The tunnel crawler for passages that already exist. A tracked crawler that enters tunnels and culverts on a fibre, maps them before anyone follows, and holds a passage on a person's confirmation.
Five figures size the machine. Four reasons explain why a buyer sends it in first.
CS-425 goes into a confined dark space instead of a person doing close-quarters clearance. The map, the camera feed and the gas readings come back up the fibre, so the first report on a passage never depends on someone having walked it.
Video, lidar, telemetry and command share one fibre with a person on the far end. There is no radio and no satellite receiver aboard in any tier: rock and soil stop both, and the design never leans on either.
A single payload-bay interface carries the mechanical envelope, the power budget, the data interface and the mass cap. Mapping, atmosphere sensing, node emplacement and relay work become modules on one vehicle rather than new vehicles.
On a confirmed Trembler Line CS-435 cue, and only on a person's confirmation, it moves to a block position and holds the passage. Nothing detonates, fires or is thrown, and there is no warhead, fuze or energetic material in any variant.
The product specification and the systems engineering behind it, grouped the way an integration lead reads a tracked crawler: envelope, structure, drive, power, tether, locating, payload, response.
Envelope and massStructure and materialsDrive and mobilityPower and enduranceTether and linkGuidance and locatingSensing and payloadResponse and safetyCompliance
| Parameter | Value | Basis |
|---|---|---|
| Chassis footprint | ~300 mm W × 260 mm H × 520 mm L | design value, the product specification table |
| Chassis mass | ~25 kg | design value, the product specification table |
| Passage clearance | Tunnels and culverts, ≥ ~450 mm diameter | design value, the product specification table |
| Configuration | Tracked crawler, sized for tunnel and culvert clearance | the product specification table |
| Stance | Low and wide inside a circular envelope; track base as wide as the invert allows | geometry rule: a curved floor is a tipping problem |
| Running-gear symmetry | Top-bottom symmetric; runs inverted after a rollover | geometry rule: a crawler that cannot run inverted in a pipe nobody can reach is a lost unit |
| Rear profile | No rearward-facing shoulder to catch a joint lip | geometry rule: reverse-out along the laid fibre is the primary recovery mode |
| Parameter | Value | Basis |
|---|---|---|
| Chassis, track frames, load-bearing shell | Moulded glass-filled nylon | the fleet materials boundary: structural resin wherever a part carries load |
| Covers, spool flanges, handling fixtures | Recycled PET | the fleet materials boundary: parts that carry no drive loads |
| Axles, gears and fasteners | Metallic | where polymer cannot go |
| Governing load cases | Rollover · snag during reverse-out · a season of abrasive silt in the seals | the structural reading: an ingress and geometry problem rather than a stress case |
| Parameter | Value | Basis |
|---|---|---|
| Drive | Tracked, dual electric drive | the product specification table |
| Running gear | Twin tracks, skid-steered, each track independently driven | the configuration the sewer and pipe-inspection trade settled on for wet, silted, stepped floors |
| Crawl speed | ~0.8 m/s · ~2.9 km/h | design value, the product specification table |
| Locomotion power while halted | Zero; brakes passive | a crawler pays nothing to stop |
| Working pattern | Creep, stop, look | speed costs traction, payout tension and map quality, and buys almost nothing |
| Parameter | Value | Basis |
|---|---|---|
| Energy aboard | Battery; the fibre carries comms and guidance, not power | the crawler's power architecture |
| Battery endurance | ~4 h continuous recon | design value, the product specification table |
| Egress reserve | 30 % of the pack, held for the way out | design rule of the recovery doctrine |
| Endurance lever | Duty-cycling the lidar and the lights | the power budget: on a small crawler the sensors and the computer out-consume the tracks |
| Parameter | Value | Basis |
|---|---|---|
| Fibre per spool | ~500 m, breadcrumb return | design value, the product specification table |
| Spool architecture | Robot-spooled: the spool rides the vehicle and pays the fibre out stationary onto the floor | the tether architecture |
