Robotic Systems Flashcards
(42 cards)
2 social & ethical implications of using telerobotics in healthcare
Legal liabilities - who to blame when malpractice occurs
Security of data when medical records pass through different hands/across digital platforms
Workspace
area containing all the points an end effector can reach
Forward dynamics
calculate joint trajectories, velocities & accelerations from known torque/forces from actuators at joints
Inverse dynamics
calculate forces/torques from known joint motion
path planning
mapping sequence of moves from start to end point for efficient movement & to avoid obstacles (geometry & environment of robot)
Trajectory
Specifies velocity, acceleration & timing of movement along planned path (accounts for dynamics & kinematics of robot)
Why include time history of position, velocity & acceleration of a robot? (4 points)
Achieve balance between:
- Operational efficiency (optimise velocity & acceleration for quickest & most energy-efficient path while respecting mechanical limits of manipulator)
- Precision (precisely control velocity & acceleration for smooth, repeatable movement)
- Safety (comply with physical & operational constraints e.g. max allowable velocity & acceleration, avoid abrupt movements that would endanger human operators/delicate parts in robot’s environment)
- Maintenance (deviations from norm indicate potential issues > improve lifespan & reliability of robot)
Joint (configuration) space: A&D, application
A - Smoother motion (planned path based on joint angles, directly controlling each joint’s movement) > maintains mechanical integrity & reduces wear on robot
D - lack of environmental awareness (less direct control over end-effector’s interaction with environment, doesn’t account for obstacles/specific requirements of task environment) > issues with collision avoidance
- manufacturing & assembly e.g. automotive assembly lines like screw driving/parts insertion (precise repeatable movements, consistent operation of robot’s joints where environmental interaction is minimal & controlled)
Task (Cartesian) space:
A&D, Application
A: Direct control of end-effector’s position & orientation (navigate complex paths & interact with objects in the environment) > high precision & specific interactions with objects
D: Complex computations (solve inverse kinematics at each point of trajectory > computation intensive) > slow operation but real-time applications may require rapid responses
- robotic surgery (precise control of surgical instruments’ positions & orientations is crucial to safety & effectively performing procedures on patients) > direct manipulation of end-effector to patient’s anatomy
Robot singularity
Reduced mobility, losing a DOF > large joint velocities are needed to cause robot’s end-effector to move at small velocities in cartesian space/robot cannot move any further in a specific direction > wear & tear
When is a robot in a singular condition?
Jacobian matrix doesn’t have an inverse (sine theta2 = 0) or determinant = 0
What is the Denavit-Hartenberg approach for and what are the 4 parameters?
assign coordinate frames to each joint to determine forward kinematic equations of a manipulator
L6, slide 16-19
What are the 2 assumptions on axes directions for the D-H parameters to exist & have unique values? (Sketch diagram to illustrate)
Axis xi perpendicular to axis zi-1
Axis xi intersects axis zi-1
L6 slide 15
Most important type of robot in manufacturing sector in Industry 4.0 & its features
Collaborative/commonly robot - works alongside humans
- range sensors (safe mode when humans too close)
- force sensors (halt operation when collision/impact detected)
- more compact & lightweight frame with soft round edges
5 robot configuration types & their major axes (schematic diagram & workspace)
Cartesian - PPP (accurate, heavy loads > pick-and-place, painting, rehabilitation after stroked)
Cylindrical - RPP
Spherical - RRP
SCARA (selective compliant articulated robot for assembly) - RRP
Articulated - RRR
Factors that determine workspace of manipulator
link lengths, joint types & limits, presence of limiters
4 common end effectors & applications
- Mechanical gripper for objects with uneven surfaces e.g. mugs
- suction for vacuum seal with flat even surface e.g. papers, glass sheets (control pressure better)
- screw e.g. insert nail into wall
- magnet e.g. magnetic objects
Specifications of a robot
- DOFs (planar manipulator has 2 translations & 1 rotation)
- no. of axes determine flexibility (major - arm positions wrist, minor - wrist orients end-effector)
- Workspace
- payload weight (max weight while remaining within other specifications)
- horizontal reach
- precision (resolution, accuracy, repeatability)
What is a robot?
Autonomy - makes independent decisions
Has sensors, actuators, control systems
Robot concerns
- Bias - based on learning e.g. fail to recognise certain ethnic groups
- Deception - to vulnerable users through emotional attachment/dependency
- Employment - displace certain classes of workers (retrain for better paid & less dangerous job)
- opacity - unjust decisions aren’t open to correction/transparent > GDPR - right to explanation
- safety - accidents
- Oversight - difficult to monitor & assess RAS (robots & autonomous systems) behaviour in open environments
- Privacy - allow stalker to track someone/law enforcement to track criminal
Robot principles
- Reflective equilibrium (assess benefits & drawbacks of institutions & judgement of trade off)
- Situational awareness (can drivers of AVs drive after a period of autonomous driving?)
- Participatory design for responsible innovation (reduce bias, understand impact on employment/privacy/safety/ practicality of oversight)
Purpose of robots
- dangerous environments (chemical spill cleanup, space exploration)
- boring & repetitive tasks (vehicle painting, part pick & place)
- high precision/speed (micro-surgery, precision machining)
- replace/augment human function (artificial limbs, exoskeleton)
Mechanical structure
- Arm - mobility, positions end-effector
- rigid bodies - links connected by joints
- wrist - at end of arm for angular position control
- end-effector - at moving end of manipulator to perform required task
Types of joints
Revolute (rotary)
Prismatic (translational)
Spherical (rotation at all 3 axis)
Screw (rotation & translation at 1 axis)
