Question

57. A robot arm called ISAC Intelligent Soft Arm Control) can be used as part of a system to feed people with disabilities (see Figure P6.14(a)). The control system guides the spoon to the food and then to a position near the person's mouth. The arm uses a special pneumatically controlled actuator called a rubbertuator. Rubbertuators consist of rub ber tubes covered with fiber cord. The actuator contracts in length when pneumatic pressure is increased and expands in length when pressure is decreased. This expansion and contraction in length can drive a pulley or other device. A video camera provides the sight for the robot and the track ing loop (Kara、 1992). Assume the simplified block diagram shown in Figure P6.14( for regulating the spoon at a distance from the mouth. Find the range of K for stability. (Use of a program with symbolic capability is recommended.) Actual and load D) RIGURE P6.14 a.ISAC used for feeding (Courtesy of Kanahiko K awamura, Vanderbik University) h simplified Nock iagram

Answer 1

the range of K for stability is found by root locus:

matlab code:

clc;

clear all;

s=tf('s');

g=10/(s^2+10*s+29);% actuator and load

gc=(s+0.01)*(s+6)/(s*(s+20)*(s+200));% controller

rlocus(g*gc);% root locus

Root Locus 400 Pole: 0.216 70.5 Damping: 0.00306 Overshoot n101 Frequency (rad:O -200 Real Axis (seconds
from the locus the maximum value for K is 100000