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Why Touch Screens Only Respond to Fingers: The Science Behind the Sensitivity

  I. Introduction Touch screen technology enables direct interaction with devices through touch. Using either capacitive or resistive methods, these screens detect user input, translating it into commands. Widely used in smartphones, tablets, and kiosks, touch screens offer intuitive navigation, eliminating the need for physical buttons and enhancing user experience across various applications. Understanding how touch screens work is crucial for users and developers alike. It enhances user experience by ensuring effective interaction, informs choices in device selection, and guides troubleshooting. For developers, knowledge of touch technology is vital for creating intuitive applications and improving interface design, ultimately leading to greater user satisfaction. This blog aims to explore why touch screens predominantly respond to fingers, delving into the science behind touch sensitivity. By examining the principles of capacitive and resistive technology, we will uncover the

steering-angle sensor || How does the steering-angle sensor work?

 What is steering-angle sensor?

The steering-angle sensor is based on Giant Magnetoresistance technology (GMR element) and provides an absolute steering-angle value over the complete steering-angle range (multi-turn sensor). A unique feature of this steering-angle sensor is the output of the correct angle within the measurement range directly after ignition-on. Movement of the steering wheel or other measures for initialization of the sensor (True Power-on) is not required even after disconnection and re-establishment of the power supply.

No standby current is necessary. The steering angle and steering-angle velocity is made available via CAN interface. Sensor-internal plausibility tests and special self-diagnostic functions allow the use of this sensor in safety systems. The sensor concept also allows the integration of a second microprocessor for safety-related applications.



 Why do we need to Measure Steering Angle?

The angle of the steering on its own can be used to determine where the front wheels are pointed. When combined with other pieces of information from the yaw, accelerometer and wheel speed sensors, it is possible to measure the dynamics of the vehicle.

With the collected information, the stability control system can be used to determine the driver’s intentions, how the vehicle is reacting and what corrections can be made with the ABS hydraulic control unit.

 How does the steering-angle sensor work?

The steering-angle sensor is fixed onto the steering shaft, where the hub gear wheel of the sensor transmits the rotary movement of the shaft to two measuring gear wheels. In each measuring gear wheel a magnet is mounted, whose field changes its direction in accordance with the rotational movement. Below each magnet, a GMR sensor element is located to detect the angle position of the magnet above. The analog values of the GMR elements are converted into digital information directly on the circuit, which is then sent to the microprocessor via serial interface.

The measuring gears have different numbers of teeth and therefore change their turning position at different speeds. By means of mathematic functions, it is possible to determine the absolute steering-wheel angle from the position of the measuring gears. In addition, this function enables error correction and a plausibility test of individual signals. This measuring principle enables the measurement of the complete angle range of several steering-wheel turns without the use of a rotation counter.

 


What is the Difference Between Analog and Digital?

Analog SASs are similar to throttle position sensors. SASs are wired with a 5-volt reference, chassis ground and signal outputs, and can be tested via a port under the steering column. As the steering wheel is turned, the SAS produces a signal that toggles between 0 and 5 volts as the wheel is turned 360º. It is possible to observe the 0- to 5-volt signal with meters connected to the two SAS sensors. When the wheels are straight, the sensors read 2.8V and 0.4V. If the readings are the same, the two sensors could be shorted together. Most vehicles produce a positive voltage turning right and a negative voltage turning left.

Digital steering angle sensors measure the angle and turn it into information that can be shared on a serial data bus or discrete connection with a module. Instead of changing voltage, these sensors produce a signal in code that indicates the steering angle. This data PID can be used for electric power steering, intelligent headlights and even stop/start systems.

Types of Steering Angle Sensors

Steering angle sensors come in two types… digital sensors and analog sensors. Digital sensors utilize a small LED light to calculate data about the rate of turn and angle positioning. Analog sensors detect the differences in voltage to calculate this.

When digital sensors detect data related to the rate of turn, the angle of the wheel, the direction of the turn and other important information, it transmits it all to the main computer of the vehicle.

If the steering angle sensor notices an inconsistency between the steering wheel’s position and the direction in which the vehicle is going, then it will implement a stability action to help the driver maintain control of the vehicle. If an understeer state is experienced by your vehicle, the rear brake on the inside of the vehicle will be used to automatically fix this problem.

Now, if the vehicle is experiencing an oversteer state, the rear wheel on the outside will have a brake applied to it by the stability system so that the vehicle will go in the right direction. If the sensor ever malfunctions or stops working, then you should see a warning light on your dashboard turn on to warn you. Once this happens, your stability system is not functioning correctly.

Calibration and Diagnostics

 

When you don’t have the steering position centered in certain Toyota car models, replacing or disconnecting the car battery will result in symptoms of the car wanting to drive itself. You may also notice the output of the engine dropping at certain times.

If you experience any of these symptoms, you must use a good quality automotive scan tool so you can get a reading on the faults. Just remember that not all scanners will detect every kind of fault. If the scan does not produce any engine codes to represent the reason for any power loss, you may still notice that the SAS is reflecting a -560º reading as the steering remains centered. Why would that be?

After you replaced the battery, the vehicle’s wheels may have been turned completely to the left rather than remained in a central position. The reason for this was due to the wheels being in a tight parking area which meant that they needed to be pushed out to get to the battery.

Once the vehicle got its power back and the battery was put back in and connected to the vehicle, the wheels continued to face left while the steering angle sensor detected a zero reading.

In Toyota vehicles, they have a reset process that is known as zero-point calibration. At the beginning of the process, you disconnect the battery from the vehicle. Calibration will not be lost by the vehicle’s stability control module when this happens.

However, there will be a recalibration within the system for the newest position. It does not matter the direction in which the wheels are facing either. That means zero will be given for this position now.

You can use a scan tool to diagnose the problem by graphing the stability system sensors on it. Make sure you use leveled ground to perform these diagnostics. If you cannot find ground that is leveled, then an alignment rack may help.

 https://cartreatments.com/steering-angle-sensor-info/#:~:text=Steering%20angle%20sensors%20come%20in,in%20voltage%20to%20calculate%20this.


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