure/Display 1 $1,000 $1,000 $450

Microcontroller 1 $200 $200 $180

PC 1 $400 $400 $0

Electric circlts 1 $400 $400 $559

Total 　 $3,238 $3,728 $2,745

Video Demo

Questions?