Estimating planetary terrain slopes from range measurements using a two dimensional spline smoothing technique

A new scanning scheme is presented for implementation for terrain slope estimation on a Martian exploratory rover. The rover will be equipped with a laser rangefinder as a principal sensing device for distance in its navigational equipment. A scan of the horizontal terrain from 5-50 m is indicated, and calculations are devised for quantifying the range errors. A constant incremental pointing angle is ruled out and a set of three pointing angles for different sub-areas of scan are defined. A two-dimensional smoothing algorithm is described for estimating slopes. The resultant scanning scheme involves the use of the characteristic curves derived from the relationships between the incremental elevation angle and the horizontal data spacing and the slope error index. A simulation was run and wavy terrain was produced from noise corrupted range measurements.