107
Development of a Low-Noise Bio-Inspired Humanoid Robot Neck
combination of universal, prismatic, and spherical joints. The actuators for
the parallel necks can be DC motors or pneumatic cylinders. Parallel mechanisms have the characteristics of rigidity, high load capacity, and high precision; however, it is hard to achieve a large range of motion and they are
not suitable for use in limited neck space. The motion of a spherical neck is
based on a spherical joint. Using screw theory, Sabater et al. (2006) designed
and analyzed a spherical humanoid neck. A spring neck uses a spring as the
spine to support the head and facilitate its motion. A spring neck is usually
driven by motors (Beira et al. 2006; Nori et al. 2007) and artificial muscles
(Hashimoto et al. 2006). According to previous investigations, a spring neck
is similar to a real human neck and it is economical to build; however, it is
hard to achieve high precision positioning control because of the complicated dynamics of the springs.
Most of the research on humanoid robotic necks provides insight into how
to make the neck move similar to a real human neck. However, little research
has adequately addressed how to design a robotic neck that can move quietly.
Inspired by the human neck structure (White and Panjabi 1990), the main
part of the developed head/neck is a compressed column spring that has a
similar function to that of the spine. It supports the artificial/robotic head
and can bend around the neutral axis to generate 2-DOF rotation including
pitch and roll motions (bending of the head forward and backward and left
and right, respectively). A cable–pulley structure mounted above the spring
is used to realize the yaw motion (rotating the head to the left and right).
The 3-DOF motion of the neck is realized through six cables that have similar functions of human neck muscles. These cables are pulled by the actuators sealed in a sound insulation box. Because no sound generation parts are
embedded into the robotic neck, only very low motion noises are generated.
6.2 Low-Motion–Noise Robotic Head/Neck System
6.2.1 System Overview
The structure of the developed robotic system is shown in Figure 6.1. The
system consists of three main parts: a humanoid robotic unit, a sound insulation box, and a personal computer. The robotic unit has a movable robotic
head, a torso, and a height-adjustable support frame used to match humans
of different heights either sitting or standing. The size of the head and torso
is designed based on the head size of a human adult so that a full-size personal protective uniform fits the robotic system well. The movable robotic
head has a 3-DOF neck framework to mimic human neck movements. These
movements are driven by the remote motor-based actuators installed in the
sound insulation box through the compound cable-and-housing group. The
Development of a Low-Noise Bio-Inspired Humanoid Robot Neck
combination of universal, prismatic, and spherical joints. The actuators for
the parallel necks can be DC motors or pneumatic cylinders. Parallel mechanisms have the characteristics of rigidity, high load capacity, and high precision; however, it is hard to achieve a large range of motion and they are
not suitable for use in limited neck space. The motion of a spherical neck is
based on a spherical joint. Using screw theory, Sabater et al. (2006) designed
and analyzed a spherical humanoid neck. A spring neck uses a spring as the
spine to support the head and facilitate its motion. A spring neck is usually
driven by motors (Beira et al. 2006; Nori et al. 2007) and artificial muscles
(Hashimoto et al. 2006). According to previous investigations, a spring neck
is similar to a real human neck and it is economical to build; however, it is
hard to achieve high precision positioning control because of the complicated dynamics of the springs.
Most of the research on humanoid robotic necks provides insight into how
to make the neck move similar to a real human neck. However, little research
has adequately addressed how to design a robotic neck that can move quietly.
Inspired by the human neck structure (White and Panjabi 1990), the main
part of the developed head/neck is a compressed column spring that has a
similar function to that of the spine. It supports the artificial/robotic head
and can bend around the neutral axis to generate 2-DOF rotation including
pitch and roll motions (bending of the head forward and backward and left
and right, respectively). A cable–pulley structure mounted above the spring
is used to realize the yaw motion (rotating the head to the left and right).
The 3-DOF motion of the neck is realized through six cables that have similar functions of human neck muscles. These cables are pulled by the actuators sealed in a sound insulation box. Because no sound generation parts are
embedded into the robotic neck, only very low motion noises are generated.
6.2 Low-Motion–Noise Robotic Head/Neck System
6.2.1 System Overview
The structure of the developed robotic system is shown in Figure 6.1. The
system consists of three main parts: a humanoid robotic unit, a sound insulation box, and a personal computer. The robotic unit has a movable robotic
head, a torso, and a height-adjustable support frame used to match humans
of different heights either sitting or standing. The size of the head and torso
is designed based on the head size of a human adult so that a full-size personal protective uniform fits the robotic system well. The movable robotic
head has a 3-DOF neck framework to mimic human neck movements. These
movements are driven by the remote motor-based actuators installed in the
sound insulation box through the compound cable-and-housing group. The