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Robotic arms often perform industrial tasks requiring complex dextrous manipulation within constrained spaces. For example, automobile unibody assembly can require more than 5000 welds, with many performed within the vehicle’s interior. An arm can be designed specifically for this type of task by permuting link lengths and degrees of freedom (DOF)...
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Typical unibody assembly can require more than 5000 welds to connect the pressed-metal sheets that form the unibody. Robotic arms can be designed specifically for this task by permuting arm link-lengths and degrees-of-freedom (DOF) to find a set of feasible designs, with each design evaluated for joint-angle displacement, dexterity, simulated speed...
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Citations
... Interestingly, from a design point of view, the considered robot in this paper can replace the used robotic arm proposed by Wunderlich,32 in which he has built up a dexterous robotic arm to navigate in hard-to-reach and constrained areas inside vehicles. However, their rigid links cannot radically change its original shape which prevents the robot from squeezing through the twisted path. ...
Multi-section continuum robots’ (CRs) behavior is still an outstanding problem because of the highly non-linearity of its equation of motions. To this end, in this paper, particle swarm optimization (PSO) is adopted to solve the inverse kinematic model (IKM) of CRs. First, the CR’s structure is properly described. Then, the aforementioned algorithm is elaborately discussed and implemented in figuring out the IKM of CR and verified through forward kinematic model by choosing the PSO parameters, namely, cognitive factors [Formula: see text] and inertia weight [Formula: see text] for 200 positions on an arc-like trajectory. The optimal angle values ([Formula: see text] and [Formula: see text]) which ensure the lowest distance between the attainably desired position and the robot’s end effector are [Formula: see text] which is perfectly accurate. After that, simulation through MATLAB is carried out, namely, in the first simulation, a three-section CR follows a linear trajectory with a precision approximately equal to [Formula: see text]. Furthermore, PSO takes 7 ms as a mean consumption time to make the robot’s end effector attain to each position. Then, a circular trajectory is followed using PSO. Comparatively speaking, PSO is compared with four meta-heuristic approaches; it is remarked that PSO is a good compromise between accuracy and time consumption. Based on the obtained results, PSO can be considered as a trade-off between accuracy and time consumption for solving the IKM of CRs with complex structure.
... When it comes to the manipulators whose link lengths are relatively high with respect to their widths, the mapping of these links to this curve gets harder and is prone to result in intersecting with the obstacles [19]. A path-planning method where pseudoinverse velocity control is combined with the attractive poles concept can be used in enclosed workspaces [20]. There is also a motion planning method based on sensory data [21]. ...
This paper presents a simple, effective and robust geometrical approach for path-planning of redundant/hyper-redundant manipulators in real-time within confined spaces cluttered with obstacles. A discretized path for point robots to the goal gives all the information for navigation of the manipulator. As long as it is physically possible, the employment of maneuvering space is maximized by making the links almost pinch the walls of the convoluted terrain. The maneuvering ability of the method fully utilizing maneuvering space is far beyond those of others proposed in the literature. The exemplary computer simulations verify the effectiveness of the method.
... Offline path planning is suitable for a routine-tasked robot with static obstacles (Wunderlich, 2004), while online path planning is preferable to be used with robots that work in an unknown environment, where collision with dynamic obstacles might occur. ...
The growth of automation sector has brought numerous autonomous technology developments in many sectors, especially automotive. The autonomous features are proven to be helpful in reducing road fatalities globally. Advanced Driver Assistance Systems (ADAS), a system which helps the driving process automation, has growing roles in recent road vehicle features. It is the base for the development of a fully autonomous vehicle. One of the main features of ADAS is Collision Avoidance (CA) system. A sufficient CA architecture usually encompasses threat assessment, path planning and path tracking strategies. There are many ways of developing precise CA architecture using the combination of these strategies. This paper aims to review current available methods for CA as an introductory idea for researchers who are new to this field. Each of the methods in each strategy is categorised into several groups. Their advantages and drawbacks are discussed. In addition to that, several improvement suggestions for a comprehensive CA system were highlighted.
... Offline path planning is suitable for a routine-tasked robot with static obstacles [97], while online path planning is preferable to be used with robots that work in an unknown environment, where collision with dynamic obstacles might occur. ...
