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This paper describes a new approach to the design of a lightweight robotic arm for service applications. A major design objective is to achieve a lightweight robot with desired kinematic performance and compliance. This is accomplished by an integrated design optimization approach, where robot kinematics, dynamics, drive-train design and strength a...
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The industrial demand for high-performance and low energy consume has highlighted the need to develop lightweight manipulators and robots. However, their design and control result more difficult with respect to rigid-link robotic systems mainly due to the structural flexibility of the arms. To this end, the Equivalent Rigid-Link System (ERLS) appro...
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... Application-oriented robot design, which optimizes robot for a specific application, offers a great potential to deliver more cost-effective solutions, e.g., higher productivity, less energy consumption, and lower initial cost. Robot design is multidisciplinary in nature, involving battery [2], structural mechanics [3], kinematics [4], dynamics [5], thermodynamics [6], and control [7]. The design objectives are also multidisciplinary, e.g., weight [2], [3], [5], [6], [8], energy consumption [6], [9], [10], task completion time [9], [10] or workspace maximization [8]. ...
... Robot design is multidisciplinary in nature, involving battery [2], structural mechanics [3], kinematics [4], dynamics [5], thermodynamics [6], and control [7]. The design objectives are also multidisciplinary, e.g., weight [2], [3], [5], [6], [8], energy consumption [6], [9], [10], task completion time [9], [10] or workspace maximization [8]. Much of the established robot design methods have been disciplinespecific. ...
... Co-design, which reconciles the coupling and conflict of subsystems at an early stage [6], is of interest for its potential to overcome sub-optimality that results from a discipline-specific design process. Its use can be found in applications such as manipulators [1], [3], [5], [14], [15], legged robots [16], [17], aerial/ground manipulators [2], service robotic arms [8] and industrial robots [6], just to name a few. Particularly, the work [15] co-designs the drivetrain and joint trajectories of an industrial robot, where the drivetrain is parameterized in terms of the motor shaft length and gearbox ratio. ...
This work investigates an application-driven co-design problem where the motion and motors of a six degrees of freedom robotic manipulator are optimized simultaneously, and the application is characterized by a set of tasks. Unlike the state-of-the-art which selects motors from a product catalogue and performs co-design for a single task, this work designs the motor geometry as well as motion for a specific application. Contributions are made towards solving the proposed co-design problem in a computationally-efficient manner. First, a two-step process is proposed, where multiple motor designs are identified by optimizing motions and motors for multiple tasks one by one, and then are reconciled to determine the final motor design. Second, magnetic equivalent circuit modeling is exploited to establish the analytic mapping from motor design parameters to dynamic models and objective functions to facilitate the subsequent differentiable simulation. Third, a direct-collocation-based differentiable simulator of motor and robotic arm dynamics is developed to balance the computational complexity and numerical stability. Simulation verifies that higher performance for a specific application can be achieved with the multi-task method, compared to several benchmark co-design methods.
... Optimizing the structure and size of the robotic arm, reducing its own weight, and improving its load to weight ratio under the premise of ensuring its load capacity can effectively reduce consumables and control production costs on the one hand, and reduce energy consumption and improve work efficiency on the other. There are various ways to optimize the robotic arm, which can be optimized and improved in terms of structure [17][18][19][20], material [21][22][23][24], and process [25][26][27], in particular, combining topology optimization with manufacturing processes [28][29][30]. Rout et al. [31] used evolutionary optimization methods for two-degree-of-freedom planar manipulators and four-degree-of-freedom SCARA manipulators to design dimensional parameters and weights, and the method minimized the sensitivity of disturbing factors affecting accuracy and repeatability to minimum. ...
... Rout et al. [31] used evolutionary optimization methods for two-degree-of-freedom planar manipulators and four-degree-of-freedom SCARA manipulators to design dimensional parameters and weights, and the method minimized the sensitivity of disturbing factors affecting accuracy and repeatability to minimum. Zhou L et al. [17] from Aalborg University combined finite element strength analysis based on kinematic performance, dynamics requirements, and lightweight design of a five-degree-of-freedom robotic arm in terms of both drive chain and structural dimensions. Liu W [32] used the non-inferiority ranking genetic algorithm NSGA-II (non-dominated sorting genetic algorithm II) with bit matrix representation to optimize the topology for multiple objectives such as mass and load capacity for lightweighting. ...
The current reliance on manual rescue is inefficient, and lightweight, highly flexible, and intelligent robots need to be investigated. Global seismic disasters occur often, and rescue jobs are defined by tight timetables and high functional and intellectual requirements. This study develops a hydraulically powered redundant robotic arm with seven degrees of freedom. To determine the force situation of the robotic arm in various positions, the common digging and handling conditions of the robotic arm are dynamically simulated in ADAMS. A finite element analysis is then performed for the dangerous force situation to confirm the structural strength of the robotic arm. The hydraulic manipulator prototype is manufactured, and stress–strain experiments are conducted on the robotic arm to verify the finite element simulation’s reliability.
