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This paper provides a methodology for the estimation of resistance, thrust, and resistive torques on each wheel of a rigid-wheeled vehicle generated at the vehicle--terrain interface, and from these forces and moments, a methodology to estimate terrain parameters is presented. Terrain force estimation, which is independent of a terrain model, can infer the ability to accelerate, climb, or tow a load independent of the underlying terrain properties. When a terrain model is available, parameters of that model, such as soil cohesion, friction angle, maximum normal stress, and stress distribution parameters, are determined from estimated vehicle-terrain forces using a multiple-model estimation approach, providing parameters that relate to accepted mobility metrics. The methodology requires a standard proprioceptive sensor suite--accelerometers, rate gyros, wheel speeds, motor torques, and ground speed. Sinkage sensors are not required. Simulation results demonstrate efficacy of the method on three terrains spanning a range of soil cohesions reported in the literature. Index Terms--Mobile robot dynamics, terrain factors.

Historians have examined the significant contributions John and William Bartram made to 18th- and 19th-century knowledge of indigenous North American flora. However, the Bartrams' contribution to medicinal botanical knowledge, particularly William Bartram's compilation of Indians' knowledge on the preparation and use of medicinal botanicals, is not well-known. In addition, while William Bartram's contemporaries relied on his accounts of medicinal botanicals, they rarely acknowledged Bartram or Indians in their own works. Contemporaries plagiarized Bartram's writings and used his exquisite illustrations to ornament their own publications. This paper reconstructs William Bartram's careful collection and recording of medicinal botanical knowledge that became part of late 18th- and early 19th-century American pharmacology, as well as provides evidence for 54 Bartram-identified indigenous species and the pirating of William Bartram's work by contemporaries.