Figure - available from: International Journal of Advanced Robotic Systems
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(a) An illustration of the parallel manipulator and (b) its global reference frame placed on the patient’s nose tip.
Source publication
Surgical robots are safety-critical devices that require multiple domains of safety features. This article focuses on the passive gravity compensation design optimization of a surgical robot. The limits of this optimization are related with the safety features including minimization of the total moving mass/inertia and compactness of the design. Th...
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A neurosurgical robot with 3-dimensional (3D) distal manipulation can increase instrument workspace for reaching peripheral regions of intracranial lesions to achieve complete lesion removal and minimal brain manipulation in a keyhole procedure. In this work, we designed a Nitinol-based symmetrically notched continuum robot based on the neurosurgic...
Citations
... For instance, Kuo et al. proposed a gravity compensator in a reconfigurable mechanism [36], proving that a single spring can compensate for gravitational force in two one-DOF reconfigurable systems. Maaroof et al. used Particle Swarm Optimization to compute the spring properties for a remote center-of-motion (RCM) mechanism [37], aiming to minimize the summation of actuator torques. ...
Robotic manipulators are typically engineered with high-power systems to handle payloads and counteract gravity, owing to their robust and weighty structures. However, there is now a growing need for eco-friendly and safe human-robot collaboration solutions that require power-efficient innovations. Currently, gravity compensation techniques employ various counterbalancing mechanisms that are specific and challenging to expand for systems with higher degrees of freedom (DOF). In response, this research introduces a novel gravity compensator system capable of effectively counterbalancing manipulators with multiple degrees of freedom (DOF) using only one spring. The proposed system uses parallelogram mechanisms, cam follower systems, and a square-root mechanism to solve potential equations mechanically. The proposed system can generalize the design of a gravity compensator for a multi-DOF manipulator using only one linear spring. This paper outlines the design and development of prototypes, focusing on one- and three-degree-of-freedom manipulators that serve as experimental testbeds. The experiment demonstrated that our gravity compensator system significantly reduced the required torques, power, and overall energy consumption of the robotic system. This innovative approach addresses existing challenges and paves the way for sustainable and power-efficient robotic manipulator design.
... Safety can be increased by reducing the mass and inertia of robots because the harm of the collision between machine and human body 5 could be weakened when the mass and inertia of robots become smaller. Therefore, the lightweight design plays a significant role in improving the safety of robots, 6,7 which can be achieved using new lightweight materials or optimizing the structures of parts. [8][9][10] To reduce the mass of robots, many researchers employed new lightweight materials in their designs. ...
Topology optimization is an effective method for the lightweight of collaborative robots. The extreme working conditions of the robot for the existing topology optimization approach are usually determined by design experience, which may cause mismatch between the chosen load boundary condition of the parts to be optimized and the actual maximum one. In this article, a kind of topology optimization method based on orthogonal experiment was proposed to avoid this mismatch. For this method, the extreme working condition of robots was determined by finding out the combination of robot joint angles when the stress of the part was maximum based on orthogonal experiment. And then, the structure of the part was optimized with the objective of minimizing mass and the constraint of the maximum end displacement of the robots. Finally, the proposed method and the existing method were applied to the lightweight design of a 7 degree of freedom upper limb powered exoskeleton robot, and the results demonstrated that the presented approach can reduce 6.78% maximum end displacement of the robot on average compared with the existing one. It can be concluded that the proposed method in this article is more reasonable and applicable to the structure optimization of collaborative robots.
Motivation
A fluorescence emission-guided microscope used to monitor the outcome of cancer removal surgery is highly effective when employing a manipulator to motorize and switch the observation direction. It is necessary to minimize the alignment of looper tension between the stands for pull/push to change the direction of the manipulator and reduce the error rate caused by tension differences. This paper presents a method to minimize the error rate of looper tension between the stands.
Methods
\The looper is inserted between the stands of the manipulator to minimize the difference in tension and make the stress on the pull and push of the looper constant. The constant stress allows the manipulator to move stably in left/right, up/down, and left/right movements, which will be effective for full-camera observation and close-up shots of the end effector.
Results
Reducing the tolerance for differences in the manipulator’s looper tension (angle and tension) is crucial. When the input value of the looper tension angle is 50°, the output should closely match 50°. Consequently, the measured response has a tolerance of ±49.98%, resulting in an error rate of .02% (1/50th level).
Conclusion
A method is proposed to minimize the error rate of the manipulator’s looper tension in a robot-based fluorescence emission-guided microscope used to observe the status of cancer surgery. As a result, a stable manipulator with a minimal error rate can achieve a 3.986x magnification for close-up observation by switching between high and low orientations.
This work addresses the gravity balancing of a 2R1T (2 rotations – 1 translation) mechanism with remote center of motion. A previously developed balancing solution is modified and applied to a prototype, and test results are presented. The mechanism is an endoscope holder for minimally invasive transnasal pituitary gland surgery. In this surgery, the endoscope is inserted through a nostril of the patient through a natural path to the pituitary gland. During the surgery, it is vital for the manipulator to be statically balanced so that in case of a motor failure, the patient is protected against any harmful motion of the endoscope. Additionally, static balancing takes the gravitational load from the actuators and hence facilitates the control of the mechanism. The mechanism is a 2URRR-URR type parallel manipulator with three legs. The payload mass is distributed to the legs on the sides. By using counter-masses for two links of each leg, the center of mass of each leg is lumped on the proximal link which simplifies the problem of balancing of a two degree-of-freedom inverted pendulum. The two proximal links with the lumped mass are statically balanced via springs. Dynamic simulations indicate that when the mechanism is statically balanced, generated actuator torques are reduced by 93.5%. Finally, the balancing solution is implemented on the prototype of the manipulator. The tests indicate that the manipulator is statically balanced within its task space when the actuators are disconnected. When the actuators are connected, the torque requirements decrease by about 37.8% with balancing.
In this paper, a novel 4 degrees-of-freedom articulated parallel forceps mechanism with a large orientation workspace (±/−90deg in pitch and yaw, 360deg in roll rotations) is presented for robotic minimally invasive surgery. The proposed 3RSR-1UUP parallel mechanism utilizes a UUP center-leg which can convert thrust motion of the 3RSR mechanism into gripping motion. This design eliminates the need for an additional gripper actuator, but also introduces the problem of unintentional gripper opening/closing due to parasitic motion of the 3RSR mechanism. Here, position kinematics of the proposed mechanism, including the workspace, is analyzed in detail, and a solution to the parasitic motion problem is provided. Human in the loop simulations with a haptic interface are also performed to confirm the feasibility of the proposed design.
