This tricky application involves controlling a robotic system for neurosurgery that represents the most advanced medical robotic device available in the world. The system comprises of two robotic arms, each with at least six degrees-of-freedom, and a third arm equipped with two cameras providing 3-D stereoscopic views. It functions under the direct control of a surgeon at the robotic workstation for all intra-cranial functions.
The workstation incorporates a computer processor, hand controllers to manipulate each arm, a joystick controller for positioning the camera and lights, and three types of display and data/video recorders:
* A video display that presents a view of the surgical site taken by the stereo cameras so that the 3D stereoscopic view provides the surgeon with a sense of depth.
* An MR display that shows the patient’s MR scan with a virtual tool position superimposed in the image enabling surgeons to view and track the tool in real-time so facilitating image-guided surgery. In addition the MR image may be enhanced to show the lesion margins to ensure the complete removal of tumours.
* The control panel display provides data on the system configuration, robot status, and force sensor data.
Importantly, the system allows for updated MR images to be obtained during all phases of an operation whether pre, post or intra-operative, without moving the patient as the 3D stereoscopic and MRI generated views provide real-time data to the surgeon.
Working with a specially designed set of tools, the robotic system can perform soft tissue manipulation, needle insertion, blunt dissection, suturing, grasping of tissue, cauterising, cutting, manipulation of a retractor, tool cleaning, suction and irrigation.
This project will serve as a base platform that can be extended to other types of surgery; in particular operations that require image guidance and precise motion. Future applications will include spinal surgery where intra-operative images can be used to guide tools to precise targets while avoiding critical structures.
Clearly the control system had to work fast and operate a complex multi axis systems in real time and for this the Delta Tau UMAC Turbo PMAC controller was the answer. The hardware used comprised of the Turbo PMAC CPU, DP RAM option, expanded memory, it had to be of course battery backed and required the electronic identification number option. The 16 axes of control had the 4 ACC 24E2A with option # 1 and incorporated16 axes of high-resolution analogue encoder interpolator’s 5- ACC 51 E with option # 1. This all came in a 21 slot Euro-card rack.
The clever software employed was the PMAC Executive Pro Suite to meet the stringent machine design challenges: controlling products designer for MRI compatibility such as non-magnetic motors and feedback devices. The demand for a stand alone 16 axes controller with interpolator feedback and a USB interface to a central computer.
The PMAC features that made this possible was the processing power and ability to control non-magnetic motors. The inverse kinematics ability was another essential requirement and also that it would interface with the selected encoder, and in addition to all that it allowed the USB to interface to the main computer.
For a solution that had engineers and surgeons scratching their heads it was Delta Tau that put their minds at rest with the powerful PMAC system. Micromech Systems is an authorised systems integrator for Delta Tau high level, multi-axis motion control products.