{"id":"934214ef-2c1a-403d-97f6-67ae596a6de4","arxiv_id":"2505.12624","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":5.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":3,"one_line_summary":"EndoForce measures ureteroscope insertion force externally with a commercial load cell, achieving about 0.4 N RMSE in bench tests.","lead":"The authors built EndoForce, a clip-on device that measures how much axial force a robotic endoscope feels as it is pushed into the body. In bench tests against a straight and a curved artificial ureter, it matched a two-sensor reference to within about 0.4 newtons.","discovery_kind":"new_method","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Reported RMSE is computed against an unvalidated testbed sum, not against a known force, so the central accuracy claim is not established.","rationale":"The reader's weakest assumption identifies the same core issue: the ground-truth reference is not established. I agree with the reader that the sum of the two testbed load cells may not equal the true axial force at the gripper, and therefore the reported RMSE is not a valid accuracy measure until the reference is calibrated. This is the most load-bearing concern because the entire quantitative claim depends on the reference. I also note the sensor noise level (≈0.45 N) approaching the reported RMSE as a secondary concern, but the reference validity is more fundamental. A concrete calibration check would settle the issue. The paper presents a plausible mechanical design and the prototype could still be useful with a validated evaluation, so a conditional acceptance remains appropriate; no change in verdict is needed.","tokens_in":12384,"tokens_out":5740,"duration_ms":63137,"concrete_test":"Apply a known axial force to the proximal gripper using a calibrated force gauge or dead weights while the ureteroscope is in the testbed, in both straight and curved configurations, and record the sum of the two testbed load cells during insertion and after collision. If the testbed sum deviates from the applied force by more than the reported RMSE (e.g., >0.1 N), the reference is biased and the RMSE values in Section IV do not measure EndoForce accuracy.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The RMSE in Section III compares EndoForce with the sum of two testbed load cells, but this sum is assumed to be the true axial force without independent calibration. The first load cell is said to sit beneath the sheath plate, so it may measure vertical/normal reactions rather than axial friction; in the curved pathway the scope exerts significant lateral forces that would couple into this cell. Bending stiffness, inertial forces from the moving transport, and friction in the gripper/lever can all contribute to the EndoForce reading without appearing in the testbed sum. The paper also reports a moving-average filter and an average standard deviation of about 0.45 N in the EndoForce signal, which is larger than the reported RMSE of 0.43 N / 0.39 N; without the force range and the reference noise, these RMSE values are not interpretable. Thus the claim of accurate axial force measurement is not supported unless the testbed reference is validated as a true measure of the force transmitted to the gripper.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper proposes EndoForce, an external device for measuring the axial force exerted on an endoscopic insertion tube during robotic endoscopic procedures. The device uses a commercial load cell coupled to the insertion tube through a lever mechanism, with an overload limiter, a detachable disposable gripper/sterile drape, and a linear transport stage. The authors validate the device in a bench testbed using a commercial ureteroscope inserted through straight and curved access sheaths, and compare the EndoForce reading with the sum of two testbed load cells, one measuring friction under the sheath plate and one measuring distal collision force. They report RMSE values of approximately 0.43 N for the straight pathway and 0.39 N for the curved pathway, and claim that the device measures axial force with high accuracy. The paper also discusses future integration of haptic feedback and AI-based noise reduction.","tokens_in":12564,"tokens_out":2242,"duration_ms":26810,"significance":"If the accuracy claim were established, the contribution would be practically valuable: an externally mounted, cost-effective, sterilizable axial force sensor that avoids the bulk and environmental sensitivity of distal or model-based approaches. The design has clear strengths: use of a commercial load cell, an overload protection mechanism, a disposable sterile cover concept, and physical experiments covering both straight and curved insertion pathways. However, the central quantitative claim rests on the assumption that the sum of the two testbed load cells is a valid reference for the true axial force at the gripper, and that assumption is not independently calibrated or justified. Additionally, the reported RMSE values are comparable in magnitude to the reported noise level of the EndoForce signal, so the