Lect 6

Question 1

Write four major wheel classes and their degrees of freedom?

Answer 1

1)Standard Wheel 2 DOF
(rotation aorund the wheel axle and the contact point)
2) Castor Wheel 2DOF
(two degrees of freedom, rotation around an offset steering joint)
3)Sweedish wheel 3DOF (if you want to make a turn you cant)
(rotation around the wheel axle, around rollers and around contact point)
Swedish wheel is omnidirectional wheel
4) Spherical Wheel 3DOF

Swedish and spherical wheels are truly omnidirectional

Question 2

Three fundamental characteristics of wheeled locomotion?

MSC **

Answer 2

1)Stability:
it is guaranteed with 3 wheels and can be improved with 4.
2) Maneuverability:
The combination of the mobility available based on the sliding constraints plus additional freedom by the steering
3) Controllability:
from an initial posture to a final one it can be achieved in a finite time by manipulating the speed and steering

Tradeoff: Between controllability and maneuverability , controllability increases the complexity and it will be more difficult to manage

Question 3

What is omnidirectional robot?
OMNIDIRECTIONAL ROBOT 3 DOF

DIFFERENTIAL DRIVE 3 DOF

SYNCHRODRIVE 3 DOF

Answer 3

Some robots are omnidirectional meaining that they can move at any time in any direction along the ground plane regardless of orientation of the robot on vertical exis. Omnidirectional robots usuallt employ swedish or spherical wheels