Safety functions and limits

WD-20EFirmware: WD-20E mount build; AHC 1.1.0 interface reference

In this chapter

• 6.1 Safety-function overview
• 6.2 Motion and altitude limits
• 6.3 Meridian limits
  • East and West boundaries
  • Factory defaults and flip window
  • Imaging-software timing
  • What happens at the West limit
• 6.4 EC HA Limit
  • Read the boundary illustrations
  • Watch the coordinate-error animation
  • Configure the boundaries
  • Reference and encoder checks
  • When an EC HA boundary is reached
• 6.5 AEB
  • Illustrated AEB response
  • Check AEB and its settings
  • AEB Auto Tune
  • Cancellation or interrupted tuning
  • After an AEB event
• 6.6 Other protective functions
• 6.7 Stop movement and handle abnormal operation
• 6.8 Recover after a protection event

6.1 Safety-function overview

Open Settings > Safety & Limits on AHC. Read and record existing values before changing them. The reference interface contains Altitude, EC/HA, Meridian and AEB controls.

Function	Purpose	Important dependency
Altitude limits	Restrict calculated pointing below/above configured altitude boundaries.	Correct time, location and pointing coordinates.
Meridian limits	Govern allowable GEM travel and flip behavior around the meridian.	Correct mode, pointing state and software coordination.
EC HA Limit	Preventive control: constrain encoder-based RA travel, including when sky coordinates are incorrect.	Valid encoder data, correct reference, enabled limits and suitable physical boundaries.
AEB	Passive/reactive protection: respond after abnormal motor loading is detected and help mitigate its consequences.	Enabled state, valid baseline/threshold and firmware-supported behavior; payload, inertia and slew speed affect the outcome.
Physical RA brake	Provides rated holding torque during the relevant power/brake state.	Load torque within its holding capability.

WARNING · Protective functions are not a clearance guarantee

Inspect the complete mechanical arrangement and travel before moving. AEB is a response to abnormal loading, not a system that sees an obstacle before contact. The RA brake, AEB and EC HA Limit are different protections and must not be treated as interchangeable.

Check safety settings at first use and after firmware updates, Home-reference changes, site/mode changes or alterations to the telescope, camera, counterweights and cables.

WARNING · Restart the mount after changing safety settings

Every change to a safety setting requires a WD-20E mount restart before the new value takes effect. This includes altitude and Meridian limits, EC HA boundaries or enabled state, and AEB settings or a newly saved baseline. Saving or reading back a value on AHC does not mean the active protection has changed. Stop the observation, save the setting, restart the mount and reconnect AHC. Read the setting back and verify the mount's Home/reference state, observing data and applicable coordinate-limit initialization before relying on the protection or resuming normal movement.

WARNING · Coordinate limits need start-up initialization

Forcing Tracking ON before the mount's location and time have been updated does not activate coordinate-based Meridian, Horizon or Overhead / Zenith protection. First verify the site, date and time, then complete a supervised initial GoTo or a verified alignment/plate-solving Sync to establish the pointing state. Merely solving an image, saving limit values or seeing Tracking ON is insufficient. Follow 5.6 Start-up and coordinate-limit initialization and check physical clearance throughout the initial movement.

6.2 Motion and altitude limits

Horizon is the lowest allowed calculated target altitude. Overhead, shown as Zenith in the AHC altitude page, is the upper altitude limit. These concern sky pointing, not a measurement of physical tripod clearance.

1. Verify observing location, time and pointing state.
2. Open Settings > Safety & Limits > Altitude.
3. Read the current Horizon and Zenith settings. Choose values suitable for the site, observing plan and mount behavior.
4. Save/apply using the displayed control, then restart the mount to activate the new limits.
5. Reconnect AHC, reopen the page and read the settings back.
6. Confirm that ordinary targets inside the intended region remain available without testing a dangerous motion.

NOTE · Zenith and flip behavior

A restrictive upper-altitude limit can affect a near-zenith GoTo or flip. Older OnStep-based instructions describe a 90° setting as disabling the overhead check; do not use that as a universal WD-20E recommendation. Coordinate the chosen setting with the actual firmware and physical clearance.

Do not lower Horizon simply to overcome an implausible target altitude. First check the observing data and target coordinates.

