Robotic Drilling Research Articles

A multi-modality tracking, navigation and calibration for a flexible robotic drill system for total hip arthroplasty.

This paper presents a novel multi-modality tracking and navigation system that provides a unique capability to guild a flexible drill tip inside the bone with accurate curved tunnelling. As the flexible drill tip cannot be tracked optically inside the bone, this research focuses on developing a hybrid tracking and navigation system for tracking a flexible drill tip by using both optical and kinematic tracking. The tracking information is used to guide the THA (total hip arthroplasty) procedure, providing a real-time virtual model of the flexible drill. The flexible and steerable drill tip system is then tested on total hip arthroplasty followed by evaluation of the positioning and orientation of femoral stem placement by femoral milling. Based on this study, we conclude that the tracking and navigation system is able to guide the flexible drill to mill inside femoral canal.

Development of Hand-Held Surgical Robot ODRO-2 for Automatic Bone Drilling

Abstract This paper represents the development of a prototype robotic system for automatic bone drilling in orthopaedic surgery. A new design of the mechanical structure is proposed, answering the surgical requirements for the robot dimensions and weight to be as small as possible. The new structure design is based on idea of parallelism of the axis of the linear actuator and the axis of the rotary one. The control system is improved by using a new micro-controller. A new type of linear drive and a new force sensor (load cell) are built in, so that the quality characteristics of the “Orthopaedic bone Drilling Robot” (ODRO) are not only the same as previous its two versions, but becomes better. An experimental setup is arranged and experiments are executed to test and to verify the robot quality features and functional capabilities.

Automatic bone drilling using a novel robot in orthopedic trauma surgery

Background: Currently, applications of robotized systems in orthopedic trauma surgery steadily increase due to their functional abilities facilitating surgeon skills. The aim of this study is to present the functional advantages of a recently developed robot for bone drilling.Methods: Ex-vivo experiments were performed on fresh porcine and bovine bones, as well as on fresh and embalmed human bones such as femora, vertebrae and rips, by the use of the robot for bone drilling to identify diverse control parameters and analyse thrust force and drill bit temperature during drilling.Results: Experimental data during drilling is shown, control algorithms are described and bone drilling modes are characterized. Maximal values of thrust force and temperature are detected. Controlling thrust force seems to be the proper way to reduce force resistance and hence temperature during drilling. In automatic drilling mode, preliminary defined channel depth is drilled with accuracy of 0.1 mm, and far cortex end recognition is proved to work reliably for automatic stop with minimal controlled soft tissue penetration. Cortex and bone marrow thickness are measured and analysed in real time.Conclusion: The bone drilling robot is programmed to follow with high accuracy parameters defined by the surgeon. Enhancing surgeon’s freedom and responsibility to make decisions, it can perform precise manipulations, decreasing the influence of subjective factors and increasing patient’s safety.

Tool Accessibility Analysis for Robotic Drilling and Fastening

Robotic applications in aerospace manufacturing and aircraft assembly today are limited. This is because most of the aircraft parts are relatively crowded and have complex shapes that make tasks like robotic drilling and fastening more challenging. These challenges include tool accessibility, path, and motion planning. In this paper, a process methodology was developed to overcome the tool accessibility challenges facing robotic drilling and riveting for aircraft parts that are located in crowded work environments. First, the tool accessibility was analyzed based on the global accessibility area (GAA) and the global accessibility volume (GAV) to determine the accessible boundaries for parts with zero, one, and two surfaces curvatures. Then, the path for the tool was generated while taking in consideration the approachability planning. This approach generates a number of intermediate points that enable the tool to maneuver around obstacles to reach the final target points if they are accessible. Last, a software application was developed to simulate the drilling and riveting tasks, and to validate the proposed process. The results of the simulation confirmed the proposed methodology and provided a numerical feedback describing the level of crowdedness of the work environment. The accessibility percentage can then be used by the design team to reduce the design complexity and increase the level of tool accessibility.

A low-cost and flexible solution for one-shot cooperative robotic drilling of aeronautic stack materials

In this paper, a general architecture for robotized cooperative drilling of hybrid metal/Carbon Fibre Reinforced Polymer (CFRP) aeronautic stacks is presented. The main objectives are to reduce non-added value operations as dismantling, deburring, cleaning and to improve hole quality by reducing the occurrence of delamination and inter-laminar cracking. The approach to achieve such targets is the adoption of a one-shot drilling automatized system based on low cost cooperative robots. The proposed technology consists in a general robot architecture and a cooperative drilling process using only standard low-cost robots and off-the shelf components. A first robot is in charge of drilling the hybrid stack, while a second manipulator ensures the right clamping force between the parts of the stack. Both robots are equipped with force control capabilities to control the generalized forces raising during the interaction with the stack. In this perspective, thanks to the adoption of a fuzzy inference system, the tuning of the force controllers might be carried out by operators that have knowledge of the drilling process but not of control system technology. Such feature makes the solution appealing for industrial production environments. The approach is experimentally validated on a cell with two Comau SmartSix robots drilling an aluminium-carbon fibre stack.