evidence does not yet support the paper's 'high accuracy' claim.","major_comments":[{"comment":"The evaluation defines the true axial force as the sum of the two testbed load cells, but this reference is not independently validated. The first load cell is mounted beneath the plate holding the ureteral access sheath, so it can respond to normal and lateral forces from sheath deformation and bending, especially in the curved pathway; it is not obviously a pure measurement of axial friction. Bending stiffness of the scope, inertial forces from the moving linear transport, and friction in the gripper or lever can also contribute to the EndoForce reading without appearing in the testbed sum. The authors should calibrate the reference against a known applied force or compare the EndoForce reading with an independent force sensor at the gripper, and report the resulting systematic error.","section":"Section III, Experimental Design"},{"comment":"The reported RMSE values of 0.43 N and 0.39 N are not interpretable without additional context, because the average standard deviation of the filtered EndoForce signal is reported as approximately 0.45 N, which is comparable to or larger than the stated error. The paper should report the force range over which the RMSE was computed, per-trial RMSE values and their variance, the noise level of the reference load cells, and the signal-to-noise ratio. As written, the central claim of accurate measurement is not supported by the reported statistics.","section":"Sections IV and V, Results and Discussion"},{"comment":"The moving average filter used on the load cell data is not specified: the window size, whether it was applied causally or non-causally, and whether it was applied to the EndoForce signal, the reference signals, or both, are all omitted. Since the RMSE depends directly on the filtering, the reported accuracy cannot be reproduced or assessed without these details.","section":"Section III, Data Processing"},{"comment":"Each experiment was performed only three times per pathway, and the paper reports a single RMSE value per pathway without any measure of trial-to-trial variability or a statistical comparison. Given the small number of trials and the noisy signal, the authors should report the mean, standard deviation, and individual trial values for the RMSE, or justify that three trials are sufficient for the claimed accuracy.","section":"Section IV, Results"}],"minor_comments":[{"comment":"The text refers to 'all the data represented in lite red in Fig. 7'; 'lite' should be 'light'.","section":"Section V, Discussion"},{"comment":"The phrase 'research will be performd' contains a typo; it should read 'performed'.","section":"Section VI, Concluding Remarks"},{"comment":"The affiliation for the third author lists 'Department of Mechnical Engineering'; the spelling should be 'Mechanical'.","section":"Author Information, Appendix A"},{"comment":"The insertion speed is described as constant but its value is not reported, and the collision threshold is not quantified; both are implementation parameters that affect the measured force profile and should be stated.","section":"Section III, Experimental Design"},{"comment":"The figure uses red, green, blue, and orange traces that may be difficult to distinguish for color-blind readers; consider adding distinct line styles or markers in addition to color.","section":"Figure 7"}],"recommendation":"major_revision","confidential_remarks":null},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Colleague, here's my take on arXiv:2505.12624 (EndoForce). The paper describes a proximal axial force sensor for endoscopic robots: a lever arm with ball tip, tension spring, and commercial load cell, mounted on a linear transport with a disposable gripper. The mechanical design is thoughtful – the overload limiter and detachable sterile cover show practical thinking. That part is the real contribution. The paper also validates on a ureter testbed with straight and curved pathways, which is reasonable for a first prototype.\n\nThe soft spot is the validation. The RMSE is computed against the sum of two testbed load cells, one under the sheath plate and one at the distal end. That sum is assumed to equal the axial force at the gripper, but no independent calibration or error analysis of that reference is given. The first load cell likely sees normal reactions, not just friction; bending stiffness and inertial forces in the moving transport can also contribute to the EndoForce signal without appearing in the reference. On top of that, the reported average std of the EndoForce signal is about 0.45 N, which is larger than the reported RMSE of 0.43/0.39 N. That suggests the RMSE values are not meaningfully below noise, and without per-trial variance or filter details they aren't convincing. The paper honestly reports the std, which I credit, but the central claim of high accuracy is not established by this experiment.\n\nAll that said, this is honest engineering progress. The device concept is sound, the results are not over-interpreted beyond the accuracy claim, and the authors clearly know the related work. The weak evaluation is a typical early-stage prototype issue, not a sign of bad faith.