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F. Liang et al.
3D printing [1–5], and put forward a concept of multi-directional printing. This multidirectional 3D printing can accumulate materials to the formed surface along different
directions, and improve the quality of layered manufacturing. However, robots are
required to have at least four degrees of freedom. Lee et al. [6] designed a 5-DOF 3D
printing robot to realize multi-directional printing. Keating et al. [7] combined 3D
printing technology with multi axis milling technology, and realized multi-functional
and multi-material processing with 6-DOF robot. However, the above robots mainly
use series mechanism, which has large inertia and large error. At present, most 3D
printing robots on the market adopt series structure, and the precision and relative
complexity of printed products are relatively low [8]. Parallel robot has the advantages
of high precision, high stiffness, fast speed and strong bearing capacity. Moreover,
when applied in 3D printing, it has the following advantages: Firstly, the position
and posture of the end effector (nozzle, laser or UV light source) can be changed
by the 6-DOF additive manufacturing equipment, and the stacking direction can be
changed according to different curved surfaces instead of a single vertical direction.
It can avoid the influence of ‘step effect’ on the surface quality of smooth surface.
Secondly, for the fused deposition modeling additive manufacturing technology, the
6-DOF additive manufacturing equipment can quickly cool and solidify the molten
resin extruded from the nozzle through the appropriate cooling system during the
printing process, so as to realize unsupported printing. Thirdly, changing the posture
of the end effector of the mechanism can improve the printing quality and avoid the
printing part interference, which could greatly increase the complexity of the printable surface. For example, Song et al. of the University of Iowa studied the additive
manufacturing technology based on Stewart type 6-DOF parallel robot, and applied
the Stewart 6-DOF parallel robot to 3D printing [9].
The development of 6-DOF parallel robot is the key technology of 6-DOF 3D
printer. Before manufacturing the parallel robot, the mechanical system and control
system of parallel robot must be simulated to provide theoretical basis and main
parameters for structure optimization, controller design and motion simulation.
The traditional mechanical and electrical system design is to design the mechanical and control system separately. When the physical prototype is tested, the two
design results are combined for the first time, which is easy to cause the mismatch
between the mechanical and control system, the design modification is large and
the design efficiency is low. Therefore, there is an urgent need for a design method
that considers both mechanical and control systems from the beginning of design and
establishes them in the same simulation model for electro-mechanical co-simulation.
Co-simulation is a method in which different simulation programs exchange data at
the same step time, and then solve the problem separately. This method can effectively combine the advantages of many kinds of software, realize the design requirements of parallel robot and improve the efficiency and quality of design. ADAMS
can exchange control data with MATLAB. In this paper, the electro-mechanical cosimulation of a Stewart 6-DOF parallel robot is realized through the interface of
ADAMS/control module and MATLAB.
F. Liang et al.
3D printing [1–5], and put forward a concept of multi-directional printing. This multidirectional 3D printing can accumulate materials to the formed surface along different
directions, and improve the quality of layered manufacturing. However, robots are
required to have at least four degrees of freedom. Lee et al. [6] designed a 5-DOF 3D
printing robot to realize multi-directional printing. Keating et al. [7] combined 3D
printing technology with multi axis milling technology, and realized multi-functional
and multi-material processing with 6-DOF robot. However, the above robots mainly
use series mechanism, which has large inertia and large error. At present, most 3D
printing robots on the market adopt series structure, and the precision and relative
complexity of printed products are relatively low [8]. Parallel robot has the advantages
of high precision, high stiffness, fast speed and strong bearing capacity. Moreover,
when applied in 3D printing, it has the following advantages: Firstly, the position
and posture of the end effector (nozzle, laser or UV light source) can be changed
by the 6-DOF additive manufacturing equipment, and the stacking direction can be
changed according to different curved surfaces instead of a single vertical direction.
It can avoid the influence of ‘step effect’ on the surface quality of smooth surface.
Secondly, for the fused deposition modeling additive manufacturing technology, the
6-DOF additive manufacturing equipment can quickly cool and solidify the molten
resin extruded from the nozzle through the appropriate cooling system during the
printing process, so as to realize unsupported printing. Thirdly, changing the posture
of the end effector of the mechanism can improve the printing quality and avoid the
printing part interference, which could greatly increase the complexity of the printable surface. For example, Song et al. of the University of Iowa studied the additive
manufacturing technology based on Stewart type 6-DOF parallel robot, and applied
the Stewart 6-DOF parallel robot to 3D printing [9].
The development of 6-DOF parallel robot is the key technology of 6-DOF 3D
printer. Before manufacturing the parallel robot, the mechanical system and control
system of parallel robot must be simulated to provide theoretical basis and main
parameters for structure optimization, controller design and motion simulation.
The traditional mechanical and electrical system design is to design the mechanical and control system separately. When the physical prototype is tested, the two
design results are combined for the first time, which is easy to cause the mismatch
between the mechanical and control system, the design modification is large and
the design efficiency is low. Therefore, there is an urgent need for a design method
that considers both mechanical and control systems from the beginning of design and
establishes them in the same simulation model for electro-mechanical co-simulation.
Co-simulation is a method in which different simulation programs exchange data at
the same step time, and then solve the problem separately. This method can effectively combine the advantages of many kinds of software, realize the design requirements of parallel robot and improve the efficiency and quality of design. ADAMS
can exchange control data with MATLAB. In this paper, the electro-mechanical cosimulation of a Stewart 6-DOF parallel robot is realized through the interface of
ADAMS/control module and MATLAB.