Realization and Control of Robotic Injection Prototype With Instantaneous Remote Center of Motion Mechanism

OBJECTIVE

Although there have been studies conducted on the instantaneous remote center of motion (RCM) mechanism, the general closed-loop control method has not been studied. Thus, this article fills that gap and employs the advantages of this mechanism to develop a novel injection system.

METHODS

The injection prototype involves the instantaneous RCM mechanism, insertion unit and injection unit. The RCM system is investigated in the presence of time-varying axial stiffness of the screw drive and underactuated case. For safe interaction, compliance control is designed in the insertion system. The stability of all separate systems is investigated with the bounded parameter variation rate. The injection prototype and a robot end-effector were then combined to perform injection.

RESULTS

Our RCM prototype can achieve a large workspace, and its control effectiveness was verified by multiple frameworks and comparison with previous studies. Compliance-controlled insertion can achieve accurate depth regulation and zero-impedance control for manually operating the needle. With the help of three-dimensional reconstruction and hand/eye calibration, the manipulator can guide the injection prototype to a proper pose for injection of a face model.

CONCLUSION

The injection prototype was successfully designed. The effectiveness of the whole control system was verified by simulations and experiments. The particular robotic injection task can be performed by the prototype.

SIGNIFICANCE

This article provides alternative schemes for developing an instantaneous RCM system, screw drive-based surgical tool, and robotic insertion with small needles.

A Handheld Steerable Surgical Drill With a Novel Miniaturized Articulated Joint Module for Dexterous Confined-Space Bone Work

OBJECTIVE

Steerable surgical drills have the potential to minimize intraoperative tissue damage to patients. However, due to their large shaft diameters, large bend radii, and small bend angles, existing steerable drills are unsuitable for dexterous operations in confined spaces. This article presents a handheld steerable drill with a 4.5-mm miniaturized tip, capable of abruptly bending up to 65.

METHODS

To achieve a small tip diameter and a large bend angle, we propose a novel articulated joint module composed of a tendon-driven geared rolling joint and a double universal joint for steering the drill shaft and transmitting drilling torques, respectively. We integrate this joint module with a customized compact actuation unit into a handheld device. The integrated handheld steerable drill is slim and lightweight, supporting burdenless, single-handed grips and easy integration into existing surgical procedures.

RESULTS

Experiments and analysis showed the proposed steerable drill has high distal dexterity and is capable to remove target tissues dexterously through a small passage/incision with minimized collateral damage.

CONCLUSION

The results suggest the potential of the proposed miniaturized articulated drill for dexterous bone work in confined spaces.

SIGNIFICANCE

By enhancing distal dexterity and reach for surgeons when dealing with hard bony tissues, the proposed device can potentially minimize surgical invasiveness and thus collateral tissue damage to patients for a better clinical outcome.

Stereotactic technology for 3D bioprinting: from the perspective of robot mechanism

Three-dimensional (3D) bioprinting has been widely applied in the field of biomedical engineering because of its rapidly individualized fabrication and precisely geometric designability. The emerging demand for bioprinted tissues/organs with bio-inspired anisotropic property is stimulating new bioprinting strategies. Stereotactic bioprinting is regarded as a preferable strategy for this purpose, which can perform bioprinting at the target position from any desired orientation in 3D space. In this work, based on the motion characteristics analysis of the stacked bioprinting technologies, mechanism configurations and path planning methods for robotic stereotactic bioprinting were investigated and a prototype system based on the double parallelogram mechanism was introduced in detail. Moreover, the influence of the time dimension on stereotactic bioprinting was discussed. Finally, technical challenges and future trends of stereotactic bioprinting within the field of biomedical engineering were summarized.