Abstract— Rotational speed measurement with the help of wheel speed sensor is most essential task in today´s world .Wheel speed sensor in one the most important component of Anti-lock Braking System (ABS).They not only senses the rotational speed of the wheel but also helps for traction control & stability control system. Mostly used wheel speed sensors are magnetic which are under passive sensors. They develop an alternating current (AC) which increases frequency and amplitude with wheel speed. These wheel speed sensors works on different principles like Hall Effect. Magneto-resistive Effect etc. Sensors which are used to measure rotational wheel speed works well for conventional Anti-lock Braking System. For electric vehicles conventional …show more content…
∆R is in the range of 2 to 3% of R0 .
Magneto-resistive effect is non- linear by nature. Many of magneto-resistive sensors use a `barber pole´ construction to linearize the resistance and magnetic field relationship. These types of sensor have the biggest range of linearity. In order to achieve maximum signal output, four magneto-resistive sensors elements are arranged in a Wheat-stone-bridge with the orientation of the barber-pole stripes [10]. Perm-alloy is usually used material for magneto-resistive sensors because of mainly two reasons. First is due to its high magneto-resistive coefficient. Secondly its characteristics are suitable with the fabrication techniques which help to make silicon integrated circuits. Perm-alloy consists of 20%Fe and 80%Ni. Fig.7 shows typical magneto-resistive curve for perm-alloy. Resistance will change only 2% under saturation condition [11-15].
A. Rotational Speed Measurement with Magneto-resistive sensor Rotational speed measurement using magneto-resistive sensor is derived by counting ferromagnetic marks like in the same way as teeth of passive gear wheel. Except this we can use Hall Effect as well as Inductive sensor for this task. But because of some advantages like high sensitivity, more temperature stability, high reliability ,Wide air gap , Insensitive to vibration makes them first choice now a
The electronics industry relies heavily on devices that acquire, store and transmit data. NVE Corp’s spintronics technology focuses on magnetic sensors, couplers, and memory which perform these activities w...
Microelectromechanical Systems (MEMS) are systems that are designed on a micro metre scale and have become more popular as the demand for devices to get smaller has increased. The main uses of these systems are for sensors, such as accelerometers and gyroscopes and other such devices like microscopy and inkjet nozzles for example. There are many materials that can be used for MEMS as the cost of the material is almost eradicated due to the micro size of the systems being produced. This brings materials such as gold, platinum and diamond can be used, as these materials have some properties which are very desirable for a MEM systems. The most common material that is currently used in MEMS is silicon and silicon based compounds as they possess many good properties for MEMS production. Most of the materials chosen for MEMS are semiconductor materials Figure 1 shows the properties of commonly used materials.
A change in resistance is observed by changing the current (or voltage), keeping the voltage (or current) constant. Each taxel contains a pressure sensitive crystal in the form of conductive rubber, elastomer or conductive ink. Measuring change in resistance requires a simple circuitry and hence, these are simpler to manufacture. Applied for touch sensing in anthropomorphic hands (Weiss & Worn 2004), piezoresistive tactile sensing, has become popular among the MEMS and silicon type tactile sensors (Woffenbuttel & Regtien 1991; Beebe, Hsieh et al.
Magnetism is very useful in our daily life. A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. In addition, magnetic field is a region which a magnetic material experiences a force as the result of the presence of a magnet or a current carrying conductor. Current carrying conductors also known as wire. As we know there have north pole and south pole of a magnet. If same pole of magnet approaches each other, there will repel each other. In contrast, if different pole of magnet approaches each other, they will attract. These are same with the electric charge, if same charge it will repel, different charge it will attract. Although magnets and magnetism were known much earlier, the study of magnetic fields began in 1269 when French scholar Petrus Peregrinus de Maricourt mapped out the magnetic field on the surface of a spherical magnet using iron needles [search from Wikipedia]. Noting that the resulting field lines crossed at two points he named those points 'poles' in analogy to Earth's poles. Each magnet has its own magnetic field which experiences a force as the result of the presence of a magnet and magnetic field has made up of magnetic field lines. The properties of magnetic field lines is it begin at the north pole and end at the south pole. The north pole always flow out while south pole always flow in. The closer the magnetic field lines, the strength of magnetic field increases. Furthermore, these line cannot cross each other. Ferromagnetism is the basic mechanism by which certain materials (such as iron) form permanent magnets, or are attracted to magnets. Ferromagnetic materials...
