Design and development of a Stewart platform based force±torque sensor T.A. Dwarakanath a , Bhaskar Dasgupta b, * , T.S. Mruthyunjaya c a Division of Remote Handling and Robotics, Bhabha Atomic Research Centre, Mumbai 400 085, India b Department of Mechanical Engineering, Indian Institute of Technology, Kanpur 208 016, India c Department of Mechanical Engineering, Indian Institute of Science, Bangalore 560 012, India Received 23 June 1998; received in revised form 30 May 2000; accepted 7 June 2000 Abstract This paper details the design and development of a force±torque sensor based on the Stewart platform structure. The optimal synthesis of the sensor structure is performed with the objective of achieving well-conditioned transformation between the input and output forces.The in¯uence ofsize ofplatform on sensitivity and the load bearing capacity are discussed in the light of capabilities of available sensing elements. Thus, the design is obta by satisfying the dual objective of isotropy and sensitivity of the force±torque sensor. Max- imization of signal to noise ratio (S/N ratio) is considered at various stages in arriving at various component shapes and dimensions. The above design has been implemented in the development of a compactforce±torque sensor. Ó 2001 ElsevierScience Ltd.All rights reserved. 1. Introduction The Stewart platform is a six-degree-of-freedom mechanism obtained by gener- alization of the aircraft simulator proposed by Stewart [1] in 1965. It is often referr to as a parallel manipulator because of its form, where two plates are connected b six in-parallel legs. Because of the reciprocal nature of its structure to that of a ser manipulator (see Waldron and Hunt [2]), the properties of Stewart platform are als quite reciprocal to that of serial mechanism employed for robots. It has high load Mechatronics 11 (2001) 793±809 * Corresponding author. Tel.: +91-512-597-095; fax: +91-512-597-995. E-mail addresses: tad@magnum.barc.ernet.in (T.A. Dwarakanath), dasgupta@iitk.ac.in (B. Dasgupta), tsmjaya@mecheng.iisc.ernet.in (T.S. Mruthyunjaya). 0957-4158/01/$ - see front matter Ó 2001 Elsevier Science Ltd. All rights reserved. PII: S 0 9 5 7 - 4 1 5 8 ( 0 0 ) 0 0 0 4 8 - 9