engineering

Motion compensator

Motion compensator is a engineering 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 Motion compensator rather than just read about it. In short: A motion compensator is a device that decreases the undesirable effects of the relative motion between two connected objects. Description A motion compensator is a device that decreases the undesirable effects of the relative motion between two connected objects.

Key takeaways

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

Reference excerpt

A motion compensator is a device that decreases the undesirable effects of the relative motion between two connected objects.

Description A motion compensator is a device that decreases the undesirable effects of the relative motion between two connected objects. The motion compensator does not prevent the motion, but tries to eliminate the negative effects of the movement. These negative effects include (1) the changes in force and stresses, and (2) the hysteresis, i.e., the rapid start-and-stop "jerking" of the objects. Motion compensators are usually placed between a floating object and a more stationary object, such as a vessel or a structure fixed to the seabed. Most general motion compensators will compensate for movement in all directions The simplest motion compensator is the anchor chain of a ship. Not only does the anchor prevent the ship from drifting, but the chain itself dampens the movement of the ship due to undulating motion of the waves. Generally, motion compensators are implemented as springs. For very large forces (dozens to hundreds of tonnes), the springs are implemented as gas springs: hydropneumatic devices — a plunger cylinder buffered by a volume of gas.

Heave compensation

A heave compensator is a kind of motion compensator that compensates for movement in only one direction.

Examples Examples of heave compensators include:

Drill string compensators, typically used in the offshore oil and gas industry Riser tensioners a heavy compensator on crane vessels Conductor tensioners Guideline tensioners

Worked examples

Example 1 — a first encounter with Motion compensator

Start with the simplest possible case. Write down what Motion compensator claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, 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 Motion compensator 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 Motion compensator 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 Motion compensator

In research: Motion compensator appears in engineering 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 Motion compensator 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: Motion compensator is common in secondary-school and first-year university syllabi. It links to neighbouring topics Mechanisms (engineering), so understanding it makes those chapters shorter.
In everyday life: Look for Motion compensator 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 Motion compensator in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Motion compensator 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 Motion compensator out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Motion compensator in simple terms?

A motion compensator is a device that decreases the undesirable effects of the relative motion between two connected objects. Description A motion compensator is a device that decreases the undesirable effects of the relative motion between two connected objects.

Why does Motion compensator matter?

Because it connects several engineering 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 Motion compensator?

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 Motion compensator.