Benjamin V. Johnson

In this paper, we present the design of a miniaturized actuation system for robotic lumbar discectomy tools. Lumbar discectomy is one of the most common types of back surgery in the United States. Our previous work proposed a new robotic lumbar discectomy (RLD) system consisting of teleoperated articulated instruments inside a robotic cannula for performing this operation. The

We present the MAZE((Micro) Magnetic Actuation Zone control Environment) platform for independent control of multiple magnetic microrobots for performing individual and collaborative micromanipulation tasks. We present a new local magnetic field generating coil system design, microrobot design, actuation scheme, and orientation control for actuating multiple magnetic microrobots independently. The new designs are validated and experiments showcasing their abilities are presented. The demonstrations include closed-loop independent and simultaneous control of four microrobots and a sample micromanipulation task involving two microrobots pushing micro-parts into a prescribed formation.

We present the modeling, control and planning for multiple magnetic mobile microrobots actuated on a planar array of coils that generates local magnetic fields. The system is capable of actuating multiple microrobots independently. Such systems have a future in micromanufacturing and biomedical applications. The coils are modeled extensively to understand the forces generated by various coil combinations of the array, and solutions for different actuation force directions are discovered. The path planning problem is formulated as a Markov decision process that solves a policy to reach a goal from any location in the workspace. The presence of multiple robots in the workspace can interfere with their motion. Hence, the coil models are used concurrently with models of interaction force between multiple magnetic robots to plan efficient paths to reach a goal in the workspace in the presence of other robots.

Soft, untethered microrobots composed of biocompatible materials for completing micromanipulation and drug delivery tasks in lab-on-a-chip and medical scenarios are currently being developed. Alginate holds significant potential in medical microrobotics due to its biocompatibility, biodegradability, and drug encapsulation capabilities. Here, we describe the synthesis of MANiACs—Magnetically Aligned Nanorods in Alginate Capsules—for use as untethered microrobotic surface tumblers, demonstrating magnetically guided lateral tumbling via rotating magnetic fields. MANiAC translation is demonstrated on tissue surfaces as well as inclined slopes. These alginate microrobots are capable of manipulating objects over millimeter-scale distances. Finally, we demonstrate payload release capabilities of MANiACs during translational tumbling motion.

In this paper, the design of compliant three-dimensional (3D) printed surgical end-effectors for robotic lumbar discectomy is presented. Discectomy is the surgery to remove the herniated disk material that is pressing on a nerve root or spinal cord. This surgery is performed to relieve pain or numbness caused by the pressure on the nerve. The limited workspace of the spine (<27 cm3) results in challenging design requirements for surgical instruments. We propose a new cannula-based robotic lumbar discectomy procedure that can accommodate multiple articulated tools in the workspace at the same time and can be controlled teleoperatively by the surgeon. We present designs for two instruments for this proposed system: an articulated nerve retractor and an articulated grasper. The end-effectors of each are 3D printed with multiple materials, with flexible links acting as joints of the mechanism. These flexible links are actuated by cables which provide sufficient articulation and manipulation forces in the surgical workspace. The end-effector's articulated flexible joint kinematics is modeled and tested for range of motion capabilities. The retraction forces for the nerve retractor and the grasping force for the grasper are also experimentally tested and verified to meet all the design requirements. Additionally, fatigue testing of the flexible joint is presented and teleoperated control for the instruments is demonstrated. Finally, conceptual designs for new actuation systems are presented that will enable feasible surgical operations with the enhanced attributes of the designed end-effectors.

In this paper, we present a control framework that allows magnetic microrobot teams to accomplish complex micromanipulation tasks captured by global Linear Temporal Logic (LTL) formulas. To address this problem, we propose an optimal control synthesis method that constructs discrete plans for the robots that satisfy both the assigned tasks as well as proximity constraints between the robots due to the physics of the problem. Our proposed algorithm relies on an existing optimal control synthesis approach combined with a novel sampling-based technique to reduce the state-space of the product automaton that is associated with the LTL specifications. The synthesized discrete plans are executed by the microrobots independently using local magnetic fields. Simulation studies show that the proposed algorithm can address large-scale planning problems that cannot be solved using existing optimal control synthesis approaches. Moreover, we present experimental results that also illustrate the potential of our method in practice. To the best of our knowledge, this is the first control framework that allows independent control of teams of magnetic microrobots for temporal micromanipulation tasks.

In this paper, we present a control framework that allows magnetic microrobot teams to accomplish complex micromanipulation tasks captured by global linear temporal logic (LTL) formulas. To address this problem, we propose an optimal control synthesis method that constructs discrete plans for the robots that satisfy both the assigned tasks as well as proximity constraints between the robots due to the physics of the problem. The proposed algorithm relies on an existing optimal control synthesis approach combined with a novel sampling-based technique to reduce the state-space of the product automaton that is associated with the LTL specifications. The synthesized discrete plans are executed by the microrobots independently using local magnetic fields. Simulation studies show that the proposed algorithm can address large-scale planning problems that cannot be solved using existing optimal control synthesis approaches. Moreover, we present experimental results that also illustrate the potential of the method in practice. To the best of our knowledge, this is the first control framework that allows independent control of teams of magnetic microrobots for temporal micromanipulation tasks.