Motion Control & Kinematics Flashcards

What is the workspace of a robotic manipulator?

Answer: The set of all reachable end-effector positions and orientations

The workspace is the complete set of poses the end-effector can achieve given all joint-limit constraints.

In a ball-screw linear actuator, what determines the relationship between motor rotations and linear travel?

Answer: Lead (pitch × starts) of the screw

The lead defines how far the nut travels per full screw revolution, directly linking rotary to linear motion.

Which kinematic chain type has its end-effector constrained by multiple independent legs attached to a fixed base?

Answer: Parallel manipulator

Parallel manipulators such as the Stewart-Gough platform use multiple legs in a closed-chain arrangement for high stiffness.

An encoder outputs 2000 pulses per revolution. If quadrature decoding is used, what is the effective resolution?

Answer: 8000 counts/rev

Quadrature decoding counts all four edges of the A/B pulse pair, multiplying the base count by 4 (2000 × 4 = 8000).

In a PID position controller, persistent steady-state error after a constant disturbance is eliminated by which term?

Answer: Integral (I) term

The integral term accumulates error over time and outputs an increasing correction until steady-state error reaches zero.

What is the purpose of gravity compensation in a robot controller?

Answer: To counteract gravitational torques so the robot holds position without continuous high-gain feedback

Gravity compensation adds a model-based feedforward torque that cancels gravitational loading on each joint.

Which parameter describes the ratio of output speed to input speed in a gearbox used for motion control?

Answer: Gear ratio (transmission ratio)

The gear ratio N = ω_input / ω_output and simultaneously multiplies torque by N (ignoring losses).