Control of Robotic Systems — Winter 2025

What is the difference between open-loop and closed-loop control?

Define transfer function and give its significance in control systems.

Draw and explain a Nyquist plot and describe how it helps in determining system stability.

Explain Bode plot analysis for determining gain margin and phase margin of a system.

Differentiate between transfer function and state-space model.

Design a PID controller for a simple robotic manipulator and explain its working.

What are P, PI, and PID controllers?

What is the significance of phase-plane method in control systems?

Aunity feedback system has open-loop transfer L(s) = K / [s (s + 4)]. (a) Determine range of Kfor closed-loop stability. (b) Find gain margin and phase margin at K = 8.

Explain the concept of observer design in control systems.

Explain the describing function method for analyzing non-linear systems.

Explain Liapunov’s method for determining stability of non-linear systems in detail.

Explain the characteristics of a common physical non-linear system.

Define hybrid position/force control. Page 1 of

Arobot must apply a constant normal force of 30 Nwhile tracking position normal to surface with stiffness 1000 N/m. If position control has PI controller with P=500 N/m, I=1000 N/(m·s), derive closed-loop stiffness seen by environment and compute steady-state position error under 30 Nload.

For characteristic equation s³ + 6 s² + 11 s + K = 0, use Routh-Hurwitz to find range of Kfor stability.

Explain Cartesian control and joint-based control in robotics.

Explain trajectory generation techniques used for robotic manipulators with suitable examples.

Explain force control in robotic manipulators.

List different frequency response plots used in control system analysis.

Discuss the process of system analysis using describing function and phase-plane methods. Page 2 of

Define non-linear system with suitable examples.

Explain the procedure for constructing a root locus diagram.

For point-to-point move of 300 mm with trapezoid profile and max accel 2000 mm/s², minimum time (bang-bang) = 2 √(distance / a). Compute minimal time.

Define controllability and observability.