The method of aiming towards the normal direction for robotic drilling

During the robotic drilling of an aircraft assembly, the normal directions of the workpieces are to be measured to guide the robot by aiming the spindle at the real normal directions of the curved surfaces. This paper describes the development of a method of using four laser displacement sensors to measure the normal direction and the implementation of the proposed method in a robotic drilling system to meet industrial application requirements. First, a novel mechanical structure is introduced to achieve a higher installation accuracy for the laser displacement sensors with a micro adjusting method. Next, the hardware structures and a convenient method of calibrating the sensors are introduced. To accommodate the complexity of the industrial circumstance, a procedure of measuring and adjusting is developed with consideration of both an angular deviation threshold and a limited adjusting iteration. Finally, the experiments of measuring and adjusting iteratively show that two iterations can achieve a satisfactory angular deviation of 0.1° for planar workpieces and three iterations are required for curved workpieces, with the perpendicularity errors of the drilled holes being less than 0.3°. The results can meet the required perpendicularity accuracy of 0.5°.

The optimal clamping force option for robotic drilling of stacked aluminum sheets based on shell theory

In aircraft assembly, the influence of interlayer burr formation in drilling of stacked metal sheets is an important problem. This article aims to develop a deeply understanding of the relationship between the clamping force and interlayer burr formation. The minimum clamping force, which would just make the stacked sheets entirely contact each other, is considered as the optimal clamping force. Hence, the additional deformation would appear at the contact region when the clamping force keeps rising up. The optimal clamping force is obtained first through theoretical calculation. Then, numerical simulations and experimental verifications are conducted. The results demonstrate the effectiveness of the theoretical analysis based on shell theory.

A remote controlled haptic drilling robot for oral and maxillofacial surgery

A remote controlled haptic drilling robot for oral and maxillofacial surgery

Robotic cochlear implantation: surgical procedure and first clinical experience

Conclusion: A system for robotic cochlear implantation (rCI) has been developed and a corresponding surgical workflow has been described. The clinical feasibility was demonstrated through the conduction of a safe and effective rCI procedure.Objectives: To define a clinical workflow for rCI and demonstrate its feasibility, safety, and effectiveness within a clinical setting.Method: A clinical workflow for use of a previously described image guided surgical robot system for rCI was developed. Based on pre-operative images, a safe drilling tunnel targeting the round window was planned and drilled by the robotic system. Intra-operatively the drill path was assessed using imaging and sensor-based data to confirm the proximity of the facial nerve. Electrode array insertion was manually achieved under microscope visualization. Electrode array placement, structure preservation, and the accuracy of the drilling and of the safety mechanisms were assessed on post-operative CT images.Results: Robotic drilling was conducted with an accuracy of 0.2 mm and safety mechanisms predicted proximity of the nerves to within 0.1 mm. The approach resulted in a minimal mastoidectomy and minimal incisions. Manual electrode array insertion was successfully performed through the robotically drilled tunnel. The procedure was performed without complications, and all surrounding structures were preserved.

Multi-sensor measurement system for robotic drilling

In this paper we present a multi-sensor measurement system for robotic drilling. The system enables a robot to measure its 6D pose with respect to the work piece and to establish a reference coordinate system for drilling. The robot approaches the drill point and performs an orthogonal alignment with the work piece. Although the measurement systems are readily capable of achieving high position accuracy and low deviation to perpendicularity, experiments show that inaccuracies in the test scenario and slippage on the work piece when exerting clamping force considerably impact the results. With the current robotic drilling system an average position deviation of 0.334mm and an average deviation to perpendicularity of 0.29 are achieved. A multi-sensor measurement system for robotic drilling is presented.The system enables a robot to measure its 6D pose with respect to the work piece.Out of measurements a reference coordinate system for drilling is established.At the drill point the robot performs an orthogonal alignment with the work piece.A deviation of less than 0.1mm in position and less than 0.2 is within reach.

Modeling and experimental investigation of Cartesian compliance characterization for drilling robot

Industrial robot due to its high flexibility and low cost is wildly used in many areas. However, the low stiffness properties are the main limitation to the application of industrial robots in the field of precision machining. This paper addresses a modeling method of the Cartesian compliance for a drilling robot. The stiffness characterization in the drilling axial direction is analyzed, and the diversity of the axial stiffness in different robot postures is investigated. Based on the Cartesian compliance model, a quantitative evaluation index of the robot drilling performance is defined. Finally, experiments were developed on KUKA KR500-2 robot to validate the correctness of the model proposed, and specific conclusions regarding the robot compliance characterization are presented.

