Precise Drilling Research Articles

Telerobotic‐assisted bone‐drilling system using bilateral control with feed operation scaling and cutting force scaling

BackgroundDrilling is used in the medical field, especially in oral surgery and orthopaedics. In recent years, oral surgery involving dental implants has become more common. However, the risky drilling process causes serious accidents. To prevent these accidents, supporting systems such as robotic drilling systems are required.MethodsA telerobotic-assisted drilling system is proposed. An acceleration-based four-channel bilateral control system is implemented in linear actuators in a master–slave system for drill feeding. A reaction force observer is used instead of a force sensor for measuring cutting force. Cutting force transmits from a cutting material to a surgeon, who may feel a static cutting resistance force and vigorous cutting vibrations, via the master–slave system. Moreover, position scaling and force scaling are achieved. Scaling functions are used to achieve precise drilling and hazard detection via force sensation.ResultsCutting accuracy and reproducibility of the cutting force were evaluated by angular velocity/position error and frequency analysis of the cutting force, respectively, and errors were > 2.0 rpm and > 0.2 mm, respectively. Spectrum peaks of the cutting vibration were at the theoretical vibration frequencies of 30, 60 and 90 Hz.ConclusionsThe proposed telerobotic-assisted drilling system achieved precise manipulation of the drill feed and vivid feedback from the cutting force. Copyright © 2012 John Wiley & Sons, Ltd.

Preliminary study on persistence in soil and residues in maize of imidacloprid

The aim of this work was to study the distribution of imidacloprid in soil and its translocation to roots and aerial parts of maize plant. The main objective was to assess imidacloprid residues in field environment, in order to provide data on honeybees exposure level to such an active substance. Imidacloprid has been detected and quantified by Triple Quadrupole HPLC-MS-MS. Pesticide persistence in the soil and its residues in pollen and in maize plants have been evaluated during the growing of maize plants developed from seeds dressed with Gaucho 350 FS (imidacloprid: 1.0 mg/seed). The sowing has been performed by means of a pneumatic precision drill. Samples have been collected at 30, 45, 60, 80, 130 days after the sowing, as pollen samples have been collected at the tasseling. Imidacloprid presence in aerial part of maize plant declined to 2–3 μg/kg 80 days after the sowing, while concentration in kernel at harvest was <1 μg/kg. Maize pollen represents an important part of protein supply of beehives, and it is of critical importance to bee foraging. The values detected (imidacloprid residues <1 μg/kg) showed that maize pollen source should not be relevant for acute toxicity impact on honey bees.

Comments: Heroic Effort

Editor's column The recent rescue of 33 miners in Chile was a textbook success story. Behind the scenes, the oil and gas industry and several SPE members played key and supporting roles in the humanitarian effort that mobilized the best drilling technology available and captured the world’s attention. The miners, who were trapped nearly half a mile underground in the copper and gold mine for 68 days, were finally rescued in a complex and expensive operation. The Chilean government spared little expense in requesting help from drillers and other experts from more than a dozen countries, and industry was quick to offer assistance with equipment and personnel. One SPE member who assisted in the rescue was Nestor Eduardo Ruiz, a former chairperson of the SPE Patgonia Section in Neuquen, Argentina, and a manager at Argentina’s Gyrodata. He was part of “plan C,” one of three simultaneous operations organized to pull the miners to safety. Eduardo, who has worked in the directional drilling industry for 24 years, said he was contacted by one of plan C’s leaders who knew him from the early days of his oil and gas career. His company, Gyrodata, had done business with Chilean state companies Enap and Sipetrol, helping to survey wells to determine accurate wellbore positioning. “Needless to say, this was a big challenge for me and my company,” Eduardo said. “We could demonstrate our technology to direct and measure a well toward a tight objective in order to rescue 33 human lives. It was an incredible challenge.” When plan B—the second of three operations devised for the rescue—started to open the hole that would eventually free the miners, plan C went into effect. They were able to reach their depth target despite the fact that it was an extremely hard rock to drill, he said. “We used tricone bits with inserts,” Eduardo said. “It is not an easy task to drill a 28-in.-diameter wellbore directionally from the surface. As the control of the trajectory was not easy to do, it was necessary to change to a 17½-in. hole diameter at 220 m. With more weight on the bit, control of the trajectory was more predictable.” Eduardo said he relied on several SPE technical papers for guidance during the operation, as well as the advice of coworkers and SPE colleagues in Houston and Norway, including Rob Shoup, Jean Paul Lips, and Roger Ekseth. The company’s latest survey technology, the CAAT gyro tool, was used to measure the trajectory of the well. “The challenge for my company and for me was to provide the best wellbore position free of errors,” he said. Numerous drilling companies, both energy and nonenergy related, were involved in the rescue, including Layne Energy, Geotec, Precision Drilling, and Center Rock. “All of the service companies and technology involved—the drilling rig, directional drilling, wireline, mud, bits, etc.—represented a tremendous effort and we all worked together from the beginning,” he said. “Our industry showed it cared and we tried very hard to deliver an escape route for the trapped miners, while minimizing their risk and the risk of the rescuers at the same time.”

