Most of us are fans of Video Games. We played a lot of games on our mobiles like PUBG, Call Of Duty and my personal favorite Asphalt. In all these games one thing we all notice is that as we rotate or bend our phone, the car also rotates in the same direction. Have you ever imagined how this would happen? Well their are electronic sensors: accelerometer and Gyroscope Lets dive into this blog, to know the Ans for this!!! What is an ACCELEROMETER WORKING Let us assume a small ball being placed in a box filled with vacuum and no external force is applied to it (i.e., consider the situation of outer space). Now initially the ball will be at the center of the box. Consider each side of the box as an axis. Suddenly we start moving the box to the left side with the acceleration of ‘g’ (i.e., 9.8m/s2), the ball will hit the +X side of the box. Since no external force is acting on it, and the entire thing is weightless (vacuum state), hence the force comes out to be ‘g’. Consider another scenario when the box is moved upwards with the same acceleration ‘g’. Now again the ball will hit the downward side of the box i.e. +Z axis with the force equal to ‘g’. This is just a simple explanation on how an accelerometer works but in practical scenario accelerometers are based on MEMS technology built on a silicon wafer with companion CMOS electronics through wafer-level bonding. Taking the above situation in mind, there consists of a silicon wafer having polysilicon springs connected with a suspended plate covered with fixed mass around it on the wafer where in between the space, this fixed plate moves. This entire structure reflects the changes whenever acceleration is applied across the X,Y and Z axis. This reflection is reflected by the capacitance change placed in between the fixed masses as the suspended plate moves thus the sensor records this change in capacitance as the final reading. GYROSCOPE WORKING Since the accelerometer measures the linear acceleration, the gyroscope on the other hand measures the angular rotation which is accomplished by Coriolis Effect. Coriolis Effect The Coriolis Effect states that when a mass (m) moves in a specific direction with a velocity (v) and an external angular rate (Ω) is applied, the Coriolis Effect generates a force (F) that causes the mass to move perpendicularly. The value of this displacement is directly related to the angular rate applied. Consider two masses oscillating in opposite directions at a constant frequency. When an angular rate is applied, the Coriolis effect produced by each mass is in opposite directions, resulting in a proportional change in capacitance between the masses. By measuring this change in capacitance, the angular rate can be calculated. The MEMS sensor consists of a proof mass (i.e., it consists of 4 parts M1, M2, M3. M4) that continuously oscillates inward and outwards in the plane, thus causing a coriolis effect. When the structure is being rotated, the Coriolis Force acts on the moving mass causing oscillations in the plane. There are three modes depending upon the axis along which the angular rotation is applied: Roll Mode: When the angular rate is applied at the X-axis Pitch Mode: When the angular rate is applied at the Y-axis Yaw Mode: When the angular rate is applied at the Z-axis What is A MUST HAVE Motion Interfacing one finds in almost every smartphone and tablet. It is a 3-axis gyroscope and 3-axis accelerometer, in total an integrated 6-axis MotionTracking device all in a single small 4x4x0.9mm package. This package size has been achieved by the MEMS (MicroElectroMechanical System) innovation. Coming to some technical aspect of the IC, It comes with a dedicated I2C sensor bus at 400KHz Features 3 16-bit analog-to-digital converters (ADC) each for digitizing gyroscope and accelerometer outputs. Gyroscope full-scale range of 250,500,1000 and 2000 degree/sec (DPS). Accelerometer full-scale range of 2g,4g,8g,16g and On-chip 1024 Byte FIFO buffer which enables the system to read the sensor data in burst and then enter the low-power mode. Lastly, it operates at a power supply voltage range of 2.375V – 3.46V. Features of ACCELEROMETER in MPU6050IC Features of GYROSCOPE in MPU6050IC Features of ACCELEROMETER in MPU6050IC Features of Accelerometer in MPU6050IC The triple-axis MEMS accelerometer in MPU-60X0 includes a wide range of features: Digital-output triple-axis accelerometer with a programmable full scale range of ±2g, ±4g, ±8g and ±16g Integrated 16-bit ADCs enable simultaneous sampling of accelerometers while requiring no external multiplexer Accelerometer normal operating current: 500µA Low power accelerometer mode current: 10µA at 1.25Hz, 20µA at 5Hz, 60µA at 20Hz, 110µA at 40Hz Orientation detection and signaling Tap detection User-programmable interrupts. Features of GYROSCOPE in MPU6050IC GYROSCOPE FEATURES The triple-axis MEMS gyroscope in the MPU-60X0 includes a wide range of features: Digital-output X-, Y-, and Z-Axis angular rate sensors (gyroscopes) with a user-programmable fullscale range of ±250, ±500, ±1000, and ±2000°/sec External sync signal connected to the FSYNC pin supports image, video and GPS synchronization Integrated 16-bit ADCs enable simultaneous sampling of gyros Enhanced bias and sensitivity temperature stability reduces the need for user calibration Improved low-frequency noise performance Digitally programmable low-pass filter Gyroscope operating current: 3.6mA Standby current: 5µA Factory calibrated sensitivity scale factor MPU6050 of MPU6050 Block Diagram of MPU6050 IC Gyroscope sensor Accelerometer sensor Digital Motion Processor (DMP) engine Primary I2C Auxiliary I2C Clock Generation Sensor Data Register FIFO Buffer Interrupts Digital Output Temperature Sensor Bias and LDO Charge Pump Gyroscope sensor Three-axis MEMS rate gyroscope sensor with 16-bit ADCs and signal conditioning It consists of three independent vibratory MEMS gyroscopes, which detect the rotation about the X, Y, Z axis. The capacitive change due to Coriolis Effect is observed whenever a rotation is caused about any of the axes. The corresponding signal is then amplified, demodulated and filtered to the corresponding voltage levels that relate to the angular rate. The sensor has an on chip 16 bit ADC to
