Mobile robots for outdoor applications require solving many difficult tasks such as maintain stability, traction, control motion, avoid obstacles.
The locomotion is solved by studying the robot’s kinematic model; Jacobian matrices are derived in conjunction with the contact angle estimation between the wheel-ground. Then, Inverse Kinematic is used to obtain the wheels’ angular velocities according to the mobile robot’s pose and desired velocity of the Center of mass.
Torque control analyzed the normal force, friction at each wheel to overcome obstacles and avoid slipping. In both cases, velocity and torque control, the contact angle between the wheels and ground plays an essential role in detecting where the wheel is in contact, flat surface, vertical obstacle, slope, others.