| dc.description.abstract | The main purpose of this master thesis is to develop the kinematic equa-
tions for NMBU Mobile Agricultural Robot. A geometrical approach to nd
the kinematic model is proposed. Kinematic constraints is identi ed, and a
short discussion whether dynamics can be neglected or not is included. As
crab steering is wanted on NMBU Mobile Agricultural Robot, a short discus-
sion of the kinematics is presented. Ackerman geometry is introduced, and
four wheel Ackerman equations are derived.
Curvature and turning radius is used in the kinematic equations, and a
singularity condition is both identi ed and taken care of. Kinematic equa-
tions are developed further for unambiguous steering angles in all wheel po-
sitions and separate equations for all four wheels are presented. A map from
signed turning radius to inner and outer side is also found, and this gives
us unique kinematic equations. Input like signed turning radius and desired
speed in center of robot, outputs correct positions and velocity of all actuated
joints.
Numerical singularity threshold in singularity workaround are discussed
and found. A map from steering angles to number of motor turns is found,
as well as a map from ground speed in center of robot to RPM in propulsion
motors. An intuitive example where the robot follows a simple path is in-
cluded. And in the end, two proposals intended to minimize wheel slip when
a vehicle is operating in uneven terrain is shown, and the relevance for these
system in NMBU Mobile Agricultural Robot is discussed.
A sub-goal is to introduce the concept of mobile agricultural robots, and
nd a suitable steering system. Battery as energy source is also discussed,
and propulsion, traction and frame of NMBU Mobile Agricultural Robot is
mentioned. This is one of ve thesis's forming a project that aims to design
and build a working prototype of a Mobile Agricultural Robot. | nb_NO |
