Nobutomo Matsunaga

Control of cutting torque in the drilling process using disturbance observer

In the drilling processes of machine tools an increase of the drilling speed is usually required, but it often leads to breakage of the drill due to the excessive torque. Thus it is necessary to measure and control cutting torque in real time. In this study a new sensorless control system is developed of cutting torque irrespective of drill wear and the material of target work-pieces. The authors (1994) proposed an estimation method for the cutting torque using a disturbance observer. This paper is concerned with a sensorless PID torque control system for the drilling process based on the estimated torque information. Experimental results demonstrate the effectiveness of the proposed method.

Optimal quantization interval design of dynamic quantizers which satisfy the communication rate constraints

This paper proposes the design method of the dynamic quantizer for the networked control systems. It is well known that the dynamic quantizers, which consist of filter and static quantizer, are effective for compressing the data with small quantization error of control. Many methods for designing the dynamic quantizers have been proposed from the perspective of filter design. When it is required to control with network communication, the data size of signal should be minified appropriately by quantizers because of the communication rate constraint. Since the quantization interval (distance between two quantizer outputs) of the quantizer makes an impact on the data rate, determination of quantization interval is important matter in the dynamic quantizers. However, the design method of quantization interval has not been proposed explicitly in the past researches of the dynamic quantizer design. In this paper, we propose the design method of the smaller quantization interval which satisfy the communication rate constraints. The design method is derived as an LMI problem based on the invariant set analysis. By the proposed method, the quantization interval guarantees that the signals are quantized appropriately within the given data size. The effectiveness is illustrated by numerical examples.

A New Model with Feedback Structure for Thermal Process and its Application to Decoupling Control

In thermal processes, thermal distribution on a heating plate is observed in both steady and transient states. Recently, uniform temperature control is extremely required in many industrial application fields for quality im-provement. Conventional decoupling control based on a black-box model is cheap for the control of thermal plant with strong interference. In this paper a novel model with feedback structure that expresses the thermal interaction explicitly and its application to decupling control are proposed. Firstly, the cell model is derived based on physical conservation law, and is applied to experimental plant, and the thermal distribution is simulated using the FEM method. The design of the decoupling controller using the proposed model is shown and the effectiveness is evaluated.

Fuzzy control using knowledge acquired from PD control

The authors propose a design method for a fuzzy controller by using knowledge acquired from proportional derivative (PD) control. Two types of fuzzy controller are presented. One is identical and the other is approximately equivalent to the PD controller. The mathematical model of the fuzzy controller is derived and the properties of the output of the fuzzy controller are clarified. A design method of the fuzzy controller which satisfies two specifications, the dynamical properties of the rising and settling regions of the response, is presented using the mathematical model.<<ETX>>

Learning control of an inverted pendulum using neural networks

Several problems in control using neural networks are pointed out, and a method for using some knowledge about the properties of the controlled object is indicated. As an example, a hierarchical control system of an inverted pendulum using a neural network is proposed. The controller consists of a pendulum part driven by the neural network and a cart part generating the virtual signal. As a result, the neurocontroller can be constructed easily and can be learned rapidly. The effectiveness of the control system has been confirmed by simulation and experimental results.<<ETX>>

Impedance control of CPM device with flex-/extension and pro-/supination for upper limbs

Continuous Passive Motion (CPM) is a surgical treatment or physiotherapy after surgery or trauma. Most of the CPM devices used for treatment of the elbow joint have one degree of freedom in flex-/extension. For this reason, the patients are limited in pro-/supination of the forearm with flex-/extension of the elbow joint according to the arm movement of the CPM device. In this paper, a novel impedance control scheme of pro-/supination is proposed for CPM device with flex-/extension and pro-/supination. Impedance control is designed for the reference trajectory measured from a normal subject, and the parameters for impedance control are designed in order to suppress the excessive force at the limitation of range of motion. The effectiveness of the proposed scheme is evaluated by experiments.

Integrated Design of Filter and Interval in Dynamic Quantizer under Communication Rate Constraint

Abstract This paper proposes an design method of feedback type dynamic quantizers under communication rate constraints. It is well known that feedback type dynamic quantizers such as Delta/Sigma modulator are effective for encoding high resolution data into lower resolution data. The dynamic quantizers include a set of a filter and a static quantizer. When it is required to control under the communication rate constraint, the data size of signal should be minimized appropriately by quantization. In the field of control engineering, many dynamic quantizer design methods have been proposed in terms of the filter design. However, design of the static quantizer part has not been considered though it is also important to satisfy constraint of the data size. The quantization interval of the static quantizer part is strongly related to the data size. In this paper, an integrated design method of the filter and the quantization interval is proposed under the communication rate constraint. The proposed method is derived based on our previous work which design the interval to guarantee the communication rate constraint. By our proposed quantizer, the quantizer output satisfy the communication rate constraint and it gives good performance. The effectiveness of proposed quantizer is shown by numerical examples.

On effective movement in CPM for shoulder joint

Continuous passive motion (CPM) is an orthopedic treatment or physiotherapy method that promotes recovery of impaired joints, and is tried to apply for treatment of the shoulder joint disorders. The shoulder joint has a complex structure, where the inner/outer rotation torque of the shoulder joint varies due to ad-/abduction angle. Wrong ad-/abduction angle causes the excessive inner/outer rotation torque of the shoulder joint, and aggravates joint disorders. So, it is required to adjust suitably the ad-/abduction angle to suppress the inner/outer rotation torque. In this paper, the ad-/abduction motion that suppresses the inner/outer rotation torque is clarified. The variation of the inner/outer rotation torque due to ad-/abduction angle is analyzed in experiments with fixed ad-/abduction. From the experiments, we clarify the ad-/abduction motion suppressing the inner/outer rotation torque. To realize the clarified ad-/abduction motion, we developed the CPM device that has two d.o.f with the inner/outer rotation and the ad-/abduction. Finally, the experiment with the CPM device is performed in order to confirm that this motion is effective to suppress the excessive inner/outer rotation torque of the shoulder joint.

Bilateral Control for Steer-by-Wire Vehicles

Steer-by-wire system, in which the conventional mechanical linkages between the steering wheel and the front wheel are removed, is suited to active steering control, improving vehicle stability, dynamics and maneuverability, as well as to autonomous steering control to assist the driver. Conventional controller for SBW system is designed by general feedback control method. However, driver can not exactly feel reaction torque generated from tire. And SBW system has another important problem about fault tolerant function. In this paper, we propose the bilateral control method based on the disturbance observer to improve steering feeling and the design of the sensor fault detection for SBW vehicles using sliding mode observer

Control scheme of two d.o.f. CPM device to suppress the extension of ligament of the elbow

Abstract Continuous passive motion (CPM) is an orthopedic treatment or a physiotherapy and has been applied after surgery. After surgery for the injured ulna collateral ligament (UCL) which is a major clinical case in the elbow joint, the reaction force at the hand of the patient increases and may be excessively large due to an increase of the joint stiffness. For this, it will be effective to reduce the excessive reaction force by controlling pro-/supination of forearm. The UCL in the elbow joint is extended due to pro-/supination of forearm, but the excessive extension may aggravate the injury of the UCL. Thus, it is required to suppress both the excessive extension of the UCL and the reaction force. In this paper, a control scheme of CPM device that can suppress both the excessive extension of the UCL and the reaction force is proposed, and its effectiveness is confirmed from the experimental results.