Life in the AtacamaCarnegie Mellon Hyperion Mobility Testing Dimi Apostolopoulos Michael Wagner Kevin Peterson July 28, 2003

Life in the AtacamaCarnegie Mellon Lab and Field Differences Current limits increased to 5 A continuous Rover mass 140 kg in the lab, 180 kg in field

Life in the AtacamaCarnegie Mellon Drawbar Pull Tests Drawbar pull is the force a vehicle can pull on a given soil The drawbar pull is measured by attaching the robot to a load cell and steel cable The robot is driven until the cable is tensioned and its wheels begin to slip The drawbar pull is the maximum force sensed by the load cell Direction of travel Steel cable Load cell Wall

Life in the AtacamaCarnegie Mellon Drawbar Pull Tests Drawbar pull is a useful metric because it can be used to find the maximum climbable slope for a given soil type: Max slope = atan(DP / weight) Performed tests in cohesionless sand This soil provides very little traction, similar to regions of loose sand seen in the Atacama

Life in the AtacamaCarnegie Mellon Drawbar Pull Tests – Results c a b d e a.Robot driving normally b.Cable tension rapidly increases c.Wheels slipping d.Motion controller fault, at least one wheel stops servoing e.Robot reverses, cable goes slack Max DP: 550 N Max slope: 22 deg

Life in the AtacamaCarnegie Mellon Flat Floor and Climbing Tests Torque is calculated through the following equation: T = These torque measurements are most accurate when robot driving straight and at higher velocities  I V v / r  = 0.35

Life in the AtacamaCarnegie Mellon Flat Concrete Floor – Power

Life in the AtacamaCarnegie Mellon Flat Concrete Floor – Torque

Life in the AtacamaCarnegie Mellon 20-cm Obstacle on Concrete Floor

Life in the AtacamaCarnegie Mellon Sandbox – Power

Life in the AtacamaCarnegie Mellon Sandbox – Torque

Life in the AtacamaCarnegie Mellon 20-cm Obstacle in Sandbox

Life in the AtacamaCarnegie Mellon Flat Desert Terrain - Power

Life in the AtacamaCarnegie Mellon Flat Desert Terrain - Torque

Life in the AtacamaCarnegie Mellon 10 cm Obstacle in Desert

Life in the AtacamaCarnegie Mellon Slope Climbing Tests

Life in the AtacamaCarnegie Mellon Slope Climbing: 10 deg Wheels climbing onto ramp Entire robot climbing ramp Wheels climbing onto ramp Entire robot climbing ramp 35 Nm 20 Nm

Life in the AtacamaCarnegie Mellon Slope Climbing: 30 deg Entire robot climbing ramp Entire robot climbing ramp 50 Nm 65 Nm

Life in the AtacamaCarnegie Mellon Slope Climbing in the Desert: 10 deg

Life in the AtacamaCarnegie Mellon Slope Climbing in the Desert: 14 deg

Life in the AtacamaCarnegie Mellon Maximum Obstacle Climb in the Desert a.Robot is stopped b.Left front wheel starts to climb c.Left front wheel peaks the obstacle at a height of meters d.All four wheels are on flat ground, left rear wheel starts to climb e.Left rear wheel peaks the obstacle f.Left rear wheel hits the ground and bounces a b c d e f

Life in the AtacamaCarnegie Mellon Rolling Resistance Comparisons Rolling resistance is the ratio of tractive force to vehicle weight Tractive force is dependent on soil properties Rolling resistance in sandbox: 0.03 Rolling resistance on concrete floor: 0.02 Rolling resistance on ramp: 0.26 Rolling resistance in the desert: 0.08