Three types of Variable Stiffness Actuators @ IRL
- Research Background
- Simultaneous control of position and stiffness is required for the dexterous manipulation.
- Compliant motion is advantageous to contact motion as well as dynamic motion.
- Research Objectives
- Development of an actuator unit capable of providing simultaneous control of position and stiffness
- Development of a small and light-weight actuator unit for robotic applications
- Related Documents
- Jae-Bok Song and Byeong-Sang Kim, Three Types of Dual Actuator Units for Variable Impedance Actuation, Variable Impedance Actuation Workshop (VIA 2010) .
- Jae-Bok Song, Variable Stiffness Actuation based on Dual Actuators Connected in Series and Parallel, Robotics Science and Systems Workshop (RSS2008).
Hybrid
type
Variable Stiffness Actuators (HVSA) - Research Outcomes
- The adjustable moment arm mechanism is adopted for the
stiffness variation.
- The modified planetary gear train is used for the
compact design of actuator unit.
- Constant stiffness irrespective of passive deflection can
be achieved.
- Control of Position and Stiffness
- Hitting Blocks
- Fast retraction motion is required to avoid collapse
of the stack of the blocks.
- Using variable stiffness control is advantageous to dynamic motion.
- Playing Darts
- From the conversion of potential energy to kinetic
energy, the joint velocity can be increased faster than the motor velocity.
- Related Papers/Patents
- Paper 1. Byeong-Sang Kim and Jae-Bok Song, Design and Control of a Variable Stiffness Actuator based on Adjustable Moment Arm, IEEE Transactions on Robotics (Accepted as short paper)
- Paper 2. Byeong-Sang Kim and Jae-Bok Song, Hybrid Dual
Actuator Unit: A Design of a Variable Stiffness Actuator based on an Adjustable
Moment Arm Mechanism, Proc. of IEEE Int. Conf. on Robotics and Automation (ICRA
2010), pp. 1655-1660, 2010. (ICRA2010 Best Automation Paper Finalist)
 - Patent 1. Active Actuator Module (10-2010-0030725,
Domestic)
Parallel
type
Variable Stiffness Actuators (PVSA) - Research Outcomes
- Two actuators are antagonistically connected to
control the position and stiffness simultaneously.
- The linear characteristic of spring is converted to
nonlinear via the cam-follower mechanism.
- The dual cam-follower mechanism is used for the
compact design of an actuator unit.
- Collision safety is mechanically guaranteed when
the external torque is larger than the user-specified force.
- Position and stiffness control
- (a) → (b): Increase of joints stiffness while maintaining position
- (a) → (c): Position while maintaining joint stiffness
- (a) → (d): Simultaneous control of position and stiffness
- Collision Safety
- The features of collision safety can be obtained by
designing the cam profile.
- AAM: Antagonistic Actuation Mode for simultaneous
control of position and stiffness.
- CSM: Collision Safe Mode for collision safety.
- Demonstration
- Hammering a Nail
- High impact force can be obtained from the
conversion of potential energy to kinetic energy.
- Damage of gear reducer and motor can be avoided
since the passive element absorbs the impact force.
- Cutting a Zucchini
- High impact force can be obtained from the conversion of potential energy to kinetic energy.
- Damage of gear reducer and motor can be avoided since the passive element absorbs the impact force.
- Related Papers/Patents
- Paper 1. Ki-Hoon Nam, Byeong-Sang Kim and Jae-Bok,
Song, Compliant Actuation of Parallel-type Dual Actuator Unit based on
Antagonistic Actuation, Journal of Mechanical Science and Technology (JMST), Vol. 24, No. 11, pp. 2315-2321, 2010.
- Patent 1. Active Actuator Module and Active Actuator
System Having the Same (10-2009-0092786, Domestic)
Serial type Variable Stiffness Actuators (SVSA) - Researchers
- Research Period
- Research Outcomes
- Two actuators are connected in series via the
planetary gear train.
- The positioning actuator (PA) has high gear ratio for
high poisoning accuracy.
- The stiffness actuator (SA) has low gear ratio for
soft manipulation.
- The joint stiffness can be adjusted by controlling the
current of the SA.
- Joint torque can be estimated by measuring the encoder
information provided by two encoders.
- Environment Estimation
- Stiffness estimation: Stiffness of the environment can be estimated by measuring
the contact force and the displacement.
- Surface estimation: The shape of the environment can be estimated while maintaining low contact force.
- Wall Following
- Contact force can be modulated by using force
estimation feature of SVSA.
- With force estimation: The manipulator can follow an arbitrary
shaped wall while maintaining a small variation of contact force.
- Without force estimation: The contact force varies as the manipulator follows the wall.
- Related Papers/Patents
- Paper 1. Byeong-Sang Kim, Jung-Jun Park, Jae-Bok Song,
Serial-type Dual Actuator Unit with Planetary Gear Train: Basic Design and Applications,
IEEE/ASME Transactions on Mechatronics (TMECH), Vol. 15, No. 1, pp. 108-116, 2010.
- Paper 2. Byeong-Sang Kim, Jae-Bok Song, Environment
Estimation using Serial-type Dual Actuator Unit Capable of Force Estimation,
Proc. of Int. Conf. on Ubiquitous Robots and Ambient Intelligence (URAI 2008),
pp. 395-399, 2008.11.
- Paper 3. Byeong-Sang Kim, Jung-Jun Park, Jae-Bok Song,
Double Actuator Unit with Planetary Gear
Train for a Safe Manipulator, Proc. of IEEE Int. Conf. on Robotics and
Automation (ICRA 2007), pp. 1146-1151, 2007.
- Paper 4. Byeong-Sang Kim, Jung-Jun Park, Jae-Bok Song,
Improved Manipulation Efficiency using a Serial-type Dual Actuator Unit, Proc.
of Int. Conf. on Control, Automation and Systems (ICCAS 2007), pp. 30-35,
2007.10.
- Patent 1: Double Actuator Unit, Double Actuator
Apparatus with the same and the method for controlling the Double Actuator
Apparatus (10-0835908)
- Last updated: 2012. 5. 9 |
