Hand Detection, Basic Function - GF82.90-S-9904A
All models (Light vans) with steering wheel generation 5 (Capacitive steering wheel) and code CA3 (Active Steering Assist)
Example illustration of hand detection sensor
Example illustration of hand detection control unit
Overview
This document contains information on:
- General
- Function requirements
- Function
- Networking
- Hand-detection sensor
General
Hand detection detects whether the driver is in contact with the steering wheel via the hand detection sensor (1). The hand detection system control unit (2) then processes, passes on, and uses this information to implement various functions.
Function requirements
- Circuit 15 ON
Function
Networking
The hand detection system control unit (2) receives signals from the hand detection sensor (1) and is connected with the steering column tube module control unit.
The hand detection system control unit (2) processes the signals from the hand detection sensor (1) and sends the following signals, among others:
- Hand detection system status (system status active/inactive)
- "Hands-Off-Detection" status (hand detection system control unit (2) cannot detect the steering wheel being touched)
Hand-detection sensor
With model series 214, Mercedes-Benz is introducing a completely newly developed steering wheel.
The hands-off detection function now uses a two-zone sensor mat, which is located in soft foam below the steering wheel surface in the steering wheel rim and detects whether the driver's hands are on the steering wheel. One of the sensor surfaces is located on the front side and another on the rear side of the steering wheel rim.
This eliminates the need to carry out an active steering movement in order to signal to the vehicle that the vehicle is being controlled. This increases the operational comfort for partially automated driving SAE level 2.
Touching the sensors causes a capacitance change that is converted into a digital signal by the hand detection system control unit (2). If the driver's hands do not fully grasp the steering wheel but only make contact at the front or side, a lower capacitance change is measured. This is only recognized as touch if the measured value exceeds a specified threshold. If the driver's hands are not on the steering wheel at all for a certain period of time, a warning cascade is started, which ultimately activates the Emergency Stop Assist when the driver is inactive for a prolonged period.
| Component descriptions | |||
| Hand detection sensor, component description | Model 447 with code CA3 (Active Steering Assist) with code XM7 (MOPF II) |
GF82.90-S-0007A | |
| Hand detection system control unit, component description | Model 447 with code CA3 (Active Steering Assist) with code XM7 (MOPF II) |
GF82.90-S-0008A |