Aim To investigate what affects temperature has on the strength of a magnet. Hypothesis: My hypothesis is that as the temperature of the magnet increases the strength of the magnet will decrease. This is because of the atomic structure of the elements that make up the alloy.
In fabrication micro-sensors and devices micro-electro-mechanical systems (MEMS) provides significant opportunities, which are borrowed it fabrication abilities from semiconductor technology.
A direct current in a set of windings creates a polar magnetic field. A torque acts on the rotor due to its relation to the external magnetic field. Just as the magnetic field of the rotor becomes fully aligned with the external magnetic field, the direction of the current in the windings on the armature reverses, thereby reversing the polarity of the rotor's electromagnetic field. A torque is once again exerted on the rotor, and it continues spinning.
...ads. The theory behind this is that a non-rotating tire has less traction than a spinning one. The ABS will allow the vehicle to stop faster than when the wheel is skidding and allow the driver to remain in control of the vehicle while it stops. With the technology today, there are sensors attached to the wheels to sense when one wheel is spinning at a different speed than another.
ABS (Anti-lock Braking System) is a system which stops the wheels locking up into a skid when braking on slippery surfaces. It works by using a computer which monitors wheel speeds and drives pistons which alternatively increases and decrease brake pressure several time a second on individual wheels when it senses they are about to lock up.
Magnets are stones that produce magnetic fields. The magnetic field is invisible, but is responsible for the most noticeable aspect of a magnet: the attraction of a metal object or the repulsion of another magnet. Magnets are used in common everyday household items: credit cards, TVs, speakers, motors, and compasses. A magnets strength is measured by its magnetic moment. (“Magnetism”)
Magnets have had a slow and humble start but quickly took off, the discovery of their ability to be affected and effect electrical currents around them. They have been attempted to be used in conventional and nonconventional ways alike from converting energy to relieving pain. We’ve learned that because they are unable to generate their own power we cannot use them as a power source but we can in fact use them for power conversions. I believe further studies in field of magnets will reveal further applications of magnets in the future and quite possibly the application of magnets as a power source.
Magnetic bearings can be broken down into two different categories depending on what type of application it will be implemented in: passive magnetic bearings and active magnetic bearings. Passive magnetic bearings use permanent magnets, which allow the the shaft to hold the position through the center of the bearing without the necessary use of electrical input power. These permanent magnet are placed around the inside of the cylindrical bearing to make sure the shaft levitates freely without the help of surface friction. The advantage is that these magnets are able to keep the shaft in equilibrium without the help of external electricity. The problem that the passive magnetic bearing faces is that it is very difficult to design these types of permanent magnetic bearings because of limitations in the actual permanent magnet. The limitations are that since there is no need for external electricity in a permanent magnet, that actual lack of it makes it hard to create an assemblage of point charges that buil...
Electric motors are the most common device for converting electrical energy into mechanical power. According to the laws of physics "whenever a current carrying conductor is placed in a magnetic field, it experiences a mechanical force"[1]. The Armature which is simply a coil of wires is places between two magnets. When the current is supplied through the armature an electromagnetic force is induced on it according to the Lorentz law so the coil will start to rotate. As the armature is connected to the commutator rings which is connected to power supply of opposite polarity. This guarantees that the rotation action is always in the same direction throughout the motion of the armature, so the coil will continue on rotating. This rotation is
There are two types of motors dc motors and AC induction motors, the two motors have both the same function to convert the electrical energy into mechanical energy but the difference is the type pf power which is used in each motor the DC motors use the direct current while the AC induction motors use the alternating current. The speed of the two motors is varied the DC motor use armature current to control it while the AC induction motor is being controlled by the frequency. The AC motors is classified into two types the first type is induction motor which is operated by applying the magnetic field on the rotor while the other type is synchronous motor which is rotating at the supply frequency but the speed and velocity of synchronous motor is higher than the induction motors.
Electrical motors play an important role in today’s society, from powering domestic appliances like blenders to industrial equipment such as trains. It almost seems impossible to not use an electric motor in our daily lives. In the comfort of our home, electric motors will operate fans, refrigerators, and air conditioners to just name a few. Researchers are constantly looking for new ways to incorporate electrical motors into our lives. Electrical motors function by converting electrical energy into mechanical energy by using the energy stored in the magnetic field (Sarma, 1981).