6.3 Meridian limits

In GEM mode, the meridian is the north–south line through the sky. A target's hour angle (HA) is negative before it crosses the meridian and positive afterward. A meridian flip moves the telescope from one side of the pier/tripod to the other so tracking can continue. The East and West settings describe where each pier-side arrangement may operate around that crossing; they are not motor-direction buttons. The meridian limits depend on correct location, time and pointing coordinates. They are separate from the encoder-based EC HA Limit.

East and West boundaries

Mount setting	Effect on real movement in GEM mode
Meridian East (E)	Sets the earliest position east of the meridian at which the telescope may use the pier-east arrangement (the arrangement normally used after a flip). At HA less than −E, the mount stops RA travel farther into that boundary in this arrangement; a GoTo may instead choose the pier-west arrangement if that route is allowed. A positive E can permit an earlier flip before transit.
Meridian West (W)	Sets how far west of the meridian the telescope may continue in the pier-west arrangement (the arrangement normally used before a flip). At HA greater than +W, the mount attempts its automatic flip if the conditions below are met; otherwise it stops further travel toward that boundary. A positive W allows tracking beyond transit while the imaging application finishes an exposure and requests a flip.

When E and W leave an overlap, both pier-side arrangements can reach targets between HA −E and HA +W, subject to other limits and physical clearance. A GoTo or flip request inside this interval can select the other arrangement; pier-side preference and the requested command affect the result. The mount does not flip merely because the target crosses HA 0°. Moving E or W changes real allowed RA travel, so check the OTA, camera, counterweight, tripod/pier and cables throughout both routes.

Factory defaults and flip window

The current WD-20E mount firmware's initial values, used when its nonvolatile limit settings have not been initialized, are:

Setting	Firmware initial value	Approximate time from meridian transit
Meridian East	0°	0 minutes before transit
Meridian West	+5°	20 minutes after transit
Automatic meridian flip	Enabled	Attempts a flip at the West boundary when tracking and a flip can be executed

Sidereal HA changes by approximately 1° in 4 minutes. With these initial East/West values, the nominal two-arrangement window runs from the meridian to about 20 minutes after transit. A mount that has previously been configured can have different stored values, including a stored automatic-flip state; firmware initial values do not overwrite its saved settings. Verify the installed mount's actual settings before scheduling unattended imaging. In the current AHC implementation, the Meridian page can display locally stored field values rather than reading both limits back from the mount, so an untouched AHC screen alone does not prove the mount's effective values.

CAUTION · Leave Meridian East at its factory setting

Do not change Meridian East for routine use. Keep it at the firmware's 0° factory value. Changing East alters when the other pier-side arrangement becomes available and can cause an unexpectedly early or refused flip. AHC saves the East and West fields together: before saving a West adjustment, make sure its East field shows 0° unless WarpAstron has specified another value for your mount. If the mount may already have a different stored East value, confirm its configuration with WarpAstron support before saving.

Imaging-software timing

Set the imaging application's flip window inside the mount's verified window, leaving time for any active exposure to finish, for its flip request to reach the mount and for the setup to remain clear. In N.I.N.A., Minutes after Meridian is the earliest requested flip time and Max. Minutes after Meridian is the latest end of that exposure-dependent window. For example, with a verified West value of +5° (about 20 minutes), a N.I.N.A. window of 5–10 minutes after transit leaves a nominal 10-minute margin before the mount's West boundary. It is an example, not a universal safe setting: first verify clearance, the actual pier side, exposure length, sequence timing, driver behavior and EC HA boundaries. See 4.8 N.I.N.A. Meridian flips and the N.I.N.A. flip documentation.

N.I.N.A. can wait for an exposure already in progress to finish and, when it ends within the configured window, request the flip before starting another exposure. This avoids interrupting that frame only while the mount still has room to track. N.I.N.A. does not move the mount's West boundary or guarantee that a delayed, failed or disconnected application will finish the frame. If tracking reaches the mount's West limit during an exposure, the mount-level response below takes precedence; the frame and guiding may be lost. Use reliable pier-side reporting in the ASCOM driver and supervise the first flip with the actual exposure duration. Avoid competing flip requests from multiple applications.