| Tether drag | ≈ zero at any range and any corner count | paid-out fibre lies where it falls; a dragged tether compounds friction at every corner |
| What the fibre carries | Teleoperation video · lidar stream · telemetry · commands | one fibre, both directions |
| Emissions, any tier | None: no radio, no GNSS | the product specification table |
| Loss of link | Stop, hold, wait, silent; never pushes forward blind through unmapped passage | the loss-of-link rule for confined space |
| Fibre break | Egress on the machine's own map | the minimum onboard autonomy the robot-spooled tether sets |
| Parameter | Value | Basis |
|---|---|---|
| Guidance tiers | Fibre-tethered teleoperation, the default · autonomous mapping (SLAM) | the product specification table |
| Autonomy ceiling | Mapping autonomy only; engagement autonomy does not exist | the product specification table |
| Dead reckoning | Inertial unit · track odometry · paid-out fibre length | fused: the fibre-length odometer does not slip |
| Map matching | Lidar SLAM; junctions, joints and defects are the landmarks | the mapping sensor doubles as the locating sensor |
| Parameter | Value | Basis |
|---|---|---|
| Sensor suite | Forward and aft cameras · lidar and mapping (SLAM) · gas sensor (O₂, CH₄, CO, H₂S) | the product specification table |
| Core set, always fitted | Visible camera with active illumination · thermal imager · small lidar | the core sensor set of the payload bay |
| Payload-bay interface | Mechanical envelope · power budget · data interface · mass cap | one interface for every module, so a variant is a module change |
| Bay modules | Mapper · atmosphere · node dropper · interpose fit · relay | the variant set |
| Payload | Sensor suite only; no warhead, fuze or energetic material | the product specification table |
| Parameter | Value | Basis |
|---|---|---|
| Interpose response | Moves to a block position on a confirmed Trembler Line CS-435 cue | the product specification table |
| Engagement authority | A person confirms before any physical engagement, always | the product specification table |
| Interpose fit | Obstruction with high-intensity light and sound, switched on by a human command over the fibre | the interpose module, non-injurious by design |
| Stops | Hardwired e-stop · wired stop over the fibre | the fleet safety chain |
| Recovery | Reverse-out along the fibre on redundant drive channels; one failed motor still brings it home | the recovery doctrine |
| Last resort | Abandonment rule: a unit that has streamed its map up the fibre is a loss of hardware, not of the mission | the recovery doctrine |
| Parameter | Value | Basis |
|---|---|---|
| Munitions classification | Carrier, not a munition: no warhead, fuze or energetic material in any variant; no autonomous strike capability of any kind | the product specification table |
| Patent status | Patent pending | the product specification table |
| Export control | Export-controlled; international transfer subject to Canadian government permits; counsel first | the product specification table |
A tunnel robot's useful cross-section is set by the worst passage on the mission, not the average one: partial blockages, offset joints, root intrusion and standing water.
CS-425 is sized to clear tunnels and culverts of about 450 mm in diameter and above, on a chassis of about 300 mm wide, 260 mm high and 520 mm long at about 25 kg. The class it works is the culvert, utility-tunnel and sewer class, the network that actually runs under a facility, a road or a perimeter.
Three geometry rules follow from the worst-passage premise, and each is a requirement rather than a feature.
The track base is as wide as the invert allows, because a curved floor is a tipping problem before it is a traction problem.
The running gear is top-bottom symmetric. A crawler that cannot run inverted after a rollover, in a pipe nobody can reach, is a lost unit.
No surface presents a rearward-facing shoulder that can anchor on a joint lip, because reversing out along the laid fibre is the primary recovery mode.
The body lives continuously in ground that is wet, abrasive, corrosive and dark, and that keeps trying to jam the mechanism with silt.
The governing load cases are a rollover, a snag during reverse-out and a season of abrasive silt in the seals. None of them is a stress case: the body is a sealing and geometry problem rather than a strength problem.
