TGSS Radar Breakthrough: Accurate Ultra-Low Speed Detection at 0.1 m/s

Introduction

In today’s precision agriculture and mobile-machinery landscape, measuring true ground speed at extremely low velocities is no longer a luxury — it’s a requirement. Whether you’re performing headland turns, semi-automatic seeding at crawl pace, or dynamic spraying in narrow rows, having a reliable speed reference at sub-1 km/h can make the difference between optimized input use and costly waste. The TGSS (True Ground Speed Sensor) from ZLYRadar is making waves by delivering ground-speed detection down to 0.1 m/s (~0.36 km/h) — a significant advancement over many legacy wheel sensors or GPS-based systems.

The Challenge of Low-Speed Ground-Speed Measurement

Historically, ground-speed sensing in agricultural machines has been served by two main technologies: wheel/axle encoders or magnets, and GPS/INS systems. However, each approach has well-known limitations at very low speeds.

Wheel/axle encoders: These depend on wheel rotation or a magnet passing a reader. Under conditions of wheel slip (mud, wet soil, stubble), variable tire circumference, or when the vehicle is barely moving (very low RPM), the pulse count may either stop or produce unstable readings.

GPS/INS systems: While modern GPS receivers track ground movement well at moderate speeds, at very slow speeds (< 1–2 km/h) the positional drift, multipath errors, and update latency make the reading unstable or unusable. Under canopy or near structures the performance further degrades.

For applications like precision planting, headland turns, variable-rate spraying or machine automation, where speeds can crawl down to 0.2-1 km/h, neither wheel encoders nor standard GPS offers consistently reliable data. This is where radar-based ground-speed sensing comes into play.

Radar Technology: Enabling True Low-Speed Detection

Radar ground-speed sensors like TGSS leverage the Doppler effect—the change in frequency of a reflected wave relative to the transmitter when target and sensor are moving relative to each other. In the case of Doppler Ground Speed Sensor:

A continuous-wave (CW) 24 GHz Doppler radar transmits a narrow beam toward the ground surface.

The radar receives the reflected signal from the terrain, measures the Doppler shift, and calculates the real‐time velocity of the sensor relative to the ground.

Because the radar is measuring surface motion directly, the reading is independent of wheel slip, tire circumference variation or transmission gearing.

By optimizing RF sensitivity, antenna design, signal processing and mounting geometry, the TGSS is able to detect motions as slow as 0.1 m/s — meaning even barely moving machine speeds can be measured reliably.

Key technical enablers for this performance include:

• High sensitivity RF front-end: The TGSS specification lists an output power (EIRP) of ~18-20 dBm and narrow beamwidth (~15°×15°) for focused ground return.
• Reliable signal processing: Filtering of clutter (e.g., soil vibration, crop stubble reflections), calibration of mounting geometry, and compensation of noise extend reliable detection into crawl speeds.
• Mounting best practices: A sensor height of ~0.3-1 m above ground and a slight pitch angle ensure the beam intercepts diffuse ground reflections rather than specular reflections that might vanish at low speed.
• Multi-interface architecture: TGSS supports Pulse, RS-485 and CAN interfaces, allowing low-speed data to be made available in formats suitable for both legacy and advanced controls.

Why 0.1 m/s (≈0.36 km/h) Matters

Detecting ground speed at such low values may seem academically interesting — but in real-world operations it brings several very practical advantages:

1. Precision Planting & Seeding

In planting operations, especially in tight‐row or specialty seeders, ground speed directly affects seed drop timing and population control. When the machine slows to navigate a headland, adjust row spacing or turn to enter another pass, unreliable speed readings can lead to over-seeding or skipping. With TGSS’s ultra-low speed detection, the planter control logic receives a valid signal even during crawl speeds, improving seed singulation, uniformity and reducing waste.

2. Sprayer Rate Control at Low Speeds

Modern variable-rate sprayers often slow to 0.5-2 km/h to apply heavy rates or operate in complex terrain. Having accurate, stable ground-speed input at 0.2-1 km/h means the flow-control can maintain correct chemical application rather than relying on rough estimates or aborting low-speed spraying. TGSS supports this by maintaining signal validity at extremely low motion.

3. Headland and Turn Maneuvers

During headland turns, machines often slow dramatically, change orientation and may even reverse or shuffle sideways. Wheel sensors often drop out or produce erratic pulses, and GPS may flicker or freeze. A radar sensor with < 0.5 km/h capability keeps the controller aware of motion and enables smoother transitions between passes, reduced drift and better field overlap.

4. Autonomous/Assisted Machine Motion

For future‐proofing autonomous tractors, robotic implements or driver-assist features, fine motion control—even at near-zero speeds—is critical (e.g., aligning to implement, creeping for row entry). Having a ground-speed sensor that reliably reports motion from 0.1 m/s means the automation logic has accurate real-time feedback rather than blind-assumptions.