What happens at the West limit

If N.I.N.A. or another application requests a valid flip before West is reached, the mount follows that request. If no flip request arrives and the mount reaches West while still in the pier-west arrangement, the WD-20E firmware automatically requests a flip to the pier-east arrangement when automatic flip is enabled, the mount is tracking and the GoTo/flip request can be accepted. The mount does not wait for the imaging application's exposure or guiding to finish. If automatic flip is disabled, tracking is not active or the automatic flip is refused, the mount stops further RA travel toward the West boundary and reports a meridian-limit condition. Other protections can intervene earlier. Do not rely on automatic flip as a substitute for correctly scheduled software flips or confirmed physical clearance.

WARNING · Changing a meridian window

Do not widen the window without checking both pier-side configurations, accessory clearance and cable travel. A permitted software position may still be physically unsafe. A wrong time/location or incorrect plate-solving Sync can also make a coordinate-based meridian boundary correspond to the wrong physical position. Keep EC HA Limit correctly configured as an independent preventive RA boundary.

1. Stop the current observation and record existing settings.
2. Open Settings > Safety & Limits > Meridian.
3. Confirm the actual mount values and the units shown by each interface. AHC displays degrees; N.I.N.A.'s flip timing uses minutes. 1° ≈ 4 minutes near the meridian.
4. Leave Meridian East at 0° for normal use. If a different Meridian West limit is needed, check the full physical route before changing it. Coordinate the imaging application's earliest/latest flip timing, including exposure duration and a margin before West.
5. Check that EC HA Limit leaves room for the intended normal flip, while still stopping before unsafe mechanical travel.
6. Save/apply the new values, restart the mount and reconnect AHC. Confirm the mount's stored values through a supported readback method, re-establish the observing/pointing state as needed, then supervise the first actual flip.

EC HA Limit can stop RA travel before a software flip is completed if its boundary is reached first. Conversely, increasing a software meridian limit does not increase safe physical travel.

6.4 EC HA Limit

EC HA Limit is encoder-based mechanical RA travel protection. The AHC interface calls it EC/HA; older WarpAstron material also uses EC Guard. It measures RA rotation relative to the stored encoder Home reference. This mechanical angle is different from the target's celestial hour angle or the sky coordinates reported after a pointing Sync.

NOTE · Preventive control

EC HA Limit provides a preventive travel constraint. With valid encoder/Home reference data, enabled limits and correctly placed boundaries, it can prevent unsafe RA travel caused by incorrect synchronized sky coordinates. It checks encoder-referenced RA travel rather than depending only on the celestial pointing solution. This provides an additional barrier when a GoTo or Park command is based on incorrect coordinates.

An incorrect plate-solving Sync can change the mount's pointing coordinates so that software Meridian, Horizon and Overhead limits no longer correspond to the actual physical position. EC HA Limit's encoder-referenced RA boundary provides an additional preventive constraint in that situation. Verify time and location and the solved position before Sync; do not deliberately use an incorrect Sync to test protection.

It limits the consequences of a coordinate error; it does not correct that error. Keep time, site and pointing synchronized, and leave a stopping margin inside known physical clearance. Its RA boundary does not establish DEC, accessory or cable clearance.

For the supplied firmware reference, this is a GEM-mode protection. Do not assume the same function is available in AltAz mode. A valid physical Home/encoder reference and usable encoder readings are essential.

Read the boundary illustrations

The center position below is the RA encoder Home reference (0°). The left and right examples show mechanical RA rotation from that reference toward two separate boundaries. The −95° and +95° shown are illustrative positions based on the current reference firmware's initial EC HA settings, not a guaranteed safe range for every telescope, DEC orientation, camera or cable route. A previously configured mount may retain other settings. The picture's Left and Right are viewing directions from behind the mount looking north; do not equate them automatically with the East and West field names on a particular controller.

The angles refer only to mechanical RA rotation from its Home reference. The center image does not imply that the DEC axis is also at Home.

Set both limits only after checking the complete loaded assembly at the relevant DEC orientations. Keep each boundary inside verified clearance, allowing for movement during deceleration. If the RA Home reference changes, the same numerical boundaries describe different physical positions and must be checked again.

Watch the coordinate-error animation

The following 12-second conceptual animation compares a wrong pointing-coordinate solution with EC HA Limit off and on. Use the playback controls to pause at the key stages; the solid mount is the actual mechanical position and the translucent mount is the incorrect coordinate alias shown for comparison.

A conceptual comparison of coordinate-based Meridian protection and encoder-referenced EC HA travel protection. The angles and geometry are examples, not a clearance test.