Modelling of Robotic Drilling

Recently, industrial robots are increasingly used in machining activities such as drilling, milling and grinding operations. However, due to their low stiffness and anisotropic behavior, the robotic drilling may lead to some circularity, position or perpendicularity errors. In this paper, two robotic drilling models are proposed. The first one focuses on the cutting process where the chip section is discretized and computed at each step. The second model takes into account the stiffness of the robot at hand. Some additional developments are carried out in order to analyze the elasto-static behavior of the robot while drilling.

Vision Based Navigation for Omni-directional Mobile Industrial Robot

In this paper, an Omni-directional mobile industrial robot drilling system for aerospace manufacture is introduced. Mecanum wheels are used for the robot's maneuverability in congested workspace. An industrial robot is applied to complete the drilling work for a rocket shell. A vision system is applied to enhance the precision of mobile drilling. Additional sensor systems such as laser measurement system and displacement measurement system are equipped to do the autonomous navigation and anti-collision job. To increase the flexibility and working volume of the mobile industrial robot, the autonomous mobile drilling scheme is presented. In order to fulfil the requirement for drilling precision in aerospace industry, a vision-based deviation rectification solution is developed. Some experiments are carried out to compare the influence of different calibration targets on the robot system. Numerical tests show that the rectification system is able to satisfy the accuracy of the positioning in the autonomous drilling work.

The Study of Design Method for Robotic Drill End Effector

The drill end effector is a key sub-system to flexible robotic drilling system, which performance will have an effect on drilling quality and efficiency. As a highly-integrated small electro-mechanical system, the design of drill end effector should be based on the robot and the process. The effect of the stiffness, the payload and the accuracy of the robot, the mounted configuration of the end effector, the technological process, and the orbital drilling technique were analyzed. And according to the analysis results, the design method of the drill end effector is established.

An error-similarity-based robot positional accuracy improvement method for a robotic drilling and riveting system

It is important to improve the absolute positional accuracy of the industrial robots used in the robotic drilling and riveting systems. The purpose of this paper is to propose a method to compensate for the absolute positional errors of the industrial robots. Firstly, the spatial similarity of the positional errors is qualitatively and quantitatively analyzed using semivariogram function and experiments. Secondly, the positional error model is established based on the spatial similarity, and a linear unbiased optimal estimation method of the target positional errors is proposed. Finally, experiments are used to verify the proposed methods with measuring the robot’s positional errors after compensation. The analysis shows that there is a spatial similarity of positional errors in the robot joint space, which can be used to establish error model and to estimate the target’s positional errors. Experimental results show that the proposed method can reduce the maximum absolute positional errors by 84.08 % from 2.01 to 0.32 mm, which can meet the accuracy requirements of the robotic drilling and riveting system.

Automatic Bone Drilling – More Precise, Reliable and Safe Manipulation in the Orthopaedic Surgery

Abstract Bone drilling manipulation often occurs in the orthopaedic surgery. By statistics, nowadays, about one million people only in Europe need such an operation every year, where bone implants are inserted. Almost always, the drilling is performed handily, which cannot avoid the subjective factor influence. The question of subjective factor reduction has its answer - automatic bone drilling. The specific features and problems of orthopaedic drilling manipulation are considered in this work. The automatic drilling is presented according the possibilities of robotized system Orthopaedic Drilling Robot (ODRO) for assuring the manipulation accuracy, precision, reliability and safety.

New design of a compact aero-robotic drilling end effector: An experimental analysis

This paper presents the development of a normal adjustment cell (NAC) in aero-robotic drilling to improve the quality of vertical drilling, by using an intelligent double-eccentric disk normal adjustment mechanism (2-EDNA), a spherical plain bearing and a floating compress module with sensors. After the surface normal vector is calculated based on the laser sensors’ feedback, the 2-EDNA concept is conceived specifically to address the deviation of the spindle from the surface normal at the drilling point. Following the angle calculation, depending on the actual initial position, two precise eccentric disks (PEDs) with an identical eccentric radius are used to rotate with the appropriate angles using two high-resolution DC servomotors. The two PEDs will carry the spindle to coincide with the surface normal, keeping the vertex of the drill bit still to avoid repeated adjustment and position compensation. A series of experiments was conducted on an aeronautical drilling robot platform with a precise NAC. The effect of normal adjustment on bore diameter, drilling force, burr size, drilling heat, and tool wear was analyzed. The results validate that using the NAC in robotic drilling results in greatly improved vertical drilling quality and is attainable in terms of intelligence and accuracy.

