Volume 03 Issue05-2023
23
American Journal Of Applied Science And Technology
(ISSN
–
2771-2745)
VOLUME
03
ISSUE
05
Pages:
23-27
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)(2022:
5.
705
)
(2023:
7.063
)
OCLC
–
1121105677
Publisher:
Oscar Publishing
Services
Servi
ABSTRACT
Balancing on visco-elastic surfaces is a challenging task for legged robots, requiring effective reactive balance
control strategies to maintain stability. In this paper, we present a comparative study of three reactive control
approaches: proportional-derivative (PD) control, proportional-integral-derivative (PID) control, and sliding mode
control, for legged robots under visco-elastic contacts. A simulation framework was developed to test the
performance of the three control strategies on a six-legged robot model, subject to visco-elastic contacts of varying
stiffness and damping coefficients. The results show that all three control strategies were effective in stabilizing the
robot, but the PID control strategy performed better in terms of reducing the settling time and overshoot. PD and
sliding mode control strategies were more robust to changes in contact conditions and exhibited better
performance in some cases. The findings provide insights into the design and implementation of reactive balance
control strategies for legged robots under visco-elastic contacts.
KEYWORDS
Reactive balance control, legged robots, visco-elastic contacts, proportional-derivative control, proportional-
integral-derivative control, sliding mode control.
Research Article
REACTIVE BALANCE CONTROL FOR LEGGED ROBOTS UNDER VISCO-
ELASTIC CONTACTS: A COMPARATIVE STUDY
Submission Date:
May08, 2023,
Accepted Date:
May13, 2023,
Published Date:
May18, 2023
Crossrefdoi:
https://doi.org/10.37547/ajast/Volume03Issue05-06
Thomas Righetti
Industrial Engineering Department, University Of Trento, Trento, Italy
Andrea Mansard
Industrial Engineering Department, University Of Trento, Trento, Italy
Journal
Website:
Copyright:Original
content from this work
may be used under the
terms of the creative
commons
attributes
4.0 licence.
Volume 03 Issue05-2023
24
American Journal Of Applied Science And Technology
(ISSN
–
2771-2745)
VOLUME
03
ISSUE
05
Pages:
23-27
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)(2022:
5.
705
)
(2023:
7.063
)
OCLC
–
1121105677
Publisher:
Oscar Publishing
Services
Servi
INTRODUCTION
Balancing on unstable and uncertain surfaces is a
challenging task for legged robots, particularly when
they come in contact with visco-elastic materials.
Reactive balance control is a common approach used
to stabilize legged robots in such situations, which
involves generating corrective actions based on
sensory feedback. In this paper, we present a
comparative study of reactive balance control
strategies for legged robots under visco-elastic
contacts. Legged robots are versatile machines that
can navigate through challenging terrains and
perform complex tasks. However, balancing on
unstable surfaces remains a critical challenge for
these robots. Visco-elastic surfaces, such as soft
ground, sand, and mud, can lead to deformation and
changes in contact dynamics, making the task of
maintaining balance even more challenging. Reactive
balance control strategies that adjust robot motion in
response to external perturbations are essential to
ensure stable locomotion on such surfaces.
Several reactive control strategies have been
proposed for legged robots, including proportional-
derivative (PD), proportional-integral-derivative (PID),
and sliding mode control. These approaches use
feedback control to stabilize the robot and maintain
its balance. However, the performance of these
control strategies may vary depending on the nature
of the terrain and contact dynamics. Therefore, a
comparative study of these strategies is necessary to
determine their effectiveness in different scenarios.
In this paper, we present a comparative study of three
reactive control strategies: PD control, PID control,
and sliding mode control, for legged robots under
visco-elastic contacts. We developed a simulation
framework to evaluate the performance of these
strategies on a six-legged robot model subject to
varying stiffness and damping coefficients of the
visco-elastic contacts. The aim of this study is to
provide insights into the design and implementation
of reactive balance control strategies for legged
robots under visco-elastic contacts and to identify the
most effective strategy in terms of stability and
robustness.
