Kojiro musculoskeletal system mimics the human body

Kojiro mimics the human body and can handle more complex movements.

Kojiro is a humanoid which is built by the University of Tokyo’s JSK Robotics Laboratory.

Kojiro  musculoskeletal humanoid robot has a detailed musculoskeletal system built to mimic the human body.

via Engadget

To develop control algorithms for Kojiro, the JSK team is using an iterative learning process. This kind of system has lots of nonlinearities and is hard to model precisely.

The main drawback of using a musculoskeletal system is that controlling the robot’s body is difficult. For balance, the robot uses three gyros and a three-axis accelerometer on its head. To keep track of its posture and limb positions, they embedded joint angle sensors on spherical joints and six-axis force sensors on the ankles. To make the robot safer, the researchers built its body using mostly light and flexible materials. The results are transmitted to a computer and displayed on a control screen developed by Takanishi. A driver circuit board automatically adjusts the current fed to the motors based on temperature measurements.

Each motor unit has a rotary encoder, tension sensor, and current and temperature sensing circuit. Its brushless motors are quite small but can deliver a substantial 40 watts of output power. These tendon-muscle structures — Kojiro has about 100 of them — work together to give the robot some 60 degrees of freedom, or much more than could be achieved with motorized rotary joints. However in Kojiro, the motors are lightweight and used to pull cables attached to specific locations on the body, simulating how our muscles and tendons contract and relax. Traditional robots have limbs and torsos powered by DC motors at the joints. In one scientific paper, they wrote: ‘Currently normal humanoid robots are not suitable for working in our daily environment. The team, led by Professor Nakanishi, said this newly developed spine would allow them to manufacture lighter and more flexible robots in the future to serve in the home. Kojiro is an advanced musculoskeletal humanoid robot under development at the University of Tokyo’s JSK Robotics Laboratory, has a detailed musculoskeletal system built to mimic the human body, sporting artificial bones, muscles and tendons to create a robot that is theoretically more light and agile than your regular bot, and which moves in a more natural fashion, and bends and twists via his artificial spine.

More details at Spectrum IEEE org