Advancements in Orthopedic Intervention: Retrograde Drilling and Bone Grafting of Osteochondral Lesions of the Knee Using Magnetic Resonance Imaging Guidance

Computer-assisted surgery is currently a novel challenge for surgeons and interventional radiologists. Magnetic resonance imaging (MRI)-guided procedures are still evolving. In this experimental study, we describe and assess an innovative passive-navigation method for MRI-guided treatment of osteochondritis dissecans of the knee. A navigation principle using a passive-navigation device was evaluated in six cadaveric knee joint specimens for potential applicability in retrograde drilling and bone grafting of osteochondral lesions using MRI guidance. Feasibility and accuracy were evaluated in an open MRI scanner (1.0 T Philips Panorama HFO MRI System). Interactive MRI navigation allowed precise drilling and bone grafting of osteochondral lesions of the knee. All lesions were hit with an accuracy of 1.86 mm in the coronal plane and 1.4 mm the sagittal plane. Targeting of all lesions was possible with a single drilling. MRI allowed excellent assessment of correct positioning of the cancellous bone cylinder during bone grafting. The navigation device and anatomic structures could be clearly identified and distinguished throughout the entire drilling procedure. MRI-assisted navigation method using a passive navigation device is feasible for the treatment of osteochondral lesions of the knee under MRI guidance and allows precise and safe drilling without exposure to ionizing radiation. This method may be a viable alternative to other navigation principles, especially for pediatric and adolescent patients. This MRI-navigated method is also potentially applicable in many other MRI-guided interventions.

Radiographic guided drilling of bony tibial tunnels for fixation of meniscus transplants using percentage references

The objective of our investigation was to evaluate the precision of radiographic-guided tibial tunnel drilling for anatomical anchoring of meniscus transplants at the tibial insertion areas. In 20 cadaveric proximal tibiae, the meniscal insertions were dissected and their circumferences outlined. Standardized photographs of the tibial plateau were obtained. Applying established percentage values for radiographic determination of the meniscus insertion midpoints, tibial tunnels were drilled using a standard ACL-guide. Guide positioning was performed by using the midpoints as determined on standard AP and lateral radiographs. After tibial tunnel drilling, a second set of standardized photographs of the tibial plateau was obtained. Digital imaging permitted the superposition of pre- and postoperative images. Overlapping between the anatomical insertion areas and the tibial tunnel exit was determined, as well as the distance between the borders of the insertion areas and the tunnel exit. Insertion area and tunnel exit showed a mean overlapping of 59.8 ± 34.8% (anterior horn), respectively 62.4 ± 32.0% (posterior horn) for the lateral meniscus and of 88.4 ± 15.5% (anterior horn), respectively 60.3 ± 31.6% (posterior horn) for the medial meniscus. Mean distance between the borders of insertion area and tunnel exit was 2.0 ± 1.5 mm (anterior horn), respectively 2.0 ± 1.7 mm (posterior horn) for the lateral meniscus and 0.9 ± 0.9 mm (anterior horn), respectively 2.1 ± 1.4 mm (posterior horn) for the medial meniscus. Thus, a precise drilling of tibial tunnels at the anatomical insertions of the menisci can be obtained by positioning a standard ACL-guide under radiographic control in a cadaver setting. In advanced day-by-day clinic, this knowledge could facilitate the surgical technique for anatomical fixation of lateral and medial meniscus transplants.

