Industrial Robot Components

Controller
1. initially mini computer
2. now multi purpose processor system
Arm
1. Degree of Freedom
  1. number of independent position variables that would have to specified in order to locate all parts of the mechanism
  2. number of single axis rotational joints in the arm
  3. higher number increased flexibility
  4. standard 6 D.O.F
    1. 3 joints controlling position of end effector
    2. 3 joints controlling orientation of end effector
2. joints
  1. sliding/prismatic (P)
  2. rotating/revolute (R)
  3. Wrist
    1. SCARA
      1. limited to vertical and horizontal movement
      2. 1wrist joint for roll
      3. pitch and yaw result in tilting of part when encounters contact force
    2. revolute
    3. 2 joints sufficient (pitch and roll)
    4. pitch
    5. roll
    6. yaw
3. Configurations(from base)
  1. PPP
  2. RPP
  3. RRP
  4. RRR
4. Base
  1. Pedestal
  2. Gantry
    1. large workspaces
5. Types
  1. Articulated
    1. dominent type
    2. Parallel
      1. 3 joints operate in parallel
      2. high contact forces
      3. high speed
      4. high stiffness
      5. high accuracy
      6. limited workspace
    3. Series
      1. high flexibility
      2. low accuracy
      3. low stiffness
      4. large workspace
  2. Polar
    1. perpendicular axis (RRP)
    2. not common
  3. SCARA
    1. RRP
    2. Parallel Axis
    3. 2nd most popular
    4. assembly applications
Driver
1. each individual joint must be driven independently
2. Pneumatic
  1. drive manipulators or pick and place because suitable for mechanical stops and clamping
  2. low cost
  3. reliable
  4. poor positioning
  5. inability to stop quickly
  6. overshoots because air is highly compressible
  7. NOT viable choice for joints of arm
3. Hydraulic
  1. oil highly incompressible
  2. no overshoot problem
  3. higher power to weight ratio than electric motors
  4. high cost
  5. high pressure oil system required
  6. precision engineered servo valve required
  7. now virtually non existent
  8. initially used for paint spraying b/c flammable fumes dangerous from electric spark
  9. before advances in electric used in all larger machines e.g. spot welding
  10. cost does not decrease with size
  11. heavy motors reduce lifting capacity and increase inertia
4. Electric
  1. initially small robot application
  2. power to weight ratio not important for small robot
  3. cost less than equivalent hydraulic
  4. no need for oil supply or servo values
  5. cost of actuators decreased with lifting capacity
  6. technical advances produce reduction in size and weight
  7. power depends on current
    1. current limited by heat
      1. brushless motors / oil cooling systems allow higher currents
      2. brushes a main source of heat
  8. drive majority of joints near 100%
5. Drive Transmission Systems
  1. Direct Drive
    1. gearing causes mechanical problems limiting spend and accuracy
    2. motor at each joint directly drives joint
      1. but motors have to run below optimum
        larger motors larger toque but increases inertia and so decreased lifting capacity
    3. SCARA AdeptOne
      1. 2 joints driven directly
      2. 2 joints driven remotely
      3. belt drive instead of gearing
      4. expensive
  2. to reduce inertia actuators are located as close to the base as possible
    1. so some joints must be driven remotely
      1. transmission system between motor and joint
End Effector
1. Grippers
  1. Mechanical
    1. 2 fingers that move parallel to each other
  2. Vacuum
    1. one or more suction cups connected to vacuum pump or air ejector
    2. handling light weight components on smooth surfaces
  3. Magnetic
    1. electro magnets
    2. ferrous components
    3. picked up/released by switching on/off current
2. Manufacturing Implements and Tools
  1. all end effectors that are not grippers
    1. spray guns
    2. welding torches
    3. drills
    4. grinders
    5. ladles
3. increasingly fitted with sensors
  1. opticile lenses
  2. tactile pads
4. Automatic tool changer can be used to change the end effector

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Industrial Robot Components

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	Created by tazaboo92 almost 11 years ago