Modern mobile machinery relies on many analog sensors to monitor pressure, temperature, position, level, and other operating conditions.
These sensors do not simply send an ON/OFF signal. Instead, they provide continuously changing electrical signals that must be accurately read and interpreted by the controller.
A mobile machinery controller therefore needs suitable analog input channels, signal conversion, filtering, scaling, and fault detection.
This article explains how mobile controllers process common analog sensor signals and how these signals are used in real machine applications.
Analog sensors typically use several common signal types:
0–5 V
0–10 V
4–20 mA
Resistive signals
Each type has different characteristics and is suitable for different applications.
0–5 V sensors are widely used in mobile machinery.
Typical applications include:
Pressure sensors
Position sensors
Throttle sensors
Joysticks
The sensor converts a physical value into a voltage signal.
For example:
0.5 V → Low Pressure 2.5 V → Medium Pressure 4.5 V → High Pressure
The controller reads the voltage through an analog input and converts it into an engineering value.
A typical process is:
Pressure Sensor ↓ Voltage Signal ↓ Analog Input ↓ Controller Calculation ↓ Pressure Value
Many sensors avoid using exactly 0 V and 5 V during normal operation. This allows the controller to detect some wiring faults when the signal falls outside the expected range.
0–10 V signals are also common in industrial and mobile control systems.
They may be used for:
Position measurement
Level sensors
Hydraulic pressure
Auxiliary equipment
Compared with 0–5 V, the wider voltage range can provide convenient integration with industrial sensors and devices.
However, engineers need to ensure that the controller input supports the required voltage range.
Applying a signal outside the supported input range may lead to incorrect measurements or hardware damage.
4–20 mA is widely used in industrial measurement systems and can also be found in mobile machinery applications.
Typical sensors include:
Pressure transmitters
Temperature transmitters
Level sensors
The sensor represents the measured value by changing current.
For example:
4 mA → Minimum Value 12 mA → Mid-Range Value 20 mA → Maximum Value
One advantage of 4–20 mA signals is their suitability for longer cable distances and electrically noisy environments.
Because the minimum normal signal is 4 mA instead of 0 mA, the controller can also detect some wiring faults.
For example:
0 mA → Possible Open Circuit 4–20 mA → Normal Measurement Range
This makes current-loop signals useful in applications where reliable signal transmission is important.
Some mobile machinery sensors change resistance instead of producing a voltage or current output.
Common examples include:
Temperature sensors
Fuel level sensors
Oil level sensors
The controller measures the resistance indirectly and converts it into a useful engineering value.
For example, a temperature sensor may change resistance as temperature changes.
The controller software then converts this electrical measurement into:
Resistance ↓ Temperature Value ↓ HMI Display / Control Logic
Resistive sensors can be simple and cost-effective, but they require correct input circuitry and calibration.
Reading the electrical signal is only the first step.
The controller must convert the raw analog value into a useful physical measurement.
This process is often called scaling.
For example, assume a pressure sensor outputs:
0.5 V → 0 bar
4.5 V → 250 bar
The controller converts the measured voltage into pressure according to the configured relationship.
The final value can then be used for:
Hydraulic control
Safety monitoring
HMI display
Fault detection
Data logging
Without correct scaling, the raw voltage itself has little meaning to the machine control system.
Mobile machines operate in electrically and mechanically noisy environments.
Sensor signals may be affected by:
Vibration
Electrical interference
Ground noise
Rapid mechanical changes
If every small signal change is used directly, machine control may become unstable.
Controllers therefore often apply software filtering.
For example:
Raw Sensor Signal
↓
Filtering
↓
Stable Measurement
↓
Control Logic
Filtering helps reduce unwanted fluctuations while preserving useful changes in the signal.
However, too much filtering can also make the system respond too slowly.
The filtering strategy should therefore match the application.
A hydraulic pressure control function may require a faster response than a fuel level display.
Hydraulic systems are one of the most common uses of analog sensors in mobile machinery.
A typical control loop may include:
Pressure Sensor
↓
Analog Input
↓
Mobile Controller
↓
Control Logic
↓
PWM Output
↓
Proportional Valve
The controller continuously monitors the pressure sensor and adjusts the valve output according to the required operating condition.
This allows functions such as:
Pressure regulation
Load control
Hydraulic protection
Automatic operating sequences
Analog inputs and PWM outputs therefore often work together in modern mobile hydraulic systems.
Position sensors are commonly used to monitor:
Boom position
Steering angle
Cylinder position
Pedal position
Joystick position
The controller can use this information for both monitoring and automatic control.
For example:
Position Sensor
↓
Analog Signal
↓
Controller
↓
Position Calculation
↓
Movement Control
In an aerial work platform or crane, position information may also be used as part of the machine's operating limits or safety logic.
A reliable controller should not assume that every analog signal is valid.
Possible sensor problems include:
Open circuit
Short circuit
Broken wire
Incorrect supply voltage
Signal outside expected range
The controller can monitor the signal and compare it with predefined limits.
For example, if a sensor normally operates between 0.5 V and 4.5 V:
Below 0.3 V → Possible Fault
0.5–4.5 V → Normal Range
Above 4.7 V → Possible Fault
When a fault is detected, the control system may:
Generate a diagnostic code
Display a warning on the HMI
Limit machine operation
Switch to a safe fallback value
The exact strategy depends on the function and machine safety requirements.
Another important factor is analog input resolution.
Higher resolution allows the controller to distinguish smaller changes in the sensor signal.
This can be important for applications requiring precise control, such as:
Proportional hydraulics
Steering systems
Load measurement
Position control
However, high resolution alone does not guarantee accurate measurements.
Engineers also need to consider:
Sensor accuracy
Wiring quality
Input circuit design
Calibration
Electrical noise
The complete measurement chain determines the final system accuracy.
Different sensor signals are suitable for different situations.
| Signal Type | Typical Applications | Main Advantage |
|---|---|---|
| 0–5 V | Pressure, position, joystick | Common and simple |
| 0–10 V | Industrial sensors, auxiliary systems | Wide voltage range |
| 4–20 mA | Pressure, level, temperature | Good for longer distances and noise resistance |
| Resistive | Temperature, fuel level | Simple sensor design |
There is no single best analog signal type for every mobile machine.
OEM engineers should select sensors and controller inputs according to:
Cable length
Environment
Required accuracy
Existing machine architecture
Diagnostic requirements
Analog sensor signals provide essential real-time information for modern mobile machinery.
Mobile controllers must accurately process voltage, current, and resistive inputs and convert them into useful machine data.
By combining proper signal scaling, filtering, fault detection, and control logic, OEM manufacturers can create more precise and reliable machine control systems.
From hydraulic pressure and position monitoring to temperature measurement and operator inputs, analog signal processing remains a fundamental capability of modern mobile machinery controllers.
SonnePower provides programmable controllers and electronic control solutions for mobile machinery, including:
Analog input channels
Digital inputs and outputs
PWM outputs
CAN communication
Our control solutions help OEM manufacturers integrate sensors, actuators, and communication systems for construction equipment, agricultural machinery, cranes, aerial work platforms, and other mobile applications.
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