Robots can be classified based on their power source as pneumatic, hydraulic, or electric. The drive system provides motion to the robot and determines its speed, strength, and applications. Common drive systems include hydraulic, electric, and pneumatic. Hydraulic drives provide great speed and strength but require electric pumps and have oil leakage issues. Electric drives are smaller, more accurate and repeatable, and occupy less space, making them suitable for assembly. Pneumatic drives are used for simple pick and place with fast cycles. The document also discusses factors that influence robot speed and load carrying capacity.

1. CLASSIFICATION OF ROBOTS BASED ON POWER SOURCE
 Pneumatic
 Hydraulic
 Electric

2. ROBOT DRIVE SYSTEMS
 The robot’s capacity to move its body, arm and wrist is provided by the drive system
used to power the robot.
 The drive system determines the speed of arm movements, the strength of the robot,
and its dynamic performance.
 To some extent, the drive system determines the kind of applications that the robot can
accomplish.

3.  The term used for a mechanism that drives a Robot arm is actuator.
 These actuators may be electric motors of some type or hydraulic or pneumatic
cylinders.
 Hydraulic and pneumatic actuators are generally suited to driving prismatic joints
since they produce linear motion directly. They are often referred to as linear
actuators.
 Electric motors which produce rotation are more suited to driving revolute joints.
However various gear mechanisms may be used to convert linear to rotary motion
and vice versa.

4. DriveSystems
Hydraulic Drive
Electric Drive
Pneumatic Drive

5. Hydraulic Drive
 It is associated with larger robots such as Unimate 2000 series.
 Generally provide great speed and strength.
 Requires electric drives to pump oil.
 Can be used to actuate rotary as well as linear joints.
 Has problem of oil leakage.
 Bulky and adds to floor space.
Electric Drive
 Electric robots are smaller and have better accuracy and repeatability.
 They occupy less floor space and applications include in assembly.
 The MAKER 110 is an example of an electric drive robot.
 They are actuated by dc stepping motors or dc servomotors.
 Appropriate transmission like gears are used to transfer motion.

6. Economic considerations of electric and hydraulic actuators.
The graph suggests a break even point below which electric drives are economic after which
hydraulic drives are better
Pneumatic Drive
 It is used for robots having few degrees of freedom(two – to - four joint motions).
 They are used for simple “pick-and-place” operations with fast cycles.

7. Speed of Motion
 The speed capabilities of current industrial robots range up to a maximum of 1.7
m/s.
 The speed is measured at the wrist only.
 The speed determines how quickly the robot can accomplish a given work cycle.
 The most desirable speed depends on the following factors:
• The accuracy with which the wrist (end effector) must be positioned.
• The weight of the object being manipulated.
• The distance to be moved.

8. Load Carrying Capacity
 The size, configuration, construction and drive system determine the load carrying
capacity of the robot.
 The load carrying capacity is specified under the condition that the robot’s arm is in
its weakest position i.e. at maximum extension.
 To determine this specification, the weight of the end effector is taken into
consideration.
 For Example, if rated load capacity of the robot is 3 kg (say) and the end effector
weighs 1 kg (say), then the net weight-carrying capacity of robot would be 2 kg.