What types of feedback sensors exist besides encoders and resolvers?
Modern automation and robotics rely on a wide range of sensors to provide accurate feedback for control systems. While encoders and resolvers are the most common, many other sensor types play a crucial role in monitoring motion, force, pressure, and environmental conditions. Selecting the right feedback sensor ensures optimal system performance, safety, and reliability.
- LVDT (Linear Variable Differential Transformer): Non-contact sensor for precise linear displacement; widely used in aerospace and automation.
- Tachometer Sensor: Measure rotational speed of motors/shafts; provide analog or digital output for speed control.
- Force Sensors (Load Cells): Detect force, weight, or load; common in robotics and material testing.
- Accelerometers: Measure acceleration and vibration; used in machinery monitoring, vehicles, and devices.
- Gyroscopes: Provide angular velocity data; essential in navigation, drones, and robotics.
- Pressure Sensors: Detect gas or liquid pressure; used in HVAC, hydraulics, and fluid systems.
- Temperature Sensors: Thermocouples, RTDs, and thermistors track heat in manufacturing and electronics.
- Proximity Sensors: Sense presence/absence of objects for automation and safety systems.
- Hall Effect Sensors: Detect magnetic fields for position/speed; often used in motors and vehicles.
- Strain Gauges: Measure mechanical strain in structures and aerospace applications.
These sensors complement or compete with encoders and resolvers, depending on application needs for accuracy, reliability, and performance.
What specific quantities do these sensors measure?
Sensors are designed to detect specific physical quantities, converting them into measurable signals for control and monitoring systems.
- Temperature Sensors: Measure heat levels; results in °C, °F, or K.
- Pressure Sensors: Detect force from gases/liquids; expressed in Pa, bar, or PSI.
- Proximity Sensors: Measure distance without contact using IR, ultrasonic, or capacitive tech.
- Accelerometers: Detect acceleration, vibration, or shock; measured in m/s².
- Gyroscopes: Measure angular velocity; given in °/s or rad/s.
- Light Sensors: Detect light intensity; results in lux or lumens.
- Humidity Sensors: Measure air moisture; shown as %RH.
- Gas Sensors: Detect gas concentration; reported in ppm.
- Magnetic Sensors: Measure magnetic fields; expressed in gauss or tesla.
- Sound Sensors (Microphones): Detect sound levels; measured in dB.
These sensors are applied across automation, environmental monitoring, industrial control, and consumer electronics to ensure accurate data collection and reliable system performance.
When might you choose an LVDT or a tachometer for feedback?
LVDT is chosen when you need high-precision, contactless linear displacement measurement - such as in hydraulic actuator position feedback, material testing machines or precision assembly equipment.
Tachometer sensor is selected for direct, real-time rotational speed feedback in motor control, conveyor monitoring or any application requiring closed-loop speed regulation and over-speed protection.
How do force sensors enable closed-loop force control?
A force sensor measures the actual force applied and sends that signal to the controller, which compares it to the desired force setpoint. The controller then adjusts the actuator’s drive commands (current or pressure) to eliminate any difference. This continuous sense–compare–correct cycle maintains precise, consistent force in tasks like robotic assembly, torque control in screwdriving, or pressure regulation in sealing processes, protecting both tool and workpiece.