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How to Choose a Motion Platform
Most guides on this subject explain degrees of freedom and stop there. That is the easy part. The decisions that actually determine whether a motion platform project succeeds are procurement decisions — what order to make them in, how to tell a supplier who engineers from one who assembles, what belongs in the RFQ, and what you agree before signing rather than after delivery.
Buying guide · CSCMotion Engineering Team · Updated August 12, 2026 · Reading time ~16 min
What this guide covers
Procurement, not engineering theory
The technical selection questions have their own guides. This page assumes you will read those and focuses on everything around them.
Technology
Which architecture, which drive, how to size it — the engineering decisions.
This page
Sequence, supplier qualification, RFQ contents, quotation comparison, cost drivers, acceptance and risk.
Technical questions are linked where they arise rather than repeated — the Technology section holds those in full.
2 of 6
Irreversible decisions
Decisions that cannot be reversed after fabrication.
7 questions
Engineer or assembler
That separate an engineering supplier from an assembler.
12 scope items
Normalise first
To normalise before comparing any two quotations.
32-point
Free checklist
Checklist across five project phases, free to download.
The Decision Sequence — and Which Steps Cannot Be Undone
Motion platform projects go wrong far more often from sequence than from any individual choice. Each decision below produces the input the next one needs, and two of them are locked permanently once the platform is fabricated.
Direct answer. Define the physical job first, settle architecture second, qualify suppliers third, issue a comparable RFQ fourth, compare on scope fifth, and agree acceptance before placing the order. Skipping straight to comparing products — which is where most projects begin — means choosing before the question has been defined.
Define the physical job
What must the platform reproduce, test or move, and how will success be measured? Establish gross moving load, one representative combined trajectory and the duty cycle. This is the input everything else depends on, and it is the step most often skipped.
For scale while you frame the requirement: our own delivered base spans 20 kg to 35,000 kg rated load across 215 configurations in 15 platform lines, and almost none of them are repeats. The useful question is rarely “which model” — it is “what has to be true when it is finished”.
Settle the architecture
Axis count and drive technology, decided from the motion requirement rather than the budget. Both determine the machine that gets built, and neither can be changed afterwards — a 3DOF platform cannot become 6DOF, and an electric platform cannot become hydraulic.
Qualify the suppliers
Before sending a specification, establish who is capable of engineering it. This filters the list far more effectively than comparing datasheets, and it takes one conversation per supplier.
Issue a comparable RFQ
Identical, complete information to every supplier — including the scope boundary and acceptance expectation. An RFQ that omits these produces quotations that cannot be compared, and you will not discover that until they arrive.
Normalise and compare
Adjust every quotation to the same scope before looking at price. The cheapest quotation is frequently the one that excludes the most, and the difference typically appears as a change order later.
Agree acceptance, then order
Test load, trajectory, reference point, instrument, tolerance and record format — agreed in writing before the purchase order, not negotiated after the platform arrives.
Seven Questions That Separate Engineers From Assemblers
Many companies selling motion platforms buy actuators, buy a controller and bolt them to a frame. That is a legitimate business, and for some projects it is sufficient. But it is a different capability from designing the mechanism, and you should know which one you are buying from. These seven questions cannot be answered from a catalogue.
Question 01
Mechanism ownership
“Who determined the attachment geometry on this platform, and against what requirement?”
What it reveals: an assembler will describe the layout as “a standard Stewart configuration”. A designer will talk about joint circle radii, angular phase and the trade-offs made for a particular workspace. There is no universally optimal geometry, so “standard” is not an answer.
Question 02
Dynamic analysis
“With my payload and trajectory, what peak actuator force results, and at which pose does it occur?”
What it reveals: this requires running a multibody dynamic solution. A supplier who can answer it — or who tells you precisely which inputs they need first — has the capability. One who quotes from static payload alone is guessing, and static sizing produces under-rated machines.
Question 03
Structural verification
“What natural frequencies would a platform of this size and load show, and how do you verify them?”
What it reveals: whether structural analysis actually happens. Ask what tool is used, and whether results are cross-checked — solving modal behaviour on two independent solvers is a meaningfully stronger answer than one. Ask separately what design factor is applied to the mechanical components: ours is more than three times rated load, with finite-element verification on the cylinders.
Question 04
Control software origin
“Who wrote the motion control software, and can you change its behaviour if my integration needs it?”
