Page 106 - Robot Design Handbook ROBOCON Malaysia 2019

A. Thus it can be powered with a XL4005 5A step-down adjustable voltage regulator

module that can be bought from RobotEdu [8].
These servo motors were selected because they are lighter than direct current

(DC) geared motor, angular position can be controlled with pulse-width modulation
(PWM) signal, and servo motor with torque higher than 50kgcm has maximum current

consumption up to 10A which will result in difficulty designing high current voltage

regulator and replacing the servo motor’s cable with a thicker one by soldering. Two
RDS3128 servo motors will be powered with a XL4005 module, thus limiting each servo

motor current consumption to 2 A to prevent overheating, so the servo motor capped
torque is 15.625 kgcm. The maximum weight capacity of the robot is where the

calculation is shown in Eq. (2) based on the capped RDS3128 servo motor torque of
15.625 kgcm and leg specification shown in Figure 7 with two legs supporting the

weight as it walks.

Figure 7: MR2 leg specification.

15.625⁡ ÷ 27.5⁡ × 4 + 15.625⁡ ÷ 19.21⁡ × 4 = 5.526⁡ (2)

The extension mechanism used a MG995 servo motors with torque of 10kgcm to lift

up the Gerege and its holder. The MR2 will be able to extend to a height higher than 1m
with the extension mechanism at the highest position and legs fully extended. The robot has

a length of 0.795 m, width 0.55 m, and height below 0.8 m at normal standing position.

2.3 Electronic Design of MR1

The MR1 will be powered with a 22.2 V 2600 mAh Li-Po rechargeable battery and

several XL4005 voltage regulator module supplying power to Arduino Mega 2560 at 7.2 V.

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