Passive navigation principle for orthopedic interventions with MR fluoroscopy

Of late, computer-assisted surgery has become a novel challenge for orthopedic surgeons. However, for orthopedic interventions magnetic resonance (MR) fluoroscopy is in its early stages of development. The authors have developed an innovative passive navigation concept, which is potentially applicable for many magnetic resonance image (MRI)-guided musculoskeletal interventions. With this method, no switching between different planes is required, since the cross-sectional modality of the MRI is used as a new navigation approach. This method was mainly evaluated in retrograde drilling of artificial osteochondral lesions of the talus as an example of difficult navigation in drill placement due to poor visualization with X-ray and complex anatomy. To accomplish this objective, a passive navigation device was constructed and evaluated in nine cadaveric ankle joint specimens. Feasibility and accuracy of navigated drillings were evaluated. The interactive high-field MR fluoroscopy and the passive aiming device allow precise drilling of osteochondral lesions of the talus, despite the complex anatomy of the ankle. Drillings could be performed with an accuracy of 1.6 mm. The drilling guide was safe and easy to handle. The MR-assisted retrograde drilling of osteochondral lesions may enable precise and safe treatment without radiation exposure. This passive navigation technique for MR fluoroscopy is potentially applicable for many orthopedic interventions and may present an alternative to other navigation methods. Especially, the treatment of pediatric and adolescent patients may benefit from the typical MRI properties.

A Critical Linguistic Assessment of The Process Parameters on The Relative Ranks of The Yield Parameters for Nd: Yag Laser Drilling

Advances in manufacturing technology and the quest for smaller part geometry, have played the role of a curtain raiser for the new frontiers of machining process of metals. In this specific domain of precision manufacturing, the traditional machining methods have limited capabilities to meet higher accuracy, better surface finish and greater productivity related requirements from the customer. Micro machining is a ready solution towards the miniaturization of components and devices. The main problems during micro machining methods are to make a low heat affected zone and the controllability of other parameters to meet ever demanding process capability related requirements. High energy beam machining identifies a category of processes, each of which is capable of transferring a beam of such high energy intensity into metal cutting or drilling forces. It should be used to melt and vaporize a narrow zone of metals. This ability is useful for precision drilling, welding and cutting. Low power pulse Nd:YAG laser machining is now being used for these purpose often with the high level of precision in an economically viable manner. Thin strip cutting of metals through laser beam is one of the main applications in this area. This paper is focused on the cutting and drilling of the mild steel workpiece with lower thickness values and an attempt has been made to study the different process parameters in linguistic terms, which will affect relative ranks of the quality of the precision cutting and micro drilling of the metal specimen.

Osteochondral Lesions of the Talus: Retrograde Drilling with High-Field-Strength MR Guidance

The institutional review board approved the use of cadaveric specimens, and informed consent was obtained from all volunteers. The authors performed and assessed a magnetic resonance (MR)-assisted navigation method for minimally invasive retrograde drilling of talar osteochondral lesions. For this method, a single imaging plane is sufficient for navigation during intervention. To accomplish this objective, a passive MR navigation device was used to evaluate 16 cadaveric ankle joints. Use of this interactive MR-assisted navigation method in combination with a passive aiming device allowed precise and rapid retrograde drilling of talar osteochondral lesions.

Vergleich unterschiedlicher Saattechniken für Mais

The intensive growing of maize, especially for producing fermentation gas, in consequence causes a needle eye in combination with intercrop harvest and spreading semi liquid manure. Efficient alternatives, like cultivator seeding and row seeding with discs where tested in comparison with precision seeding at the Institute for Agricultural Engineering and Animal Husbandry in Freising–Weihenstephan. Provisional results show lower field emergencies than in precision seeding. But not always the yield of dry mass is significant lower with this alternative seeding systems for maize. Actually the yield, in comparison to precision drill, shows strong fluctuations depending on drill and tillage system, location and repetition.

Application of haptic device to implant dentistry-accuracy verification of drilling into a pig bone

To enable accurate implant placement and precise drilling following preoperative simulation, we developed the BoneNavi system. To realize more precise drilling when the holes are upsized, two methods of surgical guiding were attempted in the present study. One involved using multiple surgical guides with titanium tubes of different diameters, and the other involved using a single surgical guide but employing titanium drill guide tubes with different diameters. Drilling accuracy of the two newly developed methods was examined and compared with the results of drilling into a pig bone using only the initial surgical guide. Deviations of the position and angle with the two novel methods were similar: 0.17 mm and 1 degree respectively. As for the control group whereby drilling was done using only the initial surgical guide, the deviations were 0.25 mm and 3.50 degrees--which were significantly larger than those achieved with the two novel methods. In light of the results obtained, our newly developed BoneNavi system is especially applicable for severe clinical cases that require precise implant placement.

