ST Rolls Out IMU Geared for Industrial and Robotic Designs

STMicroelectronics has released a new inertial measurement unit (IMU) solution that integrates a six-axis IMU, embedded machine-learning processing, and analog sensing. The ISM330BX includes a three-axis accelerometer and a three-axis gyroscope in a compact package.

Engineered for precision, the highly integrated device targets applications requiring accurate motion sensing, such as industrial, automotive, and consumer electronics.

A Highly Integrated Six-Axis IMU

The ISM330BX leverages a 16-bit data output for both the accelerometer and gyroscope. The accelerometer can measure up to ±16 g, while the gyroscope covers up to ±2,000 degrees per second (dps). The IMU’s architecture includes a low-noise density of 70 µg/√Hz for the accelerometer and 3.8 mdps/√Hz for the gyroscope. The sensor’s performance is further enhanced by its ability to output data at up to 6.6 kHz. The ISM330BX (datasheet linked) also supports programmable digital filters, which allow developers to tailor the sensor’s response to specific application needs.

A notable feature of the ISM330BX is its high level of integration, including an embedded machine-learning core. This enables advanced motion detection algorithms to run directly on the sensor, reducing the processing burden on the main application processor and lowering system power consumption. The IMU also includes a finite state machine and an analog hub for sensor expansion in the same package.

With an eye on low power and space-constrained designs, ST designed the ISM330BX to operate on a voltage range of 1.71 V to 3.6 V and in a 2.5 mm x 3 mm x 0.83 mm package. In normal mode, the accelerometer and gyroscope consume 0.65 mA each. In power-down mode, consumption drops significantly, conserving energy for battery-powered applications. The ISM330BX features FIFO buffers of 3 kB for the accelerometer and gyroscope. This reduces constant processor intervention by allowing batch processing of sensor data.

What Is Qvar Sensing?

Among the other integrated features in the ISM330BX, ST included support for its unique Qvar electric charge variations sensing.

Qvar sensing leverages electrostatic charge detection to enable a variety of applications such as human presence and motion detection, touch interfaces, and water detection. This technology operates on the principle that electrostatic charges are generated whenever two materials come into contact and then separate, a phenomenon known as triboelectricity. When a charged object moves near or touches an electrode, it induces an electrostatic charge variation that can be detected and measured.

Qvar sensing can detect both contact and non-contact human motion by measuring quasi-electrostatic potential changes. For instance, when a person walks, static electricity generated by the interaction between their body and the environment causes detectable electric potential changes. This capability makes Qvar highly effective in applications like human gait analysis and presence detection. The sensor can also function in different configurations, such as on-body with or without direct skin contact, or in a radar mode where no direct contact is necessary​.

The Qvar sensing channel includes external electrodes, an analog front end (AFE), an analog-to-digital converter (ADC), and a digital processing unit. The electrodes, which can be made from materials such as copper, silver, or tin, detect electrostatic charges. The AFE processes these charges and converts them to digital signals by the ADC. The digital processing unit further processes these signals and interfaces with external systems via SPI or I2C communication protocols.

Advanced Sensing for Advanced Solutions

As modern electronic solutions become more intelligent and autonomous, we need better ways to capture, interpret, and analyze positional data from IMUs. With the ISM330BX, STMicroelectronics is hoping to bring the power of AI and analog sensing into a single package to provide a robust and comprehensive solution in the industrial and robotic sectors.

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