\n\nI'd send this to peer review – it's a legitimate mechanical design contribution that reviewers can help improve, especially if they ask for a validated reference, per-trial data, and a filter specification. I wouldn't cite it myself in the next year, but it's worth having on the radar for anyone working on force feedback for endoscopic robots.","headline":"EndoForce is a thoughtfully designed proximal force sensor for endoscopic robots, but its accuracy claim rests on an unvalidated testbed reference and noise-level RMSE.","tokens_in":13061,"tokens_out":1501,"would_cite":false,"duration_ms":14923,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"EndoForce claims to measure axial insertion force in endoscopic robots with under half a newton of error on straight and curved paths.","keywords":["axial force sensing","endoscopic robotics","force feedback","ureteroscopy","load cell","haptic feedback","insertion force measurement","surgical robotics"],"falsifier":"Attach a calibrated force gauge to the distal end of the ureteroscope and apply a known axial push or pull while EndoForce holds the tube in air, bypassing the sheath; if EndoForce's reading deviates from the gauge by more than about 0.4 N, the claimed accuracy does not generalize beyond the testbed.","tokens_in":12190,"feed_emoji":"🩺","tokens_out":7312,"duration_ms":76454,"temperature":0.7,"pith_summary":"This paper introduces EndoForce, an add-on device that measures the axial force acting on the insertion tube of an endoscopic robotic system from outside the body. The authors' claim is that this reproduces the force a clinician's hand would feel during manual ureteroscopy or GI endoscopy, without modifying the scope and without the bulk, cost, or environmental sensitivity of embedded sensors. The device uses a lever and hinge to redirect the insertion force onto a commercial load cell, with an overload limiter and a disposable sterile contact part. In a benchtop ureter model, the force it reported matched the sum of the friction and collision forces measured in the testbed with about 0.43 N RMSE on a straight path and 0.39 N on a curved path. If accurate, the device gives endoscopic robots the force feedback they currently lack, which the authors argue is needed to prevent tissue damage and complications.","feed_headline":"EndoForce reads scope insertion force to within 0.43 N","feed_subtitle":"A bolt-on load cell gives endoscopic robots the same axial force feedback a surgeon's hand feels.","key_machinery":"The load-bearing component is the sensing part: a force transmission arm mounted on a hinge joint, with a ball tip pressing on a seat that leads to a commercial load cell. The arm reverses the direction of the insertion-tube force and, because the ball tip forms a point contact, transmits only the axial component; the tension-spring preload removes zero-region nonlinearity; and the overload limiter stops large accidental loads from reaching the cell. Around this sit the detachable gripper and insertion tube holder with a bistable mechanism for sterile, secure tube gripping, and a timing-belt linear transport that reproduces the grasp-advance-release cycle of a clinician's hand. Together they convert a varying axial load at the scope into a linear electrical signal without embedding any sensor in the scope itself.","core_discovery":"The paper's central claim is that axial force from the distal scope can be captured accurately at the proximal end by an external mechanism, provided the mechanism transmits force through a kinematic chain that preserves only the axial component. EndoForce holds the insertion tube in a gripper; the tube pushes a force transmission arm that rotates about a hinge, reversing the force direction and delivering it through a ball-tip point contact to a load cell. A tension spring preload keeps the ball tip seated so the load cell operates in its linear range, while an overload limiter mechanically blocks excessive forces. The paper reports that in a testbed with a 4 mm access sheath, EndoForce's reading tracked the sum of the two reference forces (friction under the sheath and collision at the distal end) with an RMSE of 0.43 N on the straight pathway and 0.39 N on the curved pathway, across three trials each.","pith_inferences":["An independent check of the claimed accuracy would compare EndoForce against a known force applied directly at the distal tip, rather than the sum of two testbed load cells.","The current device captures only the axial component; bending and torque cues, which also guide a clinician's hand, would require additional sensing axes.","Because the sensor is external and scope-agnostic, it could be used to collect labeled insertion-force data for training distal-force estimators without altering the instrument.","If the transport mechanism's own friction or inertia contributes to the handle force, the reported RMSE may depend on insertion speed; testing at multiple speeds would bound that effect."],"forward_implications":["A robotic