... Service robots should be fulfilled with a lightweight mechanism with desired kinematic performance and compliance. [6] propose an integrated design optimization approach where robot kinematics, dynamics, powertrain design, and strength analysis are considered. In such an approach, kinematic and structural dimensions, motors, and gearboxes are parameterized as design variables. ...
This paper aims to concurrently select and control off-the-shelf BLDC motors of industrial robots by using a synergistic model-based approach. The BLDC motors are considered with trapezoidal back-emf, where the three-phase (a,b,c) dynamics of motors are modeled in a mechatronic powertrain model of the robot for the selection and control problem, defining it as a multi-objective dynamic optimization problem with static and dynamic constraints. Since the mechanical and electrical actuators' parameters modify the robot's performance, the selection process considers the actuators' parameters, their control input, operational limits, and the mechanical output to the transmission of the robot joints. Then, three objective functions are to be minimized, the motor's energy consumption, the tracking error, and the total weight of installed motors on the robot mechanism. The control parameterization approach via a cascade controller with PI controllers for actuators' voltage and a PID controller for actuators' torque is used to solve the multi-objective dynamic optimization problem. Based on simulations of the closed-loop system, a Pareto front is obtained to examine trade-offs among the objective functions before implementing any actuators in the existing robotic system. The proposed method is tested on an experimental platform to verify its effectiveness. The performance of an industrial robot with the actuators originally installed is compared with the results obtained by the synergic approach. The results of this comparison show that 10.85% of electrical power can be saved, and the trajectory tracking error improved up to 57.41% using the proposed methodology.
... The same authors finally succeded in creating an integrated drivetrain, dimensional and static structural optimisation for the same five DOF robot arm. 7 They used MATLAB for optimisation cycle, ADAMS for dynamic simulation and ANSYS for static strength analysis, that is, they used three different types of software for co-simulation. The objective was again to minimise the total weight and the drive-train library was very limited. ...
Due to the complexity of the process, there is no single solution for determining the motors, gearboxes and structures of a robot manipulator according to the desired dynamic performance while minimising both the deflections in the structure during the dynamic motion and total robot weight. The solution of this integrated drive-train and dynamic structural optimisation problem is generalised for three degrees of freedom (DOF) robot manipulator via Non-Dominated Sorting Genetic Algorithm II (NSGA-II) to obtain the Pareto front of any desired robot manipulator overall conceptual design, including motors, gearboxes and thicknesses of the links. A flexible body dynamic simulation model was created in the MATLAB Simmechanics environment. The flexible bodies were defined via lumped parameter estimation method, which allows observation of the deflections in links during the dynamic motion. A library containing technical data related to motors and gearboxes was created to be utilised in the optimisation algorithm. The method accelerates the time-consuming iterative process for obtaining optimum conceptual design solutions for a dynamic system and allows for easy modification of design parameters and constraints. It also makes the algorithm suitable for different types of dynamic system designs.
... An emblematic example is robotics. Nowadays, robot mechanisms are much more lightweight and, consequently, flexible than in the past [1,2], in particular when compliant joints are adopted [3,4]. Therefore, the conception of smooth motion profiles, suitable for reducing residual vibrations and overshoot, plays a noteworthy role in the optimization of the task execution [5]. ...
The paper discusses the analytical expressions of a motion profile characterized by elliptic jerk. This motion profile is obtained through a kinematic approach, defining the jerk profile and then obtaining acceleration, velocity, and displacement laws by successive integrations. A dimensionless formulation is adopted for the sake of generality. The main characteristics of the profile are analyzed, outlining the relationships between the profile parameters. A kinematic comparison with other motion laws is carried out: trapezoidal velocity, trapezoidal acceleration, cycloidal, sinusoidal jerk, and modified sinusoidal jerk. Then, the features of these motion profiles are evaluated in a dynamic case study, assessing the vibrations induced to a second-order linear system with different levels of damping. The results show that the proposed motion law provides a good compromise between different performance indexes (settling time, maximum absolute values of velocity and acceleration).
... KEYWORDS modular robotic arm, anti-parallelogram mechanism, Bowden cable, humanoid arm, lightweight joint design 1 Introduction Lightweight and dexterous humanoid arms have been widely researched, and achieving similar function and performance to human arms is the ultimate goal [1-3]. Currently, most humanoid arms are bionic in appearance, whereas their weight, sizes, and safety are closer to those of industrial robotic arms [4,5], which are quite different from those of human arms and difficult to be applied to humanoid services. In human arms, joint drive is realized by the contraction and extension of muscles. ...
... As shown in Fig. 15, the static and dynamic load-carrying tests of the MCDH-Arm were conducted. Figure 15(a) shows the static load-carrying experiment of the arm in two different stretched poses: in pose I, the elbow is bent (insets 1-3), and in pose II, the arm is horizontally stretched (insets [4][5]. In these two poses, the weight was first loaded directly from 0 to 1 kg, and then was increased by 0.2 kg each time. ...
