Image based Horizontal Velocity Estimation Algorithm for the Descent phase of an Interplanetary Lander

Onboard camera images can be used to estimate the horizontal velocity of a lander during the descent phase. This can be used to update the velocities computed by Inertial Navigation System which is based on Accelerometer/Gyro outputs. This paper gives the details of an algorithm developed to estimate the velocity of an interplanetary lander during its descent phase using onboard camera images. An algorithm is developed to estimate the relative horizontal velocity using the complete camera perspective projection model. The test results indicate good accuracy in horizontal velocity estimation.