Page 75 - Robotics and AI class 10
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Example: Let’s consider an example of a robotic arm that requires precise motion control and high torque
transmission. A planetary gear system can be employed in this scenario. The sun gear is connected to the input
shaft, the planet gears are mounted on a carrier, and the ring gear serves as the output. The gear ratio is set
based on the number of teeth on the sun gear, planet gears, and ring gear.
For instance, if the sun gear has 20 teeth, the planet gears each have 10 teeth, and the ring gear has 40 teeth,
the gear ratio would be 2:1. When the input shaft rotates the sun gear, the planet gears mesh with the sun gear
and the ring gear, resulting in the rotation of the output shaft. This gear ratio allows for torque amplification,
enabling the robotic arm to handle heavier loads with reduced speed.
Planetary gears are commonly used in robotics, automotive transmissions, aerospace applications, and various
other systems where compactness, high torque capacity, and multiple gear ratios are required.
Rack and Pinion Gears
These gears are a type of gear mechanism used to convert rotational motion into linear motion. They consist of
a linear gear called a rack and a circular gear called a pinion.
Here are some key details about rack and pinion gears:
• Rack: The rack is a flat, linear gear with teeth along its straight edge. It is usually a straight bar with the teeth
running parallel to the length of the rack. The teeth of the rack mesh with the teeth of the pinion gear.
• Pinion: The pinion is a small circular gear with teeth that mesh with the teeth of the rack. It is mounted on a
rotating shaft and transfers rotational motion to the rack.
• Motion Conversion: When the pinion gear rotates, the teeth of the pinion engage with the teeth of the rack,
causing the rack to move linearly. The direction of the linear motion depends on the direction of rotation of the
pinion.
• Linear Motion Control: Rack and pinion gears offer precise linear motion control. By controlling the rotation
of the pinion, the position and speed of the rack can be accurately adjusted. This makes them suitable for
applications that require linear motion control, such as in steering systems, robotics, and linear actuators.
• Mechanical Advantage: Rack and pinion gears provide a mechanical advantage by converting rotational
motion into linear motion. The gear ratio between the pinion and rack is determined by the number of teeth on
each component. A larger number of teeth on the pinion compared to the rack will result in a higher mechanical
advantage, enabling greater force and speed amplification.
• Efficiency and Backlash: Rack and pinion gears offer high efficiency due to their direct contact and minimal
sliding friction. However, they may have some backlash, which is the slight movement or play between the
teeth when changing direction. Backlash can be minimised through proper design and precision manufacturing
techniques.
Components of Robots as a System 73