Glass-filled nylon where it carries load. The chassis, the track frames and any load-bearing shell are moulded in the fleet's structural resin on moulds the group cuts in its own shop. In sewer atmospheres carrying hydrogen sulphide and chlorides the polymer does not rust, and it is light.
Recycled PET where it does not. Covers, spool flanges and handling fixtures carry no drive loads and are moulded in recycled PET. Metallics stay where polymer cannot go: axles, gears and fasteners.
A sealed body in still tunnel air has no forced convection. Every watt of the electronics load leaves through the shell by natural convection, by conduction through the tracks and by radiation, and a mud-coated shell insulates. The design answers are the chassis as the heatsink and duty-cycling the lidar, which is also what the energy budget asks for.
Twin tracks, skid-steered, each independently driven: the configuration the sewer and pipe-inspection trade settled on for floors that are wet, silted and stepped.
The drive is tracked, with dual electric drive and a crawl speed of about 0.8 m/s. Obstacle capability scales with sprocket and track height: the climbable step is of the same order as the front sprocket radius, which is a statement about the machine's geometry. The ground is the harder half. A tunnel invert is the worst traction surface the fleet meets, with wet biofilm on concrete, loose silt over hardpan and sloped culvert walls.
On a small crawler the sensors and the computer out-consume the tracks, and that one finding sets the way the machine is worked.
Unlike anything airborne, a crawler pays nothing to stop: locomotion power on station is zero and the brakes are passive. The electronics load runs whether the machine moves or not, and lighting is a first-class consumer of it, because a tunnel is absolutely dark and nothing is seen that is not lit. Endurance is therefore bought by duty-cycling the lidar and the lights rather than by drivetrain efficiency.
The working pattern that falls out is creep, stop, look: move slowly, halt often and sense hard while halted. Speed costs almost nothing in energy and a great deal in traction risk, fibre payout tension and map quality. The battery runs about four hours of continuous recon, and 30 % of the pack is held for the way out, which makes the reserve a range rule before it is a battery rule.
A tethered crawler has two possible architectures, and the choice between them decides how far one can go.
Surface-spooled. The console pays out and the robot drags the whole laid length behind it. A dragged tether's friction grows with that length and every corner multiplies it, which is what range-limits a dragged-tether robot.
Robot-spooled, the architecture here. The spool rides the vehicle and pays the fibre out stationary onto the floor behind it. The fibre lies where it fell, so tether drag stays near zero at any range and any number of corners.
Each spool carries about 500 m of fibre, and what it lays is the breadcrumb back out. The architecture has a cost: the spool rides the vehicle, the fibre is committed as it goes, and a snapped fibre ends communications. Egress then runs on the machine homing on its own map, which is what sets the minimum onboard autonomy on a platform whose working mode is a person driving.
One fibre carries the teleoperation video, the lidar stream, the telemetry and the commands together. Against this sensor suite its bandwidth is effectively unlimited, and latency is nil at these lengths.
Underground, the hard problem is knowing where the machine is, with no external reference of any kind to lean on.
An inertial unit, track odometry and the paid-out fibre length. The tracks slip and a small inertial unit drifts, but paid-out fibre length is a path-length odometer that does not slip. Fused, the three bound along-path error better than any one alone.
Lidar SLAM matches what the machine sees to the map it has built. Long uniform pipe is the hard case for scan-matching, and it is exactly where the fibre-length odometer carries the solution. Junctions, joints and defects are the landmarks.
A long run of identical pipe can fool a scan-matcher, and a slipping track can fool odometry. Neither can fool a count of fibre that has left the spool, and that makes the one input worth more than it looks. The locating record fused with the lidar map is also the product the mapper variant delivers.
The core sensor set is fitted on every build. Everything else rides one bay interface, so a new variant is a packaging change rather than a new vehicle.
