41
Analysis and Design of a Bionic Fitness Cycle
C 2
C 1
B 2
B 1
B
l 1
l 2
l 4
l 3
D
A
C
FIGURE 3.7
Crank-rocker mechanisms formed by pedal movement.
the step of people in their natural state, and the bionic riding motion, which
is driven by both hands and legs, imitates the running methods of animals;
thus the hand crank’s length should be kept the same as the pedal crank
length; that is, 170 mm.
3.3.2 Design of the Saddle Pole
There are two main parameters for the saddle pole: the tilt angle and the
length adjustment range.
1. Analysis of the tilt angle
When the user rides a fitness cycle, the relationship of the plane
location of the user’s thigh, shank, pedal crank, and saddle pole
is shown in Figure 3.8a (N. Y. Zhang 2001). The limit location
as shown in Figure 3.8b is taken to determine the tilt angle of
the saddle pole; that is, the location where the user’s legs are
straight and the pedal crank is horizontal. The first human template provided by the GB/T 15759-95 standard form is adopted
(General Administration of Quality Supervision, Inspection
and Quarantine of China, 1995). That is, the female minimum
perineum height h = 673 mm is selected as the design standard;
therefore, most users will not need to unbend their legs and
almost all will be able to tread the pedal crank to the bottom
of its motion. According to physiological characteristics, angle α
should not be greater than 90 degrees (Das and Behara 1998); α =
90 degrees was chosen.
Analysis and Design of a Bionic Fitness Cycle
C 2
C 1
B 2
B 1
B
l 1
l 2
l 4
l 3
D
A
C
FIGURE 3.7
Crank-rocker mechanisms formed by pedal movement.
the step of people in their natural state, and the bionic riding motion, which
is driven by both hands and legs, imitates the running methods of animals;
thus the hand crank’s length should be kept the same as the pedal crank
length; that is, 170 mm.
3.3.2 Design of the Saddle Pole
There are two main parameters for the saddle pole: the tilt angle and the
length adjustment range.
1. Analysis of the tilt angle
When the user rides a fitness cycle, the relationship of the plane
location of the user’s thigh, shank, pedal crank, and saddle pole
is shown in Figure 3.8a (N. Y. Zhang 2001). The limit location
as shown in Figure 3.8b is taken to determine the tilt angle of
the saddle pole; that is, the location where the user’s legs are
straight and the pedal crank is horizontal. The first human template provided by the GB/T 15759-95 standard form is adopted
(General Administration of Quality Supervision, Inspection
and Quarantine of China, 1995). That is, the female minimum
perineum height h = 673 mm is selected as the design standard;
therefore, most users will not need to unbend their legs and
almost all will be able to tread the pedal crank to the bottom
of its motion. According to physiological characteristics, angle α
should not be greater than 90 degrees (Das and Behara 1998); α =
90 degrees was chosen.