A Robust Control Framework for Human Motion Prediction
IEEE ROBOTICS AND AUTOMATION LETTERS
Authors: Bajcsy, Andrea; Bansal, Somil; Ratner, Ellis; Tomlin, Claire J.; Dragan, Anca D.
Abstract
Designing human motion predictors which preserve safety while maintaining robot efficiency is an increasingly important challenge for robots operating in close physical proximity to people. One approach is to use robust control predictors that safeguard against every possible future human state, leading to safe but often too conservative robot plans. Alternatively, intent-driven predictors explicitly model how humans make decisions given their intent, leading to efficient robot plans. However, when the intent model is misspecified, the robot might confidently plan unsafe maneuvers. In this letter, we combine ideas from robust control and intent-driven human modelling to formulate a novel human motion predictor which provides robustness against misspecified human models, but reduces the conservatism of traditional worst-case predictors. Our approach predicts the human states by trusting the intent-driven model to decide only which human actions are completely unlikely. We then safeguard against all likely enough actions, much like a robust control predictor. We demonstrate in simulation and hardware how our approach safeguards against misspecified human intent models while not leading to overly conservative robot plans.
Primary tumour location is an important prognostic factor in colorectal cancer liver metastases following radiofrequency ablation
CLINICAL RADIOLOGY
Authors: Yang, D.; Zhuang, B.; Lin, M.; Xu, M.; Lv, M.; Kuang, M.; Xie, X.; Xie, X.
Abstract
AIM: To examine the outcomes and different prognoses for colorectal cancer patients with liver metastases (CRCLM) treated with radiofrequency ablation (RFA) based on the origin of the primary tumour (rectum versus colon). MATERIALS AND METHODS: Patients diagnosed with CRCLM from July 2011 to June 2018 were assessed in the study. The study included 114 patients with 176 lesions. All of the patients underwent RFA of their CRCLM. The overall survival (OS) and progression-free survival (PFS) were assessed with Kaplan-Meier survival function estimate curves and Cox regression analysis between the group of patients with rectal cancer liver metastases (RCLM) and colon cancer liver metastases (CCLM). RESULTS: Patients with RCLM exhibited worse OS and PFS than those with CCLM. The 1-, 2-, and 3-year OS rates were 87.5%, 75%, and 54.2% in the RCLM group and 93.9%, 87.8%, and 81.8% in the CCLM group (p=0.001), respectively. The 1-, 2-, and 3-year PFS rates were 43.7%, 22.9%, and 20.8% in the RCLM group and 57.6%, 45.4%, and 36.5% in the CCLM group (p=0.001), respectively. Multivariate analysis showed that primary tumour location, carcinoembryonic antigen (CEA), and response to pre-ablation chemotherapy were independent variables for OS and PFS. The N state of the primary tumour also had a significant impact on OS. CONCLUSION: This study showed that patients with CCLM had better prognoses than those with RCLM following RFA treatment. If patients intend to undergo RFA for CRCLM, the location of the primary tumour should be considered in the assessment of long-term therapeutic effects. (c) 2020 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.