The product specification carries forward and aft cameras, a lidar mapping unit and a gas sensor package reading oxygen, methane, carbon monoxide and hydrogen sulphide. The core set behind them is a visible camera with active illumination, a thermal imager and a small lidar for geometry capture. The thermal channel earns its place underground: a warm target or a recent heat trace stands out against cold tunnel walls.
The bay is one interface carrying four things, so every module in the variant set is a swap:
Every module is a sensor, an annunciator, an emplaced node or an inspection package, and none carries a warhead, a fuze or energetic material, for any customer.
CS-425 is the one platform in the family designed to confront a threat at all, and it does that by parking its own mass in a passage too narrow to go around.
Autonomy stops at the map. The machine builds its own passage map and creeps a known run on SLAM, and it cannot decide on its own to move into a block position. When a Trembler Line cue arrives over the fibre it presents the block position as an option. A person confirms before it moves in and holds, and a person confirms again before any physical engagement follows. There is no autonomous engagement tier in the design to enable, gate or unlock.
The interpose fit adds high-intensity light and sound to the obstruction: presence, warning and denial by being unmistakably there. It is non-injurious by design and switched on by a human command over the fibre. Nothing detonates, nothing fires and nothing is thrown.
No radio and no GNSS in any tier. No warhead, no fuze and no energetic material in any variant. The one physical response the family owns is a machine standing in the way, on a person's word, in a passage nobody had to walk.
The interpose role depends on the Trembler Line CS-435, the buried picket of CS-430 nodes that detects, localizes and cues.
The buried nodes of the Trembler Line hear digging, tunnelling, footsteps or a vehicle.
The head-end places the source from the pattern of arrival times along the chain.
The cue reaches a person at the console, never an actuator. A person stands between the cue and any movement.
On that person's confirmation, a crawler already standing by on the network moves to a block position ahead of the intrusion's path and holds it.
CS-425 does not sprint to intercept. The picket's detection range and the standby position buy the interpose timeline; vehicle speed does not. A mission is loaded as either a recon route or a standby on a Trembler Line cue, so the sensing line and the response element are specified together. The node is CS-430 and the line it makes is Trembler Line CS-435.
A dead crawler deep in a small pipe cannot be fetched, so the recovery system is the machine itself, run backwards along the fibre it laid on the way in.
The safety chain matches the rest of the fleet: a hardwired e-stop, a wired stop over the fibre, and a loss-of-link rule written for confined space that ends in stop, hold, wait, silent. The machine never pushes forward blind through unmapped passage. If a leg ends early it holds exactly where it stopped, silent and waiting for a person, and recovery is a walk down the fibre rather than a search.
The core sensor set rides every build. The bay takes one module at a time through the same interface.
The lidar record fused with the locating stack is the product: tunnel-network geometry and condition assessment. The civil inspection build is this module with reporting software, so the defence build and the civil one are the same build.
Oxygen, carbon monoxide, hydrogen sulphide and methane at the lower explosive limit. It answers whether a passage is survivable and whether there has been recent combustion or equipment activity, and it is the civil confined-space-entry survey.
Carries and releases CS-430-class listening nodes at chosen points, extending a Trembler Line CS-435 into passages no surface emplacement reaches.
The response fit for a Trembler Line cue: the vehicle as a physical obstruction ahead of the threat's path, with high-intensity light and sound, switched on by a human command over the fibre. Non-injurious by design.
A parked unit whose spool end becomes a network drop, so later units and emplaced nodes tap the laid fibre as backhaul.
The lines that hold in every variant, in every passage and for every customer.
The page this sheet specifies, and the sheets beside it in the line.
The page this sheet specifies, with the pictures and the reasoning.
The buried picket of fibre-linked listening nodes.
A first conversation needs the passage classes, the access points and the distances between them, and what should happen when the picket cues.
Not an offer. Enquiries are screened, international transfer is subject to Canadian government permits taken per shipment, and all designs, systems and technologies shown are patent pending.
