Biomechatronic Hand Ppt

INTRODUCTION

The objective is to develop an artificial hand aimed at replicating the appearance and performance of the natural hand or to obtain a complete functional substitution of the natural hand.

Main problems to be solved in order to improve the performance of prosthetic hands are:

1) lack of sensory information gives to the amputee 2) lack of “natural” command interface. 3) limited grasping capabilities 4) unnatural movements of fingers during grasping.

DESIGN OF THE BIOMECHATRONIC HAND

• BIOMECHATRONIC DESIGN

• ARCHITECTURE OF THE BIOMECHATRONIC HAND

• ACTUATION SYSTEM

BIOMECHATRONIC DESIGN

The main requirements to be considered are:

- cosmetics - controllability - noiselessness - lightness - low energy consumption

ARCHITECTURE OF THE BIOMECHATRONIC HAND

It uses small actuators (two of each finger) and micro motors instead of one single large actuator and motor.

ACTUATION SYSTEM Heavy actuator system

Traditionalactuators One/two DOF’s

Low adaptability

Little contactareas

Low grasp robustness

Large forces

Micro actuator system

Micro actuators Small forces

High graspstability

Rise in contactareas

High grasp stability

Rise in DOF’s

SMOOVY Characteristics

3Gear stages1:125Transmission rate

25NMaximum load (radial)

40NMaximum load (axial)

3.2 gWeight20mm/sMaximum speed

12NNominal force

Kinematics architecture

The kinematics of each finger joints are:

MP (Meta carpophalengal) joint

PIP (Proximal interphalengal) joint

DIP (Distal interphalengal) joint

HAND PROTOTYPE

POSITION AND FORCE SENSORS

SENSORS 1) Tactile sensors 2) Proximity and range sensors 3) Position sensors 4) Hall effect sensors

HALL EFFECT SENSORS

There are two basic forms of this sensor, LINEAR $ THRESHOLD.

SENSORS CHARACTERISATION CHARACTERISATION OF POSITION SENSOR.

0

1

2

3

4

5

6

0 10 20 30 40 50 60 70 80 90joint angle(degree)

outp

ut v

olta

ge(v

)

CHARACTERIZATION OF FORCE SENSOR

CALIBRATION CURVE OF THE FORCE SENSOR

02468

10121416

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8OUTPUT VOLTAGE (V)

FOR

CE

(N)

FINGERED TRIP FORCE ANALYSIS

FUTURE IMPROVEMENTS

Natural fingers movements during grasping and force sensor measurements should be further investigated.

CONCLUSION

The biomechatronic design approach can lead to the development of hand and prostheses.

It requires low cost and low energy consumption for adequate autonomy (at least 8 hours between recharges).

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