Robotics (ME-604 (A)) - Important Questions

Explain the criteria for sensor evaluation and selection in robotic systems. Discuss the key parameters (accuracy, precision, resolution, range, bandwidth, response time, repeatability, hysteresis, environmental robustness, cost and ease of integration) and show how you would select sensors for position, velocity and force measurement in a pick-and-place robot.

Describe piezoelectric sensors. Explain their working principle, construction, important characteristics (sensitivity, frequency response, temperature dependence), typical signal conditioning requirements and applications in robotics. Also list advantages and limitations.

Explain the common methods for linear position and displacement sensing used in robotics. Compare potentiometers, LVDTs, linear encoders (optical/ magnetic), laser range sensors and time-of-flight sensors in terms of principle, resolution, accuracy, bandwidth, suitability and typical applications.

Discuss rotary encoders used in robotics. Explain the working principles of incremental and absolute encoders, concepts of resolution, pulses per revolution, quadrature decoding, error sources and typical interfacing considerations with motion controllers.

Explain methods of velocity measurement in robotic systems. Compare direct velocity sensors (tachogenerators) with encoder-based differentiation and Doppler/radar methods. Discuss noise issues when differentiating position signals and filtering techniques to obtain reliable velocity estimates.

Describe various proximity sensing technologies used in robotics (inductive, capacitive, ultrasonic, infrared/photoreflective, laser triangulation). For each technology, explain the sensing principle, typical range, advantages, limitations and typical application examples.

Discuss tactile sensing for robotic manipulation. Explain types of tactile sensors (pressure arrays, force/torque sensors, single-point force sensors), their working principles, signal conditioning, spatial resolution considerations and applications such as grasping and slip detection.

Explain compliance and range sensing in robotic systems. Describe how compliance (mechanical and sensed via force/torque sensors or series elastic actuators) is measured and controlled. Also outline range sensing methods (LIDAR, structured light, stereo vision, time-of-flight) used for environment mapping and obstacle detection.

Describe image processing and object recognition techniques used in robotics. Outline the typical pipeline: image acquisition, preprocessing, feature extraction, segmentation, feature matching/classification and post-processing. Discuss algorithms used at each stage (filters, edge detectors, SIFT/ORB features, region-based segmentation, CNN-based classifiers), real-time constraints, and examples of robotic applications (object picking, localization and obstacle avoidance).

Explain the principle and construction of a resolver. Compare resolvers with optical and magnetic encoders in terms of robustness, accuracy, digital interface needs, and suitability for harsh environments. Give application examples where resolvers are preferred.

Discuss integration strategies for vision, tactile and proximity sensors in a robotic gripper for robust grasping. Include sensor fusion considerations, timing and synchronization, data bandwidth and example decision logic used to handle sensor disagreements.