ureteroscope fitted with EndoForce can provide real-time axial force feedback to the operator, restoring the tactile cue lost in remote control.","The disposable holder and sterile drape let the tube-contacting part be discarded after each case, so the load cell itself never needs sterilization.","The similar RMSE on straight and curved paths indicates the measurement is not disrupted by the bending of the insertion pathway in this testbed.","With a gripper that adapts to different diameters and a more compact drive, the same external sensing approach is intended to extend to GI endoscopes.","Connecting the measured force to a motor or vibration on the master device would give the surgeon real-time haptic feedback based on actual insertion force."],"supporting_citations":[{"why":"Documents the physical burden of conventional endoscopy, the clinical problem that motivates restoring intuitive force feedback.","marker":"[7]"},{"why":"Describes flexible endoscope navigation through tortuous anatomy, the setting where axial force feedback matters.","marker":"[19]"},{"why":"Reports scope retention and tissue-contact complications in flexible ureteroscopy, the safety case for measuring insertion force.","marker":"[20]"},{"why":"Presents a master manipulator with force feedback for natural-orifice surgery, establishing that measured force is the input haptics need.","marker":"[26]"},{"why":"Proposes deep-learning distal-force prediction from proximal measurements, the model-dependent approach EndoForce aims to avoid.","marker":"[27]"},{"why":"Proposes learning-based distal force estimation for tendon-sheath robots, another model-dependent baseline.","marker":"[28]"},{"why":"Reviews fiber Bragg grating force sensing for medical use, an alternative technology with cost and environmental limitations.","marker":"[34]"},{"why":"Demonstrates FBG force sensing on flexible endoscopic robots, the sensor class the authors contrast with a commercial load cell.","marker":"[35]"}],"fun_headline_variants":["EndoForce: bolt-on load cell reads scope force to 0.43 N","Hand-like force feedback for endoscopic robots, bolt-on","EndoForce: axial force sensing for endoscopes, within 0.43 N","Bolt-on load cell measures scope insertion force to 0.43 N"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The accuracy claim depends on the assumption that the two testbed forces — friction along the sheath and collision at the distal end — are the only forces the insertion tube transmits to the gripper, so their sum is the true axial force EndoForce should read.","fun_headline_variants_meta":{"raw":{"variants":["EndoForce: bolt-on load cell reads scope force to 0.43 N","Hand-like force feedback for endoscopic robots, bolt-on","EndoForce: axial force sensing for endoscopes, within 0.43 N","Bolt-on load cell measures scope insertion force to 0.43 N"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.00114,"raw_usage":{"total_tokens":4736,"prompt_tokens":951,"completion_tokens":3785,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":567,"completion_tokens_details":{"reasoning_tokens":3702}},"tokens_in":567,"tokens_out":3785,"duration_ms":26210,"temperature":1.0,"reasoning_tokens":3702,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-15T20:28:59.976270+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Attach a calibrated force gauge to the distal end of the ureteroscope and apply a known axial push or pull while EndoForce holds the tube in air, bypassing the sheath; if EndoForce's reading deviates from the gauge by more than about 0.4 N, the claimed accuracy does not generalize beyond the testbed.","supporting_citations":[{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Documents the physical burden of conventional endoscopy, the clinical problem that motivates restoring intuitive force feedback."},{"cited_title":"V aldastri, M","cited_arxiv_id":null,"evidence_quote":"Describes flexible endoscope navigation through tortuous anatomy, the setting where axial force feedback matters."},{"cited_title":"Huynh, S","cited_arxiv_id":null,"evidence_quote":"Reports scope retention and tissue-contact complications in flexible ureteroscopy, the safety case for measuring insertion force."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Presents a master manipulator with force feedback for natural-orifice surgery, establishing that measured force is the input haptics need."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Proposes deep-learning distal-force prediction from proximal measurements, the model-dependent approach EndoForce aims to avoid."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Proposes learning-based distal force estimation for tendon-sheath robots, another model-dependent baseline."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Reviews fiber Bragg grating force sensing for medical use, an alternative technology with cost and environmental limitations."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Demonstrates FBG force sensing on flexible endoscopic robots, the sensor class the authors contrast with a commercial load cell."}],"review_version":1}