physics

Self-adaptive mechanisms

Self-adaptive mechanisms is a physics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Self-adaptive mechanisms rather than just read about it. In short: Self-adaptive mechanisms, sometimes simply called adaptive mechanisms, in engineering, are underactuated mechanisms that can adapt to their environment. One of the most well-known example of this type of mechanisms are underactuated fingers, grippers, and robotic hands.

Key takeaways

Self-adaptive mechanisms belongs to physics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Self-adaptive mechanisms to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Self-adaptive mechanisms from memory before moving on to harder problems.

Reference excerpt

Self-adaptive mechanisms, sometimes simply called adaptive mechanisms, in engineering, are underactuated mechanisms that can adapt to their environment. One of the most well-known example of this type of mechanisms are underactuated fingers, grippers, and robotic hands. Contrary to standard underactuated mechanisms where the motion is governed by the dynamics of the system, the motion of self-adaptive mechanisms is generally constrained by compliant elements cleverly located in the mechanisms.

Definition Underactuated mechanisms have a lower number of actuators than the number of degrees of freedom (DOF). In a two-dimensional plane, a mechanism can have up to three DOF (two translations, one rotation), and in three-dimensional Euclidean space, up to six (three translations, three rotations). In the case of self-adaptive mechanisms, the lack of actuators is compensated by passive elements that constrain the motion of the system. Springs are a good example of such elements, but other can be used depending on the type of mechanisms. One of the earliest example of self-adaptive mechanism is the flapping wing proposed by Leonardo da Vinci in the Codex Atlanticus.

Underactuated hands The first commonly known underactuated finger was the Soft-Gripper designed by Shigeo Hirose in the late 1970s. The most common type of transmission mechanisms used in self-adaptive hands are linkages and tendons.

Kinetostatics Underactuated fingers and hands are usually analyzed with respect to their kinetostatics (negligible kinetic energy, static analysis of a mechanism in motion) rather than the dynamics of the system, as the kinetic energy of these systems is generally negligible compared to the potential energy stored into the passive elements. The forces applied by each phalanx of an underactuated finger can be computed with the following expression:

F = J − T T ∗ T t {\displaystyle \mathbf {F} =\mathbf {J} ^{-T}\mathbf {T} ^{*T}\mathbf {t} }

where F is the vector made of the forces applied, J is the Jacobian matrix of the finger, T* is the transmission matrix, and t is the torque vector made (actuator and passive elements).

Applications A self-adaptive robotic hand, SARAH (Self-Adaptive Robot Auxiliary Hand), was designed and built to be part of the Dextre’s toolbox. Dextre is a robotic telemanipulator that resides at the end of CANADARM-2 on the International Space Station. The Yale OpenHand is an example of open source self-adaptive mechanisms that can be found online. Some companies are also selling self-adaptive hands for industrial purposes. Prosthetics is another application for self-adaptive hands. One known example is the SPRING (Self-Adaptive Prosthesis for Restoring Natural Grasping) hand.

Other examples Self-adaptive mechanisms can be used for other applications, such as walking robots. Compliant mechanisms are another example of self-adaptive mechanisms, where the passive elements and the transmission mechanism are a single monolithic block.

References

Illustrations

Self-adaptive mechanisms: Flapping wing mechanism proposed by Leonardo da Vinci in the Codex Atlanticus. — Flapping wing mechanism proposed by Leonardo da Vinci in the Codex Atlanticus.

Worked examples

Example 1 — a first encounter with Self-adaptive mechanisms

Start with the simplest possible case. Write down what Self-adaptive mechanisms claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Self-adaptive mechanisms before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Self-adaptive mechanisms ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Self-adaptive mechanisms

In research: Self-adaptive mechanisms appears in physics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Self-adaptive mechanisms in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Self-adaptive mechanisms is common in secondary-school and first-year university syllabi. It links to neighbouring topics Mechanical engineering, so understanding it makes those chapters shorter.
In everyday life: Look for Self-adaptive mechanisms outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Self-adaptive mechanisms in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Self-adaptive mechanisms means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Self-adaptive mechanisms out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Self-adaptive mechanisms in simple terms?

Why does Self-adaptive mechanisms matter?

Because it connects several physics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Self-adaptive mechanisms?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Self-adaptive mechanisms.