This paper proposes a novel modular cable-driven humanoid arm (MCDH-Arm) with anti-parallelogram mechanisms (APMs) and Bowden cables. The lightweight arm realizes the advantage of joint independence and the rational layout of the driving units on the base. First, this paper analyzes the kinematic performance of the APM and uses the rolling motion between two ellipses to approximate a pure-circular-rolling (PCR) motion. Then, a novel type of one degree-of-freedom (1-DOF) elbow joint is proposed based on this principle, which is also applied to design the 3-DOF wrist and shoulder joints. Next, Bowden cables are used to connect the joints and their driving units to obtain a modular cable-driven arm with excellent joint independence. After that, both the forward and inverse kinematics of the entire arm are analyzed. Last, a humanoid arm prototype was developed, and the assembly velocity, joint motion performance, joint stiffness, load carrying, typical humanoid arm movements, and repeatability were tested to verify the arm performance.
... In the previous years, several approaches have been proposed to optimize robot parameters based on different performance criteria. Zhou and Bai [3] presented in their study a method for optimizing a robotic arm to minimize the weight of the robot with constraints on kinematics performance, drive-train, and structural strength. The kinematic performance of the robot was indexed by the global conditioning index (GCI). ...
... The conception of innovative motion profiles is an interesting and useful research area, since it can lead to productivity increase in a wide range of industrial applications, in which transfer time can significantly affect production time and efficiency. A typical application example is robotics: modern robots are more lightweight and flexible than traditional ones [1,2], especially if compliant joints are used [3,4]. Consequently, smooth motion profiles are required to limit residual vibrations and overshoot [5]. ...
... The MSJ profile is in general divided in 15 phases, alternating phases with sinusoidal, constant or null jerk [14]; as already said, in this comparison the null jerk phases (4,8,12) have been eliminated; moreover, it has been assumed that the duration of the phases with sinusoidal jerk (1,3,5,7,9,11,13,15) is 1/16 = 0.0625 and the duration of the phases with constant jerk (2, 6, 10, 14) is 1/8 = 0.125. From the analysis of the graphs of Fig. 3 it is possible to summarize the following observations: ...
The paper proposes a motion profile based on the curiosity-driven hypothesis of elliptic jerk and investigates its features. This approach is kinematic, since the dynamic model of the system is not considered, and the motion law is directly defined in terms of velocity, acceleration and jerk; consequently, this method is suitable for real-time implementation, without off-line optimization. The main features of the profile are presented, then it is compared to other motion laws (cycloidal, trapezoidal velocity, trapezoidal acceleration, sinusoidal jerk, modified sinusoidal jerk) from a kinematic point of view, with a dimensionless approach for the sake of generality. Then the comparison is extended considering a dynamic case study, evaluating the residual vibrations induced to a second-order linear system.KeywordsMotion controlElliptic jerkMotion profilesResidual vibrations
... In [11] a non-gradient optimization method is considered which is a complex method, to evaluate multiple designs within a feasible domain and find the best and worst configurations. An integrated design optimization is performed in [12] where robot kinematics, dynamics, drive-train design, and strength analysis are considered in lights of finite elements analysis to minimize the robot's weight. The genetic algorithm (GA) is used in [13] for the mechanical design (link length, diameter, and thickness) optimization of a 6DOF robot for specific tasks like automated cleaning or fish processing tanks. ...
Patients with upper and lower extremity dysfunction suffer from a non-independent life. They depend on other people to do their daily activities. Hence, the importance of assistive robots in their lives and the design challenges of these robots. The assistive robots must be capable of reaching and handling different spaces and objects. Thus, the understanding of the effects of the link lengths on the performance of the robot is a critical step in the design process. In this research, the effect of the link length of a 6 DOF serial robot applied to assistance studied. Firstly, it presents a description of the robot, from the DH parameters to the dynamic model. Later, the description of the desired workspace is observed. Finally, the study of a set of link lengths, their reachable area, and required energy consumption is discussed.
... The same problem occurs in the literature [25][26][27][28][29][30][31][32]. The kinematics of lightweight robot manipulators have been studied in the literature [33][34][35]. Through extensive literature reading, it is found that the lightweight robot manipulator is mainly oriented to real-life human-robot interaction applications with small motion speed for safety reasons. ...
In this paper, the problem of modeling and anti-disturbance control is studied for lightweight personal robotics (P-Robs) with a six-degree-of-freedom robot manipulator to solve the movement instability phenomenon caused by time-varying uncertain disturbances during the movement of the robot manipulator. The detailed dynamical equations of the P-Rob system are solved based on the Lagrange energy equation, and the actual dynamical model of the robot manipulator system is obtained. The disturbance observer is designed to estimate the disturbance effectively, and an integral sliding mode control algorithm is proposed to realize tracking control. Stability analysis of the system is carried out using the Lyapunov function. Finally, experiments are conducted on an actual P-Rob system model, and the experimental results show that the robot manipulator system tracks the desired trajectory effectively, which validates the effectiveness of the proposed control algorithm.