Collision Avoidance (CA) system is a pivotal part of the autonomous vehicle. Despite the reported advancements, development of CA system in the presence of uncertain obstacles still possesses issues. These include untimely actuators intervention, unreliable planning and tracking strategies, near-miss incidents as well as hazardous lane departure while avoiding obstacles. During the avoidance of sudden appearance of obstacles, the abrupt increment of vehicle longitudinal and lateral forces summation during the maneuver demands a system with the ability to handle the coupled nonlinear dynamics. To address these issues, this study aims to develop an integrated nonlinear control strategy for CA system of uncertain obstacles in multi-risk scenarios. A Nonlinear Model Predictive Control-based (NMPC) path tracking strategy is proposed as the automated motion guidance for the host vehicle which is integrated with the Artificial Potential Field (APF) motion planning strategy. APF measures the collision risks and formulates the desired references for the path replanning. It ensures an optimal replanned trajectory by including the vehicle dynamics into its optimization formulation. NMPC then acts as the coupled path and speed tracking controller to enable vehicle navigation. To accommodate vehicle comfort during the avoidance, NMPC is constrained. To decrease the system's computational burden, Move Blocking strategy is assimilated within the NMPC design. To validate the proposed controller, a research platform vehicle is developed and modeled. The performance of the CA system is compared with four well known integrated control strategies. The consideration of vehicle nonlinearity into NMPC is shown to yield lower mean squared error (MSE) compared to linear MPC, with 97.36 percent decrement for yaw rate tracking and 94.36 percent decrement for deceleration tracking. The inclusion of multi-actuators and vehicle states feedback into the controller prevented lane departure after CA navigation. Analysis of the system’s robustness by computational simulations in multi-risk CA scenario with uncertain obstacles revealed that collisions were avoided in all scenarios. Move Blocking strategies managed to reduce the NMPC computation time with the mean value of 2.281 seconds in six scenarios with 25.33 percent increased performance from the uniform blocking. The architecture of CA system successfully maintained the safe-distance of 2 metres towards the collision points during the minimum safe-time, thus preventing near miss incidents. Hence, this study is important for the development of a multi-actuators controller strategy for CA of the fully autonomous vehicle in varied uncertain risk scenarios.
... The following robot parameters are typically used as optimization variables: number of degrees of freedom (DOF), robot configuration, link lengths (Han et al., 2007, Zhou et al., 2012, actuator type and power (Wunderlich, 1991). The following considerations are used for cost function and constraint definition: covering a given working volume (Bergamaschi et al., 2008, Ceccarelli and Lanni, 2004, Peterson, 1999, avoidance of a singularity region in the robot workspace (Ceccarelli et al. 2005, Stocco et al. 1998), Jacobian conditional number, manipulability and dexterity indexes (Gosselin, 1992). ...
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... Collisions between the manipulator and environmental obstacles, as well as manipulator self-collision, can be prevented by taking these collisions into account in the dimensional synthesis algorithm. One way to avoid obstacles is to create obstacle avoidance points on the manipulator and simulate forces that repel these points away from obstacles if any are found in the vicinity [16]. Another method to check for collisions is to use geometric-based computer-aided design models and then prevent them. ...
In this paper, an optimization method for a redundant serial robotic manipulator's structure is proposed in order to improve their performance. Optimization was considered in terms of kinematics using the proposed objective function and the non-linear Levenberg-Marquardt algorithm for multi-variate optimization. Range limits of the joints, bounds of the design parameters, and a constrained workspace are enforced in the proposed method. A desired manipulator can be optimized to cover the required task points using dimensional synthesis. This approach effectively optimizes the link lengths of the manipulator and minimizes the position and orientation errors of the tool center point. A commercial heavy-duty hydraulic, underground tunneling manipulator was used to demonstrate the capability of the proposed optimization method. The obtained results encourage the use of the proposed optimization method in automated construction applications, such as underground tunneling, where the confined environment and the required task add challenges in the design of task-based robotic manipulators.
... A técnica mais utili- zada é a cinemática inversa que é um processo pelo qual os ângulos das juntas de um atuador são calcula- dos a partir da posição em que se deseja colocar o ór- gão terminal (AZEVEDO & CONCI, 2003). O cálculo desses ângulos possibilita a construção de sistemas de controle que tradicionalmente utilizam matrizes jaco- bianas em conjunto com as pseudo-inversas (WUNDERLICH, 2004). ...
