A robot arm called Soft Arm can be used as a part of a system to feed people with disabilities. 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 rubber actuator. Rubber actuators consist of rubber 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 tracking loop. The block diagram shows the scheme for regulating the spoon at a distance from the mouth.Sketch a root- locus plot by hand and then obtain the plot using MATLAB. From this plot, (i) Determine the gain for = 0.707 (if possible). Use MATLAB to obtain time domain plots to check the response characteristics. ) Determine the system stability in terms of gain K. (iii) Discuss the effect on the system stability and time domain response characteristics if gain K is increased by a factor of 2.

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