What it reveals: if the controller is bought in, behavioural changes become a support ticket to a third party on their schedule. If it is developed in-house, it is a development task. This matters most at integration, which is exactly when you cannot afford to wait.
Question 05
Accuracy provenance
“Your accuracy figure — was it measured, or derived from component specifications? With what instrument, at what load?”
What it reveals: a measured figure comes with a load, a pose set, a reference point and an instrument. A derived figure comes from multiplying encoder resolution by a gear ratio. Both get printed the same way. Ask which one you are reading.
Question 06
Calibration method
“How do you correct for the difference between the designed geometry and the machine you actually built?”
What it reveals: manufacturing and assembly tolerance always move the real attachment points away from the drawing. A supplier who identifies the as-built geometry and compensates it in the controller is doing the step that turns a correct calculation into an accurate machine.
Question 07
Acceptance protocol
“Can I see your factory acceptance test protocol before I place an order?”
What it reveals: whether a documented protocol exists at all. A supplier who routinely runs FAT will have one and will share it. A supplier who improvises acceptance at the end of the build will offer to write one later — which is the same as not having one.
Question 04, in a photograph
Whether the actuators are made or bought is the quickest way to place a supplier — and it decides how a control-behaviour change gets handled after delivery: a development task, or a support ticket on someone else’s schedule.
Question 07, in a photograph
A supplier who runs factory acceptance as routine has a written protocol and will hand it over before you order. One who improvises acceptance at the end of the build offers to write it later.
How to use the answers. None of these questions has a single correct response, and a supplier saying “we would need your mass properties before answering that” is giving you a good answer, not dodging. What you are listening for is whether the vocabulary is engineering vocabulary or sales vocabulary — and whether the person answering can go one level deeper when you ask a follow-up. That is usually apparent within about ten minutes.
What Belongs in a Motion Platform RFQ
The purpose of an RFQ is not only to obtain prices — it is to obtain prices that can be compared. That requires every supplier to receive the same information and to be told explicitly what the quotation must cover. Where a term below is one that suppliers use inconsistently, the glossary gives the definition we work to and a note on how else it gets used.
| Include | Why it matters | If omitted |
|---|---|---|
| Gross moving load | Everything that moves: article, fixture, cabin, occupants, cabling, instrumentation. | Suppliers size against the payload alone and the platform is under-rated. |
| CoG height and inertia | Height above the platform surface; I xx , I yy , I zz about the payload CoG. | Rotational demand is unknown, so quotations carry hidden assumptions. |
| One combined trajectory | A realistic motion profile, not a list of per-axis maxima. | Suppliers quote against maxima that never occur simultaneously. |
| Duty cycle | Hours per day, continuous or intermittent, peak versus sustained. | Thermal rating cannot be determined; actuators may be under-specified. |
| Scope boundary | Explicitly: platform only, or platform plus integration, installation, training. | The single largest source of non-comparable quotations. |
| Host interface | Protocol, update rate, coordinate convention, who owns the integration. | Interface work appears as a change order after the order is placed. |
| Acceptance expectation | How the platform will be judged to have met the specification. | Acceptance gets negotiated after delivery, from a weak position. |
| Site constraints | Ceiling height, floor loading, power supply, HVAC capacity, access route. | A platform that cannot be installed, or requires unbudgeted site work. |
| Standards and compliance | Any applicable test standard, safety category or certification requirement. | Requalification late in the project, or a platform that cannot be signed off. |
| Schedule and milestones | Required delivery date and any fixed intermediate dates. | Schedule risk is discovered rather than managed. |
A shortcut that genuinely saves time. The specification builder assembles the technical half of this list into a structured block you can paste into an RFQ, and marks anything still unknown rather than leaving it blank. A stated unknown is far more useful to a supplier than an optimistic placeholder — it tells them what to ask about instead of what to assume.
Why Two Motion Platform Quotations Are Rarely Comparable
Quotations for the same platform routinely differ by a large factor, and the difference is usually scope rather than value. Normalise first, then compare — otherwise you are selecting the supplier who excluded the most.
| Scope item | Question to ask |
|---|---|
| Motion controller | Included, or a separately priced item? Whose hardware? |
| Software licence | Perpetual or subscription? How many seats? What happens at renewal? |
| API and SDK | Included and documented, or an additional licence? |
| Interface documentation | Issued before integration starts, or at delivery? |
| Factory acceptance test | Included, witnessed or remote? Under what load and trajectory? |
| Packing and freight | Which Incoterm? Who handles customs and inland delivery? |
| Installation | Supplier-performed, supervised, or documentation only? |
| Commissioning and tuning | Included on site, or remote support only? |
| Training | Operator, maintenance or both? How many people, where? |
| Warranty | Duration, what is covered, response time, on-site or return? |
| Spares | Recommended holding, lead time for critical parts, availability period. |
| Site works | Foundation, anchoring, power and HVAC — whose scope? |
Scope items to confirm in every quotation before any price comparison.