1. Wrong coordinates, EC HA off: the displayed coordinate alias does not match the actual RA position. The expected Meridian stop can therefore occur at the wrong physical place, allowing the real telescope to move farther than intended. The contact shown is a simulated consequence.
2. Wrong coordinates, EC HA on: the same coordinate error remains, but the encoder checks actual RA rotation relative to the valid Home reference.
3. At the EC HA boundary: the reference example commands a stop at −95° mechanical RA, before the illustrated contact position. The actual stopping point may be farther along because of speed, load and deceleration; EC HA does not check DEC, accessories or cables.

The arrows show a sequence, not a time or angle scale. A wrong Sync can shift the software's apparent position; an enabled EC HA boundary uses the separate mechanical RA reference.

CAUTION · Illustration only

The contact in the animation is simulated. Never deliberately drive the telescope into a pier or tripod to test a limit. Enabling EC HA does not correct wrong coordinates, repair a bad Home reference or guarantee that a large or high-speed load will stop before contact.

Configure the boundaries

The reference firmware initializes EC HA Limit enabled with −95° / +95° mechanical RA boundaries, but a configured mount can retain other values. The current AHC page may show locally stored fields rather than reading the mount's active boundaries. Treat the illustrations and any untouched AHC fields as examples until the actual configuration is confirmed; saving from AHC writes both boundary fields.

1. Confirm the installed WD-20E firmware, GEM mode and valid Home/reference state.
2. Inspect the telescope, camera, focuser, counterweight and cable clearance on both sides of the travel.
3. Open Settings > Safety & Limits > EC/HA. Confirm the enabled state and actual stored boundaries using a supported readback or WarpAstron support if the AHC display cannot establish them.
4. Record the previous values. Change only values whose units and reference directions you understand; do not save simply to match the illustration.
5. Keep each boundary inside a known clear region, leaving a margin for deceleration and cable movement.
6. Coordinate the boundaries with meridian limits, so the intended normal flip is not unexpectedly blocked.
7. Save/apply the settings, restart the mount and reconnect AHC. Confirm the mount's stored values and enabled state through a supported method before relying on the boundary.
8. Verify normal movement within the known safe region at low speed, while supervising the equipment. Do not create a collision to test protection.

WARNING · Stopping distance

The mount can travel beyond a trigger boundary while decelerating. Leave clearance beyond the configured angle, especially at higher slew rates. A boundary positioned exactly at contact is too late.

Reference and encoder checks

An absolute encoder does not by itself make an incorrectly defined Home reference safe. Do not clear or redefine that reference casually. Follow the encoder Home calibration guidance and recheck the boundaries after a reference change. If Home was interrupted, encoder status is abnormal, or the reported position disagrees with the actual mount, stop and resolve the discrepancy before relying on EC HA Limit.

The local firmware reference requires current, valid encoder information for this check. Loss of usable encoder information must be treated as a reason to investigate; an enabled toggle alone is not proof that effective protection is present.

When an EC HA boundary is reached

During normal GEM operation, reaching an EC HA boundary commands an RA stop, aborts an active RA slew and turns Tracking off. Some subsequent motion commands may be refused. Confirm that movement has actually stopped, then stop the controlling sequence and inspect the axis position, warning, boundary setting and cable clearance.

If the mount permits a short manual movement away from the boundary and that direction is clearly safe, use low speed and verify the warning clears. A Home return should be used only when its full route is clear. If the position/reference is uncertain or recovery is refused, stop and contact support rather than widening the boundary or repeatedly restarting.

6.5 AEB

AEB is the mount's automatic emergency-braking protection. It uses motor-load information and a configured baseline/trigger setting to detect abnormal loading. The reference implementation can stop motion and briefly reverse the affected axis to relieve the load. Keep the surroundings clear for both the original and possible recovery direction.

CAUTION · Passive response and heavy-load limitations

AEB is passive/reactive protection: it responds only after abnormal motor loading is detected. Contact, obstruction or cable tension may already have occurred before it triggers. Its stop and possible relief movement can mitigate the consequences only to a limited extent; it cannot guarantee that equipment damage or personal injury will be avoided.

