A surgical robot system that overcomes manual limitations

Laparoscopic surgery is a type of surgical procedure in which a long-handled instrument is inserted through a small incision into the patient's body to be operated on. Compared with traditional open surgery, laparoscopic surgery can shorten recovery time, reduce pain, and reduce adhesions, allowing patients to have a better quality of life after surgery. However, manual laparoscopic surgery has many limitations, including the inability to sense depth, weak control of the camera, limited angles and space in which the instrument tip can freely rotate, and the range of motion of the doctor's surgical instruments. These limitations cause surgeons to endure unnatural and painful surgical postures during surgery, which can easily lead to fatigue.

Robotic-assisted laparoscopic surgery, such as the da Vinci system, allows the surgeon to remotely control endoscopic surgical instruments from a stereo console via a robotic arm at the patient’s bedside. The da Vinci system consists of three components: the surgeon’s main console, a surgical cart at the patient’s bedside for placing surgical instruments, and an imaging processor. The system’s 3D visualization provides depth perception, while its miniaturized instruments with wrist-like joints increase the surgeon’s dexterity and range of motion. The system also enhances control by reducing hand tremors and providing the surgeon’s movements in proportion to the robotic arm. The ergonomic instrument-hand-eye combination and intuitive instrument movements also reduce surgeon training time compared to manual laparoscopic surgery.

The da Vinci Si HD Surgical System shown in the picture is configured with two main surgeon consoles, a patient surgical cart and a cart for placing imaging equipment to display the surgical process.

The da Vinci robotic surgical system is based on robotic surgical technology developed at MIT (formerly Stanford Research Institute). Intuitive Surgical subsequently worked with IBM, MIT, and Heartport to further develop the system. The FDA has approved the da Vinci robotic surgical system for general surgery, thoracic surgery, urology, obstetrics and gynecology, head and neck surgery, and cardiac surgery in adults and children.

Da Vinci Robot

The da Vinci Surgical System requires up to five small (less than 1 cm) incisions in the patient's body to insert two surgical robotic arms and a camera. A matching cart placed next to the patient's bed moves the surgical instruments to the patient, and there will be a surgical assistant at the patient's bedside. At the same time, the doctor can sit at a console in the room to operate the system, and the surgeon sees and feels the same as in open surgery. The surgeon performs the operation by manipulating the main control unit (which is used to translate and transmit the surgeon's movements to the robotic arm). The surgeon grasps the main control unit below the display with his hand and moves his wrist naturally relative to his eyes. The surgeon's movements on the main control unit are converted into precise, real-time robotic arm movements inside the patient.

The surgeon's wrist, hand and finger movements are used to control the surgeon's robotic arm, just like in typical open surgery. In addition, the system also has a full range of EndoWrist surgical instruments to choose from. These surgical instruments can rotate at an angle of 7 degrees, which exceeds the dexterity of the human wrist. Each type of surgical instrument has a specific role, such as for clamping, suturing and tissue processing.

The cart next to the patient houses two robotic arms and an endoscopic arm that replicate the surgeon's movements. The laparoscopic arm pivots on the surgical site, not the patient's body cavity walls, which minimizes damage to tissue and nerves. The surgeon's assistants secure the appropriate surgical instruments, prepare the appropriate incisions on the patient, and monitor the laparoscopic arms and the tools being used.

In the top picture, the EndoWrist actuator is being used to suture. In the bottom picture, the surgeon is operating the master control unit at the main console to guide the EndoWrist actuator.

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Brake design

The da Vinci surgical system integrates high-end motion control technology so that every movement of the robotic arm can be as smooth and accurate as a skilled surgeon - even at slow computing speeds. Each da Vinci HD system contains more than 30 motors produced by Maxon Precision Motors. These motors are the heart of each robotic arm.

Maxon motors provide input and output for the da Vinci system. Through a series of feedback controls, the motors and encoders receive input signals from the surgeon, and after real-time translation by the main console circuit, they transmit output signals to the motors in the robotic arm. The robotic arm then applies force back to the surgeon's hand through the main console circuit.

The stator of the Maxon motor uses rare earth magnets and its stator adopts an iron-free design, so there will be no magnetic tooth slots even when running at low speeds.

To distinguish their dual roles, the motor used in the surgeon's bedside cart is the master motor, and the motor used in the robotic arm motor is the slave motor. The slave motor has the same accuracy as the master motor and also needs to be able to backdrive while the surgeon's assistant moves the end effector into position. The motor on top of the surgical instrument has low hysteresis.

Intuitive engineers use more than 30 motors in the da Vinci system. There are RE25 motors, some with encoder feedback and some without; RE 13 mm motors with GP13 series reducers and 13 mm magnetic encoders; and RE 35 series motors with third-party encoders.

Mike Prindiville, general manager and manufacturing engineer at Intuitive Surgical, said the Maxon motors are key to testing the da Vinci system’s core performance characteristics, including friction, clearance and compatibility, as well as a range of sensor feedback monitoring.

Software-based training

Although robotic-assisted, minimally invasive surgery has become popular, training opportunities are relatively limited. Because comprehensive practice and experience are required to be able to skillfully operate a complex tool like the da Vinci system, the development of robotic surgery training and coaching tools is critical to meeting this demand for robotic surgical training.

At the Nebraska Biomechanics Core Facility in the University of Nebraska Medical Center's Robotic Surgical Laboratory in Omaha, a group of doctoral students are working to develop a computer training program for robotic surgeons so that novice surgeons can learn how to use this advanced technology.

Endoscopic device for surgical system

For the Da Vinci robot

Researchers have developed two training platforms using National Instruments' LabVIEW graphical programming software. The first training platform is designed to monitor and record surgeons' performance during a training project and ensure that surgeons use the correct movements to complete the operation. The training platform also incorporates real-time visual feedback to show trainees how much force is applied to the training task or animated tissue. This visual feedback helps trainees reduce damage to patient tissue during surgery.

LabVIEW was also used to create a virtual reality robotic surgery training work environment. This training platform collects data and adjusts training tasks in the virtual simulator via Ethernet, providing flexibility for conducting research. Virtual robotic surgery training allows multiple surgeons to train simultaneously using software instead of actual medical equipment. This process provides a problem-oriented training protocol for novice surgeons to learn robotic surgery.

All communications within the da Vinci robotic surgical system are collected via TCP/IP, using NI's USB-6009 data acquisition card to connect to the myoelectric system and electrogoniometer. These connections collect physiological measurements from the surgeon, such as muscle activation and joint flexion. Using this data, researchers and medical staff can objectively evaluate surgical proficiency before and after a robotic surgical training protocol.