A Hybrid Position/Force Control Approach for Identification of Deformation Models of Skin and Underlying Tissues

Review of research on path planning and control methods of flexible steerable needle puncture robot

In the field of minimally invasive interventional therapy, the related research on the soft tissue puncture robot and its technology based on the flexible steerable needle as a research hot topic at present, and it has been developed rapidly in the past ten years. In order to better understand the development status of the flexible steerable needle puncture (FSNP) robot and provide reference for its design and improvement in subsequent research, it is necessary to introduce in two aspects of FSNP robot: the puncture path planning and the control methods. First, this article introduced the concept of the FSNP technology, and the necessity of the application of FSNP soft tissue robot in minimally invasive interventional surgery. Second, this article mainly introduced the principle of FSNP, the path planning of FSNP, the navigation and positioning control of the needle tip of the flexible steerable needle, the control method of FSNP system, and the controllable flexible needle. Finally, combined with the above analysis and introduction, it was pointed out that FSNP soft tissue robot and its related technology would be an important development direction in the field of minimally invasive interventional therapy in the future, and the current existing problems were pointed out. Meanwhile, the development trend of FSNP robot control technology was summarized and prospected.

Cervical Spine Mechanism for Reproduction of the Biomechanical Behaviours of the Human Neck during Rotation-Traction Manipulation

Rotation-traction (RT) manipulation is a commonly used physical therapy procedure in TCM (traditional Chinese medicine) for cervical spondylosis. This procedure temporarily separates the C3 and C4 cervical vertebrae from each other when a physician applies a jerky action while the neck is voluntarily turned by the patient to a specific position as instructed by the physician, where the cervical vertebrae are twisted and locked. However, a high rate of cervical injury occurs due to inexperienced physician interns who lack sufficient training. Therefore, we developed a cervical spine mechanism that imitates the dynamic behaviours of the human neck during RT manipulation. First, in vivo and in vitro experiments were performed to acquire the biomechanical feature curves of the human neck during RT manipulation. Second, a mass-spring-damper system with an electromagnetic clutch was designed to emulate the entire dynamic response of the human neck. In this system, a spring is designed as rectilinear and nonlinear to capture the viscoelasticity of soft tissues, and an electromagnetic clutch is used to simulate the sudden disengagement of the cervical vertebrae. Test results show that the mechanism can exhibit the desired behaviour when RT manipulation is applied in the same manner as on humans.

A Symbolic Construction Work Flow Based on State Transition Analysis Using Simplified Primitive Static States

In this paper, a quantitative analysis method for a comprehensive work flow in construction work for identifying work states in more detail is proposed. The proposed method is based on analyzing state transitions of simplified primitive static states (s-PSS), which consist of four symbolic work states defined by using the on-off state of lever operations and manipulator loads. First, practical state transitions (PST), which are common and frequent transitions in arbitrary construction work, are defined on the basis of the transition rules, according to which an operation flag changes arbitrarily and a load flag changes only during a lever operation. Second, PST is notionally classified into essential (EST) and nonessential (NST) state transitions whose definitions change depending on the task phase, including reaching, contacting, loadworking, and releasing. Third, closed loops formed by EST represent work content and those formed by NST represent wasted movements. In work-analysis experiments using our instrumented setup, results indicated that all s-PSS definitely changes on the basis of PST under various experimental conditions and that work analysis using EST and NST easily reveals untrained tasks related to wasted movements.

A Framework to Identify Task-Phase and Attentional-Condition for Supporting Complicated Dual-Arm Operations

The state identification framework we propose supports complex construction machinery operations using a dual arm. Such support requires compatibility with different types of support and commonality among various operator skill levels. Our framework is organized into (i) real-time task phase identification defined using joint load applied based on environment constraints and (ii) time-series attentional condition identification defined as an internal work-state condition classified by the operational support necessity level and dependent on the vectorial or time-series data selected by the identified task phase. Experiments are conducted using the instrumented hydraulic dual arm system for transport and removal tasks, including complex dual-arm operations. Results show that the number of erroneous contacts, internal force applied, and mental workload decreased without any increase in time, confirming that operational support based on our framework greatly improves individual operator work performance.

A new soft-tissue indentation model for estimating circular indenter 'force-displacement' characteristics

Models that predict soft-tissue indentation forces have many important applications including estimation of interaction forces, palpation simulation, disease diagnosis, and robotic assistance. In many medical applications such as rehabilitation, clinical palpation, and manipulation of organs, characterizing soft-tissue properties mainly depends on the accurate estimation of indentation forces. A new indentation model for estimating circular indenter 'force-displacement' characteristics is presented in this paper. The proposed model is motivated by a 'force-displacement' soil-tool model and is computationally efficient. The main feature of the proposed model is that it can be used to predict the force variations for a variety of tools without the need for retuning the model parameters for each tool. A six-degree-of-freedom robot manipulator with force and position sensors is used to validate the indentation model. Measured force versus tool displacement data for lamb liver and kidney, for a variety of tool diameters, are presented and compared with the forces predicted by the model, showing good agreement (RMS error < 8 per cent).

Modeling of Tool-Tissue Interactions for Computer-Based Surgical Simulation: A Literature Review

Surgical simulators present a safe and potentially effective method for surgical training, and can also be used in robot-assisted surgery for pre- and intra-operative planning. Accurate modeling of the interaction between surgical instruments and organs has been recognized as a key requirement in the development of high-fidelity surgical simulators. Researchers have attempted to model tool-tissue interactions in a wide variety of ways, which can be broadly classified as (1) linear elasticity-based, (2) nonlinear (hyperelastic) elasticity-based finite element (FE) methods, and (3) other techniques that not based on FE methods or continuum mechanics. Realistic modeling of organ deformation requires populating the model with real tissue data (which are difficult to acquire in vivo) and simulating organ response in real time (which is computationally expensive). Further, it is challenging to account for connective tissue supporting the organ, friction, and topological changes resulting from tool-tissue interactions during invasive surgical procedures. Overcoming such obstacles will not only help us to model tool-tissue interactions in real time, but also enable realistic force feedback to the user during surgical simulation. This review paper classifies the existing research on tool-tissue interactions for surgical simulators specifically based on the modeling techniques employed and the kind of surgical operation being simulated, in order to inform and motivate future research on improved tool-tissue interaction models.