JEC industrial PTU quality inspection. Project acceptance still requires a configuration-specific test method, limits, raw records, and approved evidence.
A pan-tilt positioner accuracy test should begin with the project’s pointing error budget, not the smallest angle printed on a datasheet. Freeze the PTU, payload, bracket, cable routing, controller, firmware, voltage, temperature, warm-up state, and mounting conditions. Then use an independent angular or optical reference to test a grid of pan and tilt positions, approach each point from both directions, repeat the moves, and record final error and settling time. Selected cases should be repeated after warm-up, power cycling, and installation.
The report must keep resolution, absolute accuracy, repeatability, backlash, drift, settling time, and position-report latency separate. Show worst cases, conditions, uncertainty, deviations, and retests. A fine command increment alone does not prove that a long-range EO/IR payload will point where expected.
Resolution Is Not Accuracy: Define the Metrics First
Positioning terms are often compressed into one attractive number. That makes quotations difficult to compare and creates disputes during factory acceptance testing (FAT). Use the following definitions in the RFQ and test procedure.
| Metric | What it answers | How to test it |
|---|---|---|
| Command resolution | What is the smallest commanded position increment? | Review the command interface and verify that adjacent commands are accepted. Do not treat this as measured pointing accuracy. |
| Readout resolution | What is the smallest change shown by the position feedback? | Record feedback values while making small moves. Confirm where the position is measured and how it is encoded. |
| Absolute positioning accuracy | How close is the final physical angle to the commanded angle? | Compare the commanded position with an independent calibrated reference across the usable range. |
| Repeatability | How tightly does the PTU return to the same position under repeated conditions? | Repeat the same move from a defined direction and report the result distribution and worst case. |
| Backlash or hysteresis | Does the final position change with the direction of approach? | Approach every selected target from positive and negative directions and compare the two result groups. |
| Drift | Does a stationary position change with time, temperature, vibration, or power events? | Hold selected points, repeat them after warm-up and power cycling, and compare the same reference target. |
| Settling time | How long after a command until the payload remains within the approved error band? | Use time-synchronized position or optical measurements and a project-defined stability window. |
Methods differ between manufacturers. FLIR support material explains how gearbox layout and output-shaft feedback can affect backlash in one PTU architecture; it is not JEC performance evidence. Axis notes that position accuracy affects presets and is easier to notice at high zoom. Buyers should request comparable definitions and methods, not compare isolated numbers.
Convert the EO/IR Mission into a Pointing Error Budget
Start with the narrowest operational field of view, the required target framing, and the cueing workflow. A radar slew-to-cue system may need the target to enter a defined acquisition window. A preset observation system may need a fixed object to return to a repeatable image location. These are different acceptance tasks.
For a simple geometric estimate:
linear miss = range x tan(angular error)
A hypothetical angular error of 0.1 degrees produces about 3.5 m of lateral displacement at 2,000 m. This is geometry, not a JEC product result. It shows why an apparently small angle can matter with long focal lengths. Near the image center, an approximate pixel shift can also be estimated as:
pixel shift ≈ image width x angular error / horizontal field of view
State all units and assumptions. Lens distortion, boresight alignment, stabilization, target range uncertainty, radar coordinate error, mount deflection, and image-processing latency can all contribute to the observed result. Do not assign the whole system error budget to the PTU. For broader optical and scene inputs, use JEC’s long-range surveillance camera selection guide.
Freeze the Configuration Before FAT
A result is not reproducible if the setup changes between runs. Record the exact PTU, payload mass and dimensions, center of gravity, moment of inertia, bracket, fasteners, cable bundle, connectors, controller, command mode, feedback source, firmware, speed, acceleration, voltage, and mounting structure. Also record temperature, wind or airflow, vibration, warm-up time, and calibration state.
Payload capacity is only an initial screen. A compact 15 kg assembly close to the tilt axis does not behave like a long 15 kg housing with a forward center of gravity. Cable torque can produce direction-dependent error, while a flexible pole can make the image move even when the PTU’s internal position feedback is stable. JEC’s guide to heavy-duty pan-tilt head and multi-sensor payload integration covers these mechanical selection inputs in more detail.
Batch assembly supports process control, but FAT results must identify the tested serial unit, payload, configuration, method, and conditions.
Run a Repeatable FAT Positioning Test
1. Establish the reference and zero state
Use an independent reference suitable for the required uncertainty. Depending on the project, this may be a calibrated rotary reference, autocollimator, total station, optical target arrangement, or another approved metrology method. The PTU’s own encoder readout cannot independently prove physical pointing accuracy. Document calibration status, setup geometry, alignment, and the uncertainty contribution of the reference.