Heavy or bulky equipment, added counterweights and large lever arms can increase the moving assembly's inertia. Higher slew speeds increase its kinetic energy. These factors can make stopping or load relief less effective; movement and contact forces may continue during detection and deceleration. Do not rely on AEB to make a heavy setup or a marginal-clearance route safe. Use conservative loading and slew speed, check the entire route and cables, configure preventive limits, and remain ready to press STOP.

EC HA Limit sets preventive RA travel boundaries; AEB reacts to abnormal loading. Use both within their supported operating conditions, together with physical clearance and supervision.

An incorrect plate-solving Sync can corrupt the pointing coordinates and undermine software Meridian or altitude limits. AEB responds to motor loading rather than relying only on those sky coordinates, so an enabled, correctly tuned system can offer a reactive fallback if abnormal loading occurs. It does not detect or correct a bad Sync, and contact may already have occurred before it responds. Its mitigation remains limited, particularly with heavy equipment; verify time, location and synchronization and use preventive travel limits before movement.

Illustrated AEB response

The illustration shows a conceptual abnormal-load event, assuming AEB has been enabled and tuned for the installed load. Read it from left to right: an obstruction can make contact before AEB detects the increased motor load; the mount then commands a stop and, on the supported implementation, may briefly reverse to relieve pressure. Confirm that motion has ended before inspecting or touching the equipment.

Contact → AEB stop → possible brief reversal. The close-ups show only the modeled contact point; relief at that point does not verify clearance elsewhere or rule out damage.

The 12-second animation shows the same sequence. Pause it to compare the contact point before and after the illustrative reverse movement.

A conceptual AEB response, not a real collision test. The timing, amount of reversal and clearance shown are animation choices, not firmware specifications.

CAUTION · Do not use contact to test AEB

Never deliberately drive the telescope into a pier, tripod or other object. This example isolates the AEB response; it does not simulate simultaneous EC HA or coordinate-based limits. Its contact position is beyond the separate ±95° EC HA illustration above. With a valid, enabled EC HA boundary placed before that position, the preventive RA limit should constrain travel first. AEB remains a limited fallback if abnormal loading occurs; it does not guarantee that a heavy or fast-moving setup will stop without damage.

Check AEB and its settings

AEB is disabled at the factory by default. Enable it if you intend to use the feature, and read the enabled state back. A previously used mount may retain changed settings, so check the actual state at first use and after updates.

Use the supported AEB Auto Tune workflow for the load you will operate, including telescope, camera, other accessories and counterweights. Reassess the baseline after changing that assembly. Enable the required functions and complete all prerequisites before starting Auto Tune; it must not be started merely to suppress an unexplained warning.

1. Open Settings > Safety & Limits > AEB.
2. Read its enabled state, recorded event count, baseline and threshold/ratio fields.
3. Record current values before making changes.
4. Use the supported calibration workflow to establish a valid baseline when required. Do not enter a guessed value or copy a value from another mount.
5. Save/apply the intended settings, restart the mount and reconnect AHC. Read the values back before relying on AEB or starting Auto Tune.

A baseline that is too low can cause unwanted activation. An excessively high trigger can reduce sensitivity. AEB values are not equivalent to the published payload torque and are not a direct torque calibration.

AEB Auto Tune

AHC firmware 1.1.0 or later is required for AEB Auto Tune from AHC. The WD-20E mount firmware must also support the guided workflow; meeting the AHC minimum alone is not sufficient. The presence of an AEB setting on older firmware does not establish support for guided Auto Tune. Use the workflow offered by the installed, supported combination; do not substitute a legacy PC-tool sequence for it.

WARNING · Reduced protection during recording

Auto Tune records motor loading while normal current-based AEB protective action is reduced/suppressed. Check the entire chosen travel in advance, remain beside the mount, and be ready to press STOP. Disconnect independent PC, ST4 and other command sources before starting. Do not use a deliberate collision as a calibration test.

Auto Tune sequence: Home → select East or West → prepare → record while returning Home → save the baseline and restart. The illustrated preparation angle is not a firmware setting or a required physical position.

The drawing shows RA movement for a shared baseline, with DEC kept at Home. It helps identify the stages to supervise; use the actual AHC prompts for the selected direction, any Restore Speed recovery, saving and restart. The drawing is not an instruction to move the axes manually into its pictured angles.

