week 4 dexterous manipulation

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Questions and Answers

What is the relationship between grip force (GF) and load force (LF) during object manipulation?

GF decreases while LF increases.

GF is independent of LF.

GF should increase in parallel with LF. (correct)

GF remains constant regardless of LF.

Which sensory receptors are primarily responsible for detecting slip during object manipulation?

Ruffini and SA II receptors

FA I and Pacini receptors

FA II and SA I receptors

Meissner and Merkel receptors (correct)

What happens to grip force when the weight of an object increases?

Grip force does not change and remains constant.

Grip force must increase to prevent slipping. (correct)

Grip force is only adjusted after the object slips.

Grip force decreases to maintain balance.

How does surface friction affect grip force during manipulation?

Less friction necessitates higher grip force. Signup and view all the answers

Which of the following statements about the control of fingertip forces is true?

Sensorimotor control involves feedback from sensory receptors. Signup and view all the answers

What is the primary consequence of insufficient grip force during object manipulation?

Increased likelihood of the object slipping out of the grasp. Signup and view all the answers

Which type of grip is primarily associated with manipulating small and delicate objects?

Precision grip Signup and view all the answers

Which statement best describes the dynamic nature of grip and load forces?

Grip force must adapt quickly to changing load forces. Signup and view all the answers

What does the safety margin against slips represent?

The difference between grip:load force ratio and slip ratio Signup and view all the answers

Which control strategy is primarily employed during the lifting task according to the content?

Anticipatory feedforward control adjusting grip force in advance Signup and view all the answers

What is a key characteristic of load-grip force coupling during active movements?

Grip force is modulated in phase with load force induced by movement Signup and view all the answers

What happens in feedback control as opposed to anticipatory feedforward control in this context?

It causes inevitable phase shifts in grip force response Signup and view all the answers

Which of the following best describes the relationship between grip force and load force during a lifting task?

Grip force is dynamically adjusted to closely match load force Signup and view all the answers

What is the primary outcome of excessive fingertip forces during gripping tasks?

Greater likelihood of slips occurring Signup and view all the answers

What aspect of grip control does the content emphasize as being essential for stabilization?

Preventing accidental slips and excessive forces Signup and view all the answers

What does anticipatory parameter control (APC) utilize to predict object properties?

Visual and somatosensory inputs along with memory Signup and view all the answers

In the context of lifting, how does predictive feedforward control primarily function?

It anticipates load force and calibrates grip force in advance Signup and view all the answers

How does the discrete event sensory driven control (DESC) policy react if the anticipated weight of an object is too high?

It triggers an unexpected early lift-off, prompting a corrective response. Signup and view all the answers

Which statement best describes the relationship between grip force and load force during object transport?

They are tightly coupled as part of a general control strategy. Signup and view all the answers

What is the primary purpose of anticipating weight and object properties before lifting?

To correlate sensory signals with past manipulative experiences. Signup and view all the answers

In which scenario would the anticipatory control policy (ACP) be especially beneficial?

When lifting an object with variable weight based on past experiences. Signup and view all the answers

What does a lack of an anticipated sensory signal during an object's lift indicate?

That an error in weight prediction has occurred. Signup and view all the answers

What characterizes the control strategy of grip force during transport based on the concept of motor equivalence?

It reflects a unified control strategy applicable across various grips. Signup and view all the answers

When might pre-programmed patterns of corrective responses be activated according to DESC?

As sensory inputs provide signals that contradict predictions. Signup and view all the answers

What is the relationship between slip force and grip force for heavy objects?

Grip force must increase to match higher load force. Signup and view all the answers

What does the slip ratio indicate in terms of grip stability?

It provides a measure of grip force required on slippery surfaces. Signup and view all the answers

Which factor primarily affects the amount of grip force required for stability?

Coefficient of friction between the object and fingertip skin. Signup and view all the answers

What happens to the slip force when the load force increases?

It increases accordingly. Signup and view all the answers

Why is a stronger grip force required on more slippery surfaces?

The slip ratio is higher, demanding more grip force. Signup and view all the answers

What characterizes the 'catch-up response' in grip force dynamics?

It is a rapid increase in grip force to compensate for unexpected loading. Signup and view all the answers

Which of the following statements is true regarding grip force management?

To maintain contact, grip force must exceed slip force at each load magnitude. Signup and view all the answers

If an object is being lifted with a slip ratio below the critical value, what will happen?

The object may slip due to insufficient grip force. Signup and view all the answers

How does the 'tracking response' function in relation to the catch-up response?

It runs parallel to the load force increase after the catch-up response. Signup and view all the answers

What is a critical measure for ensuring grasp stability?

The grip:load force ratio must exceed a critical value. Signup and view all the answers

What influences the scaling of the catch-up response?

The sensory input regarding load force increase and friction at initiation. Signup and view all the answers

What role does reaction time play in the catch-up response?

It causes a delay that the catch-up response aims to compensate for. Signup and view all the answers

Which of the following best describes the relationship between grip force and load force during the initial response phase?

Grip force increases in response to an unexpected load force application. Signup and view all the answers

What can be concluded about the timing of the static load and the tracking response?

The tracking response correlates with the onset rate of load changes. Signup and view all the answers

Which scenario describes a condition where the catch-up response might be ineffective?

Sensory input is absent or extremely low during application. Signup and view all the answers

What measurement indicates the moment a grip force begins to significantly respond to loading?

The onset rate of load change. Signup and view all the answers

Study Notes

Sensorimotor Control of Dexterous Manipulation

Human ability to manipulate objects has established dominance over other species.
The human hand's versatility plays a critical role in object manipulation.

Control of Fingertip Forces

Object manipulation involves managing load (weight) and grip forces.
Load forces are the downward force due to gravity, while grip forces counteract this.
The relationship between grip force (GF) and load force (LF) is crucial for stability.

Slip Force and Grip Force Ratio

The slip force is the critical grip force level below which an object slips from grasp.
Grip force must remain higher than slip force to ensure safe handling.
As object weight increases, grip force must also increase to match the load force.

Grip to Load Force Ratio

The grip:load force ratio must exceed a critical slip ratio for grasp stability.
This slip ratio is inversely proportional to the coefficient of friction between the fingertip skin and the object.
Safety margins against slips are determined by the difference between applied grip:load ratios and slip ratios.

Load-Grip Force Coupling

Predictive feedforward control is utilized during object manipulation.
Grip force is modulated in real time to align with fluctuations in load force, indicating an anticipatory strategy.
Feedback control would introduce delays, contrasting with the predictive nature of anticipatory control.

Anticipatory Control Policies

Anticipatory Parameter Control (APC) relies on sensory inputs and past experiences to inform action.
Predicted weight helps in planning, even when the exact properties of an object are unknown.
Discrete Event Sensory Driven Control (DESC) engages pre-programmed responses to unexpected sensory events.

Responses to Erroneous Predictions

If weight is misjudged too high, unexpected lifting may occur.
If weight is underestimated, lifting will not happen as anticipated, triggering corrective actions.
Real-life examples include misjudging the position of objects based on visual distractions.

Catch-Up and Tracking Responses

Grip responses consist of a ‘catch-up response’ for immediate adjustment and a ‘tracking response’ for gradual grip force increase.
The catch-up response compensates for delays caused by reaction time and is influenced by sensory feedback.
Both responses form an essential part of the adaptive strategies employed during object manipulation.

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Description

This quiz explores the intricacies of sensorimotor control in dexterous manipulation. Topics include the relationship between grip and load forces, the importance of slip force, and the critical ratios required for stable object handling. Test your understanding of how human dexterity enables effective manipulation of objects.