This paper presents a novel design of a fault-tolerant, coplanar, and gyro-free inertial measurement unit (IMU) that consists of 13 single-axis linear accelerometers and can perform six degree-of-freedom (DOF) measurements for an object in motion. This design uses a combination of redundant accelerometers, an innovative real-time fault-identification technique, together with state-estimation techniques to facilitate robust six DOF measurements, even when some of its accelerometers produce faulty outputs. A design example indicates that the proposed fault-tolerant design and compensation algorithm can detect and correct the biased accelerometer outputs in real time. In this simulation example, the accelerometer measurement noise is assumed to be white and set at 0.1 m/s2. The minimum detectable dc-offset value is 0.1 m/s2, which is the same as the standard deviation of the accelerometer measurement noise. The compensated accelerometer outputs were used to construct an "observer-based" gyro-free IMU. The angular-velocity estimation accuracy is 4 × 10-3 and the linear-acceleration accuracy is less than 0.24 m/s2. The IMU output accuracy is not affected by the proposed fault-compensation algorithm.