ICM-42688-P
Low-noise, low-latency 6-axis. No magnetometer, no fusion — you get clean raw rates and write the estimator yourself, which is what legged-robot people actually want.
The role it plays
Sensors split into proprioception — encoders, IMUs, joint torque, motor current — which tells the robot about itself, and exteroception — LiDAR, depth, force, GNSS — which tells it about the world. Build proprioception first. A robot that does not know where its own joints are cannot use a good world model anyway.
Typical use: Quadruped state estimation, VIO front ends, drones.
What the numbers actually mean
The headline figure is 3-axis accel (±16 g) + 3-axis gyro (±2000 °/s) (dof), with SPI up to 24 MHz, I²C as the next most load-bearing number (interface). At $5 in the sensors tier it sits cheap enough to prototype with and replace without regret, which is the correct way to learn a new subsystem.
How it compares
Same subsystem, closest alternatives. The primary spec column is usually the one that decides it.
| Part | Price | Primary spec | Second spec |
|---|---|---|---|
| ICM-42688-P6-axis IMU | $5 | 3-axis accel (±16 g) + 3-axis gyro (±2000 °/s) | SPI up to 24 MHz, I²C |
| AS5600 magnetic encoderAbsolute rotary encoder | $3 | 12-bit (4096 counts/rev) | I²C (also analog / PWM out) |
| AS5047P magnetic encoderAbsolute rotary encoder | $10 | 14-bit (16384 counts/rev) | SPI + ABI quadrature + UVW |
| CUI AMT102-VCapacitive incremental encoder | $25 | up to 2048 PPR (configurable) | Quadrature A/B/Z |
| BNO085 9-DOF IMUIMU with onboard fusion | $25 | 3-axis accel + gyro + magnetometer | Quaternion / Euler / rotation vector, plus raw |
Where it shows up
Platforms in this atlas that use something in this class: MIT Mini Cheetah.