MSc

A semi-autonomous robotic platform was conceptualized for performing the
intercultural operations in row crops. It was expected to be capable of navigating within
the field and performing the intended intercultural operation according to the user
command.
The dimensions of the chassis (track width and ground clearance) were
determined on the basis of agronomic characteristics of the crop. Wheel mounted geared
motors were used for self-propulsion. The wheel variables were decided based on the
rolling resistance and terramechanics relationships. A six-wheel independent drive skidsteering
drive mechanism was provided to the robotic platform. Arduino Mega was the
microcontroller used which was interfaced with the drive motors via L298N motor driver
for speed and direction control. The microcontroller was programmed in Arduino IDE
software using C++ language. The wireless communication system was based on Radio
Frequency (RF) protocol using Flysky FS i6 2.4GHz Six-channel Transmitter Remote
Controller with FS-iA6 Receiver unit. The monitoring guidance of the prototype was
accomplished on the basis of real-time video streaming using Wi-Fi enabled wireless IP
camera. The operational unit was controlled by relay driver circuits. Geared DC motor
operated cable drive slider mechanisms actuated the position control of the sprayer unit.
The developed prototype was evaluated in both lab and field conditions. The
speed of travel obtained was less than the rated speed. The total power consumed by the
prototype increased with increase in the load. The deviation of the prototype from a
straight path could be corrected by the use of steering controls by the operator. The
control unit functioned satisfactorily for every command by the user. During the basic
field trial, a non-uniform distribution of load on each ground-contact point occurred due
to the undulated terrain. Therefore, wheels were subjected to sinkage which resulted in
lack of proper traction and wheel slip. The tractive forces were then insufficient to
overcome the soil resistance. The test resulted in the requirement for a modified drive
mechanism for the prototype. The modified design of the drive mechanism comprised of
high torque motors (24 V, 8Nm, 300 RPM DC motor) with reducer unit, high power
motor drivers (BTS7960) and larger diameter pneumatic wheels (30.48 cm diameter). A
suspension could also be provided to maintain uniform load distribution on each groundcontact
points. As the torque exerted by these motors would be greater than the required
torque, the design was safe. The cost for modified prototype was estimated to be
Rs.65000/-.