5. Slip & Traction Monitoring

By comparing true ground speed (from TGSS) and wheel/axle speed, machines can compute real slip percentage. At very low speeds (crawl, spot turn), slip detection is especially challenging. TGSS’s low-speed capability makes slip calculation meaningful even in low-motion phases, improving traction control, minimizing fuel waste and reducing soil disturbance.

Implementation Considerations for TGSS in Low-Speed Applications

To fully leverage the ultra‐low speed capability of TGSS, proper integration and installation are critical. Below are key recommendations:

Mounting and Mechanical Setup

• Height: Check manufacturer’s recommended range to ensure sufficient signal reflection and minimal clutter. Too high may reduce signal strength at low speed.
• Angle: A slight pitch (e.g., 30-40° off vertical) ensures the radar beam meets the ground at an optimal incidence for Doppler return rather than direct specular reflection.
• Clear line of sight: Avoid covering the radar face with guards, dirt, crop residue or shadows; ensure there is minimal obstruction in the beam path.
• Vibration isolation: While TGSS tolerates typical mobile machine vibration, excessive vibration or shock may degrade low‐speed detection. Use proper mounting hardware and fasteners.

Signal and Electrical Integration

• Interface selection: For low speed, choose an interface capable of transmitting small value changes. Pulse output must maintain reliable pulses at low frequencies; serial (RS-485) or CAN may provide finer resolution and status information.
• Pulse scaling: If using pulse output, verify scaling (e.g., 36.6 Hz = 1 km/h) and ensure the downstream controller can count very low frequencies (e.g., 0.36 km/h corresponds to ~13.2 Hz).
• Serial interface: RS-485 or CAN output may offer higher resolution (e.g., m/s or km/h with decimals) and support status flags for valid/invalid reading — helpful when near zero motion.
• Noise, cable length & termination: For long cable runs, especially in harsh agricultural environments, twisted-pair, shielded cable, proper termination and biasing help maintain signal integrity.
• Calibration and validation: After installation, validate the sensor reading at known slow speeds (e.g., 0.5 km/h, 1 km/h) and ensure smooth signal response (no drop-outs, oscillation or latency). Confirm 0.1 m/s capability by slow creep testing.

Software & Control Logic

• Valid motion threshold: Controllers should interpret when the speed reading is valid vs. “zero motion” —e., ensure that very low values (0.1 m/s) are treated as motion, not noise.
• Filtering & smoothing: At low speed the radar reading may fluctuate slightly due to ground irregularities; apply software smoothing or integration to eliminate jitter.
• Direction and reverse handling: If the machine reverses, ensure the system correctly interprets negative or reverse ground motion if supported by the interface.
• Slip computation: When combining TGSS ground speed with wheel speed/axle speed sensors, compute slip % even at low velocities for enhanced operational insight.

Environmental & Application Conditions

• Ground texture: At extremely low speeds, the radar relies on ground surface reflections — heavy stubble, mud, standing water or vegetation may affect signal strength. Ensure good mounting and alignment.
• Weather conditions: TGSS is designed for harsh environments (e.g., –45 °C to +85 °C) and uses radar frequencies proven in dust, rain and field conditions.
• Terrain variation: Changes in ground surface (e.g., furrows, ridges) at low speed may produce rapid small variations in motion reading; control logic may need to buffer or smooth these effects.

Real-World Impact and ROI

• The ultra-low speed capability of TGSS translates into tangible benefits for agriculture OEMs, machinery dealers and end-users:
• Increased application accuracy: Because speed is measured even at crawl pace, seeding uniformity, sprayer rate control and fertilizer distribution become more consistent.
• Reduced input waste: Less over-application during slow turns or transitions; better control of material flow results in cost savings, environmental compliance and better margins.
• Improved machine productivity: Avoid false zero-speed signals or drops out during slow operation; reduced downtime or manual adjustments improve throughput.
• Enhanced automation readiness: As machines adopt more automation/robotics, having a stable low-speed measurement means better control when creeping, docking or aligning implements.
• Competitive differentiation: Machinery manufacturers can market “ground-speed sensor down to 0.1 m/s” as a premium feature — appealing to precision-farming customers and differentiating solutions in a competitive market.

Summary and Outlook

The TGSS stands out with its ability to reliably detect ground motion down to 0.1 m/s (~0.36 km/h). This breakthrough addresses one of the longstanding challenges in mobile-machinery sensing: accurate velocity feedback at near-zero speeds. For precision agriculture, headland turns, autonomous machinery and advanced control systems, this capability unlocks higher accuracy, better automation and operational productivity.

By combining radar Doppler technology, optimized mounting and signal processing, plus flexible interfaces (Pulse, RS-485, CAN), TGSS offers a forward-looking solution for both legacy and future equipment fleets. The ability to sense motion at crawl speed elevates machine intelligence, decreases waste, and positions operators for the next generation of smart-farm applications.

If your company is specifying or integrating ground-speed sensing in agricultural or mobile-equipment platforms, take note: low-speed detection no longer needs to be a blind spot. With TGSS, you now have a validated radar solution that captures even the slowest motion with high fidelity—and that matters.