Temperature Prediction Model for Bone Drilling Based on Density Distribution and In Vivo Experiments for Minimally Invasive Robotic Cochlear Implantation.

Surgical robots have been proposed ex vivo to drill precise holes in the temporal bone for minimally invasive cochlear implantation. The main risk of the procedure is damage of the facial nerve due to mechanical interaction or due to temperature elevation during the drilling process. To evaluate the thermal risk of the drilling process, a simplified model is proposed which aims to enable an assessment of risk posed to the facial nerve for a given set of constant process parameters for different mastoid bone densities. The model uses the bone density distribution along the drilling trajectory in the mastoid bone to calculate a time dependent heat production function at the tip of the drill bit. Using a time dependent moving point source Green's function, the heat equation can be solved at a certain point in space so that the resulting temperatures can be calculated over time. The model was calibrated and initially verified with in vivo temperature data. The data was collected in minimally invasive robotic drilling of 12 holes in four different sheep. The sheep were anesthetized and the temperature elevations were measured with a thermocouple which was inserted in a previously drilled hole next to the planned drilling trajectory. Bone density distributions were extracted from pre-operative CT data by averaging Hounsfield values over the drill bit diameter. Post-operative [Formula: see text]CT data was used to verify the drilling accuracy of the trajectories. The comparison of measured and calculated temperatures shows a very good match for both heating and cooling phases. The average prediction error of the maximum temperature was less than 0.7 °C and the average root mean square error was approximately 0.5 °C. To analyze potential thermal damage, the model was used to calculate temperature profiles and cumulative equivalent minutes at 43 °C at a minimal distance to the facial nerve. For the selected drilling parameters, temperature elevation profiles and cumulative equivalent minutes suggest that thermal elevation of this minimally invasive cochlear implantation surgery may pose a risk to the facial nerve, especially in sclerotic or high density mastoid bones. Optimized drilling parameters need to be evaluated and the model could be used for future risk evaluation.

Coordination error control for accurate positioning in movable robotic drilling

Purpose – This paper aims to propose a roadmap to control the robot–subassembly (R–S) coordination errors in movable robotic drilling. Fastener hole drilling for multi-station aircraft assembly demands a robotic drilling system with expanded working volume and high positioning accuracy. However, coordination errors often exist between the robot and the subassembly to be drilled because of disturbances. Design/methodology/approach – Mechanical pre-locating and vision-based robot base frame calibration are consecutively implemented to achieve in-process robot relocation after station transfer. Thus, coordination errors induced by robotic platform movements, inconsistent thermal effects, etc. are eliminated. The two-dimensional (2D) vision system is applied to measure the remainder of the R–S coordination errors, which is used to enhance the positioning accuracy of the robot. Accurate estimation of measured positioning errors is of great significance for evaluating the positioning accuracy. For well estimation of the positioning errors with small samples, a bootstrap approach is put forward. Findings – A roadmap for R–S coordination error control using a 2D vision system, composed of in-process relocation, coordination error measurement and drilled position correction, is developed for the movable robotic drilling. Practical implications – The proposed roadmap has been integrated into a drilling system for the assembly of flight control surfaces of a transport aircraft in Aviation Industry Corporation of China. The position accuracy of the drilled fastener holes is well ensured. Originality/value – A complete roadmap for controlling coordination errors and improving positioning accuracy is proposed, which makes the high accuracy and efficiency available in movable robotic drilling for aircraft manufacturing.

Robot base frame calibration with a 2D vision system for mobile robotic drilling

Mobile robotic drilling for flight control surface assembly at multiple stations demands high positioning accuracy of the equipped industrial robot. However, disturbances, arising from movement from station to station, significantly deteriorate the positioning accuracy. This paper proposes a novel in-process robot base frame calibration method with a 2D vision system. A proposal layout of flight control surface assembly, the developed mobile robotic drilling system, and the 2D vision system are first introduced. Then an iterative measurement scheme is proposed to eliminate measurement errors induced by non-perpendicularity and erroneous object distance during 2D vision-based positioning of preset reference holes. In order to obtain the third-dimension Cartesian coordinates of the reference holes, depth control with autofocus is achieved by using a new sharpness function. Based on the acquired Cartesian coordinates of the reference holes in the robot base frame, and their counterparts measured in advance in the world coordinate system, the description of the robot base frame with respect to the world coordinate system can be obtained with least-squares fitting. Numerical experiments show that depth control with autofocus contributes to enhanced accuracy of robot base frame calibration. Experiments performed on the developed mobile drilling system indicate that the maximum positioning error is about 0.6 mm with the proposed calibration method. Since position errors of drilled fastener holes will be further measured and compensated for based on the 2D vision system, the proposed in-process robot base frame calibration method is effective.