Bambang Supriyo
Assoc. Prof. Dr. Bambang Supriyo
Politeknik Negeri Semarang, Indonesia


Bambang Supriyo is currently a Senior Lecturer in the Department of Electrical Engineering, Politeknik Negeri Semarang, Indonesia. He graduated from Politeknik Universitas Diponegoro (UNDIP), Semarang, Indonesia, in 1985, received the BSEE (Bachelor Science of Electrical Engineering) from University of Kentucky, Lexington, Kentucky, USA, in 1989, received the MEngSc  (Master Engineering Science) degree from University of New South Wales, Sydney, Australia, in 2000, and received the Ph.D from Universiti Teknologi Malaysia, Johor Bahru, Malaysia, in 2012.

In 1989 he joined as a lecturer at the Department of Electrical Engineering, Politeknik Universitas Diponegoro (Later starting from 1997, it has changed to Politeknik Negeri Semarang).From 2004 to 2012, he was a Reserach Assistance at the Automotive Laboratory, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, Johor Bahru Malaysia. From 2012-2013, he was a Visiting Researcher at the Automotive Laboratory, Faculty of Mechanical Engineering,  Universiti Teknologi Malaysia, Johor Bahru Malaysia. From 2013-2015, he was a Visiting Lecturer at the Department of Automotive Engineering,  Faculty of Mechanical Engineering,  Universiti Teknologi Malaysia, Johor Bahru Malaysia. Starting from 2015 until now he has rejoined the Department of Electrical Engineering, Politeknik Negeri Semarang, as a Senior Lecurer and the Head of the Control System Laboratory.

His current interests are in the fields of Continuously Variable Transmission (CVT) control system for automotive applications, microcontroller and computer based control system and mechatronics. He has published about 35 scopus-indexed journal and conference papers in the above research fields. His current scopus h-index is 5.


Continuously Variable Transmission (CVT) is a kind of transmission based on two pulleys and belt configuration. The two pulleys consist of driving (input) pulley and driven (output), while the belt connecting both pulleys to transfer power from the input to output.  CVT has a wide range of continuous transmission ratios between its minimum and maximum transmission ratios, hence allowing smooth transmision ratio changes without any torque interruption. In Indonesia a motorcycle employs a rubber belt CVT is called Matic. This motorcycle is equipped with centrifugal based shifting and clutching actuators.The centrifugal actions highly depend on motorcycle engine speed. The sufficiently high engine speed of about 2400 rpm starts to actuate both the shifting and clutching actuators. Higher engine speed reduces the transmission ratio, hence increasing the motorcycle speed. For speed lower than 2400 rpm, both shifting and cluthing actuators go off.  When driving down to a long and steep hill road, it is likely for the driver to slow down the motorcycle to its lowest speed as possible. This condition makes both shifting and clutching actuators fail to work, hence disconnecting the rear wheel from the engine. As a result the motorcycle fails to perform engine braking. The only way to slow down the motorcycle is by applying manual braking. Braking for long periods of time causes the brake pads to overheat. This condition may results in brake failures and fatal accident. To overcome the shortcomings of the centrifugal-based CVT, an electro-mechanical (EM) CVT is proposed. The transmission ratio shifting mechanism of the EMCVT consists of a DC motor, gear train set, cam mechanism, and movable driving sheave. The shaft of the DC motor is connected to the input shaft of the gear train set, while its output gear attached to the movable cam mechanism to rotate the cam. The fixed cam mechanism is attached to the CVT casing. The cam mechanism is mainly used to convert the cam’s rotations into an axial movement that axially shift the movable driving sheave along its shaft to change the transmission ratio accordingly. It means that changing transmission rasio can be performed by controlling the position of the DC motor rotation, so it does not depend on the engine speed anymore. An electronic system is developed to control the transmission ratio of the EMCVT. The electronic system consists of speed sensors for input and output pulley shafts, rotary position sensor for the DC motor actuator, the DC motor driver, and a programmable microcontroller. By programming the microcontroller, it is possible to control the rotation position of the DC motor actuator in such a way that the desired transmision ratio can be fullfiled adequately within its minimum and maximum ratio. In addition, it is also possible to select desired transmission manually (tiptronic mode) or even automatically (automatic mode) based on its best operating point for optimal energy consumption. The application of this EMCVT is more suitable for electric motorcycle to gain its overal torque needed while climbing the uphill road.