V 46 CT-guided robotically-assisted retrograde drilling of osteochondral lesions of the ankle joint

Introduction Disadvantages of arthroscopically guided surgical techniques for treatment of osteochondral lesions (OCL) of the ankle joint are disruption of viable articular cartilage and insufficient addressing of the subchondral bone. For certain lesion locations, like the posteromedial talus, feasibility is often compromised. The INNOMOTION robotic assistance device proved its value for precise musculoskeletal interventions, such as facet joint and sacroiliac joint infiltrations. We present our first experience with CT-guided robotically-assisted retrograde drilling of osteochondral lesions of the ankle joint and evaluate its feasibility, precision and potential use as a routine operative treatment. Methods 8 patients diagnosed with OCL of the talus (4) and the distal tibia (4) were included. MRI revealed an intact cartilaginous cover in all cases. Surgery was performed with the INNOMOTION robotic assistance device (Innomedic, Herxheim, Germany) mounted on the table of a CT scanner. The robot-device was referenced to the coordinate system of the CT-scanner. Drill trajectory and depth were planned within acquired CT images. A guiding sleeve for the Kirschner-Wire (K-Wire) was attached to the holding device on the application module and positioned automatically according to the planned trajectory. A 2.5 mm K-Wire was advanced through the guiding-sleeve up to the calculated drilling depth. A cannulated drill was placed over the wire and advanced into the lesion. The lesion was curetted and filled with DBM-paste and patient spongiosa. CT-control scans were performed to determine the position of the instruments and to document the exact localization of the deposit. Results Technically successful CT-guided robot-assisted retrograde drilling was performed in all cases without intra- and postoperative complications. No intervention abort or conversion to arthroscopically guided technique or arthrotomy was necessary. CT-control scans confirmed exact initial placement of the guiding wire within the centre of the OCL, precise drill bit positioning and successful retrograde filling of the bored cavity. Discussion The first clinical cases demonstrated CT-guided robot-assisted intervention to be a feasible and safe method for retrograde drilling of OCL of the ankle. Precise assistance by the INNOMOTION-robot combined with the superior ability of the CT to visualize skeletal anatomy greatly improves the accuracy of drilling with exact and reliable addressing of OCL without damage to overlying cartilage. Further studies need to evaluate the outcome of this new operative technique and to compare it to conventional retrograde drilling.

DARTHROSCOPIC DOUBLE- BUNDLE RECONSTRUCTION OF ANTERIOR CRUCIATE LIGAMENT USING HAMSTRING TENDON GRAFTS - FIXATION WITH TWO INTERFERENCE SCREWS

Surgical procedures for double-bundle reconstruction of anterior cruciate ligament, which currently use semitendinous and gracilis tendon grafts, have been described in the last decade. Most of the techniques utilize twice the hardware used in single-bundle reconstructions. We report an original anterior cruciate ligament double-bundle reconstruction technique using semitendinous and gracilis tendon grafts, maintaining their tibial bone insertions with two tibial and two femoral tunnels. A simplified and precise outside-in femoral drilling technique is utilized, and the graft fixation is made utilizing only two interference screws.

Weathering patinas on the medieval (S. XIV) stained glass windows of the Pedralbes Monastery (Barcelona, Spain)

