The robot must be able to grasp its position and speed of movement in space to ensure its accuracy of movement to perform the actions required, and it needs to rely on gyroscopes and accelerometers to detect angular rates and accelerations of movement. This paper introduces the development and characteristics of gyroscopes and accelerometers, as well as the product characteristics of XYZ-axis gyroscopes and XYZ-axis accelerometers launched by Murata with a high integration of 6 degrees of freedom (DOF).
Microelectromechanical gyroscopes and accelerometers with high accuracy
Both gyroscopes and accelerometers are sensors used to measure the motion state of objects. They are often used in many technological products, such as mobile phones, tablets, robots, drones, etc.
The gyroscopes operate in such a way as to utilize the gyro effect, a physical phenomenon that produces a moment when a rotating object is subjected to external forces, which varies its axis of rotation. In a gyroscope, a rotor is fixed on three axes, and when the gyroscope is subjected to external forces, the rotor is subjected to torque which causes the gyroscope to rotate so that the rotation state of the object can be measured.
Accelerometers operate under Newton's second law of motion, which produces acceleration when an object is subjected to external forces. In an accelerometer, a mass is fixed on a spring and when the accelerometer is subjected to external forces, the mass is compressed or stretched by the spring so that the acceleration of the object can be measured. Typically, accelerometers are installed on three axes to measure the acceleration of objects in three directions.
A gyroscope and an accelerometer are usually combined to form a device called a six-axis sensor. The six-axis sensor can measure both the rotation and acceleration of objects and transmit data to computers or other devices for further analysis and applications.
In recent years, with technological advances, new developments have also taken place in gyroscopes and accelerometers. First, the accuracy and stability of gyroscopes have been greatly improved. A number of high-precision MEMS (Micro-Electro-Mechanical System) gyroscopes have emerged on the market, capable of achieving centimeter-level measurement accuracy and being extremely stable with anti-jamming capabilities.
On the other hand, the application of gyroscopes and accelerometers is expanding. In addition to traditional motion detection and mobile sensing applications, there are now many new applications, such as unmanned driving, smart fitness, virtual reality, and so forth. In response to these applications, the accuracy and sensitivity of gyroscopes and accelerometers are also being further improved, while additional functions and features, such as low power consumption, small footprint, and multi-axis measurements are being added.
Overall, with the advent of technology, the prospects for the application of gyroscopes and accelerometers are broadening and technological innovations and upgrades will continue to be pursued to meet the need for more and higher-end applications.
Select gyroscopes and accelerometers based on application requirements
The selection of gyroscopes and accelerometers requires consideration of multiple factors, starting with the application scenario. Different application scenarios require different gyroscopes and accelerometers, such as mobile sensing, industrial automation, UAV control, etc, and the selection of suitable gyroscopes and accelerometers is based on specific application needs.
Additionally, precision and stability are important performance indicators for gyroscopes and accelerometers, and products of varying precision and stability typically need to be selected based on specific application requirements. Then there is the need to consider the sensitivity and range, which are important parameters for gyroscopes and accelerometers. The higher the sensitivity, the smaller the acceleration range that can be measured. The wider the range, the wider the acceleration range that can be measured, and therefore gyroscopes and accelerometers of different sensitivities and ranges need to be selected based on specific application needs.
On the other hand, selecting reputable suppliers and brands ensures product quality and service. Of course, cost is also an important factor to consider when selecting gyroscopes and accelerometers, and suitable products need to be selected based on budgets.
Selecting gyroscopes and accelerometers requires a combination of factors and selecting suitable products based on specific application requirements. In selecting products, comprehensive comparisons and assessments can be made with reference to technical specifications, performance evaluation, suppliers, and brands.
Highly integrated 6-DOF gyroscopes and accelerometers
Murata develops and manufactures gyroscope and accelerometer components based on the company's mature 3D MEMS technology and highly integrated electronic devices. Murata’s industrial gyroscopes typically provide performance levels only for expensive modular products, sensing elements and measuring circuits assembled in a premolded plastic dual-in-line (DIL) package, protected with silicon gel and covered with stainless steel covers, and all products meet RoHS standards and are suitable for lead-free reflow soldering.
