Angle; Torque; Operation - Lynxmotion AL5D-PLTW Manual

Technology
The AL5D uses Hitec RC servo motor actuators at each joint. These servos are classically used
in the RC hobby industry to control ailerons and landing gear on airplanes, rack and pinion
steering on RC cars and come in a variety of sizes and torque ratings. Given their popularity,
easy of use, low price and absolute positioning, RC servos were adapted for use in animatronics
and robotics.

Angle

Standard RC servo motors only rotate 180 degrees (0 to 180 / -90 to +90). This is the case
because the internal component (rotary potentiometer) which provides the absolute positioning,
cannot provide multiple rotations and is physically limited in the angle over which it can turn.

Torque

"Torque" is not the same as a "force"; a "force" acts as a straight vector, whereas "torque" is
rotational about a point. Torque is defined as force multiplied by distance, or
is the distance between the force and the axis of rotation. Although we will not go into the details
of how to calculate torque, it is important to note that not all servos can provide the same torque,
and some are more powerful than others.

Operation

AN RC servo motor has three wires which are always in the same order:
An RC PWM signal is a repeated pulse at 5V whose duration lasts between 0.5ms (500us) to
2.5ms (2500us), followed by a delay of between 20ms to 30ms. The servo's onboard electronics
time the pulse and position the servo at the corresponding angle. The pulse must be repeated
for the servo to retain the desired position.
RobotShop Inc. 305-18005 Lapointe, Mirabel, Quebec, Canada, J7J0G2
Black = Ground (GND)
Red = Positive (4.8V ~ 6V)
Yellow = PWM Signal / Pulse
6
RC Servo
T = F * d, where d