September 01, 2015      

To achieve human-like qualities, and in particular fluid limb movement, today?s robot design engineers are challenged with the goal of developing robots with fine motor joint control of their arms, legs, waists and heads. Additionally, they require a robust solution that provides energy efficient joint motor control. As part of achieving this goal, engineers need high resolution, high accuracy, motor position feedback information for ensuring the robot joints move to the positions they are commanded to by the robot?s central processing unit. Moreover, the position feedback sensors needed to be fast, small and co-located with the joint motors. ams? AS5048 rotary magnetic position sensor IC rises to that challenge.

The AS5048, with high resolution and low propagation delay, is ideal for providing on-axis contactless motor position feedback in robot joint control applications. With its fast output refresh rate, high accuracy performance, and immunity to stray fields the AS5048 enables robots to achieve fine joint motor control and nearly human-like limb motion.

Available with either a SPI or I2C interface, depending upon the device version, the AS5048 can supply high accuracy, low latency angle measurements directly to a co-located host microcontroller. The AS5048 also supports a PWM output for remote applications where the microcontroller is not co-located with the sensor IC. In addition, multiple devices can be daisy-chained together to produce a serial data read-out, hence reducing wire material and assembly costs, and overall robot weight. At the core of the AS5048 is a highly sensitive Hall element array and a 14-bit measurement engine. These two key components enable the device to provide resolution down to 0.0219°. And with linearization and averaging implemented in a host microcontroller, the AS5048 based solution can deliver angle measurements accurate to 0.05°, thus enabling smooth robot joint motor control and limb movement.

The AS5048 is designed to provide high accuracy results, over a wide input magnetic field range of 30-70mT, when paired with a low cost two pole magnet. The device can also tolerate wide variations in air gap. And like all ams? magnetic rotary position sensors, the AS5048 is immune to any stray magnetic fields. Consequently, even in a magnetically noisy environment, which is often the case in an industrial robot production line, the AS5048 will continue to provide highly accurate and repeatable rotary position measurements.

With on-chip One-Time-Programmable (OTP) fuses the AS5048 can be end-of-line programmed for zero-position orientation with its paired target magnet, thus eliminating the need for any type of mechanical alignment of the sensor and target magnet during production. The OTP fuse technology also makes the AS5048 impervious to cyber-security hacking, a major concern with robot manufacturers, as cyber-security risks could impeded robot market growth.

The AS5048 sports an internal regulator enabling it to operate from either a 3.3V or 5.0V supply, and consumes 15mamps (max) of current. The device also supports a wide operating temperature range of -40 to 150oC, and is available in a small and ultra-low 14-pin TSSOP package, making it ideally suited for small robot joints.