The pattern to watch for. A quotation substantially below the others is worth investigating rather than celebrating. In most cases it is quoting the mechanism alone while the others quote a delivered, commissioned system — and the gap reappears as change orders during integration, at a point where you no longer have competitive leverage. Ask the low bidder directly which of the twelve items above are excluded.
What Actually Drives the Price
There is no meaningful list price for an engineered motion platform, and any supplier who quotes one before knowing your load and trajectory is quoting a different machine from the one you need. But the cost drivers are entirely predictable, and knowing them lets you find savings without compromising the project.
01 · Payload × acceleration
The dominant driver by a wide margin. Together these set peak actuator force, which sizes the cylinders, the motors, the drives, the structure and the foundation. Two platforms with the same stated payload can differ several-fold in price if one is specified for twice the acceleration.
02 · Stroke and envelope
Longer travel grows the entire machine — longer cylinders, taller neutral height, more structure, larger footprint and more ceiling. It also affects buckling margin and stiffness, so it is never simply a longer part.
03 · Centre-of-gravity height
Frequently underestimated as a cost driver. Because it acts as a lever on the actuators, a tall payload can require substantially more capability than its mass suggests. Lowering the CoG in your fixture design is often the cheapest saving available.
04 · Duty cycle
Electric actuators are thermally limited. A platform running a full shift may need a larger rating than one performing short intermittent manoeuvres at identical peak force. Stating duty honestly avoids both over- and under-specification.
05 · Precision requirement
Tighter positioning and repeatability demand better components, more calibration effort and more measurement time at acceptance. Specify what the application needs rather than the best number available.
06 · Integration and scope
Custom interfaces, non-standard protocols, certification support, unusual safety categories and on-site commissioning all add engineering hours. These are often the difference between two otherwise similar quotations.
Where savings usually exist. In our experience the largest recoverable cost sits in requirements that were never examined — an acceleration figure copied from an earlier project, a payload quoted with a large unexplained margin, or per-axis travel specified at maxima that the actual trajectory never approaches. Re-deriving the requirement from what the platform will really do frequently reveals that a smaller machine is sufficient. That review costs nothing and is worth doing before any quotation is requested.
Motion Platform Project Risk
Acceptance is the only mechanism you have for confirming that what arrives matches what was specified. It has to be defined before the purchase order, because after delivery the negotiating position is entirely different.
Risk 01
Under-specified moving load
Discovered at commissioning, when the fixture and cabin turn out to weigh more than the figure in the RFQ.
Mitigation: weigh the assembly rather than estimating it, include everything that moves, and agree a margin explicitly at specification stage. This is the most common failure and the cheapest to avoid.
Risk 02
Interface mismatch
The platform works, the host works, and they disagree about coordinate convention, units, update rate or state handling.
Mitigation: obtain the interface document before integration starts, not at delivery, and have your host developer review it while the platform is still in build.
Risk 03
Acceptance never agreed
The platform arrives and there is no written definition of what constitutes success.
Mitigation: request the FAT protocol during qualification, and attach the agreed version to the purchase order as a contractual document.
Risk 04
Support dependency
A fault occurs and the platform supplier has to escalate to the company that actually made the actuator or the controller.
Mitigation: establish during qualification who manufactures the critical components and who owns the software. Support response is bounded by whoever is furthest up that chain.
On the last point, for transparency: we manufacture our own servo cylinders, controllers and control software, so this particular risk does not apply to us in the same way. We raise it here because it is a genuine differentiator between suppliers and one that buyers rarely think to check — not because every project needs a vertically integrated supplier. If your shortlist includes integrators, simply ask them who they escalate to and what the response commitment is.
Motion Platform Procurement Checklist
Thirty-two items across the five project phases. Tick them off as you go, then download or print the result for your project file. It runs entirely in your browser, nothing is transmitted, and there is no email form in front of it. The printable version is document CSC-CHK-001 Rev A, listed with everything else in downloads.
