Adaptive Grip Force Control for Two-Finger Graspers
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Solution Overview
Problem
Gripping devices struggle to accurately and stably grip objects with varying hardness measurements, as existing technologies fail to adapt grip force effectively to the object's hardness.
Innovation Solution
A gripping device equipped with a motor, a grasper with two fingers, a force detector, and a controller that adjusts the grip force based on the detected force and object hardness, allowing for precise control of grip force to match the object's hardness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed grip force is applied by the gripping device, then the structure and control are simple, but the device cannot adapt to objects with varying hardness measurements
Solution Approach 1:
The patent implements feedback control by detecting the relationship between grip force and position change rate during the gripping process. The force detector measures the actual grip force, and the controller compares this with the commanded grip force to determine object hardness characteristics. This feedback mechanism enables the system to adapt to different hardness levels without requiring complex pre-programming for each object type.
Solution Approach 2:
The patent applies preliminary action by commanding a gradually increasing grip force before actual contact with the object. During this preliminary phase, the system monitors the relationship between applied force and position change rate to predict object hardness. This allows the controller to prepare appropriate grip force parameters before firmly grasping the object, preventing damage to soft objects while ensuring secure grip on hard objects.
2Reliability
If the grip force is increased to ensure stable gripping, then gripping stability improves, but soft objects may be damaged
Solution Approach 1:
The patent applies dynamics by continuously adjusting the grip force based on real-time detection of object characteristics. Rather than using a fixed high grip force, the system dynamically modifies the commanded grip force during the gripping process based on the detected relationship between force and position change rate. This enables the system to apply just enough force for stable gripping without exceeding the damage threshold of soft objects.
Solution Approach 2:
The patent changes parameters by modifying the grip force command based on detected object hardness characteristics. The system monitors the position change rate at different grip force levels and uses this information to adjust the optimal grip force parameter. This parameter adaptation ensures that hard objects receive sufficient grip force for stability while soft objects receive reduced grip force to prevent damage.
3Object-affected harmful factors
If the grip force is decreased to protect soft objects, then object damage is reduced, but gripping accuracy and stability deteriorate
Solution Approach 1:
The patent uses feedback control to maintain gripping accuracy despite varying object hardness. The force detector continuously monitors the actual grip force, and the controller adjusts the commanded grip force based on the detected relationship between force and position change rate. This feedback mechanism ensures that each object receives the precise amount of force needed for accurate and stable gripping, whether soft or hard.
Solution Approach 2:
The patent applies preliminary action by gradually increasing grip force from a low initial value before actual contact. During this preliminary phase, the system detects object characteristics and determines the appropriate grip force level. This gradual approach allows the system to maintain gripping accuracy by preparing the optimal force level in advance, preventing both damage to soft objects and insufficient grip on hard objects.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The gripping device can accurately and stably grip objects with different hardness measurements, ensuring secure handling regardless of the object's hardness.
Implementation Method 1
a force detector configured to detect a grip force that enables the object to be gripped by the first finger and the second finger
Data Source
AI summary
A gripping device includes a motor configured to rotate in accordance with an operational value, a grasper including a first finger and a second finger, a force detector configured to detect a grip force that enables an object to be gripped by the first finger and the second finger upon occurrence of a condition in which the object is gripped by the first finger and the second finger, and a controller that controls the operational value such that a magnitude of the grip force detected by the force detector matches a command value. The controller controls the grasper based on the command value as a reference command value. The controller changes the command value as the reference command value to an updated command value based on a change in the grip force that the force detector detects after the grasper grips the object.