For a robotic arm, expect questions on joints, torque, kinematics and accuracy. Answer with your own arm.
Structure
- How many degrees of freedom does your arm have? Count the independent joints.
- What is the work envelope? The region the hand can reach; it depends on link lengths and joint limits.
- What is the payload? State the tested load, and the margin you used.
Actuators
- How did you pick the servos? By torque at the joint with the arm stretched out. See the servo torque calculator.
- Why does the shoulder need the most torque? It carries both links and the load at the longest lever arm.
- How is a servo controlled? By a 50 Hz pulse of about 1 to 2 ms. See the servo pulse calculator.
Kinematics
- What is forward and inverse kinematics? Forward gives the hand position from joint angles; inverse gives the angles for a position.
- Show inverse kinematics of two links. Use the law of cosines. Try the arm playground and read the Python guide.
- Why are there two solutions? Elbow up and elbow down.
Accuracy and testing
- How accurate is it? Report repeatability measured by returning to a point many times.
- What causes error? Backlash, servo resolution, flex and supply sag.
Related
Free Library, Report template, Viva questions, More viva questions.
Last reviewed: November 2026. Free to copy and adapt for your own college work. Follow your department format first; its rules override this page.