Prerequisites

• AHC firmware 1.1.0 or later, compatible WD-20E mount firmware and a connected AHC.
• GEM mode, valid encoder position and enabled EC/HA and AEB functions as required by the workflow. If any of those safety settings were changed, restart the mount and verify their active states before Auto Tune.
• A physically correct, completed Home state, tracking off, no active slew or guiding, and the required unparked state.
• Clear travel toward the selected east/west preparation position and back to Home, including all attached equipment and cables.
• No independent controller issuing commands; stable power and access to STOP.

Procedure

1. Complete the prerequisite checks, then open Settings > Safety & Limits > AEB > Auto Tune.
2. Select East or West according to the side whose full route is clear. Read and acknowledge the displayed conditions.
3. Press Start Auto Tune. Watch the preparation movement and stopped-state checks.
4. Continue supervising while the mount records loading and returns to Home. Do not manually change speed, mode, protection settings or position during the workflow.
5. If motion is unexpected or clearance becomes doubtful, press STOP / Stop / Cancel and follow the recovery screen.
6. When the result is presented, confirm the mount has returned to Home and stopped. Review the outcome; a lack of actual calibration movement is not a valid successful result.
7. Choose Save Baseline to accept the result, or Discard to retain the previous baseline. Wait for the displayed save/cleanup result.
8. If the workflow requests Restore Speed, complete it and verify recovery before leaving the workflow.
9. If you saved a new baseline, restart the mount to load it. Reconnect, check AEB/EC HA status and observing data, and verify the normal operating speed before resuming.

The reference workflow derives a shared baseline from RA movement; it does not perform an independent DEC calibration. The supported guided implementation manages preparation speed and recording. Do not attempt to reproduce its motion with a stopwatch or raw commands from a terminal.

Cancellation or interrupted tuning

Cancel and wait for a confirmed stop. Keep any recovery screen visible and follow its instructions. If the AHC restarts or cleanup cannot complete, reconnect to the same mount and complete the offered restoration before normal operation.

If a save acknowledgement was interrupted, do not assume the old or new baseline is active. Restart as instructed and read the stored value back. For unresolved recovery or an invalid result, preserve the previous records and contact support.

After an AEB event

Stop the sequence and wait until motion and any protective reversal have ended. Inspect for contact, cable snagging, overload, stiff movement, loose attachments or a changed equipment configuration. Read event information and the current baseline/trigger settings.

Remove the cause before resuming. If activation repeats without an obvious obstruction, check supply stability and calibration with support; do not repeatedly raise the threshold to suppress an unexplained event.

6.6 Other protective functions

Other protections depend on the delivered hardware and firmware. They can include motor fault handling, axis-travel restrictions and electrical protective circuitry. Read the actual status and release notes for the installed version.

These must not be confused with additional functions on WD-20EP or WD-15E. In particular, the AHC reference Power telemetry/channel page is not available for WD-20E; its absence is not proof that mount DC power has failed.

Electrical protection is not permission to use the wrong voltage, polarity or connector. A motor fault is not necessarily a limit event. Keep the reported error available for diagnosis.

6.7 Stop movement and handle abnormal operation

1. Press AHC STOP when movement or clearance is unexpected. Use the software's documented abort control if that is the available route.
2. Confirm physically that motion has stopped; a lost connection alone is not confirmation.
3. Keep clear of the equipment and inspect the reported state and surroundings.
4. For smoke, electrical smell or continued uncontrolled movement, isolate power safely while accounting for the load and brake holding limit. Do not reach into a moving mechanism.
5. End other command sources so they cannot restart the mount.

WARNING · Power isolation and load holding

Removing power may be necessary in an emergency, but the brake has a finite rating. Keep people out of the possible load path and support the equipment safely once movement has stopped.

6.8 Recover after a protection event

Use this sequence for an event whose cause has been identified:

1. Stop imaging, guiding and other command sources. Record the warning and settings before clearing anything.
2. Inspect the complete setup, cables and attachments. Correct the obstruction or configuration problem.
3. Determine whether the event came from EC HA Limit, AEB, altitude/meridian settings, a motor fault or another source.
4. Follow the matching recovery procedure above, using only a clear, allowed route. Do not treat a reboot as proof that the cause is resolved.
5. Confirm physical position, Home/reference state, observing data, safety settings, tracking and Park state as applicable.
6. Make a short supervised test at low speed, then resume normal operation only if the result is consistent.

For repeated or unexplained events, collect the diagnostic information in 8.8.