Phase 1 · Define the requirement
Complete before contacting any supplier.
Phase 2 · Settle the architecture
Locked once fabrication begins.
Phase 3 · Qualify suppliers
One conversation per supplier is usually enough.
Phase 4 · RFQ and comparison
Identical information to every supplier.
Phase 5 · Acceptance and budget
Agreed before the purchase order is issued.
Buying Guide FAQ
The procurement questions we are asked most often. Engineering questions are answered in the relevant Technology guide.
What does a motion platform cost?
There is no meaningful list price for an engineered motion platform, because cost is driven by the combination of gross moving load, acceleration, stroke, duty cycle and precision requirement rather than by a model number. The dominant driver is payload multiplied by acceleration, which sets actuator force and therefore the size of every component. Two platforms with the same stated payload can differ several-fold in price if one is specified for twice the acceleration.
How do I tell a real engineering supplier from an assembler?
Ask questions that cannot be answered from a catalogue. What peak actuator force does my payload produce and at which pose? What are the natural frequencies at that configuration? How is the platform calibrated and with what instrument? Who wrote the motion control software? An assembler will redirect these to a component supplier or answer in generalities; an engineering company will answer them or tell you exactly what inputs they need first.
Why are two quotations for the same platform not comparable?
Because the scope boundary usually differs. One may include the controller, software licence, interface documentation, factory acceptance testing, installation and training; another may quote the mechanism alone. Before comparing prices, normalise every quotation to the same scope and check what each treats as an extra.
What costs are usually missed in a motion platform budget?
Host integration labour is the most commonly underestimated, and is often the largest single line after the platform itself. Others include foundation work and anchoring, HVAC capacity for the heat electric drives reject into the room, safety guarding and interlocks, spares holding, operator training, and the internal engineering time to run acceptance.
How long does a motion platform project take?
For an engineered platform the sequence is engineering review and design, manufacture, assembly, control integration and factory acceptance testing, followed by shipping, installation and commissioning. Projects adapting an existing configuration move considerably faster than those requiring new mechanism geometry. Confirm the schedule with the quotation, and ask which phase carries the most schedule risk.
Should I buy a standard platform or a custom one?
If a standard product genuinely meets your gross moving load, trajectory and duty with margin, it will normally be faster and cheaper. The trap is accepting a standard platform that nearly fits, because the shortfall usually appears at commissioning when nothing can be changed. Compare the standard option against your actual combined trajectory rather than against per-axis maxima.
What should acceptance criteria include?
The test load, the trajectory, the reference point on the payload, the measuring instrument, the tolerance and the record format. Acceptance defined only as the platform moving as expected is not an acceptance criterion. Agree the factory acceptance test protocol in writing before the order, not after delivery.
What are the main risks in a motion platform purchase?
Under-specified moving load discovered at commissioning; an interface mismatch with the host system; acceptance criteria never agreed; and long-term support depending on a component supplier rather than the platform manufacturer. All four are avoidable at specification stage and expensive afterwards.
Where the Engineering Questions Are Answered
Deliberately not repeated here. Each of these covers one decision from Phase 1 and 2 in full.
Phase 1
Payload, Stroke & Acceleration
What gross moving load includes, why CoG height matters, and the specification builder.
Phase 2
3DOF vs 6DOF
Whether the three axes you would drop carry information your task depends on.
Phase 3
Electric vs Hydraulic
Where hydraulic still genuinely wins, and why most of the market moved to electric.
Phase 3
Delivered Project Records
Requirement, engineering decision and measured result for 26 delivered platforms — the evidence behind the seven questions.
Phase 3
Supplier Categories
Six kinds of motion platform supplier, and eight criteria for evaluating any of them — published by one of them.
Phase 4
Specifications & Documents
The controlled specification document covering all 215 delivered configurations, versioned so you can cite it.
Reference
Terminology & Commercial FAQ
87 terms defined with the caveat that matters for each, plus 47 commercial answers on quotations, lead time, warranty and support.
Test This Guide on Us First
If you are early in a procurement and want to try the Phase 3 questions on a supplier before you use them on your shortlist, ask us. We will answer them properly, and if the honest answer is that another type of supplier suits your project better, we will say so — that has happened before and it costs us nothing.
What we can tell you quickly
Even at early stage, these usually take one exchange:
Whether your requirement is within the electric envelope
Roughly what platform size it implies
Which of your requirements is driving the cost
Whether a smaller machine would actually do
What is missing from your specification