3
About the Servo Motors
A servo motor has an important rule and concept concerning its mounting. If it is mounted in a
wrong way, the robot will not move correctly. When assembling the servo motor, read this page
thoroughly.
○Servo motor original position
The servo motor is controlled by the CPU and can be programmed by the user to freely run.
The servo motor VS-S020 used for the Product has frame mounting holes in the top and back
covers, into which a frame is mounted. Then, mount a servo horn to an output shaft (power
supplied shaft), followed by the frame there, to use it as the robot’s joint. A movable range of the
robot’s joint depends on this mounting of the servo horn.
The servo motor has its movable range. The VS-S020 used for the Product moves within a
range of about 130º, that is from -65º to +65º.* The central position of 0º is called the “origin.”
each servo motor has a slight angle discrepancy. Even if the angle of the origin is sent from the
CPU board to the servo motor, it may be slightly dislocated from the origin. Assuming that the
origin position based on a signal from the CPU board is correct, this robot uses software to adjust
an error produced in the actual servo motor. (An error adjusting method is described later.) In
the following description, “origin” is used as the “origin set by the CPU board.”
○Mounting a servo horn
A servo horn mounting angle to the origin is important in order to set a movable range of the joint
more accurately. If the origin is not accurately set, the robot cannot move successfully in
motions, such as getting up, which require an accurate movable range. Try each hole in the
servo horn one after another until it is located at the most accurate angle to the origin. When
mounting the servo horn to the output shaft, do not allow the servo motor’s output shaft to be
rotated.
○About “motor lock.”
Some servomotor can not rotate in 130º by some joint frame. We limit the rotating range in
software, however we can not limit the rotating range perfectly at the legs and arms.
If a hand or a foot gets caught on the body at the time of activating the servo motors, an
excessive load will be applied to the servo motors. This condition is called “motor lock.” If
this condition persists, the servo motors will be heated and go out of order(breaking
gear/case/servo circuit board/CPU board ). While compensating, touch the servo motors
periodically with your hand to check if they are heated. If they are too hot to touch, turn off
the Power switch of the Robot immediately and wait until the servo motors are cooled down.
Please be careful of Motor lock.
