An Effective Rigid Body Math Model

This technical brief summarizes an elegant algebraic description of rigid body position and attitude along with analytical derivatives associated with body motions. The equations presented here offer a fully general representation that is entirely singularity-free. The expressions capture all six degrees of freedom associated to a physical body within a math model containing exactly six free parameters based on the exponential map. A particularly pragmatic benefit is that the math model and all of its parameters have direct associations with physical characteristics that can be observed and/or measured directly by physical instrumentation and sensor systems. The expressions describing body position and attitude are necessarily non-linear, but have relatively simple forms on which simple numerical solution methods are exceptionally effective.