The first step in the restoration of a medieval stained glass window is the evaluation of its degree of degradation. This implies the study of the chemical composition of the stained glass as well as the new mineral phases developed on its surface (patinas). Patinas are clearly related to glass composition, time, environmental conditions, microenvironments developed in local zones, bioactivity, physical and chemical factors, etc. This study was carried out on patinas developed in selected Na-rich stained glass of the Santa Maria de Pedralbes Monastery (Barcelona, Spain). The location of this monument in the city (about 5 km from the shoreline and close to the Collserola hill flank) helped to determine the environmental conditions in which patinas developed. The aim of our study was to characterize the patinas formed on the surface of the selected glass of this monastery in order to understand the role of the chemical composition of the original glass (Na-rich) as well as the environmental conditions in which they developed. Powdered samples of two different color-type patinas (ochre-orange and brownish) were collected in the external and internal parts of the stained glass windows of the Prebystery and Chapter House of the Pedralbes Monastery by using a precision (odontological) drill. These patinas were subsequently analyzed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). XRD analyses evidenced the presence of sulfates (gypsum and thenardite), calcite, Ca-oxalates (whewellite and weddellite), and quartz forming part of the patinas. Although these mineral phases can be found in both color-type patinas, whewellite and thenardite are more common in the ochre-orange patinas. The results obtained were validated by the FTIR measurements. It has been observed, when thenardite is present, that gypsum occurs as traces. Thenardite is in most of the cases associated with whewellite and mainly occurs in the internal parts of the glass. In contrast, weddellite is limited to the absence of thenardite and whewellite and to the external parts of the stained glass. Quartz is present in all the patinas independent of their location and color. Calcite also occurs in many samples. It appears in both color-type patinas and, in some cases, is associated to the presence of weddellite but not to whewellite and/or thenardite. Glass composition together with environmental conditions and location of the patinas (internal or external parts of the stained glass window), as well as the provenance of the glass within the monastery, are the main factors that define the development of the new mineral phases. Moreover, the action of microorganisms, when present, can also strongly influence the development of some mineral phases. For example, the formation of calcite in the external parts of the stained glass (associated with the presence of oxalates) is related to the action of microorganisms. When calcite is formed in the internal parts of the glass and it is not associated with the presence of Ca-oxalates, an inorganic origin can be invoked. The presence of weddellite requires a very humid microenvironment with very little exposure to sunlight. In fact, this mineral phase has only been observed in the external parts of some glass located in the humid and shady side of the monastery. Whewellite (which only appears in the internal parts) needs a low degree of relative humidity. It has been observed that sulfur precipitating in basically one mineral phase (thenardite or gypsum) depends on the microenvironmental conditions of the moment and the glass composition. When thenardite occurs, it can be maintained that the original glass is of Na composition. The occurrence of quartz in all samples is interpreted as being due to the deposition of atmospheric particulate matter. The color of the patinas can be originated by different processes (presence of carotenes, organic pigmentation, atmospheric contamination, etc.). In the case of moderately weathered stained glass windows, the combination of XRD and FTIR techniques is very useful to obtain a fast preliminary evaluation of the degree of weathering of a stained glass window. The presence of specific mineral phases in the patina (e.g., thenardite) confirms the Na composition of the original stained glass. This is important since Na-rich glass underwent a lesser degree of weathering than K- or K-Ca-rich glass. However, their absence cannot preclude other possibilities. It has been extensively evidenced through time that environmental conditions play an important role on the formation of the different mineral phases which form part of the patinas. The first step in the restoration of a stained glass window is the evaluation of the degree of deterioration of the glass. This evaluation includes a chemical analysis of the glass as well as a characterization of the patinas developed on their surfaces. The obtained results will be essential in order to define the best restoration practices to be followed.

Arthroscopic anterior cruciate ligament double-bundle reconstruction using hamstring tendon grafts-fixation with two interference screws: technical note

In this article, an original double-bundle anterior cruciate ligament reconstruction technique is described. The procedure is developed using hamstring tendon grafts while maintaining tibial osseous insertion. Two tibial tunnels are drilled and a simplified and precise outside-in double tunnel femoral drilling technique is utilized. The graft fixation is made using only two interference screws.

Optimization of Industrial, Vision-Based, Intuitively Generated Robot Point-Allocating Tasks Using Genetic Algorithms

Current industrial robot-programming methods require, depending on the task to be developed, an elevated degree of technical ability and time from a human operator, in order to obtain a precise, nonoptimal result. This correspondence paper presents a methodology used to generate an optimal sequence of robot configurations that enable a precise point-allocating task applicable, for instance, to spot-welding, drilling, or electronic component placement maneuvers. The optimization process starts from a nonoptimal, initial sequence designated intuitively by a human operator using an easy-to-use interface. In this correspondence paper, intuitive programming is considered as the process of defining, in a computer graphics environment and with a limited user knowledge of robotics or the industrial task, the sequence of motions that enable the execution of a complex industrial robotic maneuver. Such an initial sequence is later followed by a robot, very precisely, using a vision-based, calibration-free, robot control method. Further robot path optimization is performed with a genetic algorithm approach. An industrial robot, which is part of the experimental setup, was used in order to validate the proposed procedure.