A cinemática de um manipulador é nada mais que estudo do seu movimento sem levar em consideração as forças físicas envolvidas. Dificuldades com o posicionamento e trajetórias de manipuladores robóticos são frequentes, principalmente nos casos onde é necessário fazer a transformação dos pontos desejados no plano espacial para os ângulos correspondentes de cada junta. A problemática ocorre por causa das equações diferencias terem mais de uma ou até mesmo nenhuma solução para a posição estipulada. Para resolver este problema, as implementações de soluções numéricas ou analíticas são indispensáveis, cada um com suas vantagens ou desvantagens em relação ao outro. Esse trabalho tem como objetivo demonstrar a utilização de um método numérico através da jacobiana pseudo-inversa para solução da cinemática inversa por meio do Matrix Laboratory (MATLAB). As simulações computacionais realizadas no toolbox robotic juntamente com testes no protótipo do manipulador são apresentadas no final desse trabalho.
... EGR/CS434 Green Robotics, Automation, and Machine Intelligence includes a required semester design project where students choose a topic from two main subject areas: (1) Green Automation, Manufacturing, and Smart-homes (discussed in next section); or (2) Conceptual design of two roversone as described above for the exploration of Europa, and the another using a modified version of the college's "Wunderbots" shown in Figure 3, and a new design of our "Aquabot" shown in Figure 4, to explore and map the environment in and around the campus lake also shown in Figure 4. Path planning may be accomplished using virtual "Attractors" and other techniques previously developed by the author [14,15,19,20,21] as illustrated in Figure 5. The two designs are required to be done simultaneously, with a final paper and presentation comparing and contrasting the decisions made for each design. ...
... To mitigate these risks, robot designers should limit the maximum velocities, torques, and motion-ranges of any industrial robotic arm; and the work-space of the robot should be caged and have restricted access to the work-cell; this is a law in the United States per the Occupational Safety and Health Act (OSHA). Figure 1 is an example robotic arm design yielded by the research in [16] where the arm design has been optimized for many parameters including limiting maximum velocities while performing a very difficult task inside an enclosure. This research was extended to the design of industrial robotic arms for welding tasks in [17]. ...
... This research was extended to the design of industrial robotic arms for welding tasks in [17]. limiting maximum velocities while performing a difficult task [16]. ...
... Global pathplanners can certainly help with this problem as was the case in 2006 when an upload of new global path-planning software was needed to free the Mar's rover from getting stuck due to multiple conflicting commands [12]. Another strategy to overcome this problem is to create "attractors" that virtually pull a mobile robot or robotic arm into and through noisy, crowded, or un-charted environments [16]. This concept is illustrated in Figure 11 where the robotic arm needs to have an educated guess where to go; else it becomes completely overwhelmed by obstacle avoidance commands repelling every elbow away from the walls of the enclosure. ...
The current hydraulic robotic manipulator mechanisms for heavy-duty machines are a mature technology, and their kinematics has been developed with a focus on the human operator maneuvering a hydraulically controlled system without numerical control input. As the trend in heavy-duty manipulators is increased automation, computer control systems are increasingly being widely used, and the requirements for robotic manipulator kinematics are different. Computer control enables a different kind of robotic manipulator kinematics, which is not optimum for direct control by a human operator, because the joint motions related to the different trajectories are not native for the human mind. Numerically controlled robotic manipulators can accept kinematics that is more efficient at doing the job expected by the customer.
To increase the autonomous level of robotic manipulator, the optimal structure is not enough, but it is a part of the solution toward a fully autonomous manipulator. The control system of the manipulator is the main part of computer-controlled manipulators. A collision avoidance system plays an important role in the field of autonomous robotics. Without collision avoidance functionality, it is quite obvious that only very simple movements and tasks can be carried out automatically. With more complicated movement and manipulators, some kind of collision avoidance system is required. An unknown or changing environment increases the need for an intelligent collision avoidance system that can find a collision-free path in a dynamic environment.
This thesis deals with these fundamental challenges by optimizing the serial manipulator structure for the desired task and proposing a collision avoidance control system. The basic requirement in the design of such a robotic manipulator is to make sure that all the desired task points can be achieved without singularities. These properties are difficult to achieve with the general shape and type of robotic manipulators. In this research work, a task-based kinematic synthesis approach with the proper optimization method ensures that the desired requirements can be fulfilled.
To enable autonomous task execution for robotic manipulators, the control systems must have a collision avoidance system that can prevent different kinds of collisions. These collisions include self-collisions, collisions with other manipulators, collisions with obstacles, and collisions with the environment. Furthermore, there can be multiple simultaneous possible collisions that need to prevented, and the collision system must be able to handle all these collisions in real-time. In this research work, a real-time collision avoidance control approach is proposed to handle these issues. Overall, both topics, covered in this thesis, are believed to be key elements for increasing the automation of serial robotic manipulators.
