Lecture 5 - Robot Locomotion Flashcards
Different word for sensor space
Perceptual space
Effectors
Devices that have an effect on the robot’s environment (arms, wheels)
(active) Actuators
Mechanisms that enable the effector to execute an action or movement (e.g. motors)
Passive Actuation
Do not use motors but only potential energy
(3) different state types
- Observable state (knows a lot about itself and world)
- Partially observable state: knows little about itself and world
- Hidden state: it can’t sense
State space
Possible values or variations of all the components represented in the state.
- External state
- Internal state
- > what can it be?
- Environment
- robot itself
- > can be representation of external information (map)
What does robot need to be truly autonomous?
What does it combine?
A controller
that combines sensor input with actuator output (decides what to do)
Degrees of Freedom
-> what does it impact?
Any of the minimum number of coordinates required to completely specify the motion of a mechanical system
-> impacts the robots abilities to interact with its environment
3 Different DoF’s
1. Holonomic
+ example
Controllable DoF’s is equal to the total DoF
cDoF = tDoF
+ Helicopter
3 Different DoF’s
2. Non-holonomic
+ example
Not all DoF’s are controllable
cDoF < tDoF
+ Car, two-wheeled robots
3 Different DoF’s
3. Redundant
+ example
Controlling more DoF’s than the total.
cDoF > tDoF
+ Human/robotic arm
What is required for locomotion (DoF)?
- minimum
- generally
- Minimum 2 DoF for lift and swing
2. Large number of DoF and cDoF
Static stability
More than two legs on ground
- > static and stable
ex: tripod
Dynamic stability
Two or less legs on the ground
- > body must actively balance
ex: inverse pendulum
Number of gaits depends on…
-> formula for possible events
depends on number of legs
N = (2*(#of legs)-1)!
human: 3! = 6
How do different numbers of legs influence motion?
- Fewer legs ->
- More legs -> (2)
- Fewer legs -> more complex locomotion
2. More legs -> more complex control and gait
What does differential steering make possible?
Maneuvering along complicated paths (ability to drive wheels independently)
Controllability vs. Maneuverability
High Maneuverability requires complex controllability
Maneuverability vs. Odometry
High Maneuverability results in worse Odometry
Trajectory planning
Searching for a path that satisfies certain conditions (in moving and manipulation (called navigation) tasks)
Optimal trajectory depends on (3)…
- Task (condition)
- Environment
- Physical robot constraint (steering mechanism)