2. Define a grid across the usable travel
Do not test only home and one convenient preset. Select positions near the center, typical operating angles, travel extremes that are contractually relevant, and tilt angles where gravity changes the load on the mechanism. If the project uses defined presets or cue sectors, include them in the grid.
3. Approach each point from both directions
Move to a known offset, then approach the target angle from the positive direction. Repeat from the negative direction. Keep speed, acceleration, dwell time, and approach distance fixed. This exposes direction-dependent effects that a one-way demonstration can hide.
4. Repeat enough times to show variation
Set the repetition count before testing. Record every run, including outliers and failed moves. A mean without the maximum error or raw results can conceal a recurring miss.
5. Measure dynamic and time-dependent behavior
Capture motion start, overshoot, entry into the tolerance band, and the time at which the position remains stable for the approved observation window. Repeat selected points after thermal stabilization and a power cycle. If home recovery or preset retention is required, test those functions explicitly.
| FAT case | Required record | Acceptance field |
|---|---|---|
| Multi-position pan and tilt grid | Commanded angle, reference angle, PTU feedback, signed error, timestamp | Project-defined accuracy limit |
| Repeated one-direction moves | Individual final positions, spread, maximum deviation | Project-defined repeatability rule |
| Bidirectional approach | Positive- and negative-approach result groups | Project-defined backlash or hysteresis limit |
| Dynamic move | Motion profile, overshoot, tolerance-band entry, stable time | Project-defined settling rule |
| Hold, warm-up, and power cycle | Baseline and elapsed-time positions, temperature, recovery state | Project-defined drift and recovery limits |
Calculate and Report Results Without Hiding Worst Cases
For each axis, retain signed error as well as absolute error:
signed pan error = measured pan angle - commanded pan angle
signed tilt error = measured tilt angle - commanded tilt angle
For small angles, a combined pointing-error estimate may be reported as:
combined error ≈ sqrt(pan error2 + tilt error2)
Keep the pan and tilt results beside the combined value because they help diagnose the cause. Report each position and direction, the selected repeatability statistic, maximum error, outliers, and measurement uncertainty. Define backlash from the separation between opposite-direction result groups using the exact calculation approved for the project.
Settling time must use a declared tolerance band and dwell period. Position-report latency is different: feedback can arrive late even when the mechanism has already settled. Where operational verification uses video, record exposure, frame rate, stabilization, zoom, focus, and timestamp behavior so image latency is not mistaken for mechanical error.
Repeat the Right Tests During SAT
SAT is not a shorter copy of FAT. It asks whether the accepted bench configuration still performs after installation. Axis troubleshooting guidance identifies shocks, vibration, strong wind, passing heavy vehicles, and unstable mounts as important influences on pan-tilt behavior. It also links drifted presets with mounting stability and calibration. Those observations are vendor-specific support guidance, but the installation risks are relevant to any project test plan.
At site, verify mounting torque and rigidity, final cable routing, supply voltage at the PTU, grounding, network and controller configuration, and the as-built calibration state. Recheck priority presets at the narrowest required field of view. Repeat bidirectional points that place the highest load on the tilt axis, then test home recovery and selected presets after a planned interruption. Include representative wind, vibration, or vehicle conditions only when they are safe, measurable, and contractually defined.
In a long-range border surveillance system, SAT should also verify the complete cueing geometry. A good PTU bench result cannot correct an inaccurate radar track, incorrect coordinate transform, boresight error, flexible tower, or stale command.
Diagnose Backlash, Drift, Compliance, and Latency
| Observed pattern | Likely areas to investigate | Next check |
|---|---|---|
| Error changes with approach direction | Gear clearance, coupling, cable torque, control deadband | Repeat the same point from both directions with cables temporarily managed under an approved setup. |
| Error grows at certain tilt angles | Center of gravity, bracket deflection, payload balance, structural compliance | Compare unloaded and representative-payload results without changing the reference method. |
| Preset shifts after time or temperature change | Thermal drift, calibration state, mount movement, feedback reference | Log temperature and elapsed time, then repeat the reference target before and after calibration. |
| Final position is correct but arrives slowly | Motion profile, overshoot control, settling criterion, feedback or network latency | Compare independent motion timing with controller feedback and video timestamps. |
| Image moves while encoder feedback is stable | Pole vibration, loose mount, payload bracket, optical stabilization | Measure the structure and optical line of sight rather than recalibrating the PTU by assumption. |
FLIR’s discussion of worn gears notes that encoder location and transmission architecture affect how backlash appears at the output shaft. Use that as a reminder to ask where position is measured; do not transfer another manufacturer’s architecture or numerical result to a JEC unit.
