High-precision steering effort sensor: The CLS

With the innovative CLSx steering effort sensor, the original steering wheel of your vehicle becomes a high-precision instrument that measures steering torque, angle, steering velocity and acceleration in x, y and z directions. Whether passenger car, truck or construction machinery, the ultra-slim sensor can be placed between the steering column and steering wheel in just a few simple steps. The functionality of the original steering wheel including airbag is completely preserved.

Important features at a glance:

  • Detects torque, angle and rotational velocity
  • Acceleration measurement in X, Y & Z directions
  • World's smallest and lightest sensor
  • Optimized for autonomous driving tests
  • Quick and easy installation on almost all vehicles

Ideal for the following standards:

  • ISO 4138 Steady-state circular driving
  • ISO 7975 Braking in a turn
  • ISO 7401 Lateral transient response test
  • ISO 3888 Severe lane-change maneuver
  • ISO 7401 Sinus weave test
  • ISO 17288 Free-steer behavior
  • ECE-R 79 Steering equipment
  • NHTSA Fishhook test (tipping stability)

Innovative steering sensor for modern tests

The innovative CLSx steering effort sensor measures torque, steering angle and velocity with high precision. Additionally, it also acquires acceleration in the center of the steering column (x, y and z direction), as well as rotational acceleration. The CLSx sets new standards in the size of the housing as well as in resolution and accuracy of measurement values.

High-resolution A/D converters with 24 bits ensure especially good signal quality and noise-free results even at small moments below 3 Nm. This is particularly important when testing driver assistance systems and autonomous driving to determine the overpressure torque. Combined with the innovative design of the sensor housing, this results in a highly accurate steering torque measurement of 0.1% FS (at ±100 Nm). The torsional stiffness of the sensor (without adaptation) is 0.025° at 100 Nm.

Measured variables

  • Torque ±100 Nm (others on request)
  • Steering angle ±1440° (± 4 revolutions)
  • Steering velocity ±2048°/sec
  • Acceleration in x, y & z directions
  • Rotational acceleration

Award Winner

The CLSx is much smaller than comparable products. In addition, we were able to significantly improve the measuring accuracy of the sensor through the optimized design.

Florian Sailer, CAEMAX Technologie GmbH

These advantages convinced both the editorial staff of the trade journal messtec drives automation and the specialist audience: The CLSx was awarded the Messtec & Sensor Masters Award in the sensor category.

Comfortable and quick mounting

The CLSx steering effort sensor is mounted between the original steering wheel and the steering column in just a few simple steps. The wiring (LIN bus) of the original wheel is simply routed through the sensor so that all electrical functions and the airbag are retained. With an extremely narrow installation height of 30 mm (without adapter), it extends the steering column only minimally.

Via the CAEMAX adapter systems, which are manufactured according to the vehicle, the steering sensor can be used on almost all vehicle types available worldwide. The ESP functionality of the vehicle is maintained by optionally available adapters for the ESP angle sensor integrated in the vehicle. With short set-up times and convenient software functions, such as remote zeroing for torque and angle of rotation, the system is test ready in a very short time.


The application possibilities of the steering effort sensor are numerous: from classical tests for the tuning of the steering system in passenger cars to verification measurements for construction machines and validations of autonomous vehicles.

Steering system setup

The CLSx steering sensor is particularly suitable for use in driving dynamics tests such as:

  • ISO 4138 Steady-state circular driving
  • ISO 7975 Braking in a turn
  • ISO 7401 Lateral transient response test
  • ISO 3888 Severe lane-change maneuver
  • ISO 7401 Sinus weave test
  • ISO 17288 Free-steer behavior
  • ECE-R 79 Steering equipment
  • NHTSA Fishhook test (tipping stability)

Evaluation of driver assistance systems and autonomous driving

When operating vehicles with driver assistance systems, Advanced Driver Assistance Systems (ADAS) and autonomous driving functions, the following still applies: the driver is responsible and must be able to control his vehicle at all times. This means that steering maneuvers by ADAS systems such as lane keeping and lane change assistants must be able to be influenced manually by the driver at any time. The steering torque required for this - also known as overpressure torque - must not exceed 3 Nm.  The CLSx steering sensor is ideal for investigating this overpressure torque, as it delivers high-resolution results even in this small measurement range. The original steering wheel with all functions, including airbag and capacitive hands-off detection, is retained. Due to the very compact size and the low weight, the sensor has a low mass inertia torque. In addition, it operates with particularly low friction. All this ensures that the mounted steering sensor has hardly any influence on the steering system of the production vehicle. The steering behavior thus remains equivalent to that of the production vehicle.

Misuse test for steering systems

In a misuse test, the behavior of a vehicle or a vehicle component is examined in extreme situations - as is the case with steering systems. A test is the sliding along an obstacle with corresponding steering torque and permanent steering angle, for example on a curb.
The CLSx steering sensor can be used to precisely examine the maximum steering torques that can occur. For safety reasons (protection of the test driver), the CLSx steering sensor has a high breaking strength of over 500 Nm.

Comfort measurements

Comfort and handling behavior are tested in continuous operation under realistic driving conditions. An important component is the measurement of steering vibrations in the x, y and z directions. With the integrated MEMS acceleration sensor, the CLSx steering effort sensor measures vibrations in all three spatial axes up to 5 g. In addition, the rotational acceleration up to ±10,000 °/s2 is also measured.


Thanks to the universal adapter system, the CLSx steering effort sensor can be used to investigate the steering behavior of almost all steering systems in vehicle construction and mechanical engineering sectors:


  • Passenger cars and trucks
  • Agricultural machinery (tractors, harvesters)
  • Road construction machines and special vehicles
  • Shipbuilding, watercraft, aviation
  • Test benches for steering systems

Technical Data - CLSx

Steering torque

Measuring principletemperature compensated strain gauge application
Measurement range±100 Nm others upon request
Accuracy0.1% FSCombined (gain error and non-linearity)
Bandwidth0 to 800 Hzsampling rate 5 kHz

Steering angle

Measuring principleincremental angle encoder
Measurement range±1440 °
Accuracy0.045 °
Bandwidth0 to 800 Hzsampling rate 5 kHz

Steering velocity (angular velocity)

Measuring principlecalculated from angle
Measurement range±2048 °/s
Bandwidth0 to 800 Hzsampling rate 5 kHz

Vibration and acceleration

Vibrationin the center of the steering column, measurement range up to 5 g in x, y and z direction
Rotational accelerationmeasurement range ±10000 °/s2

General data

Sensor heightapprox. 30 mmwithout adapter
Sensor weightapprox. 0.6 kgwithout adapter
Overload>100% of the measurement range
Mech. breaking torque>500 Nm
Adaptionspecial adaption sets for any car or truck manufacturer available

Moment of inertia

Steering wheel or column adapter

approx. 3000 g cm2

typ. approx. 500 g cm2
Working temperature-20°C to +80°C

Control unit

Supply9 to 36 V DC
CAN outputfreely configurable
Analog outputfreely configurable, max. ±10 V
Auto zerowith push-button for torque and angle at
the panel or by remote control

imc Test & Measurement is an Axiometrix Solutions company.