The gyroscope sensor launched by Murata can be used for robotic mobile sensing. This SCHA63T is suitable for industrial applications of 6-DOF XYZ-axis gyroscopes and XYZ-axis accelerometers. This single package of 6-DOF component can achieve an orthogonality margin of error better than 0.14° after cross-axis calibration. The gyroscopic bias instability has a level as low as 1°/h, the gyro noise density level reaches 0.0015°/s/√Hz, has stable offset and sensitivity throughout the temperature range, has excellent linearity and vibration performance, has extensive self-diagnostic functions, and has an angular rate measurement range of ±300°/s and ±6 g acceleration measurement range, can work at a temperature range of −40 °C ~+110 °C, supports 3.0 V ~3.6 V power supply, and has 32-pin robust SOIC housing components compliant with RoHS standards, with a size of 19.71 mm × 12.15 mm × 4.6 mm (length × height × width), which can be used for safety-critical applications.
The SCHA63T sensor is the world's first single package 6-DoF component with this level of performance, a level of inertial sensor performance previously provided only by expensive high-end inertial measurement unit (IMU) modules. This sensor can achieve centimeter-level machine dynamics and position sensing accuracy in harsh environments and help ensure safe, robust, and verified design.
SCHA63T applies to applications that require high performance and harsh environmental requirements, typically including inertial measurement units (IMU), navigation positioning, machine control and guidance, dynamic inclination, robotic control, and unmanned aerial vehicles.
Combined high performance 3-axis angular rate sensors and 3-axis accelerometers
The SCHA63T series consists of two products, SCHA63T-K01 and SCHA63T-K03. SCHA63T-K01 and SCHA63T-K03 are both modular high performance 3-axis angular rate sensors and 3-axis accelerometers. They consist of X, Y, and Z-axis angular rate sensors and an integrated 3-axis accelerometer based on Murata's mature capacitive 3D-MEMS technology. Signal processing is accomplished through two mixed signal ASICs, which provide angular rates through flexible SPI digital interfaces. Sensor components and ASIC are packaged in a premolded SOIC32 plastic housing to ensure reliable operation throughout the product life cycle.
Design, manufacture, and testing of the SCHA63T-K01 and SCHA63T-K03 meet high stability, reliability, and quality requirements. This component have extremely stable output within temperature, humidity, and vibration ranges, and have a variety of advanced self-diagnostic features suitable for SMD mounting and comply with RoHS and ELV directives.
As to gyroscope specifications, the maximum range of the SCHA63T-K01 is (XYZ) ±125°/s and the SCHA63T-K03 is (XYZ) ±300°/s. The amplitude response of the SCHA63T-K01 and SCHA63T-K03 is 13, 20, 46, or 300 Hz. The offset temperature dependence is (Z) ±0.085°/s and (XY) ±0.65°/s. The sensitivity of the SCHA63T-K01 is (Z) 160 LSB/°/s and (XY) 160 LSB/°/s, and the sensitivity of the SCHA63T-K03 is (Z) 80 LSB/°/s and (XY) 80 LSB/°/s. Both products support types of digital/SPI output.
As to accelerometer specifications, the SCHA63T-K01 and SCHA63T-K03 are the same with a maximum range of ±6 g, an amplitude response of 13, 20, 46, or 300 Hz, an offset temperature dependence of (XYZ)±7.3 mg, a sensitivity of 4905 LSB/g, and types of digital/SPI output.
Conclusion
Gyroscopes and accelerometers are key components of robotic applications and have an important impact on the accuracy of robotic movements. The highly integrated 6-DOF XYZ-axis gyroscopes and XYZ-axis accelerometers introduced by Murata using 3D MEMS technology, can meet the needs of robotic applications in accuracy, volume, and temperature range, and will be ideal for robotic applications.