Select the JEC PTU by Payload Class and Test the Final Assembly
JEC offers separate industrial pan-tilt units and positioners for payload integration. For this accuracy-test workflow, two current product pages are relevant starting points:
JEC-PTU-2315 for 15kg-class industrial payloads
The JEC-PTU-2315 15kg industrial pan-tilt unit is the first model to review for medium-load camera housings, long-zoom visible cameras, thermal modules, or other approved sensor packages within its stated load class. Final suitability depends on dimensions, center of gravity, inertia, bracket, cable routing, wind exposure, voltage, control requirements, and the acceptance motion profile.
JEC-PTU-2315. Request configuration-specific positioning evidence for the final payload rather than relying on payload class alone.
JEC-PTU-7230 for 35kg-class heavy-duty payloads
The JEC-PTU-7230 35kg heavy-duty pan-tilt unit is intended for review when the system uses larger camera housings, long-range optical assemblies, or heavy EO/IR payloads. The higher load class does not remove the need to calculate overturning moment, confirm balance, manage cables, and verify the installed structure. For either model, request the current approved specification and a test plan tied to the exact configuration.
JEC-PTU-7230 heavy-duty platform. FAT and SAT limits should be approved for the complete EO/IR assembly and operating environment.
Where the project team is still deciding between a separate positioner and an integrated camera, review pan-tilt positioner versus integrated PTZ camera before writing the acceptance procedure.
Write the Requirement into the RFQ and Acceptance Plan
A useful requirement names the metric, configuration, method, positions, directions, repetitions, conditions, limit, and evidence. Avoid a clause such as “high accuracy PTU required.” A stronger structure is:
The supplier shall test absolute pan and tilt positioning accuracy, unidirectional repeatability, bidirectional error, drift, and settling time on the proposed PTU with the approved representative payload, bracket, cable arrangement, controller, firmware, voltage, and motion settings. The procedure shall identify the independent reference, calibration status, uncertainty, test grid, approach directions, repetitions, environmental conditions, calculation method, pass/fail limits, raw records, deviations, and retest results. Selected tests shall be repeated after installation.
Define who approves the method, witnesses FAT, owns reference equipment, resolves deviations, and authorizes retesting. Require regression testing after changes to the payload, bracket, gearbox, encoder, firmware, controller, motion profile, cable routing, calibration method, or mounting structure.
What to Send JEC for a PTU Accuracy Review
Provide the payload mass, dimensions, center of gravity, mounting drawing, cable exit and bend path, narrowest field of view, working ranges, target or preset task, allowed pointing error, pan and tilt travel, speed and settling needs, voltage, controller interface, duty cycle, environment, mounting structure, and proposed FAT/SAT evidence. Mark mandatory limits separately from preferences.
Request a configuration-specific PTU accuracy review for the JEC-PTU-2315 or JEC-PTU-7230. JEC can review the payload class and proposed test inputs; final model selection, tolerances, and acceptance statements require confirmation for the submitted configuration.
Frequently Asked Questions
What is the difference between pan-tilt resolution, accuracy, and repeatability?
Resolution is the smallest command or reported position increment. Accuracy is the difference between the commanded angle and the independently measured physical angle. Repeatability describes how closely repeated moves return to the same result under declared conditions. A positioner can have fine resolution but still show offset, backlash, or variation.
How do you measure backlash in a pan-tilt positioner?
Select the same target angle, approach it repeatedly from positive and negative directions, and compare the two result groups using an independent reference. Keep approach distance, speed, acceleration, dwell time, payload, and cable arrangement fixed. State the exact calculation used because backlash and bidirectional repeatability are not always reported in the same way.
Why does PTU positioning error become more visible at long focal lengths?
A narrow field of view maps a small angular change to a larger movement in the image. At long range, the same angular error also corresponds to a larger lateral displacement. The operational effect therefore depends on range, field of view, target size, boresight alignment, stabilization, and the permitted framing window.
Which PTU accuracy tests should be repeated during SAT?
Repeat the tests most affected by installation: priority presets, narrow-field-of-view framing, bidirectional positions, high-load tilt angles, home recovery, power-cycle behavior, and any cue-to-position workflow. Also verify mount rigidity, cable torque, voltage, grounding, calibration, and representative site vibration or wind conditions defined by the contract.
What evidence should a pan-tilt positioner supplier provide?
Request the approved procedure, exact configuration, reference-equipment and calibration information, uncertainty statement, raw position records, test conditions, direction and repetition data, maximum and distribution results, settling-time traces where required, deviations, corrective actions, and signed retest results. A datasheet value or demonstration video alone is not a complete acceptance record.