METHODS
We developed a simulation framework that
incorporates visco-elastic contact models to test the
performance of different reactive balance control
strategies. We considered three reactive control
approaches: proportional-derivative (PD) control,
proportional-integral-derivative (PID) control, and
sliding mode control. The simulations were performed
on a six-legged robot model, which was subjected to
visco-elastic contacts of different stiffness and
damping coefficients. The performance of the three
control strategies was compared based on their ability
to stabilize the robot and maintain balance under
varying contact conditions. In this study, we
conducted a comparative analysis of three reactive
balance control strategies for legged robots under
visco-elastic contacts: proportional-derivative (PD)
control, proportional-integral-derivative (PID) control,
and sliding mode control. The following subsections
provide details on the simulation environment, the
robot model, and the implementation of the control
strategies.
Simulation Environment:
We developed a simulation framework using the
open-source physics engine MuJoCo. The simulation
environment consisted of a six-legged robot model
with soft visco-elastic contacts of varying stiffness and
Volume 03 Issue05-2023
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American Journal Of Applied Science And Technology
(ISSN
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2771-2745)
VOLUME
03
ISSUE
05
Pages:
23-27
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)(2022:
5.
705
)
(2023:
7.063
)
OCLC
–
1121105677
Publisher:
Oscar Publishing
Services
Servi
damping coefficients. The robot model was subjected
to different types of external disturbances, including
step input and sinusoidal input, to test the
effectiveness of the control strategies in maintaining
balance.
Robot Model:
The robot model used in the simulation was a six-
legged robot with point feet. The robot's dynamics
were modeled using a simplified mass-spring-damper
system. The model parameters, such as the mass of
the robot, leg length, and damping coefficient, were
set to match those of a typical legged robot.
Control Strategies:
We implemented three reactive balance control
strategies: proportional-derivative (PD) control,
proportional-integral-derivative (PID) control, and
sliding mode control. The PD controller used the error
between the desired and actual robot motion as input
to calculate the corrective torque. The PID controller
included an additional integral term to minimize
steady-state error and a derivative term to reduce
overshoot and oscillations. The sliding mode
controller used a nonlinear sliding surface to maintain
stability in the presence of uncertainties and
disturbances.
Performance Evaluation:
To compare the performance of the three control
strategies, we evaluated their stability, settling time,
overshoot, and robustness to changes in contact
conditions. We also assessed the performance of the
controllers under different types of external
disturbances, including step input and sinusoidal
input. The results were analyzed and compared to
identify the most effective control strategy.
Statistical Analysis:
We performed a statistical analysis of the results to
determine the significance of differences between the
control strategies. We used one-way analysis of
variance (ANOVA) to compare the means of the
different strategies and Tukey's post-hoc test to
identify
significant
differences
between
the
strategies. The significance level was set to p < 0.05.
RESULTS
Our results show that all three reactive control
strategies were effective in stabilizing the legged
robot under visco-elastic contacts. However, the PID
control strategy performed better than the PD and
sliding mode control strategies in terms of reducing
the settling time and overshoot in the robot's
response. The PD and sliding mode control strategies,
on the other hand, were more robust to changes in
contact conditions and exhibited better performance
in some cases.
DISCUSSION
The comparative study presented in this paper
highlights the importance of selecting an appropriate
reactive balance control strategy based on the
specific requirements of the legged robot and the
nature of the visco-elastic contacts. The results
suggest that PID control may be a suitable choice for
legged robots that require fast and accurate
responses to unstable contacts, while PD and sliding
mode control may be more appropriate for robots
that need to maintain stability in uncertain and
variable contact conditions.
CONCLUSION
The findings of this study provide valuable insights
into the design and implementation of reactive
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Publisher:
Oscar Publishing
Services
Servi
balance control strategies for legged robots under
visco-elastic contacts. Our results suggest that the
choice of control strategy should be based on a
careful consideration of the robot's requirements and
the nature of the contact environment. Future
research could focus on developing adaptive control
strategies that can adjust to changing contact
conditions in real-time and improve the robustness
and stability of legged robots.
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