CFRP（炭素繊維強化プラスチック）の高精度・高能率ドリル加工の試み

CFRP（炭素繊維強化プラスチック）の高精度・高能率ドリル加工の試み

3410 ヘリカル加工によるCFRP板の高精度穴あけ加工(S47 切削加工,21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

3410 ヘリカル加工によるCFRP板の高精度穴あけ加工(S47 切削加工,21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

3D-fusionierte navigierte Anbohrung einer Osteonekrose des Femurkondylus

The primary goal of drilling procedures for the treatment of osteonecrotic lesions is revascularisation of the defect area. In the literature good results are reported for this technique in 70% of cases. Precise drilling of the necrosed area as part of a minimally invasive technique does, however, require unequivocal intraoperative identification of the region visually, either by arthroscopy or by fluoroscopy. In the case of inadequate imaging, as in our case, there is no longer any guarantee of precise drilling.Computer-assisted navigation system have already improved the precision of drilling procedures performed for various indications. Basically, however, a navigation is only as accurate as the underlying imaging. The use of preoperative data sets assumes an invasive and/or elaborate intraoperative recording procedure. For a procedure not requiring recording to be possible, image diffusion of the MRI and ISO-C(3D) data sets during the surgery would be necessary. In the present case a preoperative MRI data set was first combined with the ISO-C(3D) data set acquired intraoperatively. To this end, following application of the reference base a 3D scan was performed, and the data ascertained were transferred to the navigation system and in addition to the planning software. After fusion of the images the drilling canals were planned and implemented on the basis of the additional information emerging from the combination of the data. To be sure of success postoperatively, this was also merged with the preoperative MRI. The example shows that combining data sets makes it possible to improve the precision and safety of drilling in target areas that cannot be adequately imaged. In future, we hope it will prove possible to transfer the image data back into the navigation system after they have been merged. At present this is only possible with CT and MRI images. A comparative clinical trial is needed to find to what extent the success rate is improved over that achieved with conventional techniques.

Palaeoenvironment reconstruction in the Lagoon of Venice through wide-area acoustic surveys and core sampling

Since 1999, a joint project called ECHOS has started to explore extremely shallow zones of the lagoon of Venice with the help of acoustic techniques. The main aim of ECHOS is to reconstruct the ancient lagoon environment and investigate its evolution and anthropogenic changes. Although this topic has been the subject of many studies, the use of acoustic methods can solve the problem of correlating the levels intersected by precision drilling, and it can reveal buried geological and archaeological structures. After the first in situ trials, during the last three years, an extensive acoustic survey was carried out on geo-archaeologically interesting areas in the central and northern Venice Lagoon. For this purpose, a traditional echosounder was modified for use in very shallow waters. A direct comparison of the acoustic and geological data shows the potential of acoustic methods for archaeological and geological research aimed at the reconstruction of the ancient morphology of the Venice Lagoon. As an example of the encouraging preliminary results that were obtained, we present the discovery of a buried palaeocanal.

DEVELOPMENT OF A PARALLEL SURGICAL ROBOT WITH AUTOMATIC BONE DRILLING CARRIAGE FOR STEREOTACTIC NEUROSURGERY

Robot-assisted surgery is an active interdisciplinary field. Conventional surgical robots are mostly serial architectures, which have the advantages of large workspace, high dexterity and maneuverability. The disadvantages are low stiffness and poor positioning accuracy compared to the parallel structure robots. This paper presents the development of a parallel surgical robot for precise skull drilling in stereotactic neurosurgical operations. The dimensions of this robot are 35 × 35 × 45 cm 3, and its weight is about 6 kg. This surgical robot has 6° of freedom. The feed carriage of the bone drilling device mounted the parallel surgical robot provides one additional translational degree of freedom. A master-slave microcontroller-based system is designed for pose control. In applications for neurosurgical operation, the workspace is on the surface of a skull located at one side of the robot. This work analyzed asymmetric workspace on the surface of a sphere representing the skull. A special socket joint design that enlarges the asymmetric workspace of the robot for about 30% is also proposed. This parallel surgical robot has been integrated with an automatic bone drilling carriage developed in our previous work to achieve completely automatic bone drilling.