Lecture 7a: Closed-Loop Motor Control Flashcards
Closed-Loop Control
the control of movement has been conceptualized as closed-loop or open-loop
closed-loop control:
online/moment-to-moment control of movement - involving constant processing of feedback
- feedback, error detection and error correction used to achieve a desired goal (process of detecting and correcting)
- this type of system is very useful when the body needs to control itself for longer periods of time (longer actions are more dependant on sensory information)
Four Key Closed-Loop Components
- executive
- effector
- comparator
- error signal
all closed-loop control systems have these 4 components!
Closed-Loop Component: Executive (1)
determines the actions to be taken to achieve the desired goal state (decision making)
A. in some closed loop tasks it
is just to be balanced
3 stages of information processing
Closed-Loop Component: Effector (2)
carries out the decision/desired action
- muscles (receive motor commands via the spinal cord to initiate movement)
Closed-Loop Component: Comparator (3)
compares feedback of desired goal state to feedback of actual state (the error detection mechanism/reference of correctness)
A. is what we are doing
different to what we wanted
to be doing (error detection)
- compares intended/expected movement with actual movement (feedback)
Closed-Loop Component: Error Signal (4)
information acted on by the executive
A. if there is discrepancy in
sensory information, you
can update the ongoing
movement
Closed-Loop Control: continuous processing of feedback for action success
- you might to make some corrections or carry on if you are at your desired state
- error correction is the executive system
- feedback of what is actually happening (feedback/sensory information)
- when something we expect do are violated then the system wants to act to correct it
Open-Loop Control
movement is pre-programmed fully in advance and does not rely on feedback
◦ less or not dependant on
feedback in a way that is
programmed
- feedback, error detection and error correction are NOT needed to achieve a desired goal
- this type of system is very useful in predictable environments when the movement is short
-> there is no loop in open loop system (not continually monitoring in order to make quick movement
in predictable environment)
moving a cursor, walking a beam and retrieve a fumbled football: what are these examples of?
closed-loop control
- continuous
- fine/precision
- open
key press, jab in boxing and kick a punch bag: what are these examples of?
open-loop control
- discrete
- gross
- closed/predictable
3 main factors which affect whether CNS will act in an open vs. closed-loop fashion
- time: how long will the action take?
- precision: how much tolerance is there for error? (information will be more important if you need accuracy)
- predictability: how constant/familiar is the environment? (less need to monitor with predictable stable environment)
(1) Time: How long will the action take to be completed?
- closed-loop, longer, more continuous
◦ swimming - processing
information - open-loop, shorter, ballistic (not dependant on information), discrete
◦ jab in boxing
(2) Precision: How much tolerance is there for error?
- closed-loop, fine/precise
◦ accuracy is information in
gymnastics - open-loop, gross, less precise
◦ shotput - that include power
and strength is a little less
about precision
(3) Predictability: How constant is the environment and how often has it been done before?
- closed-loop: open skills, new skills (low in predictability)
◦ basketball skills in open
environments - open-loop: closed skills, well practiced (predictable)
◦ penalty shot in soccer (could
be relatively programmed
and not include much
monitoring)
All stages of information processing represent the EXECUTIVE component of closed-loop control
- stimulus identification, response selection and response programming
- have to continually re-identify, re-select and re–program which is time consuming