  This paper articulates design and performance analysis of digital controllers
in discrete and continuous time domains for a single-joint robot arm
manipulator. The investigated robot arm system is modeled as a single degree of
freedom (DOF) plant and there is a feedback sensor implying a closed-loop
system. The design approach incorporates discrete (z-plane) and continuous-time
(warped s-plane or w-plane) domain parameters. Four digital controllers -
phase-lag, phase-lead, proportional-integral (PI) and
proportional-integral-derivative (PID) are theoretically designed and
implemented to achieve a phase margin of 40 deg. for the compensated system.
For performance evaluations, Bode plots of the compensated open-loop systems
and step response characteristics of the closed-loop systems are determined.
